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(11) | EP 1 424 286 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Apparatus and method for checking number of aluminium packaging sheets packed into box |
| (57) An inspecting apparatus 1 is configured to check the number of aluminum packaging
sheets 32 containing medicines. The inspecting apparatus 1 is provided with a transmitting
head 5A that generates an alternating magnetic flux, and a receiving head 5B that
detects an alternating magnetic flux transmitted through a packaging box 31 into which
the sheets 32 are packed, to generate a reception signal. A reception signal is generated
on the basis of the alternating magnetic flux received by the receiving head 5B. On
the basis of a change in reception signal, it is determined whether or not there are
a predetermined number of aluminum packaging sheets 32 in the packaging box 31. |
[0001] The present invention relates to an apparatus and method for checking the number of aluminum packaging sheets packed into a box.
[0002] In the pharmaceutical industry, medicines such as capsules or tablets are packed using a packing method called "blister packing" which uses PTP sheets (blister packs) that are aluminum packaging sheets each comprising an aluminum sheet as a back cover. When a predetermined amount of blister packs are packed into a packaging box, this operation may fail and in such a case, packaging boxes with an insufficient number of sheets must be removed before shipment. In particular, for medicines, very accurate inspections are required to prevent the amount of contents of a packaging box from differing from the regular amount of contents of a packaging box. These inspections are much more important than those of other articles.
[0003] For medicines, it is desirable to seal an accurate number of sheets into a packaging box. For some types of medicines, an excessive or insufficient number of sheets or both must be avoided. In the conventional technique disclosed in Japanese Patent Laid-Open No. 8-29240, to achieve this object, the weight of the packaging box is measured to check whether or not a specified amount of PTP sheets are packed.
[0004] However, with such a method, since some PTP sheets are very light, an apparatus with a very accurate scale is required to inspect these sheets. Such an apparatus is very expensive. Further, an apparatus using a method of inspecting the weight may have its measured values markedly affected by humidity or the like or may not provide a desired accuracy owing to impact effected when the box is placed on the scale (that is, impact or the like resulting from a bound occurring when the box is shifted from a conveyor to the scale). As a result, even though an accurate number of sheets are packed into the box, this box may be considered to be defective. Conversely, even though the number of sheets is excessive or insufficient, the box may be mistakenly determined to be acceptable.
[0005] The present invention is completed on the basis of these circumstances. It is an object of the present invention to provide an apparatus and method which enables the accurate detection of number of aluminum packaging sheets packed into a box using an inexpensive apparatus configuration, in a pharmaceutical production line in which a predetermined amount of aluminum packaging sheets containing medicines such as tablets are packed into a packaging box.
[0006] To accomplish the above object, an aspect of the present in claim 1 provides an apparatus which operates when aluminum packaging sheets packed into a packaging box are carried using a carrying device, to check the number of aluminum packaging sheets inside the carried packaging box, the apparatus being characterized by comprising:
a transmitting head that generates an alternating magnetic flux;
a receiving head arranged opposite the transmitting head so that sheet surfaces of the aluminum packaging sheets in the packaging box are sandwiched between the transmitting head and the receiving head, the receiving head detecting an alternating magnetic flux emitted by the transmitting head and transmitted through the packaging box to generate a reception signal; and
number-of-sheets determining means for determining whether or not there are a predetermined number of aluminum packaging sheets in the packaging box on the basis of a change in reception signal generated by the receiving head.
[0007] An aspect of the present invention in claim 2 provides the aspect set forth in claim 1, characterized by further comprising inter-head distance setting means configured to be able to change an inter-head distance between the transmitting head and the receiving head, the inter-head distance setting means setting the inter-head distance.
[0008] An aspect of the present invention in claim 3 provides the aspect. set forth in claim 2, characterized by further comprising:
input means to which the type of the packaging box is inputted; and
distance information storing means for storing information on the inter-head distance between the transmitting head and the receiving head according to the type of the packaging box, and
in that the inter-head distance setting means comprises distance control means for providing such control as reads, from the distance information storing means, the inter-head distance information corresponding to the type of the packaging box inputted through the input means and sets the inter-head distance on the basis of the inter-head distance information.
[0009] An aspect of the present invention in claim 4 provides the apparatus checking the number of aluminum packaging sheets in a box set forth in any of claims 1 to 3, characterized by further comprising:
a photoelectric detector that detects passage of the packaging box near the transmitting head and the receiving head to generate a detection signal; and
empty box determining means for determining whether or not the packaging box is empty on the basis of the detection signal generated by the photoelectric detector and the reception signal generated by the receiving head.
[0010] The expression "near the transmitting head and the receiving head" as used herein may be that position near the transmitting head and receiving head which can be photoelectrically detected. For example, with a transmission photoelectric detector, this photoelectric detector may be arranged near the transmitting and receiving heads so that a direction in which the transmitting head and the receiving head (hereinafter collectively referred to as a "transmitting and receiving head") are opposite each other is parallel or substantially parallel with a direction in which a floodlighting element and a light receiving element constituting the photoelectric detector are opposite each other. Alternatively, the photoelectric detector may be arranged near the transmitting and receiving head so that the direction in which the transmitting head and the receiving head are opposite each other crosses (for example, is orthogonal to) the direction in which the floodlighting element and the light receiving element are opposite each other. Alternatively, the photosensitive detector may be arranged closer to one of the transmitting head and the receiving head. For example, a reflection photoelectric detector may be arranged closer to one of the transmitting head and the receiving head.
[0011] An aspect of the present invention in claim 5 provides the apparatus checking the number of aluminum packaging sheets in a box set forth in any of claims 1 to 4, characterized by further comprising:
threshold setting means for operating on the basis of a reception signal generated by the receiving head when a packaging box into which a predetermined number of aluminum packaging sheets are packed is arranged between the transmitting head and the receiving head, to set a threshold used to determine the predetermined number of sheets.
[0012] An aspect of the present invention in claim 6 provides the apparatus checking the number of aluminum packaging sheets in a box set forth in claim 5, characterized in that:
the threshold has a first threshold and a second threshold, and
if a reception signal value is defined to correspond to a reception signal generated by the receiving head when a packing box into which the predetermined number of aluminum packaging sheets are packed is arranged between the transmitting head and the receiving head, the threshold setting means sets the first and second thresholds so that the reception signal value is present between the first threshold and the second threshold.
[0013] An aspect of the present invention in claim 7 provides the apparatus checking the number of aluminum packaging sheets in a box set forth in claim 6, characterized in that:
if a first reception signal value is defined to correspond to a reception signal generated by the receiving head when a packing box into which the predetermined number of aluminum packaging sheets are packed is arranged between the transmitting head and the receiving head, and
if a second reception signal value is defined to correspond to a reception signal generated by the receiving head when a packing box into which aluminum packaging sheets the number of which is different from the predetermined number are packed is arranged between the transmitting head and the receiving head, then
the threshold setting means sets the first threshold between the first reception signal value and the second reception signal value and sets the second threshold in such a way that the first reception signal is present between the first threshold and the first reception signal value so that the first reception signal value is a median between the first and second thresholds.
[0014] An aspect of the present invention in claim 8 provides the apparatus checking the number of aluminum packaging sheets in a box set forth in any of claims 1 to 7, characterized in that:
if a reference condition is defined to be such that the packaging box is not located between the transmitting head and the receiving head, the number-of-sheets determining means determines the number of aluminum packaging sheets in the packaging box on the basis of a phase difference between a reference reception signal generated on the basis of an alternating magnetic flux in the reference condition and a detection reception signal generated on the basis of an alternating magnetic flux transmitted through the packaging box when the packaging box passes between the transmitting head and the receiving head.
[0015] An aspect of the present invention in claim 9 provides the apparatus checking the number of aluminum packaging sheets in a box set forth in any of claims 1 to 7, characterized in that:
if a reference condition is defined to be such that the packaging box is not located between the transmitting head and the receiving head, the number-of-sheets determining means determines the number of aluminum packaging sheets in the packaging box on the basis of the magnitude of attenuation in amplitude level between a reference reception signal generated on the basis of an alternating magnetic flux in the reference condition and a detection reception signal generated on the basis of an alternating magnetic flux transmitted through the packaging box when the packaging box passes between the transmitting head and the receiving head.
[0016] An aspect of the present invention in claim 10 provides the apparatus checking the number of aluminum packaging sheets in a box set forth in any of claims 1 to 9, characterized by further comprising frequency setting means configured to change the alternating magnetic flux generated by the transmitting head so that the magnetic flux has one of a plurality of different frequencies, the frequency setting means setting a frequency for the alternating magnetic flux, and
in that the frequency setting means comprises:
frequency switchingmeans for switching the alternating magnetic flux among the plurality of different frequencies, reception signal storing means for storing, according to the new frequency, a reception signal generated by the receiving head when the packaging box is arranged between the transmitting head and the receiving head, and
calculating means for determining the magnitude of change in at least one of the phase difference and the magnitude of attenuation in amplitude level for each of the plurality of different frequencies, on the basis of the reception signal stored in the reception signal storing means, and
in that a frequency corresponding to an optimum one of determined magnitudes of changes is set as an inspection frequency.
[0017] The magnitude of change in claims 10 and 21 and the magnitude of change in claims 11 and 22 may be the magnitude of change in phase or amplitude level compared to the reference condition (this will be hereinafter referred to as the "absolute magnitude of change") or that obtainedby comparing two arbitrarypackaging boxes in different conditions (that is, two packaging boxes with different number of sheets), i.e. the magnitude of change in phase or amplitude level between one packaging box and the other (this will be hereinafter referred to as the "relative magnitude of change"). Then, if the absolute magnitude of change is employed, the reception signal storing means stores,accordingto eachfrequencysetbythefrequency switching means, a reception signal generated by the receiving head when the packaging box is arranged between the transmitting head and the receiving head. On the basis of the reception signal stored in the reception signal storing means, the calculating means determines the absolute magnitude of change in at least one of the phase difference and the magnitude of attenuation in amplitude level. Then, a frequency corresponding to the optimum (for example, maximum) one of the determined absolute magnitudes of changes can be set as an inspection frequency.
[0018] Further, for the relative magnitude of change, two arbitrary packaging boxes in different conditions (that is, two packaging boxes with different numbers of sheets) are positioned between the transmitting head and the receiving head. Then, the reception signal storing means stores both reception signals obtained by inspecting the packaging boxes so that the reception signals correspond to the respective frequencies set by the frequency switching means. On the basis of the reception signals stored in the reception signal storing means, the calculating means determines the absolute magnitude of change in at least one of the phase difference and the magnitude of attenuation in amplitude level, for each of the plurality of different frequencies. Then, a frequency corresponding to the optimum (for example, maximum) one of the determined relative magnitudes of changes can be set as an inspection frequency. Instead of employing the "maximum magnitude of change" as the "optimum magnitude of change", another optimum value may be employed, and a frequency corresponding to this optimum value may be set as an inspection frequency.
[0019] An aspect of the present invention in claim 11 provides the apparatus checking the number of aluminum packaging sheets in a box set forth in claim 10, characterized by comprising:
input means to which the type of the packaging box is inputted; and
detecting method storing means for storing one of a detecting method of detecting the phase difference as the magnitude of change and a detecting method of detecting the magnitude of attenuation in amplitude level as the magnitude of change which method provides the optimum magnitude of change according to the type of the packaging box, as well as a frequency obtained when the magnitude of change is optimum, and
in that, of the two detecting methods and the plurality of different frequencies, the detecting method stored in the detecting method storing means and providing the optimum magnitude of change as well as the corresponding frequency are set according to the type of the packaging box inputted through the input means.
[0020] In claims 11 and 22, for example, the "maximum magnitude of change" can be employed as the "optimum magnitude of change". In this case, in claims 11 and 22, the detecting method storing means stores one of the detecting method of detecting the phase difference as the magnitude of change and the detecting method of detecting the magnitude of attenuation in amplitude level as the magnitude of change which method provides the optimum magnitude of change according to the type of the packaging box, as well as the frequency obtained when the magnitude of change is optimum. Then, of the two detecting methods and the plurality of different frequencies, the detectingmethod stored in the detecting method storing means and providing the optimum magnitude of change as well as the corresponding frequency are set according to the type of the packaging box inputted through the input means. Although the "maximum magnitude of change" has been employed as the "optimum magnitude of change", another optimum value may be employed.
[0021] In the apparatus checking the number of aluminum packaging sheets packed into a box set forth in any of claims 1 to 11, the requirements described below may be added. In the apparatus checking the number of aluminum packaging sheets packed into a box set forth in any of claims 1 to 11, an alternating magnetic flux generated by the transmitting head may be switched to have one of a plurality of frequencies within a predetermined frequency band. The term "predetermined frequency band" as used herein refers to a frequency range between 1 KHz and 15 KHz both inclusive (more specifically, between 2 KHz and 13 KHz both inclusive). The alternating magnetic flux can be divided into a plurality of (for example, 10) frequencies within this frequency band.
[0022] According to the arrangement in claim 1, the number of sheets packed into a box can be checked accurately and stably compared to the scale-based inspecting method, while reducing the costs of the inspecting apparatus. Consequently, for medicines, damage can be prevented which results from the difference between the amount of contents and the prescribed amount.
[0023] Specifically, the expression "arrangement in which the receiving head is arranged opposite the transmitting head so that sheet surfaces of the aluminum packaging sheets in the packaging box are sandwiched between the transmitting head and the receiving head" means that the arrangementmaybe, forexample, such that sheet surfaces (specifically, for example, planar or substantially planar sheet surfaces) cross the direction in which the transmitting head and the receiving head are opposite each other, at an inspection position where the number of sheets is checked. Furthermore, the arrangement may be such that this opposite direction is orthogonal to the sheet surfaces. With this arrangement, the alternating magnetic flux is transmitted through the sheets so as to cross the sheet surfaces. This arrangement is preferable because the alternating magnetic flux varies depending on the number of sheets.
[0024] Further, more specifically, the transmitting head and the receiving head may be arranged opposite each other in the direction in which a plurality of aluminum packaging sheets are packed into a packaging box so as to be stacked together. Then, the transmitting head may generate an alternating magnetic flux directed to the receiving head so that the magnetic flux is transmitted through all stacked aluminum packaging sheets. Then, during inspections, the alternating magnetic flux transmitted through all sheets in their stacked direction is inputted to the receiving head. This arrangement is preferable because the reception signal varies depending on the number of sheets stacked.
[0025] According to the arrangement in claim 2, even if the type of the packaging box is changed, the inter-head distance can be correspondingly changed. This prevents the number of sheets from being improperly checked owing to a change in distance between the packaging box and the head. It is thus possible to set the optimum inter-head distance for various packaging boxes.
[0026] According to the arrangement in claim 3, control is provided so that the relative distance stored in the storing means is set according to the type of the packaging box inputted through the input means. Even when the type of the packaging box is changed, an operator need not set the inter-head distance. Control is thus provided so that the desired inter-head distance can be promptly and easily set according to the type of the packaging box.
[0027] According to the arrangement in claim 4, it can be ensured that a packaging box into which aluminum packaging sheets have not been successfully packed is determined to be defective. In particular, even if it is impossible or difficult to achieve detection using a magnetic sensor, this arrangement enables accurate determinations.
[0028] According to the arrangement in claim 5, on the basis of the thresholds, boxes with sheets the number of which is particularly larger than the prescribed value, boxes with sheets the number of which is particularly smaller than the prescribed value, or both can be removed from the production line or the like. It is thus ensured that boxes with an excessively large or small number of sheets can be detected.
[0029] According to the arrangement in claim 6, it is possible to detect boxes with sheets the number of which is larger or smaller than the predetermined (i.e. prescribed) value. Thus, the number of sheets can be reliably checked to provide boxes with the correct number of products.
[0030] According to the arrangement in claim 7, it is possible to detect boxes with sheets the number of which is larger or smaller than the predetermined (i.e. prescribed) value. Thus, the number of sheets can be reliably checked to provide boxes with the correct number of products. Further, the first reception signal value obtained in the case of a predetermined (that is, prescribed) number of sheets is set to be the median between the first and second thresholds. Consequently, boxes with an excessively large or small number of sheets can be detected in a well-balanced manner.
[0031] According to the arrangement in claim 8, inspections can always be accomplished with a high S/N ratio by finding the optimum frequency according to the type of the packaging box and setting this frequency. This reduces the adverse effects of noise during determinations, thus making the inspections further reliable.
[0032] According to the arrangement in claim 9, inspections can be reliably accomplished even if the magnitude of attenuation in amplitude level is small. This effect is particularly marked on sheets composed of aluminum material.
[0033] According to the arrangement in claim 10, inspections can be reliably accomplished even if a material or configuration is used which involves only a small phase difference.
[0034] According to the arrangement in claim 11, the optimum detecting method and frequency can be set according to the type of medicines (that is, the type of the packaging box or aluminum packaging sheets). Consequently, inspections can always be accomplished accurately with a high S/N ratio. It is also possible to deal with various types of medicines accurately.
[0035] According to the aspect of the invention in claim 12, effects similar to those of claim 1 are obtained. Further, According to the aspects of the invention in claims 13 to 22, effects similar to those of claims 2 to 11, respectively, are obtained.
Fig. 1 is a conceptual drawing conceptually showing an apparatus checking the number of aluminum packaging sheets packed into a box according to a first embodiment of the present invention;
Fig. 2 is an enlarged view showing the neighborhood of a magnetic sensor in Fig. 1;
Fig. 3 is a conceptual drawing conceptually showing an example of a packaging box into which aluminum packaging sheets are packed;
Fig. 4 is a flow chart showing an example of an inter-head distance setting process;
Fig. 5 is a diagram illustrating a threshold setting method;
Fig. 6 is a flow chart showing an example of a threshold setting process;
Fig. 7 is a flow chart showing an example of a number-of-sheets determining process;
Fig. 8 is a timing chart showing timings for various signals used for the number-of-sheets determining process;
Fig. 9 is a diagram illustrating a threshold setting method different from that shown in Fig. 5;
Fig. 10 is a flow chart showing an example of a frequency setting process;
Fig. 11 is a flow chart showing an example of a frequency setting method different from that shown in Fig. 10;
Fig. 12 is a table conceptually illustrating an organization of data used to determine a detecting method and a frequency according to the type of a packaging box; and
Fig. 13 is a table and a diagram conceptually illustrating an organization of stored reception signals and integral values for the reception signals.
<First Embodiment>
[0037] A first embodiment of the present invention will be described with reference to Figs. 1 and 2.
[0038] As shown in Figs. 1 and 2, an inspecting apparatus 1 is configured to use a carrying device (not shown) to carry a packaging box 31 into which aluminum packaging sheets 32 (hereinafter simply referred to as "packaging sheets") containing medicines are packed. The inspecting apparatus 1 is also configured to inspect the number of aluminum packaging sheets 32 inside the carried packaging box 31. An inspecting section of the inspecting apparatus 1 is provided with a transmitting head 5A that generates an alternating magnetic flux, and a receiving head 5B arranged opposite the transmitting head 5A so that sheet surfaces 32A (see Fig. 3) of the aluminum packaging sheets 32 in the packaging box 31 are sandwiched between the transmitting head 5A and the receiving head 5B. The receiving head 5B detects an alternating magnetic flux emitted by the transmitting head 5A and transmitted through the packaging box 31, to generate a reception signal. While carrying means is carrying the packaging box 31, for example, the sides of the packaging box 31 are held during carriage to avoid interposing a holding section between the transmitting head 5A and the receiving head 5B, the holding section holding the packaging box.
[0039] A magnetic sensor 5 comprises the transmitting head 5A and the receiving head 5B. Specifically, the transmitting head 5A and the receiving head 5B are opposite each other in the direction in which the packaging sheets 32 are stacked together. An alternating magnetic flux is transmitted through all stacked packaging sheets 32 to the receiving head 5B. Then, with this arrangement, a reception signal is generated on the basis of the alternating magnetic flux received by the receiving head 5B. Subsequently, on the basis of a change in reception signal (in other words, a change in alternating magnetic flux) , it is determined whether or not there are a predetermined number of aluminum packaging sheets 32 in the packaging box 31. Detailed description will be given later of specific configuration and functions of number-of-sheets determining means for making this determination.
[0040] The plurality of aluminum packaging sheets 32 to be inspected are packed into the packaging box 31 so as to be stacked together as shown in Fig. 3(A), constituting a packed member 30. The packaging' box 31 is constructed as a substantially rectangular parallelopiped having square sides. The packaging box 31 is packed with a predetermined number of aluminum packaging sheets 32 into each of which tablets, powders, or the like are enclosed. Further, Fig. 3(B) shows the aluminum packaging sheets 32 arranged inside a pillow pack 34. The inspecting apparatus 1 according to the present embodiment can inspect the aluminum packaging sheets around which a packaging section (for example, metal or vinyl packaging) other than a packaging box is thus installed. Figs. 3 (C) and 3 (D) show other forms of aluminum packaging sheets 32. Fig. 3(C) shows that powders are packed, and Fig. 3(D) shows aluminum packaging sheets for tablets.
[0041] Referring back to Fig. 1, in the inspecting apparatus 1, amagnetic sensor controller 16 (hereinafter referred to as a "sensor controller 16" or simply a "controller 16") is connected to the transmitting head 5A and receiving head 5B. The sensor controller 16 is connected to a control device 10 so as to transmit and receive data to and from the device 10. It contains a CPU 16A and storing means 16B (for example, a ROM, a RAM, or a nonvolatile memory).
[0042] Further, the control device 10 comprises a CPU 10A, storing means 10B (a ROM, a RAM, a nonvolatile memory, or the like). In the present embodiment, the control device 10 is connected to the magnetic sensor controller 16 via a serial line Ls and a parallel line Lp. Furthermore, the control device 10 is connected to drive means 4, an I/O device 12, and a photoelectric sensor controller 14 (described later), and a host computer 20. The control device 10 is thus configured as a sensor system in which the above components are controlled in unison.
[0043] Further, the inspecting apparatus 1 is configured to be able to change the inter-head distance between the transmitting head 5A and the receiving head 5B. The inspecting apparatus 1 is thus provided with inter-head distance setting means for setting the inter-head distance. Specifically, it is provided with the drive means 4 (for example, the drive means configured as a servomechanism or the like comprising a drive motor) for driving the transmitting head 5A and the receiving head 5B so that these heads approach each other or separate from each other. The control means 10 transmits a drive signal to the drive means 4 to control displacement of a drive section of the drive means 4 to set the inter-head distance to a desired value.
[0044] Further, an input device 12 with a display (hereinafter simply referred to as an "input device 12") is provided as input means to which the type of a packaging box is inputted. Furthermore, inter-head distance information storing means is provided inside the control device 10 as storing means such as a ROM or a nonvolatile memory, to store information on the distance between the transmitting head 5A and the receiving head 5B according to the type of the packaging box. This inter-head distance information is stored in the storing means by being organized so as to allow the inter-head distance to be determined according to the type of the packaging box.
[0045] A specific process for setting the inter-head distance is shown, for example, by the flow in Fig. 4. This flow chart will be described. First, if the type of a packaging box is inputted using the input device 12 as shown in step S100, the inter-head distance information corresponding to the inputted type of the packaging box is read from the inter-head distance information storingmeans (step S110). Then, a drive signal is transmitted to the drive means 4 so as to set the inter-head distance on the basis of the read inter-head distance information. Thus, the relative displacement of the transmitting head 5A and receiving head 5B is controlled (step S120). Accordingly, in the present embodiment, the drive means 4 and the control means 10 function as inter-head distance setting means and distance control means, respectively. The flow chart shown herein is only an example. Another method may be used provided that a process and an arrangement are used which enable the inter-head distance to be set on the basis of the type of the packaging box. Further, in the present arrangement, control is provided so that the inter-head distance is automatically set. However, an arrangement may be provided in which the inter-head distance information can be inputted as an analog or digital value. In this case, the operator provides manual settings.
[0046] Moreover, as shown in Figs. 1 and 2, a photoelectric detector 6 is provided near the receiving head 5B to detect the passage of the packaging box 31 to generate a detecting signal. On the basis of the detection signal generated by the photoelectric detector 6 and a reception signal generated by the receiving head 58, it is determined whether or not the packaging box is empty. The photoelectric detector 6 comprises a floodlighting element 6A and a light receiving element 6B. The photoelectric detector 6 is configured to output a signal of a level H when an object passes through the detector 6 to interrupt light and to output a signal of a level L when light is not interrupted, i.e. when no objects are present. The type of the photoelectric detector is not limited, and any photoelectric detector such as a transmission type or a reflection type may be used provided that an object can pass through it. Various sensors are applicable to the photoelectric detector, including a fiber sensor and other photoelectric sensors. The top of the timing chart in Fig. 8 illustrates a variation in reception signal from the photoelectric sensor 6. The reception signal has the level H if any object is detected and has the level L if no objects are detected. The specific contents of the timing chart will be described later.
[0047] Now, a threshold setting method will be described. If a reference condition is such that the packaging box 31 is not located between the transmitting head 5A and the receiving head 5B, then a reference reception signal corresponding to an alternating magnetic flux in the reference condition is defined as WO. Figs. 5(A) and 5(B) illustrate the relationship between the phase of the reference reception signal WO and the phase of a reception signal W9 indicative of the predetermined number of sheets and the phase of a reception signal W10 indicative of a number larger than the predetermined value by one. Fig. 5 (B) shows the wavelength of a voltage value resulting from induced electromotive force based on an alternating magnetic flux, showing a comparison of a wavelength indicative of the predetermined number (top) and a wavelength indicative of the number larger than the predetermined value by one (bottom). Further, Fig. 5 (A) shows corresponding important portions of the reception signals overlapping each other on a single coordinate system, illustrating the relationship between the phases.
[0048] In this case, the predetermined number (regular number) is 9. The signal W9 is generated by the receiving head 5B when the packaging box 31 into which 9 aluminum packing sheets 32 are packed is arranged between the transmitting head 5A and the receiving head 5B. Then, a first reception signal value is the phase difference T1 between the reference reception signal W0 and the reception signal W9 indicative of the predetermined number. On the other hand, if the number larger than the predetermined value by one (in this case, 10) is used as a number other than the predetermined value, the signal W10 is generated by the receiving head 5B when the packaging box 31 into which the aluminum packing sheets 32 the number of which is larger than the predetermined value by one are packed is arranged between the transmitting head 5A and the receiving head 5B. A second reception signal value is a phase difference (the phase difference T2 between the reference reception signal W0 and the reception signal W10 indicative of the number larger than the predetermined value by one).
[0049] Then, a first threshold TA is set between the first reception signal value and the second reception signal value, i.e. between the phase difference T1 and the phase difference T2. Further, a second threshold TB is set in such a way that the phase difference T1 is present between the first threshold TA and the second threshold TB so that the phase difference T1 as the first reception signal value corresponds to the median between the first threshold TA and the second threshold TB. In other words, the thresholds are set so that the median between the first threshold TA and the second threshold TB is the phase difference T1 corresponding to the predetermined number of sheets. Fig. 5 shows the first threshold as a line L (TA) and the second threshold as a line L(TB). It also conceptually illustrates that if the distance between the lines L(TA) and L(TB) is defined' as X, the phase difference T1 corresponding to the predetermined number is located at the median between these thresholds (a position X/2).
[0050] The thresholds may be set automatically on the basis of control or manually. Fig. 6 is a flow chart showing an example of a threshold setting process of providing such control as automatically sets the thresholds. A control program that executes the process shown in Fig. 6 can be provided in the storing means 10B in the control device 10, shown in Fig. 1. In this case, the CPU 10A and the storing means 10B (specifically, the process program shown in Fig. 6) function as threshold setting means.
[0051] In Fig. 6, first, the carrying means carries the packaging box 31 into which the predetermined number of aluminum packaging sheets 32 are packed. Then, this packaging box is inspected to generate a reception signal to obtain a phase difference T1 as a first reception signal value (step S210). Subsequently, the carrying means carries the packaging box 31 into which the aluminum packaging sheets 32 the number of which is not the predetermined value are packed (in this case, the packaging box 31 into which the aluminum packaging sheets 32 the number of which is larger than the predetermined value by one are packed). Then, this packaging box is inspected to generate a reception signal to obtain a phase difference T2 as a second reception signal value (step S220). Subsequently, an arithmetic process is executed to set the first threshold TA as the median between the phase differences T1 and T2 (step S230). Furthermore, the second threshold is determined so that the phase difference T1 is the median between the first threshold TA and the second threshold (step S240). The first and second thresholds are thus set and stored in the sensor-controller 16 or in the store means in the control device 10 as set values. These values are used as indices to determine the number of sheets in a number-of-sheets determining process, described later (see Fig. 7).
[0053] In the present embodiment, if the reference condition is such that no packaging boxes are located between the transmitting head 5A and the receiving head 5B, the number of aluminum packaging sheets 32 in the packaging box 31 is determined on the basis of the phase difference between the reference reception signal W0 (see Fig. 5), corresponding to an alternating magnetic flux in the reference condition, and a detection reception signal corresponding to an alternating magnetic flux obtained when the packaging box to be inspected passes between the transmitted head 5A and the receiving head 5B. Specifically, a flow such as the one shown in the flow chart in Fig. 7 can be executed. In the present embodiment, the store means 10B in the control means 10 may contain a program executing the number-of-sheets determining process according to this flow chart. In this case, the CPU 10A and the storing means 10B (specifically, the program stored in the storing means 10B) function as number-of-sheets determining means.
[0054] As shown in Fig. 7, in the number-of-sheets determining process, an inspected object is the packaging box 31 into which the aluminum packaging sheets 32 are packed. The phase difference is then determined on the basis of a detection reception signal generated by the receiving head 5A when the packaging box 31 is arranged between the transmitting head 5A and the receiving head 5B. If the phase difference obtained from the inspected object is determined to indicate a number equal to or larger than the regular value (that is, a number equal to or larger than the second threshold TB) , the procedure proceeds to YES in step S310. Then, in step S320, it is determined whether or not the number is equal to or larger than the regular value plus one. In this case, it is determined whether or not the number is equal to or larger than the first threshold TA. If the number is smaller than the first threshold TA, the procedure proceeds to NO. Then, in step S330, it is determined that the packaging box is normal. On the other hand, if it is determined in step S320 that the number is equal to or larger than the regular value plus one, the procedure proceeds to YES. Then, in step S340, it is determined that the inspected object has an excessive number of sheets. On the other hand, if it is determined in step S310 that the number is smaller than the regular value, it is determined in step S350 whether or not any aluminum packaging sheet 32 is present. In this case, if any sheet is detected, the procedure proceeds to YES. Then, in step S360, it is determined that the inspected object has an insufficient number of sheets. On the other hand, if no sheets are detected in step S350, the procedure proceeds to NO in this step. Then, in step S370, it is determined that the inspected object is empty. Thus, this process includes determining whether or not the packaging box is empty. In this case, the control device 10 (specifically, the CPU 10A and the storing means 10B) functions as empty box determining means. In this example, if it is determined that the number of sheets in the box is smaller than the regular value, it is further determined whether or not any sheet is detected. However, instead of making such a determination, it is allowable to determine all packaging boxes containing sheets the number of which is smaller than the regular value to be empty. Further, in this case, the first and second thresholds are provided to remove both packaging boxes with an excessive number of sheets and packaging boxes with an insufficient number of sheets. However, it is allowable to remove only one of these two types. In this case, only one threshold is required.
[0055] The timing chart in Fig. 8 shows timings and the like for signals inputted to the control device 10 or signals generated in the control device 10.
[0056] A packaging box detection signal is outputted to the control device 10 by the photoelectric detector 6. If the photoelectric detector 6 detects the packaging box 31, the packaging box detection signal changes to the level H. During the detection, the level H is maintained. Once the packaging box has passed through the photoelectric detector, which thus no longer detects it, the packaging box detection signal returns to the level H.
[0057] An at-least-regular-number determination signal is outputted to the control device 10 by the sensor controller 16. This signal has the level H if the detected number is equal to or larger than the regular value, specifically if the phase difference of a detection reception signal obtained from the passage of the inspected object is at least the second threshold. Further, at-least-regular-number-plus-one determination signal is also outputted to the control device 10 by the sensor controller 16. This signal has the level H if the detected number is equal to or larger than the regular value plus one (specifically if the phase difference of a detection reception signal is at least the first threshold). Accordingly, in this case, if the sensor controller 16 determines that the packaging box contains 9 or more aluminum packaging sheets, the at-least-regular-number determination signal changes to the level H. If the sensor controller 16 determines that the packaging box contains 10 or more aluminum packaging sheets, the at-least-regular-number-plus-one determination signal changes to the level H.
[0058] On the other hand, storage signals 1 and 2 are stored in the memory in the control device 10 and indicate that it has been detected that the at-least-regular-number determination signal and the at-least-regular-number-plus-one determination signal, respectively, have changed to the level H. Once the level H is detected, it remai ns stored until the corresponding signal is reset (for example, it remains stored as a flag). Further, a determination timing indicates that a determining process is started using a falling edge of the packaging box detection signal as a trigger. A reset timing indicates that the storage signals 1 and 2 are reset using a rising edge of the packaging box detection signal as a trigger.
[0059] As shown in this timing chart, in the present embodiment, the storing means 10B in the control device 10 stores information (in this case, the values for the storage signals 1 and 2) based on an output signal from the magnetic sensor (specifically, an output signal from the sensor controller 16) during the passage of the packaging box, i.e. during the output of the packaging box detection signal. Then, using, as a determination timing, the end of the packaging box detection signal, indicating that the packaging box 31 is detected, the number-of-sheets determining means determines the number of sheets 32 using the information (in this case, the values for the storage signals 1 and 2) based on an output signal from the magnetic sensor during the passage of the packaging box, the signal being stored in the storing means 10b. Then, after the number-of-sheets determining process has been started, the storage signals 1 and 2 are reset once the next packaging box detection signal is detected. In the present embodiment, in step S310 in Fig. 7, it is determined whether or not the storage signal 1 is at the level H. In step S320, it is determined whether or not the storage signal 2 is at the level H.
[0060] In this manner, the storing means retains the signal obtained during the output of the packaging box detection signal. Further, the number-of-sheets determining process is executed using the end of the packaging box detection signal as a determination timing. Then, accurate and safe inspections can be accomplished regardless of the size of the packaging box or a carrying speed. Furthermore, the empty-box detection can be reliably carried out at the end of the packaging box detection signal, i.e. when the packaging box 31 has completely passed between the heads.
<Second Embodiment>
[0061] Now, a second embodiment of the present invention will be described with reference to Fig. 9.
[0062] The second embodiment differs from the first embodiment in the magnitude of change used for detection and in the manner of setting the thresholds. However, it is similar to the first embodiment in the other arrangements of the apparatus and various other processes. In the second embodiment, if the reference condition is such that the packaging box 31 is not located between the transmitting head 5A and the receiving head 5B, it is determined whether the packaging box 31 contains a predetermined number of aluminum packaging sheets 32, on the basis of magnitude of attenuation in amplitude between a reference reception signal corresponding to an alternating magnetic flux in the reference condition and a detection reception signal corresponding to an alternating magnetic flux obtained when the packaging box 31 passes between the transmitting head 5A and the receiving head 5B.
[0063] Fig. 9 shows a method of setting the thresholds according the second embodiment. The reference reception signal is defined as W0. The reception signal indicative of the predetermined number of sheets (9) is defined as W9. The reception signal indicative of the predetermined number plus one (10) is defined as W10. In these diagrams, the reception signals are subjected to full-wave rectification, and theirpeaklevelsarematchedtooneanother. Fig. 9(A) partly enlarges the signals. As shown in Fig. 9, if the predetermined number (regular number) is 9, when the packaging box 31 into which 9 aluminum packing sheets 32 are packed is arranged between the transmitting head 5A and the receiving head 5B, a first reception signal value is obtained which indicates the magnitude of attenuation A1 in amplitude level of a signal generated in the receiving head 5A. On the other hand, if the number larger than the predetermined value by one (in this case, 10) is used as a number other than the predetermined value, when the packaging box 31 into which the aluminum packing sheets 32 the number of which is larger than the predetermined value by one are packed is arranged between the transmitting head 5A and the receiving head 5B, a second reception signal value is obtained which indicates the magnitude of attenuation A2 in amplitude level of a signal generated in the receiving head 5A. Then, as in the case with_ the first embodiment, a first threshold Am is set between the first reception signal value and the second reception signal value, i.e. between the magnitude of attenuation A1 and the magnitude of attenuation A2. Further, a second threshold An is set in such a way that the magnitude of attenuation A1 is present between the first threshold Am and the second threshold An so that the magnitude of attenuation A1, a first reception signal value corresponds to the median between the first threshold Am and the second threshold An. The thresholds are set so that the magnitude of attenuation A1 is the median between the first threshold Am and the second threshold An. Fig. 9 shows the first threshold Am as a line L(Am) and the second threshold An as a line L (An). It also conceptually illustrates that if the distance between the lines L (Am) and L (An) is defined as Y, the magnitude of attenuation A1 corresponding to the predetermined number is located at a distance Y/2 from each threshold. Then, the number of sheets can be determined on the basis of magnitude of attenuation by thus setting the thresholds and executing a number-of-sheets determining process similar to that in the first embodiment.
<Third Embodiment>
[0064] In a third embodiment, an example is shown in which an alternating magnetic flux generated by the transmitting head 5A, shown in Fig. 1, can be changed to have one of a plurality of different frequencies. This configuration includes frequency setting means for setting the, frequency of an alternating magnetic flux. Specifically, the control device 10 (more specifically, the CPU provided in the control device 10) functions as frequency settingmeans. The frequency setting means switch the alternating magnetic flux from one of the plurality of different frequencies to another. Then, a reception signal generated by the receiving head 5B when the packaging box 31 is arranged between the transmitting head 5A and the receiving head 5B is stored in reception signal storing means (in this case, the storing means 10B) according to the set frequency. Subsequently, on the basis of the reception signal stored in the reception signal storing means, the magnitude of change in at least one of the phase difference and the magnitude of attenuation in amplitude level is determined for each of plurality of different frequencies. Then, the optimum one (in this case, the maximum one) of the determined magnitudes of changes is set as an inspection frequency. Specifically, an alternating magnetic flux generated by the transmitting head 5A can be changed to have one of plurality of frequencies within a predetermined frequency band. The term "predetermined frequency band" refers to a frequency band, for example, between 1 KHz and 15 KHz both inclusive (more specifically, between 2 KHz and 13 KHz both inclusive). The alternating magnetic flux can be divided into a plurality of (for example, 10) frequencies within this frequency band.
[0065] Fig. 10 shows the specific flow of this frequency setting process. In this frequency setting process, the packaging box 31 (for example, the packaging box 31 into which a regular number of aluminum packaging sheets 32 are packed) is arranged between the transmitting head 5A and the receiving head 5B. Then, the frequency is switched among the plurality of values, and an alternating magnetic flux is generated with each frequency. A reception signal is then obtained for each of plurality of frequencies. Specifically, the process is executed as described below.
[0066] In Fig. 10, it is assumed that there are Nmax frequencies to be switched. First, N is set at 1, and a first one of plurality of frequencies is selected. Then, the packaging box 31 into which a predetermined number of packaging sheets 32 are packed is arranged between the transmitting head 5A and the receiving head 5B, to obtain a reception signal. Then, the reception signal obtained by the receiving head 5B is stored in the storing means 10B (step S420). To store the reception signal, it is possible to use the storing means 10B to store the peak value of amplitude level of the reception signal which value is used to calculate the magnitude of attenuation in amplitude level, an integral value for the reception signal which value is used to calculate a phase difference, or both peak value and integral value. In the present embodiment, both peak value and integral value are stored. Fig. 13 (A) shows an example of organization of data stored in the storing means 10B. In this figure, a reception signal (that is, both peak level and integral value) is stored for each frequency. Further, as an integral value being stored, an integral value compared to the reference signal can be stored. For example, for a certain section (in the example in Fig. 13(B), the range from 0 to 180° in the case in which the zero cross point of the reference signal is set as 0°) in which the reference signal indicates a positive value, an integral value for the reception signal can be determined and stored in the storing means. Fig. 13 (B) shows that the phases of the reference and reception signals deviate from each other by 90°. In this case, the control device 10 (specifically, the storing means 10B) functions as reception signal storing means. Further, the illustrate storage organization is only an example. Other methods may be used provided that a data organization is such that the magnitude of attenuation in amplitude level and the phase difference can be finally determined for each frequency.
[0067] Then, N is incremented to shift to the next frequency. In step S440, if N > Nmax, i.e. if reception signals have been obtained for all frequencies, then the procedure proceeds to YES in step S440. On the other hand, if it is determined that any frequency has not been processed in S440, the procedure returns to step S420 to repeat similar processing. Then, if the procedure proceeds to YES in step S440, the magnitude of change is calculated for each frequency on the basis of the reception signal for each frequency (step S450). In this case, the absolute magnitude of change for each frequency, i.e. the magnitude of change in phase difference and amplitude level compared to the reference condition for each frequency, is calculated on the basis of the reception signal (in this case, the peak level and integral value) stored as shown in Fig. 13(A). In this example, the control device 10 (specifically, step S450 and the CPU 10A) functions as calculating means. Then, the phase difference and the magnitude of attenuation in amplitude level are determined for the plurality of frequencies already set as described above. Then, those of the obtained values for the phase difference and the magnitude of attenuation in amplitude level which correspond to the optimum magnitude of change are selected (step S460). Specifically, to select the optimum values, in the case of the phase difference, the ratio of the detected phase difference α to a period T, i. e. α/T, is determined for each frequency. In the case of magnitude of attenuation, the ratio of the detected magnitude of attenuation β to an amplitude A0 in the reference condition, i.e. β/A0, is determined for each frequency. Then, a frequency and a detecting method with the largest values of α/T and β/A0 are selected and set for inspection.
[0068] Alternatively, an example of processing such as that shown in Fig. 11 may be used. Fig. 11 shows an example in which a reception signal obtained is processed before being stored in the storing means.
[0069] First, as in the case with Fig. 10, N is set at 1, and a first one of plurality of frequencies is selected. Then, the packed member 30 comprising the packaging box 31 into which a predetermined number of packaging sheets 32 are packed is arranged between the transmitting head 5A and the receiving head 5B, to obtain a reception signal. Then, the phase difference (the absolute phase difference compared to the reference condition) of this reception signal is obtained and stored in the storing means 10B (step S520). Then, the magnitude of attenuation (the absolute magnitude of attenuation compared to the reference condition) in amplitude level of this reception signal is calculated and similarly stored in the storing means 10B (step S530). Then, N is incremented to shift to the next frequency. In step S550, if N>Nmax, i.e. if the phase difference and the magnitude of attenuation have been obtained for all frequencies, the procedure proceeds to YES in step S550 to select a combination of the frequency and detecting method corresponding to the maximum magnitude of change. On the other hand, if it is determined that any frequency has not been processed in S550, the procedure returns to step S520 to repeat similar processing. The phase difference and the magnitude of attenuation in amplitude level are determined for the plurality of frequencies already set as described above. Then, as in the case with Fig. 10, the values of α/T and β/A0 are determined for each frequency. The frequency and detecting method corresponding to the maximum values of α/T and β/A0 are then selected and set for inspection.
[0070] Furthermore, in the examples shown in Figs. 10 and 11, the single packaging box 31 is arranged between the transmitting head 5A and the receiving head 5B. Then, the frequency is switched among the plurality of values to obtain a reception signal. The magnitude of change (the absolute magnitude of change) compared to the reference signal is then determined for each frequency. However, reception signals may be obtained from two packaging boxes with different numbers of sheets. Then, the magnitude of change (relative change) between the reception signals obtained from the two packaging boxes may be determined for each frequency. This processing can be executed as described below. That is, the packaging box 31 into which a regular number of aluminum packaging sheets 32 are packed is arranged between the transmitting head 5A and the receiving head 5B. Then, a reception signal is obtained for each frequency as shown in steps S410 to S440 in Fig. 10. Next, the packaging box 31 into which the aluminum packaging sheets 32 the number of which is not the regular value are packed is arranged between the transmitting head 5A and the receiving head 5B. Then, a reception signal is similarly obtained for each frequency as shown in steps S410 to S440 in Fig. 10. Then, the reception signals obtained from the two packaging boxes are compared with each other to calculate the phase difference and the magnitude of attenuation in amplitude level (that is, a difference in amplitude level) as relative magnitudes of changes. Subsequently, the frequency and detecting method corresponding to the maximum relative magnitudes of changes are set. Specifically, if the relative phase difference is defined as α' and the relative magnitude of attenuation in amplitude level is defined as β', then as in the case with Fig. 10, the values of α'/T and β'/A0 are determined for each frequency. The frequency and detecting method corresponding to the maximum values of α'/T and β'/A0 are then selected and set for inspection.
<Fourth Embodiment>
[0071] Alternatively, the apparatus maybe configured as describedbelow. The storing means stores one of a detecting method of detecting the phase difference as the magnitude of change and a detecting method of detecting the magnitude of attenuation in amplitude level as the magnitude of change which method provides the optimum magnitude of change according to the type of the packaging box, as well as a frequency obtained when the magnitude of change is optimum. Fig. 12 shows an example of this storage organization. The detecting method and frequency corresponding to the maximummagnitude of change are employed as the "detecting method and frequency corresponding to the optimum magnitude of change". That is, the detecting method and frequency corresponding to the maximum magnitude of change are set and stored in storing means 10B according to the type of the packaging box. Then, of the two detecting methods and the plurality of different frequencies, the detecting method and frequency corresponding to the maximum magnitude of change stored in storing means 10B are set according to the type of the packaging box inputted through the input means. In Fig. 12(A), the detecting methods are defined as A (the detecting method based on the phase difference) and B (the detecting method based on the magnitude of attenuation). The optimum detecting method for each type of packaging box is stored before hand so that the detecting methods correspond to the respective types of packaging boxes. Likewise, the optimum frequency for each type of packaging box is stored beforehand so that the frequencies correspond to the'respective types of packaging boxes. Consequently, setting the type of the packaging box allows the best detecting method and frequency to be instantaneously determined. This makes it possible to accomplish the best initialization easily and promptly. In the example shown in Fig. 12(B) , in addition to the detecting method and the frequency, the inter-head distance is stored so as to correspond to each type of packaging box. Accordingly, this data organization can be suitably used for the processing in Fig. 4. Specifying the type of the packaging box allows the detecting method, frequency, and inter-head distance to be determined. It is therefore possible to easily carry out the optimum inspection corresponding to the type of the packaging box.
<Other Embodiments>
[0072] The present invention is not limited to the embodiments described above and illustrated in the drawings. For example, embodiments such as those described below are included in the scope of the present invention. Furthermore, various changes may be made to these embodiments without deviating from the spirits of the present invention.
(1) In the above embodiments, the two thresholds, i. e. the upper and lower limits, are provided. However, only one threshold may be used to determine whether or not the number of sheets is excessive or insufficient.
(2) In the above embodiments, the frequency is automatically set on the basis of control. However, the frequency may be manually set.
(3) In the third and fourth embodiments, the magnitudes of changes obtained and correspondence data (see Fig. 12) are stored in the storing means 10B. However, these data may be stored in another section.
(4) The above embodiments are intended for the packaging box into which only aluminum packaging sheets or both aluminum packing sheets and pillow packs are packed. However, other articles such as manuals may be packed into the packaging box.
a transmitting head that generates an alternating magnetic flux;
a receiving head arranged opposite said transmitting head so that sheet surfaces of said aluminum packaging sheets in saidpackaging box are sandwiched between the transmitting head and the receiving head, the receiving head detecting an alternating magnetic flux emitted by said transmitting head and transmitted through said packaging box to generate a reception signal; and
number-of-sheets determining means for determining whether or not there are a predetermined number of aluminum packaging sheets in said packaging box on the basis of a change in reception signal generated by the receiving head.
input means to which the type of said packaging box is inputted; and
distance information storing means for storing information on the inter-head distance between said transmitting head and said receiving head according to the type of said packaging box, and
wherein said inter-head distance setting means comprises distance control means for providing such control as reads, from said distance information storing means, said inter-head distance information corresponding to the type of said packaging box inputted through said input means and sets said inter-head distance on the basis of the inter-head distance information.
a photoelectric detector that detects passage of said packaging box near said transmitting head and said receiving head to generate a detection signal; and
empty box determining means for determining whether or not said packaging box is empty on the basis of said detection signal generated by the photoelectric detector and said reception signal generated by said receiving head.
the apparatus further comprises threshold setting means for setting said threshold on the basis of a reception signal generated by said receiving head when a packaging box into which a predetermined number of aluminum packaging sheets are packed is arranged between said transmitting head and said receiving head.
if a reception signal value is defined to correspond to a reception signal generated by said receiving head when a packing box into which said predetermined number of aluminum packaging sheets are packed is arranged between said transmitting head and said receiving head, said threshold setting means sets the first and second thresholds so that the reception signal value is present between said first threshold and said second threshold.
if a second reception signal value is defined to correspond to a signal generated by said receiving head when a packing box into which aluminum packaging sheets said number of which is different from said predetermined number are packed is arranged between said transmitting head and said receiving head, then
said threshold setting means sets said first threshold between said first reception signal value and said second reception signal value and sets said second threshold in such a way that said first reception signal is present between said first threshold and said first reception signal value so that said first reception signal value is a median between said first and second thresholds.
wherein said frequency setting means comprises:
frequency switching means for switching the alternating magnetic flux among said plurality of different frequencies, reception signal storing means for storing, according to the switched frequency, a reception signal generated by said receiving head when said packaging box is arranged between said transmitting head and said receiving head, and
calculating means for determining the magnitude of change in at least one of the phase difference and the magnitude of attenuation in amplitude level for each of saidpluralityof different frequencies, on the basis of the reception signal stored in the reception signal storing means, and
wherein a frequency corresponding to an optimum one of determined magnitudes of changes is set as an inspection frequency.
input means to which the type of said packaging box is inputted; and
detecting method storing means for storing one of a detecting method of detecting said phase difference as the magnitude of change and a detecting method of detecting said magnitude of attenuation in amplitude level as said magnitude of change which method provides the optimum magnitude of change according to the type of said packaging box, as well as a frequency obtained when the magnitude of change is optimum, and
wherein, of said two detecting methods and said plurality of different frequencies, said detecting method stored in-said detecting method storing means and providing the optimum magnitude of change as well as the corresponding frequency are set according to the type of said packaging box inputted through said input means.
arranging a transmitting head and a receiving head in opposite so as to sandwich said packaging box between said transmitting head and said receiving head and to lie in a direction orthogonal to sheet surfaces of said aluminum packaging sheets;
using said receiving head to detect an alternating magnetic flux emitted by said transmitting head and transmitted through said packaging box to generate a reception signal; and
using number-of-sheets determining means to determine whether or not there are a predetermined number of aluminum packaging sheets in said packaging box on the basis of a change in reception signal generated by the receiving head.
using input means to which the type of said packaging box is inputted and distance information storing means for storing information on the inter-head distance between said transmitting head and said receiving head according to the type of said packaging box; and
providing such control as reads, from said distance information storing means, said inter-head distance information corresponding to the type of said packaging box inputted through said input means and sets said inter-head distance on the basis of the inter-head distance information.
using a photoelectric detector that detects passage of said packaging box near said transmitting head and said receiving head to generate a detection signal; and
determining whether or not said packaging box is empty on the basis of saiddetection signal generated by the photoelectric detector and said reception signal generated by said receiving head.
using said number-of-sheets determining means to determine the number of aluminum packaging sheets by comparing said reception signal generated by said receiving head with a predetermined threshold; and
using threshold setting means to set said threshold on the basis of a reception signal generated by said receiving head when a packaging box into which a predetermined number of aluminum packaging sheets arepackedis arrangedbetween said transmitting head and said receiving head.
wherein if a reception signal value is defined to correspond to a reception signal generated by said receiving head when a packing box into which said predetermined number of aluminum packaging sheets are packed is arranged between said transmitting head and said receiving head, said threshold settingmeans sets the first and second thresholds so that the reception signal value is present between said first threshold and said second threshold.
if a second reception signal value is defined to correspond to a signal generated by said receiving head when a packing box into which aluminum packaging sheets said number of which is different from said predetermined number are packed is arranged between said transmitting head and said receiving head, then
said threshold setting means sets said first threshold between said first reception signal value and said second reception signal value and sets said second threshold in such a way that said first reception signal is present between said first threshold and said first reception signal value so that said first reception signal value is a median between said first and second thresholds.
wherein said frequency setting means comprises:
frequency switchingmeans for switching the alternating magnetic flux among said plurality of different frequencies, reception signal storing means for storing, according to the switched each frequency, a reception signal generated by said receiving head when said packaging box is arranged between said transmitting head and said receiving head, and calculating means for determining the magnitude of change in at least one of the phase difference and the magnitude of attenuation in amplitude level for each of said plurality of different frequencies, on the basis of the reception signal stored in the reception signal storing means, and a frequency corresponding to an optimum one of determined magnitudes of changes is set as an inspection frequency.
using detecting method storing means to store one of a detecting method of detecting said phase difference as the magnitude of change and a detecting method of detecting said magnitude of attenuation in amplitude level as said magnitude of change which method provides the optimum magnitude of change according to the type of said packaging box, as well as a frequency obtained when the magnitude of change is optimum; and
if the type of said packaging box is inputted through predetermined input means, setting, of said two detecting methods and said plurality of different frequencies, said detecting method stored in said detecting method storing means and providing the optimum magnitude of change as well as the corresponding frequency according to the type of said packaging box inputted.