JP2007083558A - Image forming device and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device which can individually and practically specify a light emitting element deteriorated by a frequent use to lessen effects caused by the variation of a light quantity caused by deterioration, and an image forming method. <P>SOLUTION: A lighting quantity control part 34 controls the lighting quantity of the deteriorated element increased more than that of a reference lighting quantity with regards to a part of or the entire deteriorated elements estimated by a deteriorated element estimating part 24, based on the distribution of the accumulated lighting quantity of a part or the entire light emitting elements acquired by a light quantity acquisition part 22. Thereby, even if the LEDs of an LED head 42 have uneven lighting quantity deterioration caused by a frequent use, a specified deteriorated element can be individually increased in the lighting quantity with uniformed lighting quantity of the LED head 42. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus and an image forming method, and more particularly to an image forming apparatus and an image forming method using a light emitting unit in which a plurality of light emitting elements are arranged.

  2. Description of the Related Art Conventionally, an image forming apparatus that uses a light emitting diode (LED) as a light emitting element to form a latent image on a photosensitive drum, develops the latent image with toner, and transfers the latent image onto a sheet is used. In such an image forming apparatus, the LED heads are arranged so that the LEDs are arranged in the main scanning direction (the rotation axis direction of the photosensitive drum).

  When a drawing image is printed by the image forming apparatus, a drawing frame is drawn around the paper, but an LED that prints a vertical frame extending in the sub-scanning direction of the drawing frame is lighter than other LEDs. The frequency increases, the deterioration progresses quickly, and the amount of emitted light decreases.

  In particular, in a wide-width machine for forming a wide-width image, most of the image output is a drawing image, and the paper is often the same size, so the deterioration of the LED that prints the vertical frame is significant. Such deterioration of the LED becomes a streak when forming a photographic image or the like, which becomes a problem.

  Therefore, in Patent Document 1 below, correction data corresponding to the passage of energization time for the entire LED head is selected from a plurality of types of correction data stored, and the variation in the light amount of the LED head based on the correction data. A technique for correcting the above is disclosed.

In Patent Document 2 below, the number of times each LED is turned on is counted, and when the difference between the maximum number of times of lighting and the minimum number of times of lighting exceeds a set value, the LED with the minimum number of times of lighting is turned on at times other than writing. A technique for making the light emission amount of the LED uniform.
Japanese Patent Laid-Open No. 62-108587 Japanese Patent Laid-Open No. 3-120059

  However, in the technique of Patent Document 1, since a correction pattern is selected only by checking the energization time of the entire LED head, if the LED deterioration pattern deviates from the correction pattern, the variation in the light amount of the LED head is corrected correctly. There was a problem that I could not.

  On the other hand, the technique of the above-mentioned Patent Document 2 aims to make the usage frequency of each LED uniform, and there is a problem that once a difference occurs in the deterioration pattern of the LED, the variation in the light quantity cannot be corrected. It was.

  The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to specifically identify light-emitting elements that have deteriorated due to frequent use, and to reduce the effects of variations in light quantity due to deterioration. It is an object to provide a forming apparatus and an image forming method.

  In order to achieve the above object, an image forming apparatus according to the present invention includes a light emitting unit in which a plurality of light emitting elements are arranged, and each light emitting element of the light emitting unit is provided by a reference lighting amount according to an image signal to be printed. In an image forming apparatus that lights up and writes an image on a photosensitive member, a lighting amount acquisition unit that acquires a distribution of a cumulative lighting amount of each or all of the light emitting elements, and a part or a portion of the cumulative lighting amount based on the distribution of the cumulative lighting amount Deteriorating element estimating means for estimating all the light emitting elements as deteriorating elements, and lighting amount control means for increasing the lighting amount of the deteriorating elements beyond the reference lighting amount.

  According to the present invention, since the light emitting element that has deteriorated due to frequent use is specifically identified, it is possible to reduce the influence of variations in the amount of light due to deterioration.

  The reference lighting amount may be a reference current, and the lighting amount control means may increase the current of the deteriorating element more than the reference current.

  The reference lighting amount may be a reference lighting time, and the lighting amount control means may make the lighting time of the deterioration element longer than the reference lighting time.

  Further, the lighting amount acquisition means may acquire a distribution of the number of lighting times as a distribution of the cumulative lighting amount of each light emitting element.

  Further, the lighting amount acquisition means may acquire a distribution of cumulative lighting times as a distribution of the cumulative lighting amount of each light emitting element.

  In addition, the deterioration element estimation unit further includes a number storage unit that stores, for each light emitting element, the number of times the multi-lighting use is determined based on the distribution of the cumulative lighting amount, and the deterioration element estimation unit stores the number of times You may estimate the said light emitting element in which the frequency | count memorize | stored in the means is more than a predetermined threshold value as the said deterioration element.

  Further, the lighting amount control means may increase the lighting amount of the deterioration element above the reference lighting amount when the usage amount of the image forming apparatus is equal to or greater than a predetermined threshold.

  The image forming method according to the present invention uses a light emitting unit in which a plurality of light emitting elements are arranged, and lights each light emitting element of the light emitting unit by a reference lighting amount according to an image signal to be printed. In an image forming method for writing an image on a lighting amount acquisition step of acquiring a cumulative lighting amount distribution of a part or all of the light emitting elements, and a part or all of the light emitting elements based on the distribution of the cumulative lighting amount And a lighting control step of increasing the lighting amount of the deteriorating element beyond the reference lighting amount.

  Hereinafter, an embodiment for carrying out the present invention (hereinafter referred to as an embodiment) will be described with reference to the drawings.

  FIG. 1 is a configuration diagram of an embodiment of an image forming apparatus according to the present invention. In the present embodiment, an example in which a light emitting diode (LED) is used as a light emitting element will be described, but the present invention is not limited to this. Details of each component will be described later.

  FIG. 2A is a diagram illustrating an example of a drawing image formed by the LED head 42 and the image forming apparatus 10. The LED head 42 has a plurality of LEDs arranged in the main scanning direction. In FIG. 2A, a drawing frame 50 is drawn in the drawing image.

  FIG. 2B is a diagram showing a distribution of the number of times of lighting of each LED included in the LED head 42 acquired from the image data having the drawing frame 50 shown in FIG. is there. The LED 42b that prints a vertical frame extending in the sub-scanning direction in the drawing frame 50 has an extremely high number of lighting times compared to the other LEDs 42a. For this reason, the LED 42b deteriorates faster than the other LEDs 42a, and the amount of emitted light decreases.

  Based on the distribution of the number of lighting times of each LED acquired by the lighting amount acquisition unit 22, the degradation element estimation unit 24 uses an LED 42b (hereinafter referred to as a multi-lighting use LED) that has an extremely high number of lighting times compared to other LEDs. Identify. Then, it is estimated that a part or all of the multi-lighting use LEDs 42b are LEDs whose light amount has decreased due to deterioration (hereinafter referred to as deteriorated LEDs).

  When the deteriorated LED is estimated by the deteriorated element estimating unit 24, information for specifying the deteriorated LED is sent to the lighting control unit 32 via the CPU 30 of the image forming apparatus control unit 28. The lighting amount control unit 34 writes the light amount correction data at the time of factory shipment stored in the light amount correction data ROM 38 into the RAM 36, and then appropriately changes the light amount correction data in the RAM 36 for the deteriorated LED to obtain the deteriorated light amount. Make supplementary control.

  The LED head 42 of the image forming unit 40 lights each LED in the LED head 42 based on the image data and the changed light amount correction data written in the RAM 36. Since the degraded LED is supplied with a larger amount of current than other non-degraded LEDs, the LED head 42 as a whole is irradiated with a uniform amount of light without variation due to degradation.

  As described above, according to the present embodiment, even when the amount of light of the LED head 42 varies due to the difference in the lighting frequency of each LED, the position of the deteriorated LED whose light amount has decreased is estimated individually and specifically. The variation in the amount of light of the LED head 42 can be corrected by increasing the lighting amount of the LED head more than that of the other non-degraded LEDs.

  Hereinafter, the function of each component in FIG. 1 will be specifically described.

  The image forming apparatus 10 includes a controller unit 20, an image forming apparatus control unit 28, a lighting control unit 32, and an image forming unit 40.

  The controller unit 20 includes a lighting amount acquisition unit 22, a deterioration element estimation unit 24, and a frequency storage unit 26, and acquires image data from a personal computer, a workstation, a scanner, or the like according to an instruction from the image forming apparatus control unit 28.

  The lighting amount acquisition unit 22 acquires the distribution of the cumulative lighting amount of each or all of the light emitting elements of the LED head 42. Specifically, the distribution of the number of times each LED is turned on is acquired for all LEDs arranged in the LED head 42 based on the image data. For example, when a drawing image having the drawing frame 50 shown in FIG. 2A is printed, the number of pixels in the sub-scanning direction of the image data is counted, and the number of times each corresponding LED is turned on is counted as shown in FIG. A histogram of the number of lighting times of each LED as shown in FIG. As the distribution of the cumulative lighting amount of each LED, the distribution of the cumulative lighting time may be acquired instead of the number of lighting times.

  The degradation element estimation unit 24 estimates some or all of the LEDs as degradation elements based on the distribution of the cumulative lighting amount of each light emitting element. Specifically, first, based on the distribution of the number of times of lighting of each LED shown in FIG. 2B, it is determined that the LED 42b whose number of times of lighting is extremely large compared to other LEDs is a multiple lighting use LED. The deterioration element estimation unit 24 may estimate the multi-lighting use LED as it is as a deteriorated LED whose light amount has deteriorated due to multiple lighting, or store the cumulative number of times determined as the multi-lighting use LED as the number of times of multi-lighting use. An LED having a large number of times may be estimated as a degraded LED. Whether or not multiple lighting is used is determined by determining whether or not the number of lighting is greater than or equal to a predetermined threshold in the distribution of the number of lighting of each LED shown in FIG. A method is conceivable in which the deviation from the value is based on whether or not the deviation is greater than or equal to a predetermined threshold.

  In the above description, the number storage unit 26 is further used when the deterioration LED is estimated using the number of times of multiple lighting use. The number storage unit 26 stores, for each LED, the number of times that the deterioration element estimation unit 24 determines that multiple lighting is used. FIG. 3 shows an example of the number of times of multiple use of each LED in the number storage unit 26. That is, the number-of-times storage unit 26 stores the number of times determined to use multiple lighting in association with the light emitting element number for specifying each LED. Each time the deteriorated element estimation unit 24 identifies a multi-lighting use LED from the distribution of the number of times of lighting, the multi-lighting use number of the corresponding light emitting element number is incremented by 1. The degradation element estimation means 24 estimates an LED having a number of times of multiple lighting being equal to or greater than a predetermined threshold as a degradation LED. As described above, if the number-of-times storage unit 26 is used, it is possible to more accurately estimate the deteriorated LED in consideration of the past usage record of each LED.

  In the case of a drawing image, the position of the drawing frame is determined within a certain range. In this way, when the position of the multi-lighting use LED can be assumed in advance, the lighting amount acquisition unit 22 is configured to distribute the cumulative lighting amount limited to the LED in a certain range of the LED head 42. Also good. If limited, the storage capacity of the number-of-times storage unit 26 can be saved.

  The image forming apparatus control unit 28 is a central processing unit of the image forming apparatus 10, includes a CPU 30, and controls processing procedures and data flow of the controller unit 20 and the lighting control unit 32. For the LED that is estimated to be a degraded LED by the degradation element estimation unit 24, the light emitting element number is transferred to the lighting control unit 32 via the CPU 30.

  The lighting control unit 32 includes a lighting amount control unit 34, a RAM 36, and a light amount correction data ROM 38, and each LED arranged on the LED head 42 of the image forming unit 40 according to instructions from the controller unit 20 and the image forming apparatus control unit 28. Controls on / off of.

  The RAM 36 stores a control parameter related to the lighting amount of each LED used when the lighting control unit 32 controls the lighting of the LED head 42. The control parameter is a value obtained by appropriately changing the light amount correction data set at the time of factory shipment stored in the light amount correction data ROM 38 as an initial value. Details of the control parameters will be described later.

  FIG. 4 is a diagram illustrating an example of the reference lighting amount of each LED in the light amount correction data ROM 38. The reference lighting amount is a parameter for correcting a difference in light quantity between LEDs caused by a difference in LED characteristics existing from the time of shipment from the factory. For example, a reference current value, a reference lighting time, and the like are assumed. . As illustrated in FIG. 4, the light quantity correction data ROM 38 stores a reference current value in association with the light emitting element number of each LED. If the LED head 42 is in a period until the LED begins to deteriorate, the light amount of the LED head 42 can be kept uniform by applying a current to each LED at the reference current value.

The lighting amount control unit 34 performs control to increase the lighting amount of the deteriorated LED estimated by the deterioration element estimating unit 24 beyond the reference lighting amount. That is, the lighting amount control unit 34 reads the reference current value as the initial value of the parameter for controlling the lighting amount from the light amount correction data ROM 38 and stores it in the RAM 36. Next, the lighting amount control unit 34 updates the current value of the deteriorated LED to a value obtained by adding a predetermined value to the reference current value. In FIG. 5, the example of the electric current value after correction | amendment of each LED is shown. The RAM 36 stores the corrected current value in association with the light emitting element number of each LED. In the example of FIG. 5, the current values of the LEDs of the light emitting element numbers 2 and 4 estimated as degraded LEDs are updated from the reference current values i ₂ and i ₄ to i ₂ + Δi ₂ and i ₄ + Δi ₄ , respectively. Is shown. For other LEDs, the reference current value of the light amount correction data is used as it is. When the lighting control of each LED is performed with the current value thus determined, the lighting amount of the deteriorated LED can be increased from the reference lighting amount.

  In the above example, the lighting amount control unit 34 directly updates the current value in the RAM 36. However, the CPU 30 may directly access the RAM 36 and rewrite the current value. A register may be provided between the amount control units 34, and the lighting amount control unit 34 may rewrite the light amount correction data in the RAM 36 via the registers.

In addition, the lighting amount control unit 34 may perform control to increase the lighting time of the deteriorated LED instead of the control to increase the current value of the deteriorated LED. In FIG. 6, the example of the lighting time after correction | amendment of each LED is shown. The RAM 36 stores the corrected lighting time in association with the light emitting element number of each LED. That is, in the example of FIG. 5, the lighting times of the LEDs of the light emitting element numbers 2 and 4 that are estimated to be degraded LEDs are updated from the reference point equal time t ₀ to t ₀ + Δt ₂ and t ₀ + Δt ₄ , respectively. Is shown.

  The image forming unit 40 includes an LED head 42 and a photoconductor 44, and forms image data as an image on a predetermined sheet. The LED head 42 lights each LED based on the lighting amount control parameter in the RAM 36 corrected by the lighting amount control unit 34 in accordance with an instruction from the lighting control unit 32. Thereby, the LED head 42 can irradiate uniform light with no light quantity variation. This light is condensed by a condensing lens, and a condensing spot is formed on the surface of the photoreceptor 44.

  It should be noted that the light amount correction may not be performed when a drawing is printed, and the light amount correction may be performed when a photograph is printed.

  Hereinafter, the image forming procedure of the image forming apparatus 10 will be briefly described with reference to the flowchart of FIG. First, the controller unit 20 stores image data acquired from a personal computer, a workstation, a scanner, or the like (S100).

  The lighting amount acquisition unit 22 acquires a distribution of lighting amounts for each LED arranged in the LED head 42 based on the image data acquired in S100 (S104).

  Next, the deteriorated element estimation unit 24 identifies a multi-lighting use LED whose cumulative lighting amount is extremely larger than other LEDs based on the distribution of the cumulative lighting amount obtained by the lighting amount acquisition unit 22. (S106). Next, the degradation element estimation unit 24 may estimate that the multi-lighting use LED specified in S106 is a degradation LED as it is, and the accumulated number of times determined to be the multi-lighting use LED in the number storage unit 26. It is stored (S108), and it is determined whether or not there is an element with the number of times of multiple lighting used equal to or more than a predetermined threshold. If there is no element, the printing operation is skipped, and if there is, the element is estimated to be a degraded LED. (S110).

  When the deteriorated LED is estimated by the deteriorated element estimating unit 24, the light emitting element number of the deteriorated LED is transferred to the lighting control unit 32 via the CPU 30. The lighting amount control unit 34 reads the reference lighting amount of each LED from the light amount correction data ROM 38 as the initial value of the lighting amount control parameter, and stores it in the RAM 36. Next, the lighting amount control unit 34 updates the lighting amount control parameter of the deteriorated LED stored in the RAM 36 to a value obtained by adding a predetermined value to the reference lighting amount (S112).

  The LED head 42 lights each LED with the corrected control parameter determined in S112 in accordance with the instruction from the lighting control unit 32. Finally, the latent image formed on the photoconductor 44 is developed with toner and transferred to a sheet of paper to complete the printing process (S114). If the lighting control of each LED is performed with the lighting amount control parameter corrected in this way, it is possible to perform control to increase the light amount individually for the LEDs that have deteriorated due to heavy use, and the light amount of the LED head 42 can be made uniform. it can.

  According to the image forming apparatus 10 described above, even when the light quantity of the LED head 42 varies due to the variation in the lighting frequency of each LED, the position of the deteriorated LED whose light quantity has decreased is estimated individually and specifically. By increasing the lighting amount of the LED more than that of the other non-degraded LED, the variation in the light amount of the LED head 42 can be corrected.

  The present invention is not limited to the above embodiment.

  For example, in the embodiment described above, the configuration in which the degradation LED is estimated by the controller unit 20 of the image forming apparatus 10 is shown, but the same estimation process can be performed by a printer driver of a personal computer. The result information may be sent to the image forming apparatus 10 or may be sent to the image forming apparatus 10 by rewriting the gradation or density of the image data itself. That is, it is possible to adopt a configuration in which a personal computer, a workstation, a scanner, or the like has a configuration corresponding to the controller unit 20 of the image forming apparatus 10.

1 is a configuration diagram of an embodiment of an image forming apparatus according to the present invention. (A) is a figure which shows the example of the drawing image formed with an LED head and an image forming apparatus, (b) is from the image data in which the lighting amount acquisition part has the drawing frame shown by (a). It is a figure which shows the distribution of the acquired lighting frequency of each LED. It is a figure which shows the example of the multiple lighting use frequency of each LED in a frequency memory | storage part. It is a figure which shows an example of the reference | standard lighting amount of each LED in light quantity correction data ROM. It is a figure which shows the example of the electric current value after correction | amendment of each LED. It is a figure which shows the example of the lighting time after correction | amendment of each LED. 6 is a flowchart illustrating an example of an image forming procedure.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Image forming apparatus, 20 Controller part, 22 Lighting amount acquisition part, 24 Deterioration element estimation part, 26 Count storage part, 28 Image forming apparatus control part, 30 CPU, 32 Lighting control part, 34 Lighting amount control part, 36 RAM, 38 Light quantity correction data ROM, 40 Image forming unit, 42 LED head, 44 Photoconductor, 50 Drawing frame.

Claims (8)

In an image forming apparatus that includes a light emitting unit in which a plurality of light emitting elements are arranged, lights each light emitting element of the light emitting unit by a reference lighting amount according to an image signal to be printed, and writes an image on a photoconductor.
Lighting amount acquisition means for acquiring a distribution of the cumulative lighting amount of each or all of the light emitting elements;
A deterioration element estimation means for estimating a part or all of the light emitting elements as deterioration elements based on the distribution of the cumulative lighting amount;
Lighting amount control means for increasing the lighting amount of the deteriorating element more than the reference lighting amount;
An image forming apparatus comprising: The reference lighting amount is a reference current,
The image forming apparatus according to claim 1, wherein the lighting amount control unit increases a current of the deteriorated element more than the reference current. The reference lighting amount is a reference lighting time,
The image forming apparatus according to claim 1, wherein the lighting amount control unit makes a lighting time of the deterioration element longer than the reference lighting time.   The image forming apparatus according to claim 1, wherein the lighting amount acquisition unit acquires a distribution of the number of lighting times as a distribution of a cumulative lighting amount of each light emitting element.   4. The image forming apparatus according to claim 1, wherein the lighting amount acquisition unit acquires a cumulative lighting time distribution as a cumulative lighting amount distribution of each of the light emitting elements. 5. The deterioration element estimation means further comprises a number of times storage means for storing the number of times determined to be multi-lighting use based on the cumulative lighting amount distribution for each light emitting element,
6. The deterioration element estimation unit estimates the light emitting element whose number of times stored in the number storage unit is equal to or more than a predetermined threshold as the deterioration element. The image forming apparatus described in 1.   The lighting amount control unit increases the lighting amount of the deteriorating element more than the reference lighting amount when the usage amount of the image forming apparatus is equal to or more than a predetermined threshold value. The image forming apparatus according to claim 1. In an image forming method that uses a light emitting means in which a plurality of light emitting elements are arranged, lights each light emitting element of the light emitting means by a reference lighting amount in accordance with an image signal to be printed, and writes an image on a photoconductor.
A lighting amount acquisition step of acquiring a distribution of a cumulative lighting amount of each or all of the light emitting elements;
A deterioration element estimation step of estimating a part or all of the light emitting elements as deterioration elements based on the distribution of the cumulative lighting amount;
A lighting control step of increasing the lighting amount of the deteriorating element more than the reference lighting amount;
An image forming method comprising:

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