JP2021081650A - Image forming apparatus and image processing apparatus - Google Patents

Abstract

To provide a technology to expose a photoreceptor considering responsiveness to a light source.SOLUTION: An image forming apparatus comprises: generation means that generates a driving signal indicating exposure areas of pixels indicated by first image data based on the pixel value of the pixels; and exposure means that has a light source whose light emission is controlled based on the driving signal and scans a photoreceptor along a main scanning direction with the light emitted from the light source to form an electrostatic latent image on the photoreceptor. When the pixel value of the pixels indicated by the first image data is larger than the minimum value of a pixel value and within a first range that is equal to or less than a first threshold, or is equal to or more than a second threshold larger than the first threshold and within a second range smaller than the maximum value of the pixel value, the generation means adjusts the pixel values of a plurality of pixels that are adjacent to said pixels in the main scanning direction and include said pixels. All the pixel values of the plurality of pixels after the adjustment are outside the first range and outside the second range, and the difference between the average value of the pixel values of the plurality of pixels after the adjustment and the average value of the pixel values of the plurality of pixels before the adjustment is equal to or less than a predetermined value.SELECTED DRAWING: Figure 11

Description

The present invention relates to an exposure technique for a photoconductor.

The image forming apparatus, for example, forms an electrostatic latent image by exposing a photoconductor and attaches toner, which is a developer, to the electrostatic latent image, that is, develops the electrostatic latent image with toner. To form an image. Here, in the image forming apparatus, reduction of toner consumption is required. Patent Document 1 discloses a configuration in which an image having a certain area is formed by lowering the exposure intensity to reduce toner consumption.

Further, in the image forming apparatus, a phenomenon called sweeping may occur in which the amount of toner adhering to the rear end of the electrostatic latent image formed on the photoconductor in the rotation direction of the photoconductor increases. Patent Document 2 discloses a configuration that suppresses the influence of sweeping. Specifically, the correction area is determined by the data value of the pixel and the data value of the pixel located downstream of the pixel by a predetermined amount in the sub-scanning direction. Then, Patent Document 2 has a configuration in which pixels located upstream of the pixels in the correction area by a predetermined amount in the sub-scanning direction are further set as the correction area, and the exposure amount of the pixels in the correction area is adjusted to suppress the influence of sweeping. It is disclosed. Toner consumption is reduced by suppressing the effect of sweeping.

Japanese Unexamined Patent Publication No. 2004-299239 Japanese Unexamined Patent Publication No. 2007-272153

However, in the configurations described in Patent Documents 1 and 2, the exposure pattern of the photoconductor may be a pattern that the light source for exposing the photoconductor cannot follow. If the exposure is performed in a pattern that the light source cannot follow, the exposure amount may not be the intended value or the durability of the light source may be affected.

The present invention provides an exposure technique for a photoconductor in consideration of the responsiveness of a light source.

According to one aspect of the present invention, the image forming apparatus includes a photoconductor, a generation means for generating a drive signal indicating an exposure region of each pixel based on a pixel value of each pixel indicated by the first image data, and the drive signal. It has a light source whose light emission is controlled based on the light emission, and the photoconductor is scanned along the main scanning direction by the light emitted from the light source to expose the photoconductor and form an electrostatic latent image on the photoconductor. The generation means includes an exposure means, and the generation means is in the case where the pixel value of the pixel indicated by the first image data is larger than the minimum value of the pixel value and is within the first range of being equal to or less than the first threshold value, or When it is equal to or higher than the second threshold value larger than the first threshold value and is within the second range smaller than the maximum value of the pixel value, a plurality of pixels including the pixel adjacent to the pixel in the main scanning direction. The pixel values are adjusted, and all the pixel values of the plurality of pixels after adjustment are outside the first range and outside the second range, and are equal to the average value of the pixel values of the plurality of pixels after adjustment. The difference from the average value of the pixel values of the plurality of pixels before adjustment is not more than a predetermined value.

According to the present invention, the photoconductor can be exposed in consideration of the responsiveness of the light source.

The block diagram of the image forming apparatus by one Embodiment. Explanatory drawing of development method. Explanatory drawing of the generation principle of the edge effect. The figure which shows the image which the sweeping and edge effect occurred. Explanatory drawing of the principle of the occurrence of sweeping. The block diagram of the exposure part by one Embodiment. The explanatory view of the control method of the exposure amount of 1 pixel. The functional block diagram of the exposure control composition by one Embodiment. The figure which shows the image formed by the image data. The figure which shows the correction amount parameter by one Embodiment. The figure which shows the example of the exposure pattern. The figure which shows another example of an exposure pattern.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. The following embodiments do not limit the invention according to the claims. Although a plurality of features are described in the embodiment, not all of the plurality of features are essential to the invention, and the plurality of features may be arbitrarily combined. Further, in the attached drawings, the same or similar configurations are designated by the same reference numbers, and duplicate explanations are omitted.

FIG. 1 is a configuration diagram of an image forming apparatus 101 according to the present embodiment. The photoconductor 1 which is an image carrier is rotationally driven in the direction of the arrow in the drawing at the time of image formation. The charging unit 2 charges the surface of the photoconductor 1 to a uniform potential. The exposure unit 7 exposes the surface of the charged photoconductor 1 with light based on the image data to form an electrostatic latent image on the photoconductor 1. The exposure unit 7 is driven by a drive signal 71 output by the image calculation unit 9. The developing unit 3 includes a container 13 for storing toner, which is a developing agent, and a developing roller 14, which is a developing agent carrier. The toner may be a non-magnetic one-component toner, a two-component toner, or a magnetic toner. The regulation blade 15 is provided to regulate the layer thickness of the toner supplied to the developing roller 14 to a predetermined value. The regulation blade 15 can also be configured to charge the toner. The developing roller 14 conveys the toner to the developing region 16. The developing region 16 is a region in which the developing roller 14 and the photoconductor 1 are in close proximity to each other or in contact with each other, and is a region in which toner is adhered to the electrostatic latent image. Toner is attached to the electrostatic latent image formed on the photoconductor 1 by the developing unit 3 and visualized as a toner image. The transfer unit 4 transfers the toner image formed on the photoconductor 1 to the recording material P. The fixing unit 6 applies heat and pressure to the recording material P to fix the toner image transferred to the recording material P to the recording material P.

The CPU 10 of the image calculation unit 9 is a control unit that comprehensively controls the entire image forming apparatus 101. It should be noted that not only the configuration in which all the controls described below are executed by the CPU 10 but also a part thereof can be executed by the ASIC 18. Further, the ASIC 18 may be configured to execute all of the controls described below. The memory 11 is a storage unit, and is configured to store the image data 111 transmitted from the host computer 8. Further, the memory 11 holds the LUT 112. The LUT 112 is a look-up table and includes a correction width parameter and a correction amount parameter described later. In the present embodiment, the memory 11 is a general term for a volatile memory and a non-volatile memory, and may include a plurality of physically different memories. The LUT 112 indicating the correction width parameter and the correction amount parameter can be configured to be stored in the memory 11 in advance (before shipment). Further, the LUT 112 can be stored in the memory of the cartridge including the photoconductor 14. In this case, when the cartridge is replaced, the CPU 10 reads the LUT 112 stored in the memory of the replaced cartridge and stores it in the memory 11.

As the development method, there are a jumping development method and a contact development method. FIG. 2A shows the configuration of the developing unit 3 in the case of the jumping development method, and FIG. 2B shows the configuration of the developing unit 3 in the case of the contact developing method. In the jumping development method, the developing roller 14 and the photoconductor 1 are not brought into contact with each other, and a gap 17 having a predetermined distance is provided. Then, an AC bias in which a DC bias is superimposed is used as the development bias output by the developing roller 14. In the contact development method, the developing roller 14 and the photoconductor 1 are brought into contact with each other. Then, a DC bias is used as the development bias output by the development roller 14. In any method, the photoconductor 1 and the developing roller 14 are configured to rotate in opposite directions, that is, in the developing region 16, their surfaces move in the same direction.

Next, the edge effect in which the amount of toner adhering to the electrostatic latent image increases at the edge portion and the principle of sweeping will be described. The edge effect is an electrostatic latent image formed on the photoconductor 1, that is, an electric field is concentrated on the boundary between an exposed region and a non-exposed region other than the exposed region, so that toner is applied to each edge of the electrostatic latent image. It is a phenomenon of excessive adhesion. For example, it is assumed that the image to be formed has a uniform density. As shown in FIG. 3, the lines of electric force from the non-exposed areas 301 and 302 around the exposed area 300 wrap around the edge of the exposed area 300, and the electric field strength at the edge is stronger than the other areas of the exposed area 300. Become. Therefore, more toner adheres to the edge of the exposed region 300 than in the other regions.

FIG. 4A shows a toner image 400 in which an edge effect is generated. The arrow A in FIG. 4A is the transport direction of the toner image, that is, the rotation direction of the photoconductor 1. The image data that is the basis of the toner image 400 has the same pixel values, that is, the toner image 400 is an image having a uniform density. When the edge effect occurs, the toner concentrates and adheres to all the edge regions 402a of the toner image 400. As a result, the density of the edge region 402a is higher than the density of the non-edge region 401a. The edge effect is mainly generated by the jumping development method in which there is a gap between the photoconductor 1 and the developing roller 14.

On the other hand, sweeping is a phenomenon in which toner concentrates on the rear end of the photoconductor 1 in the toner image in the rotation direction. In the contact development method, since the thickness of the toner of the photoconductor 1 is set to a predetermined value, the peripheral speed of the developing roller 14 is made faster than the peripheral speed of the photoconductor 1. As shown in FIGS. 5 (A) to 5 (C), in the developing region 16, the electrostatic latent image is developed by the toner conveyed by the developing roller 14. In FIG. 5, the toner is indicated by a circle. Since the developing roller 14 rotates at a speed faster than that of the photoconductor 1, the positional relationship between the two on the surface is constantly deviating. As shown in FIG. 5A, when the rear end of the electrostatic latent image 600 has entered the developing region 16, the toner on the developing roller 14 is behind the starting position of the developing region 16 in the rotational direction. Located in. However, since the rotation speed of the developing roller 14 is faster than the rotation speed of the photoconductor 1, as shown in FIG. 5 (B), by the time the rear end of the electrostatic latent image 600 passes through the developing region 16, the developing roller 14 The toner overtakes the rear end of the electrostatic latent image 600. Then, as shown in FIG. 5C, since this toner of the developing roller 14 is supplied to the rear end of the electrostatic latent image 600, the amount of toner adhering to the rear end of the electrostatic latent image increases. This is the mechanism by which sweeping occurs.

FIG. 4B shows a toner image 410 in which sweeping has occurred. The arrow A in FIG. 4B is the transport direction of the toner image, that is, the rotation direction of the photoconductor 1. The image data that is the basis of the toner image 410 has the same pixel values, that is, the toner image 410 is an image having a uniform density. When sweeping occurs, the toner concentrates and adheres to the rear end region 402b of the toner image 410. As a result, the concentration of the rear end region 402b is higher than the concentration of the other regions 401b.

FIG. 6 is a configuration diagram of the exposed unit 7. The driver IC 2009 switches the switch (SW) of the driver IC 2009 according to the drive signal 71 output by the image calculation unit 9. For example, when the drive signal 71 is at a high level, the driver IC 2009 sets the SW to the ON state, causes the current IL to flow through the laser diode (LD) which is the light source of the exposure unit 7, and causes the LD to emit light. On the other hand, when the drive signal 71 is at a low level, the driver IC 2009 sets the SW to the off state and causes the current IL to flow through the dummy resistor R1 to stop the light emission of the LD. In this way, the driver IC 2009 controls the light emission of the LD based on the drive signal 71.

FIG. 7 is an explanatory diagram of a method of controlling the exposure amount of one pixel by the exposure unit 7. 7 (A) to 7 (D) each show one pixel, a black-painted area shows an exposed area, and a white-painted area shows a non-exposed area. FIG. 7A shows a state in which all the regions of one pixel are exposed with a predetermined intensity. On the other hand, FIGS. 7 (B) to 7 (D) show a state in which the exposure amount is 50% of that of FIG. 7 (A), respectively. Specifically, FIGS. 7 (B) to 7 (D) show a state in which half the area of one pixel is exposed with the predetermined intensity. As described above, in the present embodiment, the exposure amount is adjusted by adjusting the exposure period of each pixel by turning the SW on and off. In this case, the drive signal 71 becomes a PWM (pulse width modulation) signal. In this embodiment, the LD is used as the light source of the exposure unit 7, but the specific configuration of the light source is not limited to the LD, the LED can be used, and the number of light sources is one. Not limited.

In the present embodiment, a pixel in which sweeping or edge effect occurs is specified, and the pixel value of the pixel is corrected to suppress sweeping or edge effect. FIG. 8 shows a functional block for exposure control realized by the CPU 10. For example, the CPU 10 realizes the functional block shown in FIG. 8 by executing the program stored in the memory 11.

The image data 111 stored in the memory 11 is input to the image analysis unit 801. The setting unit 803 reads the LUT 112 stored in the memory 11 and holds the correction width parameter 806 and the correction amount parameter 807 indicated by the LUT 112. The correction width parameter 806 is information for identifying a pixel in which a sweeping or edge effect occurs. The setting unit 803 outputs the correction width parameter 806 to the image analysis unit 801. Based on the correction width parameter 806, the image analysis unit 801 identifies pixels to which a sweeping or edge effect can occur, that is, pixels to be corrected, from the pixels of the image formed by the image data 111. Then, the image analysis unit 801 outputs the image data 111 and the information indicating the correction target pixel to the generation unit 802.

In the present embodiment, the correction width parameter 806 indicates the correction target pixel by the number of pixels from the edge of the region to which the toner adheres. For example, it is assumed that the image formed by the image data 111 is the image 901 shown in FIG. 9, and the correction width parameter 806 indicates "5". In this case, the image analysis unit 801 specifies the pixels in the range of 5 pixels from the edge of the region 902 to which the toner adheres in the image 901 as the correction target pixels. When correcting the sweeping, the range of 5 pixels from the edge on the rear end side in the rotation direction of the photoconductor is the correction target pixel. On the other hand, when correcting the edge effect, the range of 5 pixels from all the edges is the correction target pixel.

Further, the setting unit 803 notifies the generation unit 802 of the correction amount parameter 807. FIG. 10 shows an example of the correction amount parameter 807. In FIG. 10, the correction amount parameter 807 is information indicating the distance from the edge and the correction amount. The generation unit 802 corrects the pixel value of the correction target pixel based on the correction amount parameter 807. When the pixel value of the pixel to be corrected is Y and the correction amount is "X / 32", the generation unit 802 sets the corrected pixel value of the pixel to be corrected to Y- (X × Y / 32). To do. For example, the pixel to be corrected is the fifth pixel from the edge, the pixel value thereof is 255, and the correction amount parameter 807 is as shown in FIG. In this case, the generation unit 802 sets the corrected pixel value of the correction target pixel to 255- (255 × 2/32) ≈239. The generation unit 802 generates a drive signal 71, which is a PWM signal, based on the corrected image data, and outputs the drive signal 71 to the exposure unit 7.

Here, as described with reference to FIG. 6, the exposure unit 7 controls the SW based on the PWM signal (drive signal 71). The period during which the SW is set to the ON state during the exposure period of one pixel depends on the pixel value. For example, if the pixel value Z (Z is a value from 0 to 255), the SW is set to the on state for the period of Z / 255 of the one pixel period, and the SW is set to the off state for the remaining period. Here, if the value of Z is larger than the minimum value (0) of the pixel value and is equal to or less than the first threshold value, the SW is set to the on state and the off state during the exposure period of one pixel. The period may be shortened, and the SW switching operation may not be able to follow. Similarly, when the value of Z is equal to or greater than the second threshold value (> first threshold value) and less than the maximum value (255), the SW is set to the off state and then to the on state during the exposure period of one pixel. The period until is shortened, and the SW switching operation may not be able to follow. Further, when the value of Z is within the above range, the amount of light becomes excessive from the target amount of light when switching from the non-exposed area to the exposed area, and the current increases due to the excessive amount of light, which affects the durability of the exposed portion 7. Sometimes.

Therefore, in the present embodiment, the generation unit 802 includes a pulse corresponding to the pixel value 0, a pulse corresponding to the pixel value 255, and a pixel value from (first threshold value +1) to (second threshold value -1). The corresponding pulse and is used to generate a PWM signal. That is, the pulse whose pixel value corresponds to 1 to 1st threshold value and the pulse whose pixel value corresponds to 2nd threshold value to 254 are not used. Then, when the corrected pixel value is 0, 255, or (first threshold value + 1) or more and (second threshold value -1) or less, the generation unit 802 receives a PWM signal according to the pixel value. Generate a pulse. On the other hand, when the pixel value of the corrected pixel is 1 or more and equal to or less than the first threshold value, or when the pixel value is equal to or more than the second threshold value and is equal to or less than 254, a plurality of pixels including the pixel and continuous in the main scanning direction. Adjust the pixel value of the pixel. At this time, the difference between the average value (or total value) of the exposure amounts of the plurality of pixels before and after the adjustment is set to be equal to or less than a predetermined third threshold value or minimized. It should be noted that the difference may be set to 0. Hereinafter, a specific example will be described. In the following, the first threshold value is 32, the second threshold value is 223, and the number of a plurality of pixels for adjusting the pixel value is 5. Therefore, in the following specific example, when the pixel value is 0, 33 to 222, or 255, the generation unit 802 generates a pulse corresponding to the pixel value. On the other hand, when the pixel value of the pixel is 1-32 or 223 to 254, the generation unit 802 adjusts the pixel value of five pixels including the pixel and consecutive in the main scanning direction. Then, a pulse of the PWM signal is generated based on the adjusted pixel values of these five pixels.

FIG. 11 shows the correction target pixels having a continuous pixel value of 255 in the main scanning direction. The correction amount parameter for each pixel in FIG. 11A is set to 5/32. Therefore, the corrected pixel value is 255- (5/32 × 255) ≈215. In this case, the generation unit 802 does not adjust the pixel value, and exposes each pixel with a pulse corresponding to the pixel value 215 as shown in FIG. 11A.

FIG. 11B shows a case where the correction amount parameter for each correction target pixel is 4/32. Therefore, the corrected pixel value is 255- (4/32 × 255) ≈223. In this case, the generation unit 802 sets the pixel value of 4 pixels out of 5 pixels to 215 and adjusts the pixel value of 1 pixel to 255. Therefore, the average of the pixel values after adjustment is 223, which is the same as the average of the pixel values before adjustment.

FIG. 11C shows a case where the correction amount parameter for each correction target pixel is 3/32. Therefore, the corrected pixel value is 255- (3/32 × 255) ≈231. In this case, the generation unit 802 sets the pixel value of 3 pixels out of 5 pixels to 215 and adjusts the pixel value of 2 pixels to 255. Therefore, the average of the pixel values after adjustment is 231 which is the same as the average of the pixel values before adjustment.

FIG. 11D shows a case where the correction amount parameter for each pixel is 2/32. Therefore, the corrected pixel value is 255- (2/32 × 255) ≈239. In this case, the generation unit 802 sets the pixel value of 2 pixels out of 5 pixels to 215 and adjusts the pixel value of 3 pixels to 255. Therefore, the average of the pixel values after adjustment is 239, which is the same as the average of the pixel values before adjustment.

FIG. 11E shows a case where the correction amount parameter for each pixel is 1/32. Therefore, the corrected pixel value is 255- (1/32 × 255) ≈247. In this case, the generation unit 802 adjusts the pixel value of one pixel out of the five pixels to 215 and the pixel value of four pixels to 255. Therefore, the average of the pixel values after adjustment is 247, which is the same as the average of the pixel values before adjustment.

In addition, in FIGS. 11B to 11E, pixels having a pixel value of 215 and pixels having a pixel value of 255 are mixed, but the arrangement of pixels shown in FIGS. 11B to 11E is an example. There is no limitation on the order of arrangement in the main scanning direction. For example, in FIG. 11B, the pixel value of the fourth pixel from the left is 215 and the pixel value of the fifth pixel is 255, but the pixel with the pixel value 255 is any of the first to fourth pixels. It can also be configured to be placed in.

12 (A) to 12 (E) also show continuous pixels in the main scanning direction. Note that FIG. 12A shows a case where the corrected pixel value is 40. In this case, as shown in FIG. 12A, the generation unit 802 does not adjust the pixel value of each pixel, but exposes with a pulse corresponding to the pixel value 40. FIG. 12B shows a case where the corrected pixel value is 32. In this case, the generation unit 802 sets the pixel value of 4 pixels out of 5 pixels to 40 and adjusts the pixel value of 1 pixel to 0. Therefore, the average of the pixel values after correction is 32, which is the same as the average of the pixel values before correction. FIG. 12C shows a case where the corrected pixel value is 24. In this case, the generation unit 802 sets the pixel value of 3 pixels out of 5 pixels to 40 and adjusts the pixel value of 2 pixels to 0. Therefore, the average of the pixel values after correction is 24, which is the same as the average of the pixel values before correction. FIG. 12D shows a case where the corrected pixel value is 16. In this case, the generation unit 802 sets the pixel value of 2 pixels out of 5 pixels to 40 and adjusts the pixel value of 3 pixels to 0. Therefore, the average of the pixel values after correction is 16, which is the same as the average of the pixel values before correction. FIG. 12E shows a case where the corrected pixel value is 8. In this case, the generation unit 802 sets the pixel value of 1 pixel out of 5 pixels to 40 and adjusts the pixel value of 4 pixels to 0. Therefore, the average of the pixel values after correction is 8, which is the same as the average of the pixel values before correction.

In this way, the generation unit 802 corrects the correction target pixel of the image data (second image data) based on the correction amount parameter, and generates the corrected image data (first image data). Then, the generation unit 802 determines whether the pixel value of the pixel indicated by the first image data is within the first range or within the second range. When the pixel values of the pixels indicated by the first image data are within the first range or within the second range, the generation unit 802 includes the pixels and the pixel values of a plurality of pixels that are continuous in the main scanning direction. To adjust. In the above example, the range of the first range is a range in which the pixel value is 1 to 32 (first threshold value). Further, in the above example, the range within the second range is a range in which the pixel value is 223 (second threshold value) to 254. Here, the generation unit 802 sets all the pixel values of the adjusted plurality of pixels out of the first range and out of the second range. Further, the generation unit 802 determines the difference between the average value (or total value) of the pixel values of the plurality of pixels after adjustment and the average value (or total value) of the pixel values of the plurality of pixels before adjustment. Determined to be less than or equal to the value or the minimum. The first range and the second range are determined according to the response characteristics of the light source of the exposure unit 7. This configuration prevents the light source (or SW) from being turned on and off in a short period of time that the light source cannot follow, which causes the exposure amount to not reach the intended value and affects the durability of the light source. It is possible to prevent it from happening.

When the pixel value of the pixel is within the first range, the generation unit 802 sets the pixel value of each of the plurality of adjusted pixels to the first pixel value or 0, which is larger than the first threshold value. The first pixel value can be, for example, a predetermined value. Further, when the pixel value of the pixel is within the second range, the generation unit 802 can set the pixel value of each of the plurality of adjusted pixels to the second pixel value or 255 which is smaller than the second threshold value. The second pixel value can be, for example, a predetermined value. Further, the number of a plurality of pixels to be adjusted can be a variable number or a fixed number.

In the image data after sweeping or correction of the edge effect, when all the pixel values of a predetermined number of consecutive pixels in the main scanning direction are within the first range or within the second range. The pixel values of these predetermined numbers of pixels may be adjusted to be outside the first range or outside the second range. That is, even if there are pixels having pixel values within the first range or the second range, if the number of consecutive pixels in the main scanning direction is less than a predetermined number, the pixel values may not be adjusted. This is because when the number of consecutive pixels of the pixel values in the first range or the second range is small, the influence on the image quality is small. Further, in this case, even in a configuration in which only a predetermined number of pixels in the first range or the second range are adjusted, the predetermined number of pixels and the predetermined number of pixels are included and are continuous in the main scanning direction. The configuration may be such that the pixel values of a plurality of pixels larger than the predetermined number are adjusted.

The generation unit 802 corrects the correction target pixel of the image data 111 (second image data) based on the correction amount parameter, and generates the corrected image data (first image data). After that, if the corrected image data (first image data) has pixels whose pixel values are within the first range or the second range, the pixel values are outside the first range and outside the second range. The pixel values of a plurality of pixels including the pixel are adjusted. Here, the pixels to be adjusted may be all the pixels shown by the first image data, or may be the pixels to be corrected for the sweeping or edge effect among the pixels shown by the first image data.

The pixel value of the pixel is also a value indicating an exposure period and a non-exposure period within the scanning period of one pixel in scanning in the main scanning direction by the exposure unit 7. Therefore, what the generation unit 802 executes is to adjust the exposure period / non-exposure period of a plurality of pixels that include the pixel and are continuous in the main scanning direction when the pixel indicated by the first image data satisfies a predetermined condition. But also. Here, the predetermined conditions are that the pixel has both an exposure period and a non-exposure period and the non-exposure period is equal to or less than the fourth threshold value, and the pixel has both an exposure period and a non-exposure period. , It is satisfied when the exposure period is equal to or less than the fifth threshold value.

For example, in the above example, the first range is a range of pixel values 1-32. This corresponds to adjusting the pixel value when an exposure period and a non-exposure period exist in one pixel and the exposure period is 32/255 or less of the scanning period of one pixel. Therefore, in the above example, the fifth threshold value is 32/255 of the scanning period of one pixel. Further, in the above example, the second range is set to the range of pixel values 223 to 254. This corresponds to adjusting the pixel value when an exposure period and a non-exposure period exist for one pixel and the non-exposure period is 32/255 or less for a scanning period of one pixel. Therefore, in the above example, the fourth threshold value is 32/255 of the scanning period of one pixel. The generation unit 802 makes adjustments so that all of the adjusted plurality of pixels do not satisfy the predetermined conditions. Further, in the generation unit 802, the difference between the total (or average) of the exposure periods of the plurality of pixels after adjustment and the total (or average) of the exposure periods of the plurality of pixels before adjustment is equal to or less than a predetermined value or is the minimum. Make adjustments so that

When the predetermined condition is satisfied because the non-exposure period is equal to or less than the fourth threshold value, the generation unit 802 sets the non-exposure period of each of the adjusted plurality of pixels to 0 or a value larger than the fourth threshold value. can do. Further, when the predetermined condition is satisfied because the exposure period is equal to or less than the fifth threshold value, the generation unit 802 sets the exposure period of each of the adjusted plurality of pixels to 0 or a value larger than the fifth threshold value. Can be done. A value larger than the fourth threshold value and a value larger than the fifth threshold value can be set as predetermined values.

Further, the memory 11 may be configured to store adjustment information indicating a pixel value pattern to be adjusted and a pixel value pattern after adjustment for the pattern. In this case, the generation unit 802 reads the adjustment information from the memory 11 and detects the pattern of the pixel value to be adjusted from the image data corrected by the correction amount parameter. Then, the detection unit 802 adjusts the pixel value by replacing the detected pixel value pattern with the adjusted pixel value pattern indicated by the adjustment information. As with the LUT 112, the adjustment information can be stored in the memory of the cartridge. In this case, when the cartridge is replaced, the CPU 10 reads the adjustment information stored in the memory of the replaced cartridge and stores it in the memory 11. Further, instead of using the adjustment information, the generation unit 802 detects the pixel to be adjusted based on the pixel value, and the generation unit 802 detects the adjusted pixel value based on the pixel value of a plurality of pixels including the detected image. The generation unit 802 can also be configured so as to determine the above with a predetermined algorithm.

The present invention can also be realized as an image processing device that outputs a drive signal 71 to the image forming device. The image processing apparatus has the configuration shown in FIG.

[Other Embodiments]
The present invention supplies a program that realizes one or more functions of the above-described embodiment to a system or device via a network or storage medium, and one or more processors in the computer of the system or device reads and executes the program. It can also be realized by the processing to be performed. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

The invention is not limited to the above embodiments, and various modifications and modifications can be made without departing from the spirit and scope of the invention. Therefore, a claim is attached to make the scope of the invention public.

1: Photoreceptor, 802: Generation part, 7: Exposure part

Claims (14)

Photoreceptor and
A generation means for generating a drive signal based on the pixel value of each pixel indicated by the first image data, and
It has a light source whose light emission is controlled based on the drive signal, and the photoconductor is exposed by scanning the photoconductor along the main scanning direction with the light emitted from the light source, and the photoconductor is electrostatically latent. The exposure means that forms the image and
With
In the generation means, when the pixel value of the pixel indicated by the first image data is within the first range which is larger than the minimum value of the pixel value and is equal to or less than the first threshold value, or is larger than the first threshold value. When it is equal to or more than two thresholds and is within the second range smaller than the maximum value of the pixel value, the pixel values of a plurality of pixels including the pixel and consecutive pixels in the main scanning direction are adjusted.
All the pixel values of the plurality of pixels after adjustment are outside the first range and outside the second range.
An image forming apparatus, characterized in that the difference between the average value of the pixel values of the plurality of pixels after adjustment and the average value of the pixel values of the plurality of pixels before adjustment is equal to or less than a predetermined value. When the pixel value of the pixel is not the minimum value of the pixel value and is equal to or less than the first threshold value, the generation means determines that the pixel value is within the first range, and the pixel value of the pixel is determined to be within the first range. The image forming apparatus according to claim 1, wherein when the value is equal to or higher than the second threshold value and the pixel value is not the maximum value, the pixel value is determined to be within the second range. When the pixel value of the pixel is within the first range, the generation means sets the adjusted pixel value of each of the plurality of pixels to the first pixel value larger than the first threshold value or the minimum value. The image forming apparatus according to claim 2. When the pixel value of the pixel is within the second range, the generation means sets the adjusted pixel value of each of the plurality of pixels to a second pixel value smaller than the second threshold value or the maximum value. The image forming apparatus according to claim 2 or 3. The image forming apparatus according to any one of claims 2 to 4, wherein the first threshold value and the second threshold value are values corresponding to the response characteristics of the light source to the drive signal. When the first image data indicates that the pixels having the pixel values in the first range are continuous by a predetermined number in the main scanning direction, the generation means is a pixel in the second range. When the first image data indicates that the pixel values of the values are continuous by a predetermined number in the main scanning direction, the adjustment of the pixel values of the plurality of pixels is executed.
The predetermined number is the same as the number of the plurality of pixels for which the pixel value is adjusted, or is smaller than the number of the plurality of pixels for which the pixel value is adjusted, according to any one of claims 1 to 5. The image forming apparatus according to the description. Further, a holding means for holding information for specifying the correction target pixel and information indicating the correction amount of the pixel value of each correction target pixel is provided.
The image forming according to any one of claims 1 to 6, wherein the generation means corrects the second image data based on the information held by the holding means to generate the first image data. apparatus. The generation means includes the correction target pixel when the pixel value of the correction target pixel indicated by the first image data is within the first range or within the second range, and includes the correction target pixel, and the main scanning direction. The image forming apparatus according to claim 7, wherein the pixel values of a plurality of consecutive pixels are adjusted. Photoreceptor and
A generation means for generating a drive signal indicating the exposure period of each pixel based on the pixel value of each pixel indicated by the first image data, and a generation means.
It has a light source whose light emission is controlled based on the drive signal, and the photoconductor is exposed by scanning the photoconductor along the main scanning direction with the light emitted from the light source, and the photoconductor is electrostatically latent. The exposure means that forms the image and
With
When the pixels indicated by the first image data satisfy a predetermined condition, the generation means adjusts the exposure period of a plurality of pixels including the pixels and continuous in the main scanning direction.
Pixels that satisfy the predetermined conditions have both an exposure period and a non-exposure period, and a pixel whose non-exposure period is equal to or less than the first threshold value and a pixel that has both an exposure period and a non-exposure period and an exposure period. Is a pixel below the second threshold
All of the plurality of pixels after adjustment do not satisfy the predetermined conditions, and the above-mentioned predetermined conditions are not satisfied.
An image forming apparatus, characterized in that the difference between the total exposure period of the plurality of pixels after adjustment and the total exposure period of the plurality of pixels before adjustment is equal to or less than a predetermined value. When the predetermined condition is satisfied because the non-exposure period is equal to or less than the first threshold value, the generation means sets the non-exposure period of each of the plurality of pixels after adjustment to 0 or larger than the first threshold value. The image forming apparatus according to claim 9, wherein the value is used. When the predetermined condition is satisfied because the exposure period is equal to or less than the second threshold value, the generation means sets the exposure period of each of the plurality of adjusted pixels to 0 or a value larger than the second threshold value. The image forming apparatus according to claim 9 or 10. The image forming apparatus according to any one of claims 9 to 11, wherein the first threshold value and the second threshold value are values corresponding to the response characteristics of the light source to the drive signal. It has a photoconductor and a light source whose light emission is controlled based on a drive signal, and the photoconductor is exposed by scanning the photoconductor along the main scanning direction with the light emitted by the light source to expose the photoconductor to the photoconductor. An image processing device that outputs the drive signal to an image forming device having an exposure means for forming an electrostatic latent image.
A generation means for generating the drive signal based on the pixel value of each pixel indicated by the first image data is provided.
In the generation means, when the pixel value of the pixel indicated by the first image data is within the first range which is larger than the minimum value of the pixel value and is equal to or less than the first threshold value, or is larger than the first threshold value. When it is equal to or more than two thresholds and is within the second range smaller than the maximum value of the pixel value, the pixel values of a plurality of pixels including the pixel and consecutive pixels in the main scanning direction are adjusted.
All the pixel values of the plurality of pixels after adjustment are outside the first range and outside the second range.
An image processing apparatus characterized in that the difference between the average value of the pixel values of the plurality of pixels after adjustment and the average value of the pixel values of the plurality of pixels before adjustment is equal to or less than a predetermined value. It has a photoconductor and a light source whose light emission is controlled based on a drive signal, and the photoconductor is exposed by scanning the photoconductor along the main scanning direction with the light emitted by the light source to expose the photoconductor to the photoconductor. An image processing device that outputs the drive signal to an image forming device having an exposure means for forming an electrostatic latent image.
A generation means for generating the drive signal indicating the exposure period of each pixel based on the pixel value of each pixel indicated by the first image data is provided.
When the pixels indicated by the first image data satisfy a predetermined condition, the generation means adjusts the exposure period of a plurality of pixels that include the pixels and are continuous in the main scanning direction.
Pixels that satisfy the predetermined conditions have both an exposure period and a non-exposure period, and a pixel whose non-exposure period is equal to or less than the first threshold value and a pixel that has both an exposure period and a non-exposure period and an exposure period. Is a pixel below the second threshold
All of the plurality of pixels after adjustment do not satisfy the predetermined conditions, and the above-mentioned predetermined conditions are not satisfied.
An image processing apparatus characterized in that the difference between the total exposure period of the plurality of pixels after adjustment and the total exposure period of the plurality of pixels before adjustment is equal to or less than a predetermined value.

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