JP6154762B2 - Image flow detection apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to an image flow detection apparatus and an image forming apparatus.

  In recent years, an image forming apparatus using a photosensitive drum having amorphous silicon (hereinafter referred to as a-Si) as a main material of a photosensitive layer has been used. In these image forming apparatuses, discharge products may adhere to the surface of the photosensitive drum. Under high-humidity environment, these discharge products are ionized and the surface potential of the photoconductor drum decreases, causing a phenomenon that the image is blurred and the periphery of the image is blurred (hereinafter referred to as image flow). There are things to do. When such an image flow occurs, the image quality is degraded. Therefore, in the image forming apparatus described in Patent Document 1, the charging current when the photosensitive drum is charged is measured, the image flow is detected based on the measurement result, and the surface of the photosensitive roller is cleaned based on the detection result. We are carrying out.

  Further, in the image forming apparatus described in Patent Document 2, an image flow detection pattern image is formed to extend in the circumferential direction of the intermediate transfer belt at the center position in the main scanning direction of the intermediate transfer belt. Then, the image sensor detects the image flow by reading the image flow detection pattern image with the density sensor.

JP 2011-209490 A JP 2010-032758 A

  However, in the image forming apparatus described in Patent Document 1, since the charging current is easily affected by the environment such as temperature and humidity, the image flow may not be detected accurately.

  Further, in the image forming apparatus described in Patent Document 2, the image flow can be detected only in a part of the rotation axis direction with respect to the rotation axis of the photosensitive roller, and is generated on the entire surface of the photosensitive roller. The image flow could not be detected.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an image flow detection device and an image forming apparatus that efficiently detect an image flow generated on the surface of a photosensitive roller. .

  An image flow detection apparatus according to the present invention includes an image carrier, an exposure device, a toner supply device, an imaging unit, and a processing unit. The image carrier has a photosensitive roller that is rotatable with respect to a rotation axis. The exposure machine exposes the photosensitive roller. The toner supply device supplies toner to the photoconductor roller after the exposure machine exposes the photoconductor roller, and forms a toner image based on an area of the photoconductor roller exposed by the exposure machine. To do. The imaging unit captures a toner image carried on the image carrier. The processing unit performs a predetermined process. The exposure machine exposes the photosensitive roller with an exposure pattern having a longitudinal direction parallel to the rotation axis, the imaging unit images the toner image formed according to the exposure pattern, and the processing unit Detects an image flow based on the imaging result of the toner image.

  An image forming apparatus according to the present invention includes the image flow detection device described above and an image forming unit that forms an image on a recording medium based on a document.

  According to the image flow detection device of the present invention, it is possible to efficiently detect the image flow generated on the surface of the photosensitive roller.

It is typical sectional drawing which shows the image flow detection apparatus which concerns on Embodiment 1 of this invention. It is a figure which shows the exposure pattern which concerns on Embodiment 1 of this invention. It is a figure which shows the toner image which concerns on Embodiment 1 of this invention. FIG. 3 is a development view in which the periphery of the photoconductor roller according to the first exemplary embodiment of the present invention is developed. (A) is a graph which shows the relationship between the surface potential and image flow of the photoreceptor roller according to Embodiment 1 of the present invention, and (b) is the surface of the photoreceptor roller according to Embodiment 1 of the present invention. 6 is a graph showing a relationship between a luminance value of a formed toner image and occurrence of image flow. (A) is a figure which shows the relationship between the density | concentration of the toner image and image flow which concern on Embodiment 1 of this invention, (b) is a model which shows the surface of the photoreceptor roller which concerns on Embodiment 1 of this invention. FIG. FIG. 6 is a schematic diagram illustrating a toner image transferred to an intermediate transfer belt according to a second embodiment of the invention. It is a schematic diagram which shows the image forming apparatus which concerns on Embodiment 4 of this invention. It is a block diagram concerning Embodiment 4 of the present invention.

  Embodiments of an image flow detection device and an image forming apparatus according to the present invention will be described below with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof is not repeated.

[Embodiment 1: Basic configuration]
A first embodiment of the image flow detection device of the present invention will be described with reference to FIGS. FIG. 1 is a schematic cross-sectional view showing an image flow detection device. FIG. 2 is a view showing an exposure pattern formed on the surface of the photosensitive roller. FIG. 3 is a diagram illustrating a toner image formed on the surface of the photosensitive roller. The X direction shown in the figure is a direction parallel to the rotation axis of the photosensitive roller. The Y direction is a direction orthogonal to the X direction. The Z direction is the vertical direction. In this specification, it is assumed that the resolution of the toner image is 600 dpi.

  As shown in FIG. 1, the image flow detection device 5 includes an image carrier 500, an exposure device 34, a toner supply device 32, an imaging unit 70, and a processing unit 61.

  The image carrier 500 has a photoreceptor roller 31. The photoreceptor roller 31 is a cylindrical base material. A photosensitive layer having a thickness of 10 μm to several tens of μm is formed on the surface of the photosensitive roller 31, and carries an electrostatic latent image and a toner image on the surface. The surface of the photosensitive layer of the photosensitive roller 31 is charged to a predetermined potential. The photoconductor roller 31 rotates clockwise about the X direction as a rotation axis. The photosensitive layer of the photosensitive roller 31 in the present embodiment is made of a-Si having conductivity. Alternatively, the photoreceptor roller 31 can be a selenium arsenide photoreceptor roller, an organic photoreceptor roller, or the like.

  The exposure machine 34 is disposed below the photosensitive roller 31 and irradiates the photosensitive roller 31 with the laser light L based on the exposure pattern to form an electrostatic latent image on the photosensitive roller 31. In this specification, an area where the exposure machine 34 can expose the photosensitive roller 31 is referred to as an exposure area 700.

  The toner supply device 32 develops the electrostatic latent image formed on the surface of the photosensitive roller 31. That is, a toner image 610 is formed based on the exposure pattern 710 on the photosensitive roller 31. In the present embodiment, the toner supply device 32 supplies the toner to the photosensitive roller 31 after the exposure device 34 exposes the exposure pattern 710 to the photosensitive roller 31, and is exposed by the exposure device 34 of the photosensitive roller 31. A toner image 610 is formed based on the region.

  The imaging unit 70 includes an imaging body 71. The imaging unit 70 captures the toner image 610. The imaging unit 70 images the toner image 610 formed on the surface of the photosensitive roller 31 as the photosensitive roller 31 rotates. The imaging body 71 includes a first imaging body 71a and a second imaging body 71b. Note that the image pickup body 71 may not include one of the image pickup body 71a and the image pickup body 71b.

  The first image pickup body 71 a is disposed to face the photoconductor roller 31. The first imaging body 71 a is after the toner supply device 32 has formed the toner image 610 on the surface of the photosensitive roller 31 and before the toner image 610 is transferred from the surface of the photosensitive roller 31 to the intermediate transfer belt 351. In addition, the toner image 610 is disposed at a position where it can be captured. In the present embodiment, the imaging body 71 includes at least an imaging element. The imaging body 71 may include a light source and an equal magnification imaging lens.

  The image sensor reads an image. The light source irradiates the object to be imaged with light. The equal-magnification imaging lens condenses the reflected light from the imaging target onto the imaging element. In the present embodiment, the imaging device is a CMOS image sensor (Complementary Metal Oxide Semiconductor Image Sensor). The light source is an LED array. The equal-magnification imaging lens is a rod lens array.

  The first image pickup body 71 a picks up the toner image 610 formed on the surface of the photoconductor roller 31. In the present embodiment, the first imaging body 71a is a CIS (Contact Image Sensor) having a lens array of equal magnification. The resolution of CIS is 600 dpi.

  The processing unit 61 receives signals from each unit and performs calculations. The processing unit 61 receives the signal from the imaging unit 70 and calculates the toner density of the toner image 610 captured by the imaging unit 70. Then, the processing unit 61 detects the position of the photosensitive roller 31 where the image flow is generated based on the toner density with respect to the rotation axis direction D3. That is, the image flow is detected based on the imaging result of the toner image 610. In the present embodiment, the processing unit 61 includes a central processing unit such as a CPU (Central Processing Unit).

  As shown in FIG. 2, the exposure machine 34 exposes an exposure pattern 710 from one end to the other end of the exposure region 700 in parallel with the rotation axis of the photosensitive roller 31. That is, the exposure machine 34 exposes an exposure pattern 710 whose longitudinal direction is a direction parallel to the rotation axis direction D3 of the photosensitive roller 31. The exposure pattern 710 is preferably continuous from one end of the exposure region 700 to the other end.

  The basic configuration of the image flow detection device has been described above with reference to FIGS. 1 and 2. In general, the image flow tends to occur along the circumferential direction D <b> 1 of the photosensitive roller 31. When image flow occurs in a predetermined region in the rotation axis direction D3, there is a possibility that image flow occurs along the circumferential direction D1. On the other hand, according to the image flow detection device 5 of the present invention, the processing unit 61 is a region where the image flow is generated on the surface of the photosensitive roller 31 based on the region where the image flow is generated in the rotation axis direction D3. Can be predicted. As a result, the image flow detection device 5 can efficiently detect the image flow generated on the surface of the photosensitive roller 31.

  Next, the exposure pattern 710 will be described in detail with reference to FIG. As shown in FIG. 3, the exposure pattern 710 includes a first exposure pattern 711 and a second exposure pattern 721. In the first exposure pattern 711, the direction perpendicular to the rotation axis of the photosensitive roller 31 is a short direction. The second exposure pattern 721 is parallel to the first exposure pattern 711. The width of the first exposure pattern 711 in the short direction is larger than the width of the second exposure pattern 721 in the short direction. Hereinafter, the width in the short direction of the exposure pattern is referred to as the width.

  As described with reference to FIGS. 1 and 2, the exposure pattern 710 is supplied with toner by the toner supply device 32 and becomes a toner image 610. In the present embodiment, the first exposure pattern 711 becomes a toner image 611, and the second exposure pattern 721 becomes a toner image 621. A region where a toner image can be formed is a toner image forming region 600.

  The toner image 621 is parallel to the toner image 611. The toner image 621 extends from one end of the toner image forming region 600 to the other end, and a direction perpendicular to the rotation axis of the photosensitive roller 31 is a short direction. The width W1 in the short direction of the toner image 611 (hereinafter, the width in the short direction of the toner image is referred to as the width W) is larger than the width W2 of the toner image 621. Further, the interval n between the toner image 611 and the toner image 621 is equal to the interval n between the toner image 621 and the toner image 631. In the present embodiment, the width W1 of the toner image 611 is 238 dots (10 mm). The width W2 of the toner image 621 is 2 dots (0.084 mm). An interval n between the toner image 611 and the toner image 621 is 71 dots (3 mm). The width of the toner image 611 is preferably 238 dots (10 mm) or more. The width of the toner image 621 is preferably 1 dot (0.042 mm) to 6 dots (0.252 mm). The interval n between the exposure patterns 710 is preferably 24 dots (1 mm) or more. Note that 1 dot is 0.0042 mm in a 600 dpi environment.

  Next, the relationship between the occurrence of image flow and the toner image 610 will be described in detail with reference to FIGS. FIG. 4 is a development view in which the peripheral surface of the photosensitive roller 31 is developed. FIG. 5A is a graph showing the relationship between the surface potential Sv of the photosensitive roller 31 and the image flow. FIG. 5B is a graph showing the relationship between the luminance value (density) of the toner image formed on the surface of the photosensitive roller 31 and the image flow. In general, the influence of image flow differs depending on the width of the toner image 610 (exposure pattern 710).

  As shown in FIG. 4, a toner image 610 is formed on the surface of the photosensitive roller 31. The toner image 610 is continuously formed from one end to the other end of the toner image forming region 600. The toner image 610 includes a toner image 610a, a toner image 610b, and a toner image 610c. The width Wa of the toner image 610a is 2 dots. The width Wb of the toner image 610b is 4 dots. The width Wc of the toner image 610c is 6 dots. The position P indicates the position of the surface of the photosensitive roller 31 in a direction orthogonal to the rotation axis direction D3.

  The exposure area t indicates the position of the photoconductor roller 31 from the exposure start position Ps to the exposure end position Pe. That is, the exposure area t indicates an area where the toner image 610 is formed in the toner image forming area 600. The non-exposure area f indicates the position of the photosensitive roller 31 from the exposure end position Pe to the exposure start position Ps. That is, the non-exposed area f indicates an area where the toner image 610 is not formed in the toner image forming area 600. The exposure area t and the non-exposure area f are adjacent to each other.

  With reference to FIG. 5, the relationship between the surface potential Sv of the photosensitive roller 31 and the image flow will be described. The horizontal axis of the graph shown in FIG. 5A indicates the position P of the surface of the photosensitive roller 31 shown in FIG. 4 in the direction orthogonal to the rotation axis direction D3. The vertical axis represents the surface potential Sv of the photosensitive roller 31 shown in FIG. A solid line s indicates the relationship between the position P of the photosensitive roller 31 and the surface potential Sv of the photosensitive roller 31 when no image flow occurs. A broken line b indicates the relationship between the position P of the photoconductive roller 31 and the surface potential Sv of the photoconductive roller 31 when image flow occurs.

  The surface of the photosensitive roller 31 is charged to a predetermined potential by the charging device 33. When the exposure device 34 exposes the surface of the photosensitive roller 31, the surface potential of the photosensitive roller 31 decreases.

  As indicated by the solid line s, the surface potential Sv in the exposure region t decreases to a certain value when no image flow occurs. The difference between the surface potential Sv of the exposure region t and the surface potential Sv of the non-exposure region f is large, and the boundary between the surface potential Sv of the exposure region t and the surface potential Sv of the non-exposure region f is clear.

  On the other hand, as shown by the broken line b, when image flow occurs, the decrease in the surface potential Sv at the boundary between the exposure region t and the non-exposure region f is gradual, and the surface potential of the exposure region t is non-existent. The boundary with the surface potential of the exposure region f is unclear. In particular, in the exposure area ta where the toner image 610a is formed, the surface potential Sv gradually decreases, and the difference between the change in the surface potential Sv in the exposure area t and the change in the surface potential Sv in the non-exposure area f is small. . Therefore, image flow is more likely to occur in the exposure region ta where the area of the region where the surface potential is reduced due to exposure is smaller, and less likely to occur in the exposure region tc where the area of the region where the surface potential is reduced is large. I understand. In order to detect a slight image flow, it is effective to reduce the exposure width (exposure time). That is, it is more preferable that the toner supply device 32 forms a toner image 610 having a width of 1 dot so that the image flow detection device 10 detects a slight image flow.

  Next, the relationship between the luminance value (toner density) of the toner image and the image flow will be described with reference to FIG. The horizontal axis of the graph shown in FIG. 5B indicates the position P of the surface of the photosensitive roller 31 in the direction orthogonal to the rotation axis direction D3. The vertical axis represents the luminance value Br of the toner image 610 (toner image 610a, toner image 610b, and toner image 610c) formed on the surface of the photoreceptor roller 31. A solid line s indicates the relationship between the position P of the photosensitive roller 31 in the direction orthogonal to the rotation axis direction D3 and the luminance value Br of the toner image 610 when no image flow occurs. A broken line b indicates a relationship between the position P of the photosensitive roller 31 and the luminance value Br of the toner image 610 in a direction orthogonal to the rotation axis direction D3 when image flow occurs.

  As indicated by the solid line s, the luminance value Br of the toner image 610 shows a high value when no image flow occurs. The difference between the change in the luminance value Br of the exposure region t and the change of the luminance value Br of the non-exposure region f is large, and the boundary between the luminance value Br of the exposure region t and the luminance value Br of the non-exposure region f is clear.

  On the other hand, when image flow occurs, the increase in the luminance value Br at the boundary portion of the exposure region t and the luminance value Br at the boundary portion of the non-exposure region f is moderate, and the luminance value Br of the exposure region t The boundary with the luminance value Br of the non-exposure area f is unclear. In particular, in the exposure area ta where the toner image 610a is formed, the luminance value Br is lower than when no image flow occurs. Furthermore, the boundary between the exposure area ta and the non-exposure area f is also unclear. That is, when the image flow is generated, the lateral flow of the charge is generated, so that the boundary of the surface potential Sv becomes unclear, and the developed toner image 610 corresponds to the toner image 610 according to the image flow level. A change occurs in the luminance value Br.

  As described above, the toner image 610c having the large width Wc is not easily affected by the image flow, and the toner image 610a having the small width Wa is easily affected by the image flow. Further, the toner density (luminance value) of the toner image 610 may change due to environmental changes such as temperature or humidity. Accordingly, the processing unit 61 calculates the toner density of the toner image 610c having a large width Wc and determines the reference density. Thereafter, by calculating the toner density of the toner image 610a having a small width Wa, the toner density of the toner image 610c with respect to the reference density can be calculated. As a result, it is possible to reduce erroneous detection of image flow when the reference density shows a low value.

  Next, a method for calculating the toner density by the processing unit 61 will be described in detail. For example, the exposure pattern 710 may further include a third exposure pattern 731 parallel to the second exposure pattern 721 as shown in FIG. Similarly to the second exposure pattern 721, the third exposure pattern 731 is supplied with toner by the toner supply device 32 and becomes a toner image 631. As shown in FIG. 3, the width W2 of the toner image 621 and the width W3 of the toner image 631 are equal. That is, the width of the second exposure pattern 721 and the width of the third exposure pattern 731 are equal. In the present embodiment, the number of exposure patterns 710 having the same width is two, but may be three or more.

  The first image pickup body 71 a picks up the toner image 610 formed on the surface of the photoconductor roller 31. The first image pickup body 71a first picks up the toner image 611, and then picks up the toner image 621 and the toner image 631 in this order.

The processing unit 61 calculates the toner density based on the imaging result of the first imaging body 71a. The calculation of the toner concentration ratio Tc is obtained by the following formula 1.
Tc = Ac / Bc (Formula 1)
Ac represents an average density of toner densities of the toner image 621 and the toner image 631 having the same width. Bc indicates the toner density value of the toner image 611 having a large width.

  The processing unit 61 first calculates a reference density Bc from the toner density of the toner image 611. Thereafter, the processing unit 61 averages the toner density values of the toner image 621 and the toner image 631, and calculates the average density Ac of the toner density. Then, the ratio (%) of the average density Ac of the toner density to the reference density Bc is calculated.

  In general, it is known that noise generated in the process of imaging by the first imaging body 71a affects the imaging result of the first imaging body 71a. Therefore, the exposure pattern 710 can further include a third exposure pattern 731. The third exposure pattern 731 is parallel to the second exposure pattern 721. The width W2 of the second exposure pattern 721 and the width W3 of the third exposure pattern 731 are equal. Therefore, the first image pickup body 71a can pick up the toner images 610 having the same width over a plurality of times, and can average the image pickup results. Therefore, the image flow detection device 5 can reduce the influence of noise generation on the imaging of the toner image 610 of the first imaging body 71a. As a result, the image flow can be detected more accurately.

  Next, detection of image flow based on the toner density ratio Tc by the processing unit 61 will be described with reference to FIGS. 1 and 6. FIG. 6 is a graph showing the relationship between the toner density ratio Tc and the position P of the surface of the photosensitive roller 31.

  The horizontal axis of the graph shown in FIG. 6 indicates the position P of the surface of the photosensitive roller 31 in the rotation axis direction D3. The vertical axis represents the toner concentration ratio Tc. A dotted line Am on the graph indicates a threshold value. Note that the threshold value Am is arbitrarily set.

  In the region Dp1 and the region Dp2 shown in FIG. 6, the value of the toner density ratio Tc calculated by the processing unit 61 is equal to or less than the threshold value Am. From this, the processing unit 61 can detect that an image flow has occurred in the region Dp1 and the region Dp2 on the surface of the photosensitive roller 31.

  As described above, the processing unit 61 can detect a region where image flow occurs on the surface of the photosensitive roller 31 when the toner density ratio Tc is equal to or less than the threshold value Am. Therefore, the processing unit 61 can predict a region where image flow detection has occurred on the surface of the photosensitive roller 31 based on a region where image flow occurs in the rotation axis direction D3. As a result, the image flow detection device 5 can efficiently detect the image flow on the surface of the photosensitive roller 31.

[Embodiment 2]
Next, an image flow detection device according to the second embodiment of the present invention will be described with reference to FIGS. FIG. 7 shows the toner image transferred to the intermediate transfer belt. FIG. 8 is a schematic diagram showing an image forming apparatus according to Embodiment 2 of the present invention. In the first embodiment and the second embodiment, the image carrier picked up by the image pickup body 71 is different. Hereinafter, regarding the second embodiment, matters different from the first embodiment will be described, and description of matters overlapping with the first embodiment will be omitted.

  As shown in FIG. 8, the photoreceptor roller 31 includes a photoreceptor roller 31Y, a photoreceptor roller 31C, a photoreceptor roller 31M, and a photoreceptor roller 31K. An exposure pattern 710 is exposed to each photoconductor roller 31 by an exposure machine 34. Thereafter, the toner supply device 32 supplies a yellow toner image 610Y to the photoconductor roller 31Y. The toner supply device 32 supplies a cyan toner image 610C to the photoreceptor roller 31C. The toner supply device 32 supplies a magenta toner image 610M to the photosensitive roller 31M. The toner supply device 32 supplies a black toner image 610K to the photosensitive roller 31K.

  The image carrier 500 also includes an intermediate transfer belt 351. A toner image 610 is transferred from the surface of the photoreceptor roller 31 to the intermediate transfer belt 351. The intermediate transfer belt 351 rotates around the plurality of rollers counterclockwise (circumferential direction D2). The intermediate transfer belt 351 is sandwiched between the primary transfer roller 354 and the photosensitive roller 31. The intermediate transfer belt 351 is pressed against the photosensitive roller 31 by the primary transfer roller 354. As a result, the toner image 610 is transferred from the surface of the photosensitive roller 31 to the intermediate transfer belt 351.

  As shown in FIG. 7, the toner image 610 is transferred to the intermediate transfer belt 351 from the surface of the photoreceptor roller 31 corresponding to each color. The toner image 610 includes toner images 610K, 610M, 610C, and 610Y.

  The toner image 610K is continuously transferred from one end to the other end of a transferable area of the toner image 610 (hereinafter referred to as a toner image transfer area 900) on the intermediate transfer belt 351. The toner image 610K includes toner images 611K, 621K, 631K, and 641K. Each toner image 610 is parallel to each other. The toner images 621K, 631K, and 641K have the same width. Further, the intervals between the toner images 610 in the circumferential direction D2 are equal.

  The toner image 610M includes toner images 611M, 621M, 631M, and 641M. The cyan toner image 610C includes toner images 611C, 621C, 631C, and 641C. The yellow toner image 610Y includes toner images 611Y, 621Y, 631Y, and 641Y. Since the width and interval of each toner image 610 are the same as those of the toner image 610K, description thereof is omitted.

  As shown in FIG. 1, the second imaging body 71 b is disposed downstream of the photosensitive roller 31 along the circumferential direction D <b> 2 of the intermediate transfer belt 351. After the toner image 610 is transferred to the intermediate transfer belt 351, the second image pickup body 71b images the toner images 610 on the intermediate transfer belt 351 in the order of toner images 610K, 610M, 610C, and 610Y. Note that the imaging order follows the arrangement of the photosensitive roller 31 corresponding to each toner image 610. In the case of a monochrome multifunction peripheral, the toner image 610 formed on the surface of the photoreceptor roller 31 may be captured using the first imaging body 71a. Furthermore, the position where the second image pickup body 71b is disposed may be a position facing the transfer region 900 along the circumferential direction D2 of the intermediate transfer belt 361.

  In general, the color of the intermediate transfer belt 351 is often black. When the color of the intermediate transfer belt 351 is black, the second imaging body 71b cannot accurately capture the toner image 610K even if the black toner image 610K is transferred to the intermediate transfer belt 351. Therefore, when detecting the image flow using the black toner image 610K, the image flow detection device 5 can also form the black toner image 610K on the yellow toner image 610Y. In other words, the image flow detection device 5 can also form a toner image 610 of a predetermined color among a plurality of colors on the toner image 610 of a color different from the predetermined color.

  The processing unit 61 calculates the toner density ratio Tc based on the result of imaging the toner image 610K by the second imaging body 71b. The processing unit 61 calculates the toner density ratio Tc of the toner images 610M, 610C, and 610Y, similarly to the toner image 610K. After calculating the toner density ratio Tc for each toner color, the image flow on the surface of the photosensitive roller 31 is detected based on the calculated toner density ratio Tc and an arbitrarily set threshold value Am.

  As described above, the image flow detection device 5 further includes the intermediate transfer belt 351 to which the toner image 610 is transferred from the surface of the photosensitive roller 31 as the image carrier 500, and the toner image 610 formed on the intermediate transfer belt 351 is used. It is also possible to take an image. Therefore, the image flow detection device 5 does not need to provide a plurality of image pickup bodies 71 when it has a plurality of photoconductor rollers 31. As a result, the image flow detection device 5 can be designed inexpensively and in a space-saving manner.

[Embodiment 3]
Next, with reference to FIGS. 1 to 4 and 5, imaging by the imaging body 71 in Embodiment 3 of the present invention will be described. The resolution of the imaging body 71 is different between the third embodiment and the first embodiment. Hereinafter, regarding the third embodiment, matters different from the first embodiment will be described, and description of matters overlapping with the first embodiment will be omitted.

  Generally, the resolution of the toner image is determined by the exposure size (pixels) of the exposure device 34. In the present embodiment, the exposure unit 34 exposes the surface of the photosensitive roller 31 with an exposure size corresponding to the toner image 610 having a resolution of 600 dpi. The toner supply device 32 supplies toner to the photosensitive roller 31 and forms a toner image 610 according to the exposure pattern 710 exposed by the exposure device 34. Note that the output power and output time of exposure by the exposure device 34 are constant, and the density of the toner image 610 is constant.

  The toner image 610 having a small width (the toner image 610a shown in FIG. 4) is easily affected by the image flow. Therefore, in order to detect the image flow with high accuracy, the image flow detection device 5 desirably forms a 1-dot toner image 610. However, when image flow occurs, the boundary between the surface potential Sv of the exposure region t and the surface potential Sv of the non-exposure region f becomes unclear. For this reason, the toner image 610 formed on the surface of the photosensitive roller 31 may be formed in a region slightly different from the region to be originally formed (hereinafter referred to as a slightly shifted position).

  In such a case, if the toner image 610 is captured using the imaging body 71 having a resolution of 600 dpi, the imaging body 71 cannot correctly capture the toner image 610 formed at a slightly shifted position, and detects an image flow. There are cases where it is not possible. Therefore, imaging is performed using the imaging body 71 having a resolution of 1200 dpi having a resolution twice that of the toner image 610. The imaging body 71 having a resolution of 1200 dpi can capture an image by dividing the imaging subject finely compared to the imaging body 71 having a resolution of 1200 dpi. Therefore, the image pickup body 71 can pick up the toner image 610 formed at a slightly shifted position. As a result, the image flow detection device 5 can detect a slight image flow.

[Embodiment 4]
Next, with reference to FIGS. 1, 8, and 9, an image forming apparatus including an image flow detecting apparatus according to Embodiment 3 of the present invention will be described. FIG. 9 is a block diagram of the image forming apparatus.

  As shown in FIG. 8, the image forming apparatus 1 includes a reading unit 80, an image forming unit 400, a control unit 60, and an image flow detection device 5. The image forming apparatus 1 can be a copying machine, a printer, a facsimile machine, or a multifunction machine having these functions.

  The reading unit 80 reads an image and generates image data. The reading unit 80 includes a sensor 81, a document table 82, and a movable unit 85.

  The document table 82 is, for example, transparent and formed from glass. The movable unit 85 includes a light source, a lens, and a sensor 81. The movable unit 85 moves below the document table 82. In the present embodiment, the sensor 81 is a CIS.

  For example, the reading unit 80 further includes an automatic document feeder 83. The automatic document feeder 83 includes a placement table 831, a pickup roller 832, a pickup roller 833 a, a conveyance roller 833 b, and a paper discharge table 835. The document conveyance path 834 is a conveyance path of the document M that leads from the placement table 831 to the sheet discharge table 835 via the reading position Q where the reading unit 80 performs reading.

  By placing a plurality of documents M on the placing table 831, it is possible to process a plurality of documents M at a time. When reading the document M using the automatic document feeder 83, the pickup roller 832 draws the document M placed on the placement table 831 one by one into the document transport path 834, and the document M is picked up by the pickup roller 833a. It sends to the conveyance roller 833b. The pickup roller 833a and the transport roller 833b pull out the document M, and when the document M passes the reading position Q, the reading unit 80 reads the document M.

  The image forming unit 400 includes a paper supply unit 10, a paper transport unit 20, an image forming unit 30, a fixing unit 90, and a paper discharge unit 50. The image forming unit 400 forms an image based on the image data read by the reading unit 80.

  The paper supply unit 10 accommodates a recording medium P for printing. When printing is performed, the recording medium P in the paper feeding unit 10 is transported by the paper transport unit 20 so as to be discharged from the discharge unit 50 via the image forming unit 30 and the fixing device 90.

  The paper transport unit 20 transports the recording medium P to the image forming unit 400. The paper transport unit 20 includes a registration roller pair 381.

  The image forming unit 30 forms a toner image on the recording medium P. The image forming unit 30 includes a photosensitive roller 31, a toner supply device 32, a charging device 33, an exposure device 34, and a transfer device 35.

  The charging device 33 includes a charging roller 331 disposed in contact with the surface of the photoreceptor roller 31. The charging device 33 rotates the charging roller 331 to charge the surface of the photosensitive roller 31 to a predetermined potential.

  The exposure machine 34 exposes the surface of the photosensitive roller 31 with laser light based on the image data of the document generated by the reading unit 80 to form an electrostatic latent image.

  The toner supply device 32 includes a developing roller 321. The developing roller 321 supplies toner stored in a toner storage unit (not shown) to the photosensitive roller 31 to develop the electrostatic latent image.

  The photosensitive roller 31 carries an electrostatic latent image and a toner image formed based on the image data of the document. The photoconductor roller 31 sandwiches the intermediate transfer belt 351 between the primary transfer roller 354 disposed opposite to the photoconductor roller 31, and transfers the toner image from the surface of the photoconductor roller 31 to the intermediate transfer belt 351.

  The transfer device 35 includes an endless intermediate transfer belt 351, a driving roller 352, a driven roller 353, a primary transfer roller 354, and a secondary transfer roller 355.

  The intermediate transfer belt 351 is stretched around a driving roller 352, a driven roller 353, and a primary transfer roller 354 so as to be able to go around. The intermediate transfer belt 351 rotates counterclockwise in FIG. 8 by the driving roller 352.

  The primary transfer roller 354 is disposed to face the photosensitive roller 31. The primary transfer roller 354 presses the intermediate transfer belt 351 against the photosensitive roller 31 and transfers the toner image to the intermediate transfer belt 351.

  The secondary transfer roller 355 transfers the toner image transferred to the intermediate transfer belt 351 to the recording medium P. The recording medium P is conveyed by the registration roller pair 381 to the nip portion N between the intermediate transfer belt 351 and the secondary transfer roller 355 in synchronization with the toner image formed on the intermediate transfer belt 351. As a result, the toner image is transferred from the intermediate transfer belt 351 to the recording medium P.

  In the fixing unit 90, the recording medium P is heated and pressed by the fixing member 91 and the pressure member 92, so that the unfixed toner image formed in the toner supply device 32 is melted and fixed on the recording medium P. Let

  The cleaning unit 40 cleans the surface of the photosensitive roller 31 based on the image flow detection result.

  The paper discharge unit 50 discharges the recording medium P.

  The control unit 60 controls each unit. As shown in FIG. 9, the control unit 60 includes a processing unit 61, a storage unit 62, and a control circuit 63. The processing unit 61 performs predetermined processing such as image formation or image reading. The storage unit 62 stores data or firmware. The storage unit 62 includes a RAM (Random Access Memory) or a ROM (Read Only Memory).

  The control circuit 63 electrically controls each part. The control circuit 63 controls the imaging unit 70 and the reading unit 80 with one dedicated control circuit. The control circuit 63 may further include two or more individual control circuits formed on the same substrate as the dedicated control circuit in order to control both the imaging unit 70 and the reading unit 80. The control circuit 63 includes a driving IC (Integrated Circuit), an image processing IC, or an ASIC (Application Specific Integrated Circuit).

  The image flow detection device 5 includes a photosensitive roller 31, a toner supply device 32, an exposure device 34, an intermediate transfer belt 351, and a processing unit 61. The photosensitive roller 31, the toner supply device 32, the exposure device 34, the intermediate transfer belt 351, and the processing unit 61 are also used as the image forming apparatus 1.

  As described above, as described with reference to FIGS. 1, 8, and 9, the control unit 60 can share a part or all of the first control circuit 63a and the second control circuit 63b. That is, the control unit 60 controls the imaging unit 70 and the reading unit 80. Therefore, the control unit 60 can share control of a plurality of functions. As a result, the image flow detection device 5 can be designed at low cost and at high speed.

  Next, the relationship between the resolution of the imaging body 71 and the toner image 610 will be described. For example, the image forming apparatus 1 operates in a print mode Pm in which the image forming unit 400 forms an image on the recording medium P and an image flow detection mode Km in which the processing unit 61 detects an image flow. By using the toner image 610 having a width of 1 dot, the image flow detection device 5 can detect a slight image flow. In order to capture the toner image 610 having a width of 1 dot, it is preferable that the resolution of the image pickup body 71 is at least twice that of the toner image 610 (see Embodiment 3). However, the imaging body 71 having a high resolution is expensive. Therefore, even when imaging is performed using the imaging body 71 having a resolution of 600 dpi, the rotational speed Rk of the photosensitive roller 31 in the image flow detection mode Km is half the rotational speed Rp of the photosensitive roller 31 in the printing mode Pm. By doing so, an effect similar to that obtained by imaging using an imaging body having a resolution of 1200 dpi can be obtained.

  Specifically, in the image flow detection mode Km, when the rotational speed Rk is half of the rotational speed Rp, the imaging range of the imaging object by the imaging body 71 is halved. That is, the imaging range of the imaging target in the image flow detection mode Km is half of the imaging range of the imaging target in the print mode Pm. Therefore, by adjusting the rotation speed Rk of the photoconductor roller 31, the image pickup body 71 can divide the image pickup body finely and pick up an image. As a result, the image forming apparatus 1 can detect a slight image flow with an inexpensive design. Note that the image flow forming apparatus 1 captures the toner image 610 transferred to the intermediate transfer belt 351 by setting the rotation speed Ak of the intermediate transfer belt 351 to half the rotation speed Ap in the printing mode Pm in the image flow detection mode Km. May detect the image flow.

  As described above, the image forming apparatus 1 can adjust the rotation speed of the photosensitive roller in the print mode Pm and the image flow detection mode Km. Further, the rotation speed of the intermediate transfer belt can also be adjusted between the printing mode Pm and the image flow detection mode Km. Therefore, the imaging body 71 can capture the toner image 610 formed at a slightly shifted position without using the imaging body 71 having a high resolution. As a result, the image flow detection device 5 can detect a slight image flow.

  Next, cleaning of the surface of the photosensitive roller 31 based on the image flow detection result of the image forming apparatus 1 will be described. For example, the image forming apparatus 1 exposes the exposure pattern on the surface of the photosensitive roller 31 to detect image flow, and then the image forming apparatus 1 detects the photoconductor by the cleaning unit 40 based on the image flow detection result. The surface of the roller 31 is cleaned. The image forming apparatus 1 can also repeat the detection of the image flow and the cleaning of the surface of the photosensitive roller 31 until the discharge product attached to the surface of the photosensitive roller 31 is removed.

  The embodiment of the present invention has been described above with reference to the drawings (FIGS. 1 to 9). However, the present invention is not limited to the above-described embodiment, and can be implemented in various modes without departing from the gist thereof. In order to facilitate understanding, the drawings schematically show each component as a main component, and the thickness, length, number, and the like of each component shown in the drawings are different from the actual for convenience of drawing. . Moreover, the shape, dimension, etc. of each component shown by said embodiment are an example, Comprising: It does not specifically limit, A various change is possible in the range which does not deviate substantially from the effect of this invention.

  The present invention can be used in the field of image forming apparatuses.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 5 Image flow detection apparatus 60 Control part 61 Processing part 70 Imaging part 71 Imaging body 80 Reading part 31 Photoconductor roller 32 Toner supply apparatus 34 Exposure machine 351 Intermediate transfer belt 400 Image forming part 500 Image carrier 710 Exposure pattern 711 First exposure pattern 721 Second exposure pattern 731 Third exposure pattern Am Threshold value Tc Toner density ratio Pm Printing mode Km Image flow detection mode

Claims (13)

An image carrier having a photosensitive roller rotatable with respect to a rotation axis;
An exposure machine for exposing the photosensitive roller;
A toner supply device that supplies toner to the photoconductor roller after the exposure machine exposes the photoconductor roller, and forms a toner image based on an area of the photoconductor roller exposed by the exposure machine;
An imaging unit that captures a toner image carried on the image carrier;
A processing unit for performing a predetermined process,
The exposure machine, the photoreceptor roller and the longitudinal direction parallel to the rotation axis, a direction perpendicular to the rotary shaft exposed in the exposure pattern to the lateral direction,
The exposure pattern is formed continuously from one end to the other end of the exposure region in the rotation axis direction,
The exposure area is an area where the exposure machine can expose the photosensitive roller,
The exposure pattern includes a first exposure pattern and a second exposure pattern parallel to the first exposure pattern,
The width in the short direction of the first exposure pattern is larger than the width in the short direction of the second exposure pattern,
The imaging unit captures a first toner image and a second toner image formed according to the first exposure pattern and the second exposure pattern ;
The processing unit calculates a toner density of the first toner image and a toner density of the second toner image based on an imaging result of the first toner image and an imaging result of the second toner image, and the first toner image An image flow detection device that determines a toner density of an image as a reference density and detects an image stream based on whether a density ratio between the reference density and the toner density of the second toner image is equal to or greater than a threshold value . The second exposure pattern is plural,
The width in the short direction of each of the plurality of second exposure patterns is equal,
The processing unit calculates an average toner density that is an average value of toner densities of the plurality of second toner images formed according to each of the plurality of second exposure patterns, and calculates the reference density and the average toner. The image flow detection device according to claim 1, wherein the image flow is detected based on whether or not a density ratio with respect to the density is equal to or greater than a threshold value . The imaging unit captures the toner image formed on the photoconductor roller, an image forming apparatus according to claim 1 or claim 2. The image carrier further includes an intermediate transfer belt to which the toner image is transferred from the photosensitive roller.
The imaging unit captures the toner image transferred to the intermediate transfer belt, the image flow detecting apparatus according to any one of claims 1 to 3. The imaging unit is a contact image includes a sensor, an image flow detecting device as claimed in any one of claims 4. The imaging unit has an imaging body,
Resolution of the imaging member comprises two or more times the resolution of the toner image, the image flow detecting apparatus according to any one of claims 1 to 5. The resolution of the imaging body is 1200 dpi,
The image flow detection device according to claim 6 , wherein a resolution of the toner image is 600 dpi. An image flow detection device according to any one of claims 1 to 7 ,
An image forming apparatus comprising: an image forming unit that forms an image on a recording medium based on a document. A reading unit for reading the document;
The image forming apparatus according to claim 8 , further comprising a control unit that controls the reading unit and the imaging unit. The image forming apparatus
A printing mode in which the image forming unit forms an image on a recording medium; and
The processing unit operates in an image flow detection mode in which an image flow is detected,
The image forming apparatus according to claim 8 , wherein the rotation speed of the photosensitive roller is adjustable in the printing mode and the image flow detection mode. The image forming apparatus
A printing mode in which the image forming unit forms an image on a recording medium; and
The processing unit operates in an image flow detection mode in which an image flow is detected,
The image forming apparatus according to claim 9 , wherein a rotation speed of the photosensitive roller is adjustable in the printing mode and the image flow detection mode. The image forming apparatus
A printing mode in which the image forming unit forms an image on a recording medium; and
The processing unit operates in an image flow detection mode in which an image flow is detected,
The image forming apparatus according to claim 8 , wherein the rotation speed of the intermediate transfer belt is adjustable in the printing mode and the image flow detection mode. The image forming apparatus
A printing mode in which the image forming unit forms an image on a recording medium; and
The processing unit operates in an image flow detection mode in which an image flow is detected,
The image forming apparatus according to claim 9 , wherein the rotation speed of the intermediate transfer belt is adjustable in the printing mode and the image flow detection mode.

Images