JP2969813B2 - Output density adjusting device in image forming apparatus - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for adjusting the density of an output image including characters in an image forming apparatus such as an electrophotographic copying machine, a printer, and a facsimile, and more particularly to an image forming operation for a predetermined time. The present invention relates to an output density adjusting apparatus which has improved the problem of an automatic reset type output density adjusting apparatus which automatically resets the output density when the apparatus is left unattended or when the power is turned on again.

[Conventional technology]

For example, in an electrophotographic copying machine having a relatively slow copying speed, copy density adjustment has conventionally been performed by a slide-type density setting button. Recently, a step-type copy density adjustment device has been used in order to give the device a luxurious feeling. Has come to be used. Some examples thereof will be described with reference to FIGS.

The density setting button and the density setting display device are arranged as shown in FIG. That is, the density setting button 20 and the density setting display device 23 are arranged in parallel, and the density setting button 20 includes an up button 21 for increasing the density and a down button
22, the density setting display device 23 includes, for example, five LEDs 24
The LEDs 24 correspond to five levels of set densities from the lowest density to the highest density, and are numbered from 1 to 5 in order from the lowest density. The density setting button 20 and the density setting display device 23 are connected to the CPU 10 as shown in the system configuration diagram of FIG.

An electrophotographic copying machine is, for example, as shown in FIG.
It comprises a photosensitive drum 1, a charging device 8, a developing device 9, a platen 2, an exposure lamp 4, mirrors 5, 7, a lens 6, and the like (other transfer devices, cleaning devices, static eliminators, and the like are omitted). The exposure lamp 4 is controlled for lighting and current by a lamp driving circuit 11, and the charging device 8 and the developing device 9 are controlled by a high-voltage power supply circuit 12 for charging timing, charging voltage, developing bias application timing, and developing bias voltage. . These lamp drive circuit 11 and high voltage current circuit 12
Centralized control by the CPU 10, the lighting timing of the exposure lamp 4, the applied current or voltage, the charging timing of the charger 8, the charging voltage, the developing bias application timing of the developing device 9, and the developing bias voltage are each controlled by a command from the CPU 10. Controlled. A ROM 16 and a RAM 17 are connected to the CPU 10, and the ROM 16 has an exposure lamp corresponding to a control parameter of each part of the copying machine and a density number set by a density setting button 20 and a density setting display device 23. An applied current or voltage, a charging voltage of a charger, a developing bias voltage of a developing device, and the like are stored.

FIGS. 6 and 7 show an example of a flow in the case of performing the copy density adjustment by the step method using the apparatus having the above-described configuration. In these examples, it is described that the density adjustment of the output image from the electrophotographic copying machine is performed by adjusting only the developing bias voltage of the developing unit 9; It is clear that the density can be adjusted by changing one or more parameters that determine image forming conditions, such as lamp applied current or voltage, charger charging voltage, and the like.

The density adjusting device of the flow of FIG. 6 is connected and copied unless the density once set by the density setting button 20 and the density setting display device 23 as shown in FIG. Is turned on and the apparatus is started up, the number 3 is automatically set in the density setting counter for setting the density of any number among the five density ranks. The density number 3 corresponds to a normal density, as is clear from the density setting display device 23 in FIG. The density setting counter is set in the CPU 10 or set in any area of the RAM 17. After 3 is set in the density setting counter, the LED 24 of that number on the density setting display 23
Lights up. Next, it is determined whether or not one of the buttons 21 and 22 of the density setting button 20 has been pressed to change the density. First, it is detected whether or not the down button 22 has been pressed. When the down button 22 has been pressed, the set number of the density setting counter is reduced by one. In this case, the set number of the counter becomes 2 and is not zero, so the LED 24 of that number is turned on. Then further down button 2
It is determined whether or not 2 is pressed. If the button is pressed further, the set number of the counter is reduced by 1 to 1, and the same cycle is repeated. When the down button 22 is pressed all the time and the counter set number becomes zero,
The set number of the counter is set to 1, and the 1 LED 24 is turned on. Even if the down button 22 is pressed any more, the set number of the counter and the lighting number of the LED 24 remain at 1 and do not change.
If no button is pressed or the up button 21 is pressed from the beginning, or if the pressing of the down button 22 is stopped halfway, the process proceeds to a detection step of whether or not the up button 21 is pressed. Is pressed, 1 is added to the set number of the density setting counter. Then, it is determined whether or not the set number of the counter is 6, and when the set number is 6, the number is set to 5,
If it is not 6, the LED 24 of the set number of the counter is turned on with the number as it is. Then, a similar cycle is repeated. When the up button 21 is pressed all the time and the set number of the counter becomes 6, the set number of the counter is set to 5 as described above, and the LED 24 of 5 is turned on, and thereafter, there is no change. If no button is pressed from the beginning, or if the pressing of the up button 21 or the down button 22 is stopped halfway, information on the developing bias voltage corresponding to the density of the number set in the counter at that time is stored in the ROM 16.
The CPU 10 controls the high-voltage power supply circuit 12 based on the information, and applies a developing bias voltage for giving the density of the number set in the counter to the developing unit 9. Then, after copying is performed, the process returns to the step of turning on the LED 24 of the set number of the density setting counter, and the same cycle is repeated thereafter. With such a configuration, copying is performed at the density set by the density setting button 20 and the density setting display device 23, and copying is performed at that density unless the density is changed in the middle. When the power is turned off and turned on again, the set density automatically becomes 3 (normal).

The density adjusting device of the flow shown in FIG. 7 is substantially the same as that shown in FIG. 6, except that the step of judging whether or not one minute has elapsed since the copy was performed after the copy. It is in the point provided. When a new copy is made within one minute after the copy, the density setting display is performed in the same flow as in FIG. 6, and the copy is performed at the density, but the copy is performed after the copy. If one minute elapses without the next copy being made, the process returns to the step of automatically setting 3 to the density setting counter. Therefore, even if the power is not turned on again, the set temperature automatically becomes 3 (normal) after one minute has passed after copying.

[Problems to be solved by the invention]

As described above, in the conventional step-type copy density adjusting apparatus employing the auto-reset method, when the apparatus is left unattended or the power is turned on without performing the image forming operation for a predetermined time, the output density becomes the predetermined density. Is automatically reset to the predetermined density (in FIG. 6 and FIG. 7, the density 3 (normal)) due to an environmental change such as temperature and humidity or a change in the sensitivity of the photoconductor. )), The copied image does not have the intended proper density, and there is a problem that image fogging, overprinting and the like often occur.

The present invention has been made in view of such a situation, and an object of the present invention is to provide an image forming apparatus such as an electrophotographic copying machine, a printer, and a facsimile with a density adjusting device for an output image including a character, for forming an image for a predetermined time. If the apparatus is left without operation or the power is turned on again, the output density is not automatically reset to a predetermined density value, but rather is reset to the latest density in the preset intermediate zone within the adjustable density range. An object of the present invention is to provide an output density adjusting device configured to return to a selected density value and adapted to appropriate image forming conditions changed by environmental changes such as temperature and humidity, sensitivity changes of a photoconductor, and the like.

[Means for solving the problem]

In order to achieve the above object, an output density adjusting device in an image forming apparatus according to the present invention is provided in an output density adjusting device in an image forming apparatus having an output density adjusting unit, wherein the density capable of selectively setting a predetermined adjustable density range is provided. When the power supply is turned on again or when the image forming operation is not performed for a predetermined time, the output density is not reset by the density setting means. It is characterized in that the information most recently selected by the density setting means within a further limited intermediate density range of the adjustable density range is used.

For this purpose, there is provided a first rewritable storage means and a second rewritable storage means which does not lose the stored contents even when the power supply of the apparatus is turned off.
A first writing unit that writes information stored in the storage unit into the first storage unit;
A second writing unit that writes information about the density set by the density setting unit after the information is written to the storage unit into the first storage unit, based on the information about the density stored in the first storage unit. A control unit for controlling the output density adjusting unit, and after controlling the output density adjusting unit, the information regarding the density stored in the first storage unit is stored in a further limited area in the density of the predetermined range. Determining means for determining whether or not the density is present, and writing the information on the density stored in the first storage means to the second storage means only when it is determined that the density is within the intermediate density range limited by the determination means; It is desirable to have a third writing means.

It is further desirable to provide a display unit for displaying information on the density stored in the first storage unit.

[Action]

The output density adjusting device according to the present invention has a density setting unit that can selectively set a density within a predetermined adjustable range. When the power is turned on again, or when the image forming operation is not performed for a predetermined time, the density setting unit sets the density. Unless the output density is reset by the setting means, as the information for controlling the output density adjusting means, the information most recently selected by the density setting means within the further limited intermediate density range within the adjustable density range. Since it is configured to use information, for example, even if it is set to an extreme density outside the intermediate density range limited at the time of the previous copy, no setting information remains,
Instead, the density setting information within the most recent limited intermediate density range before that is used, so it can adapt to environmental changes, sensitivity changes, etc. without setting the density again, except in exceptional cases. Thus, an image output having the optimum density can be obtained. Also,
If a normal density within the intermediate density range limited at the time of the previous copy is set, this density information will not change even in the next copy unless the density is set again.
It can be used as a density adapted to changes in sensitivity.

〔Example〕

The output density adjusting apparatus according to the present invention is configured such that a density value set by a user during image formation in a preset intermediate zone within an adjustable density range is determined by environmental changes such as temperature and humidity, or sensitivity of a photoconductor. In most cases, the values correspond to the appropriate image forming conditions changed by the change, and this value serves as a reference for the subsequent density adjustment. On the other hand, the density value set outside this intermediate zone is a special image. It is set for the formation, does not correspond to the appropriate image forming conditions changed due to environmental changes or the like, and is based on an empirical rule that it is not useful for setting the density thereafter. Based on such an empirical rule, when the output density adjusting device in the image forming apparatus is left without performing image forming operation for a predetermined time and the power is turned on again, a preset intermediate zone within the adjustable density range is set. It is configured to return to the most recently selected density value. Hereinafter, an embodiment of an output density adjusting apparatus according to the present invention will be described using an electrophotographic copying machine as an example.

FIG. 1 is a plan view of a density setting button 20 and a density setting display device 23 of the output density adjusting device according to the present invention. The density setting button 20 and the density setting display device 23 are arranged in parallel. The density setting button 20 is composed of an up button 21 for increasing the density and a down button 22.
It is composed of thirteen LEDs 24. Each LED 24 corresponds to a set density of 13 steps from the lowest density to the highest density, and is numbered from 1 to 13 in order from the lowest density. The density setting button 20 and the density setting display device 23 are connected to the CPU 10 as shown in the system configuration diagram of FIG.

As shown in FIG. 2, the electrophotographic copying machine has a photosensitive drum 1, a charging device 8, a developing device 9, a pretension 2, an exposure lamp 4, mirrors 5, 7, a lens 6, and the like, as shown in FIG. (The other transfer device, cleaning device, static eliminator, and the like are omitted from the drawing.) The exposure lamp 4 is controlled for lighting and current by a lamp driving circuit 11, and the charger 8 and the developing device 9 are connected to a high-voltage power supply. The charging timing,
The charging voltage, the developing bias application timing, and the developing bias voltage are controlled. The lamp drive circuit 11 and the high-voltage power supply circuit 12 are centrally controlled by the CPU 10, and include the lighting timing of the exposure lamp 4, the applied current or voltage, the charging timing of the charger 8, the charging voltage, and the developing bias application timing of the developing device 9. , The developing bias voltage is CP
Controlled by command from U10. CPU1 has ROM1
6, RAM 17, non-volatile memory (hereinafter referred to as NVM) 18
Is connected to the ROM 16, and a control parameter and the like of each part of the copying machine, and an exposure lamp applied current or voltage corresponding to a density number set by the density setting button 20 and the density setting display device 23, and a charger. A charging voltage, a developing unit developing bias voltage, and the like are stored.

FIG. 3 shows a flow of one embodiment of the density adjusting apparatus of the present invention when the copy density is adjusted by the step method using the apparatus having the above-described configuration. In this example, it is described that the density adjustment of the output image from the electrophotographic copying machine is performed by adjusting only the developing bias voltage of the developing unit 9; however, this is merely an example, and It is clear that the density can be adjusted by changing one or more parameters that determine the image forming conditions, such as the applied current or voltage and the charging voltage of the charger. Further, when a printer other than the electrophotographic system, for example, a thermal transfer system or an ink jet system is used as the image forming apparatus, the adjustment parameters of the respective image output density adjusting units are changed.

In the flow of FIG.
When the apparatus is turned on to start the apparatus, in step S, any one of the 13 density levels stored in the predetermined area of the NVM 18 is written to the density setting counter. In the predetermined area of the NVM 18, the number 7 representing the normal density is stored when the apparatus is shipped, but thereafter, it is sequentially rewritten to a number in the range of 5 to 9 in the steps described later. The density setting counter is set in the CPU 10 or set in any area of the RAM 17. Next, in a step, the LED 24 of the number in the density setting counter of the density setting display device 23 is turned on. And
Proceed to step and press the down button 22 of the density setting button 20
Is pressed to see if the density has been changed downward. When the down button 22 is pressed, in the step,
The number is subtracted by one from the number in the density setting counter and reset. Next, in step, it is determined whether or not the set number in the density setting counter is zero. If it is zero, the number in the density setting counter is reset to 1 in step, and the process returns to step. When it is determined in the step that the set number in the density setting counter is not zero, the process returns to the step while keeping the number in the counter as it is. While the down button 22 is being pressed, the above-described cycle is repeated, and the number of the lit LED 24 of the concentration setting display device 23 decreases, and finally the number 24 LED 1 is lit, and thereafter the down button is pressed. twenty two
Even if is kept pressed, the lighted LED 24 remains 1, and the set number in the density setting counter also corresponds to the number of the lighted LED 24. If the down button 22 is not pressed or the up button 21 is pressed from the beginning, or if the pressing of the down button 22 is stopped halfway, the process proceeds to step and it is detected whether or not the up button 21 is pressed. When this button 21 is pressed, the set number of the density setting counter is incremented by 1 in step and reset. Then, it is determined whether or not the set number of the counter has become 14 in the step. If the set number has become 14, the number is reset to 13 in the step. Then, return to the step and set the counter set number LED24
Lights up. Then a similar cycle is repeated,
LED2 lights up while the up button 21 is pressed all the time
The number of number 4 increases, and finally the LED 24 of number 13 lights up.
D24 remains 13, and the set number in the density setting counter also corresponds to the number of the LED 24 to be turned on. If no button is pressed from the beginning or if the pressing of the up button 21 or the down button 22 is stopped halfway, the process proceeds from step to step, and the developing bias voltage corresponding to the density of the number set in the counter at that time is related to the developing bias voltage. Information is RO
Called by the M16, the CPU 10 controls the high-voltage power supply circuit 12 based on the information, and applies a developing bias voltage for giving the density of the number set in the counter to the developing unit 9. Then, after copying is performed in the step, the process proceeds to the step, where the set numbers in the density setting counter are 5 to 9
In other words, it is determined whether or not the number is a density number in a slightly lighter or darker range near the normal density number 7. If the set number in the density setting counter is in the range of 5 to 9, in the next step, this number is rewritten instead of the density number already stored in the predetermined area of the NVM 18, and then the process returns to the step. Therefore, at the time of the next copy, the copy is performed at the same density in the range of 5 to 9 unless the density is reset by the buttons 21 and 22. If it is determined in step that the set number in the density setting counter is a number outside the range of 5 to 9,
The NVM 18 is not rewritten. In the step, it is determined whether or not one minute has elapsed since the copy was performed after the copy, and the process returns to the step after waiting for one minute after the copy, and the density setting counter most recently. Any number in the range of 5 to 9 is set therein, and a copy is performed based on the number. Thereafter, in a step, the number written in the NVM 18 is written in the density setting counter, and the next copy is performed using the buttons 21 and 22. Unless the density is set again, copying is performed at any density within the same range of 5 to 9.

With the above-described configuration, for example, the temperature increases and the density decreases. Therefore, the set density is changed to 9, a setting is made so that normal density copying can be performed, and a series of copying is performed. When the next copy is restarted even if one minute or more has elapsed without cutting or copying, when the next copy is restarted, the same number 9 is written from the NVM 18 to the density setting counter in the step, and the next copy is performed based on the set density. Since the copying is performed, a copy having a normal density can be similarly formed. On the other hand, if the set density is set to 2 by the down button 22 in order to copy an original having a very high density at the next copy, after the original is copied, the power is turned off or the copy is not performed. If one minute or more has elapsed, the set density 2 disappears, and at the time of the next copy, the density setting counter 9 is written from the NVM 18 to the density setting counter in the step before the copying of the dark density document. In the case where a copy of a document having a normal density is used, a copy with a normal density can be performed without changing the set density.

The above description has been made on the assumption that non-volatile memory, which does not lose its stored contents even when the power is turned off, is used separately from the RAM.However, the RAM is backed up by a battery or the like, and is stored even when the power of the apparatus is turned off. When a RAM whose contents do not disappear is used, the latest set density number in the range of 5 to 9 can be stored in a specific area of the RAM 17 instead of the NVM 18. In the predetermined area of the NVM 18, a number 7 representing a normal density is initially set when the apparatus is shipped.
Is stored, but this requirement is not always necessary. For example, a step of writing a predetermined number, for example, 7 into the NVM 18 may be provided before the step only when the power of the apparatus is first turned on. Further, the steps in the flow of FIG. 3 are omitted, and the set numbers in the density setting counter are 5 to 5 in the steps.
If it is determined that the number is outside the range of 9, the process may return to the step immediately. With this configuration, when the density is set to 1 to 4, and 10 to 13, the density is maintained unless the power is turned off. In the case where the next copy is to be performed before one minute elapses in the step, an interrupt process for the step,.

〔The invention's effect〕

The output density adjusting device in the image forming apparatus of the present invention has a density setting means for selectively setting the density in a predetermined adjustable range, and does not perform the image forming operation when the power is turned on again or for a predetermined time. In this case, as long as the output density is not reset by the density setting means, the information for controlling the output density adjusting means is the most recent density setting means in the further limited intermediate density range within the adjustable density range. For example, even if the density is set to an extreme density outside the intermediate density range limited at the time of the previous copy, the setting information does not remain. Since the density setting information within the most recent limited intermediate density range before that is used, environmental changes and sensitivity can be achieved without setting the density again, except in exceptional cases. Image output optimal concentration adapted to the reduction or the like can be obtained. Also, if a normal density within the intermediate density range limited at the time of the previous copy is set, this density information is not affected by environmental changes, sensitivity changes, etc. in the next copy unless the density is set again. Available as adapted concentration.

[Brief description of the drawings]

FIG. 1 is a plan view of an example of a density setting button and a density setting display device of an output density adjusting device according to the present invention, and FIG. 2 is an example of the configuration when an electrophotographic copying machine is used as an image forming apparatus. FIG. 3 is a flow chart showing a flow of one embodiment of a density adjusting device of the present invention, and FIG. 4 is an example of a density setting button and a density setting display device of a conventional output density adjusting device. FIG. 5 is a system configuration diagram of an example of a conventional electrophotographic copying machine, and FIG.
FIG. 7 is a flowchart showing the flow of the conventional density adjusting device. 1 ... photosensitive drum, 2 ... platen, 4 ... exposure lamp, 5, 7 ... mirror, 6 ... lens, 8 ... charger
9: developing unit, 10: CPU, 11: lamp drive circuit, 12
… High voltage power supply circuit, 16… ROM, 17… RAM, 18… Non-volatile memory (NVM), 20… Density setting button, 21…
Up button, 22 Down button, 23 Density setting display, 24 LED

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-59-131946 (JP, A) JP-A-60-207156 (JP, A) JP-A-61-77065 (JP, A) JP-A-61-77065 77066 (JP, A) JP-A-2-235076 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G03G 21/00 G03G 15/02 G03G 15/04 G03G 15/06

Claims (3)

(57) [Claims] An output density adjusting device in an image forming apparatus having an output density adjusting means includes density setting means capable of selectively setting a density within a predetermined adjustable range. When the image forming operation is not performed for a predetermined time, as long as the output density is not reset by the density setting unit, the information for controlling the output density adjusting unit is set to a value within the further limited intermediate density range within the adjustable density range. An output density adjusting device for an image forming apparatus, wherein the information selected most recently by the density setting means is used. 2. A storage device comprising: a first rewritable storage means; and a second rewritable storage means which does not lose its stored contents even when the power of the apparatus is turned off. A first writing unit that writes the stored information to the first storage unit; and information about the density set by the density setting unit after the information is written to the first storage unit by the first writing unit. A second writing unit for writing, and a unit for controlling the output density adjusting unit based on the information about the density stored in the first storage unit. Determining means for determining whether or not the information on the density stored in the means is within a further limited intermediate density range in the predetermined range of density; The only when it is judged that they are within 1
2. The output density adjusting device according to claim 1, further comprising a third writing unit that writes information about the density stored in the storage unit into the second storage unit. 3. An output density adjusting device in an image forming apparatus according to claim 2, further comprising display means for displaying information on density stored in said first storage means.