[0001] This invention relates to a method for setting and visually indicating the image
density of image forming apparatus, such as electrophotographic copying machines and
facsimile terminal equipment, according to the density of an original.
[0002] It has been known to provide an image density setting device in an electrophotographic
copying machine or the like to enable an operator to set a desired image density in
accordance with the density of the original. It is a current trend that the image
density of such an image density setting device is changed not in an analogue fashion
but in a digital fashion or steps. Such detail setting is, for example, disclosed
in JP-A-11364/1982.
[0003] JP-A-11364/1982 discloses an exposure setting device, that is, an image density setting
device, comprising means for changing the exposure amount to a desired amount in steps
and then setting the desired amount and means for visually indicating the amount in
steps in accordance with the set content of the setting means.
[0004] However, in such an image density setting device, in which the image density is set
and indicated in the digital way or in steps, it is difficult to indicate a more finely
adjusted image density on account of the fact that the difference between one indicating
step and the next indicating step is large. The drawback may be overcome by increasing
the number of image density indicating steps. However, such improvement requires an
increased number of indicators, such as light emitting diodes (LED), consequently
raising the cost. Therefore, it will be apparent that this improvement is not the
best way.
[0005] The present invention has the object of providing a method for setting and indicating
image density which makes it possible to change the image density finely and indicate
a changed image density without using a large number of indicators.
[0006] The invention is set out in the claims.
[0007] Embodiments of the invention are described below by way of example with reference
to the drawings.
[0008] In the drawings:-
Fig. 1 is a plan view of an operational panel in which a method of the present invention
is performed;
Figs. 2, 3, 4, 5 and 6 are views illustrating methods of the present invention respectively;
Fig. 7 is a block diagram of a control circuit by which the method is performed;
Fig. 8 is a flowchart in accordance with which the method of Figs. 2 and 3 is carried
out; and
Fig. 9 is a flowchart in accordance with which the method of Figs. 4 and 5 is carried
out.
[0009] Fig. 1 shows an operation panel 100 of apparatus such as copying machine in which
a method of the present invention is performed. Indicated at 101 is a copy number
indicator, indicated at 102 is a ten-key array for setting the number of copy, indicated
at 103 is a start button, indicated at 104 and 105 are setting keys for changing the
exposure in steps in accordance with the density of original. The numeral 104 indicates
an UP key and the numeral 105 a DOWN key. Indicated at L is an indicating device including
a row of a plurality of indicators(seven indicators in the case of the present embodiment)
which are lighted to visually indicate an image density changed by the setting keys
104, 105. A light emitting diode (LED) is used for the indicator. The indicating device
L visually indicates the image density in the following way. The first indicator 1
positioned at the left end is lighted when the image density is reduced so as to correspond
to the lightest original. The seventh indicator 7 positioned at the right end is lighted
when the image density is increased so as to correspond to the darkest original. The
second through sixth indicators are lighted corresponding to
an image density changed in steps by the setting keys 104, 105. The fourth indicator
4 positioned at the intermediate portion indicates a standard image density.
[0010] Fig. 2 shows the first method embodying the present invention which sets and indicates
the image density in the case of increasing and decreasing from an image density to
the next image density. In the Fig. 2(a) in which the fourth indicator 4 is lighted,
in other word, the lighted indicator 4 is colored black, an image density is set,
for example, an image density of "4". Now, if pushing the UP key 104 one time, the
fourth indicator 4 is switched on and off as shown in Fig. 2(b). Radial lines around
the indicator 4 represents the indicator being held in the ON-and-OFF state. The ON-and-OFF
state indicates that the image density is set at "4.5". Next, if pushing the UP key
104 one more time, as shown in Fig. 2 (c), the fourth indicator is changed from the
ON-and-OFF state to the OFF state and the fifth indicator 5 next to the fourth indicator
4 is lighted. That is, an image density of "5" is set. In the first embodiment, as
mentioned above, an intermediate image density is set and indicated by switching on
and off the indicator. When decreasing the image density, steps reverse to the above-mentioned
steps are executed by the use of the DOWN key 105.
[0011] Fig. 3 shows the second embodiment in which the fifth indicator 5 is switched on
and off to indicate an image density of "4.5" as shown in Fig. 3(b).
[0012] It will be noted that the following method is adoptable as a variation of the first
and second embodiments: the image density is indicated by the method of Fig. 2 when
increasing the image density and by the method of Fig. 3 when decreasing the image
density, or in reverse to the above. More specifically, an image density of "4.5"
is indicated by the ON-and-OFF state of the fourth indicator 4 in the case of increasing
the image density and by the ON-and-OFF state of the fifth indicator 5 in the case
of decreasing the density.
[0013] It will be seen that the ON-and-OFF state of the indicator gives two interpretations
in the above embodiments. More specifically, the ON-and-OFF state of the fourth indicator
4 can be interpreted in two way, that is, an image density of "3.5" and an image density
of "4.5". Also, the ON-and-OFF state of the fifth indicator 5 can be interpreted as
an image density of "4.5" or an image density of "5.5". Therefore, it is desirable
to define which of two intermediate image densities the ON-and-OFF state of the indicator
indicates according to copying machines and notify the definition. In the first embodiment
of Fig. 2, the ON-and-OFF state of the indicator indicates an image density added
"0.5" to an image density of the indicator coming on and off. The second embodiment
of Fig. 3 indicates an image density reduced "0.5" from an image desity of the indicator
coming on and off. Also, in the case that the indicating method is changed in accordance
with the increasing and decreasing of the image density, it will be seen that if the
indicator is kept in the ON-and-OFF state even after an operator finishes copying,
the next operator can not determine which image density the ON-and-OFF state indicates.
To eliminate such trouble, it is desirable that after an operator finishes copying,
the image density is made to automatically reset at a predetermined standard density
in a given period of time by means of a timer or the like.
[0014] Fig. 4 shows the third method embodying the present invention which sets and indicates
the image density. In this embodiment, in increasing and decreasing the image density,
the intermediate state is provided in which the indicators next to each other are
lighted at the same time. An intermediate image density is set in the state that the
two indicators are lighted at the same time. More specifically, a state of Fig. 4(a)
in which the fourth indicator 4 is lighted is changed to a state of Fig. 4(b) in which
the fourth and fifth indicators 4 and 5 are lighted at the same
time by pushing the UP key 104 one time, and then changed to a state of Fig. 4(c)
in which the fifth indicator 5 is lighted by pushing the UP key 104 one more time.
In the intermediate state in which the fourth and fifth indicators are lighted at
the same time, an image density of "4.5" is set. It will be apparent that instead
of the simultaneous lighting of two indicators, it is appropriate to switch on and
off two indicators next to each other at the same time.
[0015] Also, it will be apparent that it is appropriate to render the ON-and-OFF state of
the seventh indicator 7 correspond to an image density of "7.5" or an image density
of "8" if necessary.
[0016] Fig. 6 shows a variation of the embodiments of Figs 4 and 5. In the variation, before
the simultaneous lighting state as shown in Fig. 6(c) or the simultaneous ON-and-OFF
state (not shown), the state of Fig. 6(b) is provided in which one indicator, for
example the indicator 4, is lighted and the next indicator 5 is switched on and off
and an image density of "4.25" is set. Also, after the simultaneous lighting state
as shown in Fig. 6(c) or the simultaneous ON-and-OFF state (not shown), the state
of Fig. 6(d) is provided in which the indicator 4 is switched on and off and the indicator
5 is lighted and an image density of "4.75" is set. Accordingly, it is possible to
change the image density by "0.25".
[0017] The cumbersomeness of pushing the UP key or DOWN key many times to change the image
density is eliminated by redering the image density change in steps by a predetermined
period of time with the keys being held in the pushed state.
[0018] Also, it is appropriate that the body of a copying machine is provided with a selection
switch for changing from a mode in which intermediate states are provided as mentioned
above to a mode in which no intermediate states are provided as conventional method
and vice versa.
[0019] Fig. 7 shows the construction of a control circuit for carrying out the method of
the present invention. Signals from the UP key 104 and the DOWN key 105 are sent to
a microcomputer 106 constituting a control unit for controlling the whole of a copying
machine. A command of the microcomputer 106 is sent to an exposure voltage control
circuit 107 in which then render an exposure lamp 108 work at a set image density.
The indicating device L is operated by the microcomputer 106 as mentioned above.
[0020] Fig. 8 is a flowchart of procedure in accordance with which the microcomputer 106
executes the image density indication of Figs. 2 and 3. Fig. 9 is a flowchart of procedure
in accordance with which the microcomputer 106 executes the image density indication
of Figs. 4 and 5. With Fig. 8, at step S1, an image density setting routine is started.
At step S2, the fourth indicator 4 is lightee which corresponds to an image density
of "4". At step S3, it is checked whether there is an input signal from the UP key
104 or the DOWN key 105. If YES, the procedure proceeds to step S4 at which it is
checked whether the indicating device is in the light state. If YES, in other words,
when the indicating device is in the state of Fig. 2(a) or Fig. 3(a), the procedure
proceeds to step S5 at which an indicator (LED) corresponding to an input signal of
the keys is switched on and off. Cosequently, when the key input is done by the UP
key 104, the indicating device comes to the state of Fig. 2(b) or Fig. 3(b). Next,
at step S6, it is checked whether there is an input signal from the keys. If YES,
the procedure returns to step S4. If NO, the procedure returns to the main routine.
If the answer of step S4 is NO, in other words, when the indicating device is in such
switching on and off state as shown in Fig. 2(b) or Fig. 3(b), the procedure proceeds
to step S8 at which an indicator (LED) corresponding to the key input signal is lighted.
Consequently, when the key input is done by the UP key 104, the indicating device
comes to the state of Fig. 2(c) or Fig. 3(c). When the key is
pushed without a break, the answer of step S6 is kept at YES. Accordingly, the procedure
alternately proceeds to step S5 and step S8, so that indicators are put into the lighting
state and ON-and-OFF state alternately and successively. When the key is pushed with
a break, the answer of step S3 is kept at YES, the procedure proceeds to step S4 and
then alternately to step S5 and step S8, so that the indicating device operates in
the same way as mentioned above.
[0021] The flowchart of Fig. 9 is the same as that of Fig. 8 except step S4ʹ, S5ʹ, S8ʹ.
At step S4ʹ, it is checked whether only one indicator is lighted. If YES, in other
words, if the indication device is in the state of Fig. 4(a) or Fig. 5(a), the procedure
proceeds to step S5ʹ at which two indicators (LED) corresponding to the key input
signal is lighted or switched on and off. Consequently, when the key input is done
up by the UP key 104, the indicating device comes to the state of Fig. 4(b) or Fig.
5(b). Next, if the answer of step S4ʹ is NO, the procedure proceeds to step S8ʹ at
which one indicator (LED) corresponding to the key input signal is lighted. Consequently,
the indicating device comes to the state of Fig. 4(c) or in Fig 5(c). The lighting
position of the indicating device is changed according to the input signal of the
image density setting keys in such a way as mentioned above.
[0022] As described above, the present invention, which sets and indicates a set image density
in steps by lighting a particular indicator of a plurality of indicators and further
sets and indicates an intermediate image density in steps by switching on and off
an indicator, or lighting or switching on and off two indicators next to each other
at the same time, makes it possible to set and indicate the image density by an increased
number of stages without increasing the number of indicator, consequently assuring
setting and indicating of an image density more suitable to the density of original
at a reduced cost.
1. A method for setting a desired image density in an image forming apparatus wherein
the image density is increased or decreased in steps under control of a density setting
key and the image density selected by use of the setting key is indicated by selective
lighting of a plurality of indicators characterized in that one or more intermediate
density setting levels intermediate between two setting levels which are respectively
indicated by lighting individually two adjacent indicators are indicated in one of
the following ways:-
(a) changing a first one of said adjacent indicators from a lit state to an ON-and-OFF
(flashing) state when increasing or decreasing the image density by one step to an
intermediate level, and changing the first indicator from the ON-and-OFF (flashing)
state to an OFF state and putting the second of said adjacent indicators in the lit
state when changing the image density one further step, whereby the intermediate density
level is set and indicated when the first indicator is in said ON-and-OFF (flashing)
state;
(b) changing a first one of said adjacent indicators from a lit state to an OFF state
and putting the second of said two adjacent indicators in an ON-and-OFF (flashing)
state when increasing or decreasing the image density by one step to an intermediate
level, and changing the said second indicator from the ON-and-OFF (flashing) state
to the lit state when changing the image density level one further step, whereby the
intermediate image density level is set and indicated when the second indicator is
in the ON-and-OFF (flashing) state;
(c) when increasing and decreasing the image density by one step to an intermediate
level holding a first one of said adjacent indicators in a lit state or changing said
first indicator from the lit state to an ON-and-OFF (flashing) state and changing
the second of said adjacent indicators from the OFF state to bring it to the
same state as the first indicator, and when changing the image density one further
step changing the first indicator from the lit state or ON-and-OFF (flashing) state
to the OFF state holding the second indicator in the lit state or changing it from
the ON-and-OFF (flashing) state to the lit state, whereby the intermediate image density
level is set and indicated when the first and second indicators are in the simultaneously
lit state or the simultaneously ON-and-OFF states;
(d) changing the states of the two adjacent indicators to indicate a series of three
said intermediate setting levels as follows:
2. A method for setting a desired image density in an image forming apparatus wherein
the image density is increased or decreased in steps under control of a density setting
key and the image density selected by use of the setting key is indicated by selective
lighting of a plurality of indicators characterized in that one or more intermediate
density setting levels intermediate between two setting levels which are respectively
indicated by lighting individually two adjacent indicators are indicated by putting
the two adjacent indicators into respectively one or more of the following states
or combinations of states:
i) one indicator ON-and-OFF (flashing), the other OFF
ii) both indicators ON
iii) both indicators ON-and-OFF (flashing).
3. Image forming apparatus having image density setting means, image density setting
control means for the operator and a plurality of image density setting indicators,
characterized by control means for said indicators arranged to set the indicators
in accordance with the method of claim 1 or claim 2.