JP2001075318A - Method and device for adjusting density of image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately adjust image density by starting a warming up of an image forming device by receiving a release of a sleep mode and executing a density adjustment process of an image after the completion of the warming up. SOLUTION: When electric power is applied or a sleep mode is released, a warming up is immediately started and an engine controller 12 controls an engine section E so that prescribed values are set in respective sections of the device. For example, in a fixing unit 5, temperature of a fixing device is lowered while the power is turned off or in a sleep mode and the temperature is raised to a set value by the warming up. Having established the set values for image forming conditions and the device is stabilized, the warming up is completed. When the warming up is judged to be completed, a density adjustment process is immediately executed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a density adjusting method and a density adjusting device for adjusting the density of an image formed by an image forming apparatus.

[0002]

2. Description of the Related Art Since the density of an image formed by an image forming apparatus changes under various influences, conventionally, density control factors which affect the image density, such as a charging bias, a developing bias and an exposure amount, are appropriately adjusted. Many techniques for adjusting and stabilizing the image density have been proposed. For example,
According to the invention described in Japanese Patent Application Laid-Open No. H10-148979, immediately after the image forming apparatus is turned on or immediately after the sleep mode is released, the temperature of the fixing unit and the temperature inside the apparatus are detected, and both of these temperatures are equal to or lower than a predetermined value. In the case of, the image density is adjusted by executing the gradation correction process (corresponding to the density adjustment processing of the present invention).

[0003]

By the way, in the image forming apparatus, when the power is turned on or the sleep mode is released, the warm-up is executed, and after the warm-up is completed, the actual image forming process is executed. However, according to the above-described related art, the gradation correction process is performed during the warm-up, and the image formation based on the gradation correction value is performed upon completion of the warm-up. As described above, since the gradation correction process is performed in parallel with the warm-up, the time required for the gradation correction process can be saved.

However, during warming-up, image forming conditions such as temperature and humidity in the apparatus are unstable, and even if image density is adjusted, it is difficult to perform accurate density adjustment in such a state. . This is because, as is well known in the art, various characteristics affecting the image density, for example, the triboelectric charging characteristics of the toner, are not stable unless the image forming conditions such as the in-machine temperature are stabilized. If an image is formed based on the correction value determined in such an unstable state, a case may occur where a good image having a desired image density cannot be formed.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and has as its object to provide a density adjusting method and a density adjusting apparatus in an image forming apparatus capable of accurately adjusting the image density.

[0006]

In order to achieve the above object, a density adjusting method and a density adjusting apparatus according to the present invention require that the power supply to the image forming apparatus be turned on or that the sleep mode of the image forming apparatus be released. Then, the warm-up of the image forming apparatus is started, and after the warm-up is completed, the image density adjustment processing is executed.

In these inventions, when the power of the image forming apparatus is turned on or when the sleep mode of the image forming apparatus is released, the warm-up is started. Then, the image forming conditions are adjusted so as to reach a predetermined set value, and the warm-up is completed. Here, as an image forming condition, for example, when looking at the inside temperature, immediately after the power is turned on or immediately after the sleep mode is released, the inside temperature is often relatively low, but the temperature is gradually increased by warming up, When the set value is reached and stabilized,
Warm-up is completed. After the completion of the warm-up, the image forming conditions are stabilized.
If the image density is adjusted in this state, the image density can be adjusted accurately.

The density adjustment timing after the warm-up may be performed, for example, immediately after the warm-up. In this case, the warm-up and the density adjustment are performed continuously, and it is necessary from the power-on to the first image formation. The time can be reduced, and the throughput is improved.

As another density adjustment timing, a density adjustment process may be performed after a predetermined time has elapsed after the completion of warming up. In this case, the image forming conditions are further stabilized and the image density is reduced. It can be adjusted more precisely.

As another density adjustment timing, the density adjustment process may be executed after the completion of the warm-up and after the image formation command is given. In this case, the time from the density adjustment to the actual image formation may be set. Is reduced, and an image can be formed under conditions similar to the image forming conditions when the density adjustment is performed, and the formed image has a desired image density.

Depending on the image to be formed, it may be necessary to change the image forming conditions depending on the image to be formed. However, in the invention in which the image forming command is received and then the density adjustment processing is executed as described above, Can respond. That is, when an image forming command is given, it is determined whether or not it is necessary to change the image forming conditions according to the image forming command, and when it is not necessary to perform the density adjustment processing, When it is necessary to change the image forming condition, the image forming condition is changed in accordance with the image forming command, and after the image forming condition is reached, the density adjustment process is executed. The density adjustment processing can be performed in a corresponding state.

[0012]

FIG. 1 is a diagram showing an example of an image forming apparatus to which a density adjusting method according to the present invention can be applied. FIG. 2 is a block diagram showing an electrical configuration of the image forming apparatus of FIG. This image forming apparatus forms a full-color image by superimposing four color toners of yellow (Y), cyan (C), magenta (M), and black (K), or uses only black (K) toner. To form a monochrome image. In this image forming apparatus, when an image signal (image forming command) is provided to the main controller 11 of the control unit 1 from an external device such as a host computer, the engine controller 12 responds to an instruction from the main controller 11 to cause the engine controller 12 to operate. Are formed on the sheet S to form an image corresponding to the image signal (image forming command).

In the engine section E functioning as an image forming means, a toner image can be formed on the photosensitive member 21 of the image carrier unit 2. That is, the image carrier unit 2 includes a photoconductor 21 rotatable in the direction of the arrow in FIG. 1, and further includes a charging roller 22 as a charging unit, a developing unit around the photoconductor 21 along the rotation direction. Developing units 23Y, 23C, 23M, and 23K, and a cleaning unit 24 are disposed. A high voltage is applied to the charging roller 22 from the charging bias generator 121, and the charging roller 22 contacts the outer peripheral surface of the photoconductor 21 to uniformly charge the outer peripheral surface.

Then, a laser beam L is emitted from the exposure unit 3 toward the outer peripheral surface of the photoconductor 21 charged by the charging roller 22. The exposure unit 3 is configured as shown in FIG.
Is electrically connected to the image signal switching section 122, and scans and exposes the laser beam L onto the photoconductor 21 in accordance with the image signal given through the image signal switching section 122, An electrostatic latent image corresponding to an image signal (image formation command) is formed on the image signal 21. For example, based on a command from the CPU 123 of the engine controller 12, when the image signal switching unit 122 is conducting with the patch creation module 124, the patch image signal output from the patch creation module 124 is given to the exposure unit 3. Thus, a patch latent image is formed. On the other hand, when the image signal switching unit 122 is electrically connected to the CPU 111 of the main controller 11, the laser beam L is output in accordance with an image signal (image forming command) given via an interface 112 from an external device such as a host computer. Is scanned and exposed on the photoconductor 21 to form an electrostatic latent image corresponding to the image signal on the photoconductor 21.

The electrostatic latent image thus formed is developed
Is developed with toner. That is, in this embodiment, as the developing unit 23, a developing unit 23Y for yellow, a developing unit 23C for cyan, a developing unit 23M for magenta, and a developing unit 23K for black are arranged along the photoconductor 21 in this order. Have been. These developing units 23Y and 23
Each of C, 23M, and 23K is configured to be able to freely contact and separate from the photoconductor 21, and in response to a command from the engine controller 12, the four developing units 23Y, 23M,
One of the developing units 23C and 23B selectively
1 and a high voltage is applied by the developing bias generator 125 to apply the toner of the selected color to the surface of the photoconductor 21 to make the electrostatic latent image on the photoconductor 21 visible.

The toner image developed by the developing unit 23 is primarily transferred onto the intermediate transfer belt 41 of the transfer unit 4 in a primary transfer region R1 located between the black developing unit 23K and the cleaning unit 24. The transfer unit 4
Will be described later in detail.

In addition, from the primary transfer region R1 in the circumferential direction (FIG. 1)
(In the direction of the arrow in FIG. 3), a cleaning unit 24 is disposed, and scrapes off toner remaining on the outer peripheral surface of the photoconductor 21 after the primary transfer.

Next, the configuration of the transfer unit 4 will be described. In this embodiment, the transfer unit 4 includes a roller 4
2 to 47; an intermediate transfer belt 41 stretched over the rollers 42 to 47; and a secondary transfer roller 48 for secondary transferring the intermediate toner image transferred to the intermediate transfer belt 41 to the sheet S. ing. A primary transfer voltage is applied to the intermediate transfer belt 41 from a transfer bias generator 126. When the color image is to be transferred to the sheet S, the color image is formed by superimposing the toner images of each color formed on the photoreceptor 21 on the intermediate transfer belt 41, and The sheet S is taken out from the cassette 61, the manual feed tray 62 or an additional cassette (not shown) by the paper section 63, and the secondary transfer area R2
Transport to Then, a color image is secondarily transferred to the sheet S to obtain a full-color image. When a monochrome image is to be transferred to the sheet S, only a black toner image is formed on the photoreceptor 21 on the intermediate transfer belt 41, and is conveyed to the secondary transfer region R2 in the same manner as in the case of a color image. Is transferred to the sheet S to obtain a monochrome image.

After the secondary transfer, toner remaining on the outer peripheral surface of the intermediate transfer belt 41 is removed by a belt cleaner 49. This belt cleaner 4
Reference numeral 9 denotes an intermediate transfer belt which is disposed opposite to the roller 46 with the intermediate transfer belt 41 interposed therebetween. At an appropriate timing, the cleaner blade comes into contact with the intermediate transfer belt 41 to scrape the toner remaining on the outer peripheral surface thereof. Drop.

In the vicinity of the roller 43, a patch sensor PS for detecting the density of a patch image formed on the outer peripheral surface of the intermediate transfer belt 41 is arranged, and a reference position of the intermediate transfer belt 41 is detected. A reading sensor RS for synchronization is provided.

Returning to FIG. 1, the description of the configuration of the engine unit E will be continued. The sheet S to which the toner image has been transferred by the transfer unit 4 is disposed downstream of the secondary transfer area R2 along a predetermined paper feed path (two-dot chain line) by the paper feed unit 63 of the paper feed / discharge unit 6. The toner image on the sheet S conveyed to the fixing unit 5 is fixed to the sheet S. Then, the sheet S is further conveyed to the sheet discharging unit 64 along the sheet feeding path 630.

The paper discharge section 64 has two paper discharge paths 641
a, 641b, one of the paper discharge paths 641a extends from the fixing unit 5 to the standard paper discharge tray,
The other paper discharge path 641b extends between the re-feed unit 66 and the multi-bin unit substantially in parallel with the paper discharge path 641a. Along these discharge paths 641a and 641b, 3
A pair of rollers 642 to 644 are provided, and a sheet re-feeding unit for discharging the fixed sheet S toward the standard sheet discharge tray or the multi-bin unit or forming an image on the other side. To the 66 side.

As shown in FIG. 1, the re-feeding section 66
The sheet S reversely conveyed from the sheet discharge section 64 as described above is fed along the re-feed path 664 (two-dot chain line).
And the three re-feeding roller pairs 6 arranged along the re-feeding path 664.
61 to 663. As described above, the paper discharge unit 6
4 is returned to the gate roller pair 637 along the re-feed path 664 so that the sheet S
3, the non-image forming surface of the sheet S is the intermediate transfer belt 4
1 and the image can be secondarily transferred to the surface.

In FIG. 2, reference numeral 113 denotes an interface 11 from an external device such as a host computer.
2 is an image memory provided in the main controller 11 for storing an image given through
Reference numeral 7 denotes control data and CPU for controlling the engine unit E.
Reference numeral 128 denotes a RAM for temporarily storing a calculation result and the like in the 123, and reference numeral 128 denotes a ROM for storing a calculation program and the like performed by the CPU 123.

Next, a method of adjusting the density in the image forming apparatus configured as described above will be described. In the embodiment described below, the engine controller 12 adjusts the density of an image formed by the image forming apparatus while controlling the engine unit E as follows. It functions as an adjusting device.

<First Embodiment> FIG. 3 is a flowchart showing a first embodiment of a density adjusting method according to the present invention. In the first embodiment, as shown in FIG.
Immediately after the power is turned on or the sleep mode is released, the warm-up is started (step S1), and the engine controller 12 controls the engine unit E so that each unit of the device has a predetermined set value. For example, the temperature of the fixing unit 5 of the fixing unit 5 may be reduced while the power is turned off or during the sleep mode. For this reason, the internal temperature of the apparatus gradually increases as the temperature of the fixing device rises, and the internal temperature, which is one of the image forming conditions, is unstable during the warm-up. The warm-up is completed when the image forming conditions reach the set values and are almost stabilized.

In step S2, when it is determined that the warm-up is completed, the process immediately proceeds to step S3 to execute the density adjustment processing. In this embodiment, the density adjustment is performed by executing the following two steps.

(1) While fixing the charging bias applied from the charging bias generator 121 to the charging roller 22, while changing the developing bias applied from the developing bias generator 125 to the developing device 23, a plurality of patch images (solid images) are ) Is formed, the density of the patch images is detected by the patch sensor PS, and the optimum developing bias necessary for obtaining the target density is determined based on the detected values (image density of the patch image).

(2) A plurality of patch images (halftone images) are sequentially formed while changing the charging bias while the developing bias is fixed at the optimum developing bias previously obtained, and the image density of the patch images is changed. Patch sensor P
Detected by S and their detected values (image density of patch image)
The optimum charging bias required to obtain the target density is determined based on the above.

As described above, according to the density adjusting method according to the first embodiment, after the warm-up is completed and the image forming conditions including the internal temperature are stabilized,
Since the image density is adjusted, the image density can be accurately adjusted, and an image formed thereafter can be formed with a desired image density.

Further, since the density adjustment processing (step S3) is performed immediately after the warm-up, the warm-up and the density adjustment processing are continuously performed, so that the time required from power-on to the first image formation can be shortened. And the throughput can be improved.

<Second Embodiment> FIG. 4 is a flowchart showing a second embodiment of the density adjusting method according to the present invention. The second embodiment is significantly different from the first embodiment in that the density adjustment process (step S3) is executed immediately after the warm-up in the first embodiment, whereas the second embodiment has steps S11 and S12 in the second embodiment. Is that the density adjustment process is performed after a predetermined time has elapsed after the warm-up, and the other configuration is the same.

According to this embodiment, when a predetermined time elapses after the warm-up, the image forming conditions are further stabilized during the elapse of the time, so that the image density can be adjusted more accurately.

<Third Embodiment> FIG. 5 is a flowchart showing a third embodiment of the density adjusting method according to the present invention. The third embodiment is largely different from the first embodiment in that the density adjustment processing (step S3) is executed immediately after the warm-up in the first embodiment, whereas the image forming command (step S3) is executed in the third embodiment. That is, the density adjustment process (step S3) is performed after waiting for the job.
The details will be described below with reference to FIG.

In the third embodiment, similarly to the first embodiment, when the power is turned on or the sleep mode is canceled, immediately after that, the warm-up is started (step S1). If it is determined in step S2 that the warm-up is completed, the process waits for an image forming command (job) from the external device such as a host computer via the interface 112 (step S21). When a job is given, the type of the job is determined based on the image forming instruction (step S2).
2).

Here, it is necessary to change the image forming conditions depending on the job content. For example, it is necessary to change the temperature of the fixing device constituting the fixing unit 5 depending on whether the sheet S is plain paper or thick paper. More specifically, usually, when the main power supply of the image forming apparatus is turned on, the temperature of the fixing device is set to a temperature suitable for plain paper.
In order to form an image on thick paper, the temperature of the fixing device needs to be higher than that of plain paper. Therefore, when a temperature suitable for plain paper is set and a job for forming an image on thick paper is given, it is necessary to raise the temperature of the fixing unit. Conversely, when a temperature suitable for thick paper is set and a job for forming an image on plain paper is given, it is necessary to lower the temperature of the fixing unit. Therefore,
In the third embodiment, steps S23 to S25 are executed based on the determination result in step S22.

In step S23, step S22
Then, it is determined whether or not the setting of the fixing unit 5 needs to be changed on the basis of the determination result in the above. If it is determined that there is no need to change, the process proceeds to step S3, where the density adjustment process is immediately executed (step S3). On the other hand, when it is determined that a change is necessary, the setting of the fixing unit 5 is changed to a value suitable for the job (step S24), and when the setting value is reached (when YES is determined in step S25).
To execute the density adjustment processing (step S3).

As described above, according to the third embodiment, after the completion of the warm-up, the density adjustment processing is executed after the image formation command (job) is given, and therefore the actual image formation is started after the density adjustment. Time to
An image can be formed under conditions similar to the image forming conditions when the density adjustment is performed, and the formed image has a desired image density.

Note that the present invention is not limited to the above-described embodiment, and various changes other than those described above can be made without departing from the gist of the present invention. For example, in the above-described embodiment, steps (1) and (2) are executed as the density adjustment processing to determine the optimum developing bias and the optimum charging bias, respectively, but the density adjustment processing is not limited to this. Alternatively, the processing described in the conventional example (the gradation correction process in the conventional publication) may be executed.

Further, in the above embodiment, the image forming apparatus is capable of forming a color image using four color toners. However, the present invention is not limited to this. Naturally, the present invention can also be applied to an image forming apparatus that forms only the image forming apparatus. The image forming apparatus according to the above-described embodiment is a printer that forms an image given from an external device such as a host computer via the interface 112 on sheets such as copy paper, transfer paper, paper, and a transparent sheet for OHP. However, the present invention can be applied to all electrophotographic image forming apparatuses such as copying machines and facsimile machines.

In the above embodiment, the toner image on the photoreceptor 21 is transferred to the intermediate transfer belt 41, the toner image is used as a patch image, the image density is detected, and the optimum developing bias is determined based on the detection result. And the optimum charging bias is calculated, but the toner image is transferred to a transfer medium other than the intermediate transfer belt (such as a transfer drum, a transfer belt, a transfer sheet, an intermediate transfer drum, an intermediate transfer sheet, a reflective recording sheet or a transparent storage sheet). The present invention can also be applied to an image forming apparatus that forms a patch image by transferring an image. Also, instead of forming a patch image on the transfer medium, a patch sensor for detecting the density of the patch image on the photoconductor is provided, and the patch sensor detects the image density of each patch image on the photoconductor, and the detection result The optimum developing bias and the optimum charging bias may be calculated based on the above.

[0042]

As described above, according to the present invention, since the image density is adjusted after the warm-up is completed and the image forming conditions are stabilized, the image density can be adjusted accurately. The image formed thereafter can be formed with a desired image density.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an example of an image forming apparatus to which a density adjustment method according to the present invention can be applied.

FIG. 2 is a block diagram illustrating an electrical configuration of the image forming apparatus of FIG. 1;

FIG. 3 is a flowchart showing a first embodiment of a density adjusting method according to the present invention.

FIG. 4 is a flowchart showing a second embodiment of the density adjusting method according to the present invention.

FIG. 5 is a flowchart showing a third embodiment of the density adjusting method according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Control unit 2 ... Image carrier unit 3 ... Exposure unit 11 ... Main controller 12 ... Engine controller (density adjustment device) 21 ... Photoconductor 22 ... Charge roller 23 ... Development part 23Y, 23C, 23M, 23K ... Developer 41 ... Intermediate transfer belts 111 and 123... CPU 121... Charging bias generator 124... Patch creation module 125.

Claims (6)

[Claims] 1. A density adjusting method for adjusting the density of an image formed by an image forming apparatus, wherein the power supply to the image forming apparatus is turned on or the sleep mode of the image forming apparatus is canceled. A density adjustment method for an image forming apparatus, wherein the density adjustment processing of an image is executed after the warming-up of the image forming apparatus is started and the warming-up is completed. 2. The density adjusting method according to claim 1, wherein the density adjusting process is performed immediately after the warm-up. 3. The density adjustment method in an image forming apparatus according to claim 1, wherein the density adjustment processing is executed after a predetermined time has passed after the warm-up is completed. 4. The density adjustment method in an image forming apparatus according to claim 1, wherein the density adjustment processing is performed after the warm-up is completed and an image formation command is given. 5. When the image forming command is given, it is determined whether or not it is necessary to change an image forming condition in accordance with the image forming command. While executing, if it is necessary to change, change the image forming conditions in accordance with the image forming command,
5. The density adjusting method according to claim 4, wherein the density adjusting process is performed after the image forming condition is reached. 6. A density adjusting device for adjusting the density of an image formed by an image forming apparatus, wherein the image forming apparatus receives power when the image forming apparatus is turned on or when a sleep mode of the image forming apparatus is released. A density adjusting apparatus for an image forming apparatus, wherein a warming-up of the forming apparatus is started, and after the warming-up is completed, the density of the image is adjusted.