JPH0451165A - Output density adjusting device for image forming device - Google Patents

Abstract

PURPOSE:To make a device comply with a proper image forming condition which is changed by environmental change and the change of the sensitivity of a photosensitive body by returning a density value to a density value selected the last from a previously set intermediate zone within a density range where adjustment can be possible in the case that the device is left without performing an image forming action for a specified time or a power source is turned on again. CONSTITUTION:A density setting button 20 and a density setting display device 23 are connected to a CPU 10. The button 20 is constituted of an up-button 21 for making the density higher and a down-button 22 and selectively sets the density within the specified range where the adjustment can be possible. Then, the device is constituted so that information selected by a density setting means the last in a more limited area within the density range where the adjustment can be possible may be used as the information for controlling an output density adjusting means as long as output density is not reset in the case that the power source is turned on again or the image forming action is not performed for th specified time. Thus, the output of the image having the optimum density suitable for the environmental change or the change of the sensitivity is obtained even when the density is not set again.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a density adjustment device for an output image including characters in an image forming apparatus such as an electrophotographic copying machine, a printer, or a facsimile machine, and more particularly, This invention relates to an output density adjustment device that improves the problem of an auto-reset type output density adjustment device that automatically resets the output density when the device is left unattended or the power is turned on again.

[Conventional technology]

For example, in an electrophotographic copying machine with a relatively slow copying speed,
Copy density adjustment has conventionally been performed using a slide type density setting button, but recently, step type copy density adjustment devices have been used to give the device a more luxurious feel.

Some examples will be explained with reference to FIGS. 4 to 7.

The density setting button and the density setting display device are arranged as shown in FIG. It consists of an up button 21 and a down button 22, and the density setting display device 23 consists of, for example, five LEDs 24. Each LED 24 corresponds to five levels of setting density, from the lowest density to the highest density. They are numbered 1 to 5 in order.

The density setting button 20 and the density setting display device 23 are connected to the C, as shown in the system configuration diagram of FIG.
Connected to PU10.

For example, as shown in FIG. 5, an electrophotographic copying machine includes a photosensitive drum 1, a charger 8, a developer 9, a platen 2, an exposure lamp 4, a mirror 5, 7, a lens 6, etc. (other transfer devices are not included). , a cleaning device, a static eliminator, etc. are omitted in the figure.) The exposure lamp 4 is controlled to turn on and its current is controlled by a lamp drive circuit 11 , and the charger 8 and developer 9 are controlled by a high-voltage power supply circuit 12 to control charging timing, The charging voltage, development bias application timing, and development bias voltage are controlled. These lamp drive circuit 11, high voltage power supply circuit 1
2 is centrally controlled by the CPU10, and controls the lighting timing of the exposure lamp 4, the applied current or voltage, and the charger 8.
The charging timing, charging voltage, developing bias application timing of the developing device 9, and developing bias voltage are determined by the CPU.
Controlled by commands from l0. CPUl0 has
ROM1.6 and RAM17 are connected, and ROM1
6 includes control parameters for each part of the copying machine, exposure lamp applied current or voltage, charger charging voltage, and developer development corresponding to the density number set by the density setting button 20 and the density setting display device 23. Bias voltage etc. are stored.

FIGS. 6 and 7 show an example of a flow when copy density adjustment is performed in a step manner using an apparatus having such a configuration. In these examples, the density adjustment of the output image from the electrophotographic copying machine is explained as being performed by adjusting only the developing bias voltage of the developing device 9, but this is just for illustrative purposes, and the exposure It is clear that the density can be adjusted by changing any one or more parameters that determine the image forming conditions, such as the lamp applied current or voltage, the charger charging voltage, etc.

The density adjustment device according to the flow shown in FIG. 6 continues to copy as long as the density once set by the density setting button 20 and density setting display device 23 as shown in FIG. 4 is not changed. When the device is turned on and the device is started up, the number 3 is automatically set on the concentration setting counter, which is used to set the concentration of any number among the five concentration ranks. Density number 3 is the density setting display device 2 in Fig. 4.
3, the normal concentrations correspond.

Note that this density setting counter is set in either the CPU 10 or the RAM 17. After 3 is set in the density setting counter, the LED 24 corresponding to that number on the density setting display device 23 is lit. Next, it is determined whether or not any of the density setting buttons 21 and 22 of the density setting buttons 20 has been pressed to change the density. First, it is detected whether or not the down button 22 is pressed, and this button 22 is pressed.
If is pressed, the set number of the density setting counter is decremented by one. In this case, the set number of the counter is 2, which is not zero, so the LED 24 corresponding to that number is lit. Next, it is determined whether or not the down button 22 has been pressed further, and if it has been pressed further, the set number on the counter is decremented by 1 and becomes 1, and the same cycle is repeated. When the down button 22 is pressed continuously and the set number of the counter reaches zero, the set number of the counter is set to 1 and the LED 24 of 1 is lit. Even if the down button 22 is pressed any longer, the set number of the counter and the lighting number of the LED 24 remain at 1 and do not change. Do not press any button from the beginning or up button 21
is pressed, or if the suppression of the down button 22 is stopped midway, the process moves to a step of detecting whether or not the up button 21 is pressed, and if this button 21 is pressed, the concentration setting counter is set. Only 1 can be added to the number. Then, it is determined whether the set number of the counter has reached 6 or not, and if the set number has reached 6, the number is set to 5, and if it is not 6, the number remains unchanged.
The counter set number ED24 is lit. A similar cycle is then repeated. Up button 21
When is pressed continuously and the set number on the counter reaches 6,
As described above, the set number of the counter is set to 5, the LED 24 of 5 is lit, and does not change thereafter. If you do not press any button from the beginning or if you stop pressing the up button 21 or down button 22 midway through, information regarding the developing bias voltage corresponding to the density number set in the counter at that time is called from the ROM 16. ,CPUl
0 controls the high voltage power supply circuit 12 based on the information,
A developing bias voltage that gives the density of the number set in the counter is applied to the developing device 9. After the copying is completed, the process returns to the step of lighting up the LED 24 corresponding to the set number of the density setting counter, and the same cycle is repeated. With this configuration, the density setting button 20
Copying is performed at the density set by the density setting display device 23, and the copying is performed at that density unless the density is changed during the process. Then, when the power is turned off and turned on again, the set concentration automatically becomes 3 (normal).

The density adjustment device in the flow shown in FIG. 7 is almost the same as the one in FIG. It is at the point that I have set. If a new copy is to be made before one minute has elapsed since copying, the density setting display will be performed in a flow similar to that shown in Figure 6, and the copy will be made at that density; If one minute passes without the next copy being made, the process returns to the step of automatically setting 3 on the density setting counter.

Therefore, the set density is automatically set to 3 (normal) one minute after copying without turning on the power again.

[Problem to be solved by the invention]

As mentioned above, in a conventional step-type copy density adjustment device that employs an auto-reset method, if the device is left without image forming operation for a predetermined period of time or the power is turned on again, the output density will change to a predetermined density. However, due to environmental changes such as temperature and humidity,
Or, due to a change in the sensitivity of the photoreceptor, the image copied using this predetermined density (density 3 (normal) in the case of Figures 6 and 7) may not have the expected appropriate density, resulting in image fogging or black spots. There is a problem that often occurs.

The present invention was made in view of this situation, and
The purpose of this is to adjust the density of output images containing characters in image forming apparatuses such as electrophotographic copying machines, printers, and facsimiles, when the apparatus is left without image forming operation for a predetermined period of time or when the power is turned on again. Rather than automatically resetting the output density to a predetermined density value, the output density can be configured to return to the most recently selected density value in a preset intermediate zone within the adjustable density range and It is an object of the present invention to provide an output density adjusting device that can cope with suitable image forming conditions that have changed due to changes in the environment, changes in the sensitivity of a photoreceptor, and the like.

[Means to solve the problem]

To achieve the above object, an output density adjustment device for an image forming apparatus according to the present invention is capable of selectively setting an adjustable predetermined range of density in the output density adjustment device for an image forming apparatus having an output density adjustment stage. It has a density setting means, and when the power is turned on again or no image forming operation is performed for a predetermined period of time, unless the output density is reset by the density setting means, the information for controlling the output density adjustment means is: The present invention is characterized in that the information most recently selected by the density setting means within a further limited area within the adjustable density range is used.

For this purpose, a first rewritable storage means and a second rewritable storage means whose memory contents do not disappear even when the power of the device is turned off are provided, and the second storage means is stored after the power of the device is turned on. a first writing means for writing stored information into the first storage means; and a first writing means for writing information on the density set by the density setting means into the first storage means after the information is written in the first storage means by the first writing means. and a second writing means for writing, and means for controlling the output density adjusting means based on the information regarding the density stored in the first storage means, and after controlling the output density adjusting means,
determination means for determining whether or not the information regarding the concentration stored in the first storage means is within a further limited area within the predetermined range of concentration; It is desirable to have a third writing means for writing the information regarding the density stored in the first storage means into the second storage means only when it is determined that

Further, it is further desirable that the device be configured to include display means for displaying information regarding the concentration stored in the first storage means.

[Effect]

The output density adjusting device of the present invention has a density setting means that can selectively set the density within a predetermined adjustable range. Unless the output density is reset by the setting means, the information most recently selected by the density setting means within a further limited area within the adjustable density range is used as information for controlling the output density adjustment means. For example, even if an extreme density outside the limited area was set during the previous copy, that setting information will not be retained; instead, the most recent limited area before that will be copied. Since the density setting information within the area is used, an image output with the optimum density adapted to environmental changes, sensitivity changes, etc. can be obtained without having to set the density again, except in exceptional cases. In addition, if the normal density within a limited area was set during the previous copying, this density information will also be used in the next copying unless the density is set again. It can be used as

〔Example〕

In the output density adjusting device of the present invention, the density value set by the user during image formation in a preset intermediate zone within the adjustable density range is adjusted according to environmental changes such as temperature and humidity.
Alternatively, in most cases, the value corresponds to the appropriate image forming conditions that have changed due to changes in the sensitivity of the photoreceptor, and can serve as a reference for subsequent density adjustment. The values are set for special image formation, do not correspond to suitable image formation conditions that have changed due to environmental changes, etc., and are based on the empirical rule that they are not useful for subsequent density settings.

Based on these empirical rules, the output density adjustment device in an image forming apparatus is adjusted to a preset intermediate value within the adjustable density range when the apparatus is left without image forming operation for a predetermined period of time or when the power is turned on again. The configuration is configured to return to the most recently selected density value in the zone. Hereinafter, one embodiment of the output density adjusting device of the present invention will be described using an electrophotographic copying machine as an example.

FIG. 1 is a plan view of the density setting button 20 and the density setting display device 23 of the output density adjusting device according to the present invention, and the density setting button 20 and the density setting display device 23 are arranged in parallel. The density setting button 20 consists of an up button 21 and a down button 22 to increase the density, and the density setting display device 23 consists of, for example, 13 LEDs 24, and each LED
24 corresponds to 13 setting concentrations from the lowest concentration to the highest concentration.
It is numbered. The density setting button 20 and the density setting display device 23 are connected to the CPU10, as shown in the system configuration diagram of FIG.

As shown in FIG. 2, the electrophotographic copying machine includes a photosensitive drum 1, a charger 8, a developing device 9, a platen 2, an exposure lamp 4, a mirror 5.7, a lens 6, etc., as shown in FIG. (Other transfer devices, cleaning devices, static eliminators, etc. are omitted from illustration.

), the lighting and current of the exposure lamp 4 are controlled by a lamp drive circuit 11, and the charging timing, charging voltage, developing bias application timing, and developing bias voltage of the charger 8 and developing device 9 are controlled by a high-voltage power supply circuit 12. There is. These lamp drive circuit 11 and high voltage power supply circuit 12 are
The lighting timing of the exposure lamp 4, the applied current or voltage, the charging timing and charging voltage of the charger 8, the developing bias application timing of the developing device 9, and the developing bias voltage are controlled centrally by the CPU10, respectively, according to commands from the CPU10. controlled. CPU 10 has ROM
16, a RAM 17, and a nonvolatile memory (hereinafter referred to as NVM) 18 are connected to the ROM 16, and the ROM 16 contains control parameters for each part of the copying machine, and a density setting button 2.
0 and the density number set by the density setting display device 23, the exposure lamp applied current or voltage, charger charging voltage, developer developing bias voltage, etc. are stored.

FIG. 3 shows a flowchart of an embodiment of the density adjusting device of the present invention in which copy density adjustment is performed in a stepwise manner using the device having such a configuration. In this example, the density adjustment of the output image from the electrophotographic copying machine is explained as being performed by adjusting only the developing bias voltage of the developing device 9, but this is just for illustrative purposes, and the exposure lamp 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.

Furthermore, when using a printer of a thermal transfer type or an inkjet type other than an electrophotographic type as an image forming apparatus, the adjustment parameters of each image output density adjustment means are configured to be changed.

In the flow shown in Figure 3, turn off the power in step ■.
When the apparatus is started up with the setting N, in step (2), one of the density numbers among the 13 density ranks stored in a predetermined area of the NVM 18 is written into the density setting counter. In a predetermined area of the NVM 18, the number 7 representing the normal concentration is stored at the time of shipment of the device, but thereafter it is sequentially rewritten to a number in the range of 5 to 9 in step @ to be described later. Note that this concentration setting counter is
It is set in PU10 or in any area of RAM17. Next, in step (2), the LED 24 corresponding to the number in the density setting counter of the density setting display device 23
is lit. Then, the process proceeds to step (2) to check whether the down button 22 of the density setting button 20 has been pressed and the density has been changed downward. If the down button 22 is pressed, in step (2), the number in the density setting counter is decremented by 1 and reset. Next, in step ■, it is determined whether or not the set number in the concentration setting counter is zero, and if it is zero, the number in the concentration setting counter is reset to 1 in step ■, and the process returns to step ■. . Further, when it is determined in step (2) that the set number in the density setting counter is not zero, the process returns to step (2), leaving the number in this counter unchanged.

While the down button 22 is pressed, the cycle from ■ to ■ is repeated, and the number of LEDs 24 that light up on the concentration setting display device 23 decreases, and finally the LED 24 with number 1 lights up, and from then on. Even if the down button 22 is pressed continuously, the LED 24 that is lit remains at 1, and the set number in the density setting counter also corresponds to the number of the LED 24 that is lit. If the down button 22 is not pressed from the beginning or the up button 21 is pressed, or if the suppression of the down button 22 is stopped midway through, the process proceeds to step 2, and it is detected whether or not the up button 21 is pressed. . If this button 21 is pressed, 1 is added to the set number of the density setting counter in step (3) and the density setting counter is reset. Then, in step ■, it is determined whether or not the set number of the counter has reached 14. If the set number has become 14, the number is reset to 13 in step ■, and if it has not reached 14, it remains unchanged. At the number, the process returns to step (2), and the LED 24 corresponding to the set number of the counter is lit.

A similar cycle is then repeated, with up button 2
While 1 is kept pressed, the number of LEDs 24 that light up increases, and finally the LED 24 with the number 13 lights up, and even if you keep pressing the up button 21 from now on, the number of LEDs 24 that light up will remain 13. The set number in the density setting counter also corresponds to the number of the LED 24 that is lit. If you do not press any button from the beginning or stop suppressing the up button 21 or down button 22 in the middle,
The process proceeds from step ■ to step ■, where information regarding the developing bias voltage corresponding to the density of the number set in the counter at that time is called from the ROM 16, and the CPLII
O controls the high voltage power supply circuit 12 based on the information,
A developing bias voltage that gives the density of the number set in the counter is applied to the developing device 9. After copying is performed in step (2), the process proceeds to step (2), where the set number in the density setting counter is a number in the range of 5 to 9, that is, a density number in a slightly lighter or darker range near normal density number 7. It is determined whether or not there is. If the set number in the concentration setting counter is within the range of 5 to 9, this number is rewritten in the next step (■) instead of the concentration number already stored in a predetermined area of the NVM 18, and then in step (2). return. Therefore, the next copy will be made with the same density in the range of 5 to 9 unless the density is reset using the buttons 21 and 22.

In step (2), if it is determined that the set number in the density setting counter is outside the range of 5 to 9, the NV
M18 is not rewritten, and in step ■, it is determined whether one minute has passed since the copy was performed, and after waiting until one minute has passed after copying, the process returns to step ■, and the most recent concentration is Any number in the range of 5 to 9 is set in the setting counter, and copies are made based on it. Then, in step 2, the number written in the NVM 18 is written in the density setting counter, and the next copy is made by pressing the button Unless the density is reset using steps 21 and 22, copies will be made at any density within the same range of 5 to 9.

With the above configuration, for example, when the temperature rises and the density decreases, the set density is changed to 9, the settings are made so that normal density copies can be made, and after a series of copies are made, the power is turned off. If you restart the next copy even if more than one minute has passed without turning off or copying, the same number 9 is written from the NVM 18 to the density setting counter in step ①, and the next copy is made based on this set density. is performed, so a copy with normal density can be made in the same way. On the contrary,
If you use the down button 22 to set the density setting to 2 in order to copy an original with a very high density for the next copy, turn off the power or do not copy after copying that original.
If more than a minute has passed, the set density 2 will disappear, and at the next copying time, the NVM 18 will write density number 9 to the density setting counter in step ①. If you want to copy an original with normal density, you can make a copy with normal density without changing the set density.

The above explanation was based on the assumption that non-volatile memory, whose contents do not disappear even when the power is turned off, is used separately from RAM. However, if RAM is backed up by a battery or the like, If a RAM is used in which the stored contents will not be erased, the most recent setting density number in the range of 5 to 9 may be stored in a specific area of the RAM 17 instead of the NVM 18. Also,
Although it is assumed that the number 7 representing the normal concentration is stored in a predetermined area of the NVM 18 at the time of shipment of the device, this requirement is not necessarily necessary.

For example, NVM1 only appears when the device is first powered on.
A step of writing a predetermined number, for example 7, into 8 may be provided before step (2).

Furthermore, by omitting step ■ in the flow of Figure 3,
It is also possible to arrange to return to step (2) immediately if it is determined in step (2) that the set number in the density setting counter is outside the range of 5 to 9. With this configuration, when the density is set to 1 to 4 or 10 to 13, that density will be maintained unless the power is turned off. In addition, in step ■, if you try to perform the next copy before 1 minute has elapsed, repeat steps ■, ■, ■,
This can be handled by interrupt processing such as (1).

[Effects of the Invention] The output density adjusting device in the image forming apparatus of the present invention has a density setting means that can selectively set the density within a predetermined adjustable range. When no image forming operation is performed, unless the output density is reset by the density setting means, the most recent density within a more limited area within the adjustable density range is used as information for controlling the output density adjustment means. Since the configuration is configured to use the information selected by the setting means, for example, even if the density was set to an extreme value outside the limited area during the previous copying, that setting information will not remain, and instead, Since the previous most recent density setting information within a limited area is used, unless there are exceptional cases, the image is output at the optimum density that adapts to environmental changes, sensitivity changes, etc. without having to set the density again. is obtained. In addition, if the normal density within a limited area was set during the previous copying, this density information will also be used in the next copying unless the density is set again. It can be used as

[Brief explanation of drawings]

FIG. 1 is a plan view of an example of a density setting button and density setting display device of an output density adjustment 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 device. A system configuration diagram for explanation; FIG. 3 is a flowchart showing the flow of one embodiment of the density adjustment device of the present invention; FIG. 4 is an example of a density setting button and density setting display device of a conventional output density adjustment device FIG. 5 is a system configuration diagram of an example of a conventional electrophotographic copying machine, and FIGS. 6 and 7 are flow charts showing the flow of a conventional density adjusting device. DESCRIPTION OF SYMBOLS 1... Photosensitive drum, 2... Platen, 4... Exposure lamp, 5.7... Mirror, 6... Lens, 8...
...Charger, 9...Developer, 10...CPU111
... Lamp drive circuit, 12 ... High voltage power supply circuit, 16
...ROM, 17...RAM118...Non-volatile memory (NVM), 20...Density setting button, 2
1...Up button, 22...Down button, 23
...Concentration setting display device, 24...LD Applicant Fuji Xerox Co., Ltd. Agent Patent attorney Hiroshi Nirasawa (7 others) Figure 2 Figure 4 5 Convex

Claims (3)

[Claims] (1) The output density adjustment device of an image forming apparatus having an output density adjustment means has a density setting means that can selectively set the density within a predetermined adjustable range, and when the power is turned on again or for a predetermined time. When no image forming operation is performed, unless the output density is reset by the density setting means, the most recent density within a more limited area within the adjustable density range is used as information for controlling the output density adjustment means. 1. An output density adjustment device for an image forming apparatus, characterized in that the output density adjustment device is configured to use information selected by a setting device. (2) A first rewritable storage means and a second rewritable storage means whose memory contents do not disappear even when the power of the device is turned off, and the contents are stored in the second storage means after the power of the device is turned on. a first writing means for writing information regarding the density into the first storage means; and a first writing means for writing information regarding the density set by the density setting means into the first storage means after the information is written into the first storage means by the first writing means. 2 writing means, and means for controlling the output density adjustment means based on the information regarding the density stored in the first storage means, and after controlling the output density adjustment means, writing to the first storage means. comprising a determining means for determining whether or not the stored information regarding the concentration is within a further limited area within the predetermined range of concentration, and when it is determined by the determining means that the information is within the limited area; 2. The output density adjustment device for an image forming apparatus according to claim 1, further comprising a third writing means for writing into the second storage means the information regarding the density stored in the first storage means. (3) The output density adjustment device for an image forming apparatus according to claim 2, further comprising a display unit for displaying information regarding the density stored in the first storage unit.