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(11) | EP 0 631 879 A2 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Printing apparatus having a printing paper detection device |
| (57) This invention is to obtain a high precision printing apparatus with smaller number
of parts, which can detect the existence of the recording paper. For this purpose,
this invention provides a high precision and less-expensive printing apparatus which
fewer parts than in prior art, in no relation to the passing route of recording paper
by way of assembly of the sensor which detects the existence of the recording paper
directly onto the thermal head holder or the line thermal head board. |
BACKGROUND OF THE INVENTION
[0001] This invention relates to a printing apparatus which has a detecting device which detects the existence of a printing paper.
DESCRIPTION OF THE PRIOR ART
[0002] It is known as prior art such a small type printer, as shown in Fig. 5 and Fig. 6, that a multiple number of inner passing routes through which the recording paper passes is set in order to print recording data on the recording paper by means for instance, of thermal printer. In the inner passing route of the recording paper, the detecting device which detects the existence of the recording paper is set. And when the route is changed, the detecting device is also changed in prior art in accordance with the change in the route.
[0003] For example, as shown in Fig. 5, a photo-sensor 8 is soldered on the board 9 which is fixed on the sensor holder 10 and such sensor holder 10 is fixed on the frame 1. On the board 9, a multiple number of circuit pattern 11 is fixed, for example, with solder, and a connector 12 is fixed at the top of said circuit pattern 11. When the existence of a recording paper should be detected after the change in its passing route in accordance with the change in the passing route of the recording paper, there exist problems that such a sensor needs to be refixed in the other position than in the prior position which is shown in Fig. 5, as shown in Fig. 6, or that the assembly of such a sensor has to be performed in the other process, and etc.
[0004] As explained above, in the printing apparatus in prior art, there exist problems not only that such parts as a board for the fixing of sensor and its holder, etc. are required in order to change in the passing route of the printing paper, but also additional assembling process of, soldering of circuit pattern on the board, fixing of the connector, etc. is required. Therefore, those invites the increase in cost.
[0005] And since the sensor is fixed at the other position than that of the heat resistor set on line thermal head, the data that is to be printed in between the both above disappears, and therefore a datum memory for such data above is required, of which capacity corresponds to the data size which is to be disappeared as above, in order to avoid such situation as above.
[0006] The object of this invention is to solve such problems in prior art above and to obtain high precision and less-expensive printing apparatus with fewer parts.
SUMMARY OF THE INVENTION
[0007] The object of the invention is to obtain a high precision printing apparatus with smaller number of parts, which can detect the existence of the recording paper.
[0008] In order to attain such targets, this invention is to provide a high precision and less-expensive printing apparatus with fewer parts than in prior art, in no relation to the passing route of recording paper by way of assembly of the sensor which detects the existence of the recording paper directly onto the thermal head holder or the line thermal head board.
[0009] By way that the sensor which detects the existence of the recording paper is assembled directly on to the thermal head, board, sensor holder, etc. are cut, and assembling time of such parts above can be shortened. And by way that the photosensor is to be fixed around the neighborhood of line thermal head, the volume of data which may disappear originating from the interval between the sensor and the line thermal head above can be decreased, and as the result, the memory size prepared against such missing of data as above can be minimized.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] Fig. 2 shows the side view drawing of the cross section of the printing apparatus in this invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0016] The embodiment of this invention is explained bellow according to the `drawing. Fig. 1 shows a cross section drawing of a printing apparatus in this invention. In it, 1 is the frame, 2 is the platen, which is held by the frame with stem and rotates around the stem.
[0017] 3 is the line thermal head which has a plural number of head resisters, and at the rear side of such line thermal head is fixed the heat radiation board 4. The heat resister is set in the way that it has contact with and press the platen 2, on the surface of the line thermal head which has contact with the platen 2, there exists a multiple number of heat resisters 6 which is layouted in the strait line.
[0018] 7 is recording paper, which is carried out towards the thermal head 3 along one of both paper guide 1A and 1B which is formed inside of the printing apparatus as shown in Fig. 1 and Fig. 2.
[0019] The recording paper 7 is carried towards the arrow signal A through either paper guide due to the rotation of the platen by way of a driver which is not shown in these figures.
[0020] 8 is a photosensor which in the combination of both emitting element and euphoric element. The light or the ultraviolet light from the emitting element reflects itself against the recording paper and then is detected by the euphoric element. At this movement, the light or the ultra violet light from the emitting element is not reflected if the recording paper is not placed at an appropriate predetermined position. Therefore, such light from the emitting element is not detected by the euphoric element.
[0021] Movement as shown in Fig. 8, the photosensor 8 is fixed at the sealed portion 3a set at the neighborhood of the heat resistors 6 of the line thermal head 3, and is connected electrically to the input/output line of the thermal head 3. Like this above, an printing apparatus can be constituted, which can detect the existence of the printing paper without the sensor set together with sensor board or its holder those which is separately arranged, by way that the photosensor is directly set around the neighborhood of the heating resistors of the line thermal printer.
[0022] And, through the layout that photosensor 8 is set around the neighborhood of the heat resistor 8, the volume of disappearing data originated from the separated distance between the sensor and the heating resistor, which is a problem in prior art to be solved, is decreased great deal, and then, the capacity of the memory for the prevention of the disappearance of data as described above can be decreased.
[0023] Fig. 4 shows another embodiment in this invention. The constitution of this embodiment is as the photosensor 8 is set on the heat radiation board 4 which is fixed at the rear side of the line thermal head 3.
[0024] That is to say, even in this embodiment also, the photosensor 8 arranged on the heat radiation board 4 is around the neighborhood of the line thermal head 3, as a result of it, a printer apparatus can detect the existence of the printing paper without separately prepared the sensor board or holder with the sensor. And therefore even in this embodiment, too, the data which may disappear because of the above and the memory size against thereof, can be decreased, since the photosensor can be arranged even in this embodiment around the neighborhood of the heat resistors.
[0025] As explained as above, according to this invention the photosensor for the detection of the existence of the recording paper is set directly on the line thermal head or on the heat radiation board fixed at the neighborhood of the line thermal head, many kinds of the effects can be realized, such as the detection of the existence of the recording paper with smaller number of parts, the decrease in the volume of missing data originated from the distance between the sensor and the heat resistor, and therefore the decrease in the memory size for the prevention of missing data due to the above, etc.
1. In a printing apparatus for the purpose of recording input data on the recording paper,
comprising: a thermal head which has multiple number of heating resistors, a platen
which is fitted on a frame in freely rotating condition, and which keeps said recording
paper in between itself and said thermal head, and a multiple number of passing route
with which said recording paper is carried onto the printing position;
characterized in that a photosensor which is set on an appropriate position on said thermal head in order to detect the existence of the recording paper.
characterized in that a photosensor which is set on an appropriate position on said thermal head in order to detect the existence of the recording paper.
2. In a printing apparatus in the claim 1 above comprising; a thermal head which has
a multiple number of heating resistors in order to print the input data on a recording
paper, a pattern which is fitted on a frame in freely rotating condition, and which
keeps said recording paper in between itself and said thermal head, and a multiple
number of passing route with which said recording paper is carried onto the printing
position;
characterized in that said thermal head is held by a holder which slightly moves toward platen around the stem which is fixed on said frame, and that a photo-sensor which detects the existence of said recording paper is fixed on said holder at the neighborhood of said thermal head.
characterized in that said thermal head is held by a holder which slightly moves toward platen around the stem which is fixed on said frame, and that a photo-sensor which detects the existence of said recording paper is fixed on said holder at the neighborhood of said thermal head.