JP2003182149A - Imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging apparatus which realizes high-quality imaging by improving density irregularities, color tone irregularities or the like and restraining generation of black streaks, white streaks or the like. <P>SOLUTION: A plurality of light emitting elements are set at a VCSEL 1, so that latent images of a plurality of lines can be formed on an image carrier 5 by one horizontal scanning. Among the light emitting elements set at the VCSEL 1, a part of the elements is utilized as light emitting elements for auxiliary images, and the light emission is controlled by a control unit 7. For example, the light emitting elements for auxiliary images are made to emit light by some degree for a region where the density is low as a whole image, thereby raising the density. The density of the whole can be nearly uniformed accordingly. Moreover, a leading end or a rear end of the plurality of light emitting elements, or both parts are reduced in the emission amount, whereby black streaks at a boundary part of band-shaped regions formed by a plurality of horizontal scannings can be prevented. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus for forming an image or an electrostatic latent image according to an image signal by light on a photosensitive member.

[0002]

2. Description of the Related Art Generally, in an electrophotographic image forming apparatus, an image or an electrostatic latent image corresponding to an image signal is formed on a photosensitive drum or a photosensitive belt by a laser beam or the like,
After development, the image is formed by transferring it to a sheet or the like. In such a conventional electrophotographic image forming apparatus, the following problems have occurred due to various device characteristics, deterioration over time of use, environmental changes, and the like. Density unevenness and tint are locally changed in one image. (For example, the original has a uniform density, but the density is high on the left side or the leading edge side of the output image.) The density changes every time the output is performed, or the color reproducibility of the image changes. (For example, although the same original is used, there is a difference in density reproduction between morning, daytime, and night.) The density varies between products of the same model, or the color reproducibility of an image varies. (For example, although the same manuscript is used, the color reproduction of the image differs between the head office and the branch where the device with the same product name is installed.) Of these, the most demanded improvement is the barometer that shows the basic image quality of the product. It should be called. As a solution for this, the color measurement data of the output image and the sensor detection data of the surface potential / image density patch of the photoconductor drum are fed back to the image processing unit, and various image processing parameters are changed to output the image. To generate an image.

The following are specific examples of these methods. (1) Japanese Laid-Open Patent Publication No. 6-135051 provides correction tables (LUTs) for axial and circumferential color variations of a photosensitive drum, and corrects density variations using this LUT. Or a technique of correcting the density gradient by changing the gradient of the photosensitive drum itself. (2) Further, in the technique described in Japanese Patent Laid-Open No. 5-153353, based on the irradiation light amount measured by a plurality of laser irradiation light amount measuring devices (center portion and both end portions) in the axial direction of the photosensitive drum. Correcting image data.
In this way, it is intended to solve the local uneven density and the variation of the tint in one image. (3) Various fluctuations are reduced by improving the performance and accuracy of individual functional components. For example, in the case of a photosensitive drum, raw materials that are less susceptible to sensitivity deterioration due to exposure fatigue have been introduced, and processing techniques with good parallelism and straightness have been adopted to eliminate eccentricity. Further, efforts are being made to improve the accuracy of assembly adjustment, for example, to maintain the axial gap between the corotron wire and the photosensitive drum and the axial gap between the magnet roll of the developing machine and the photosensitive drum. Has been.

However, in the techniques described in (1) and (2) above, it is necessary to incorporate a dedicated hardware device and to mount a large memory capacity for image processing,
It was not always desirable because it increased the cost and increased the size of the equipment itself.

Further, with the technique described in (3), good image reproduction can be performed immediately after factory shipping inspection and after maintenance adjustment after installation. However, due to factors such as an increase in the number of output sheets and changes over time (temperature / humidity characteristics, etc.), local density unevenness and tint fluctuations that occur in one image gradually deteriorate. The impact on stability was unavoidable.

On the other hand, a vertical cavity surface emitting laser (Vertical Surface Emitting Laser) has recently been used as one of laser light sources applicable to an image forming apparatus.
ngLaser Diode: hereinafter referred to as VCSEL) has been developed. FIG. 9 is an explanatory diagram of an example of an array of light emitting elements in the VCSEL. In the figure, 21 is a light emitting element. In the VCSEL, a plurality of light emitting elements 21 serving as light sources can be arranged two-dimensionally. In this example, 6 × 6 light emitting elements 21 are arranged in each row with a slight shift so that no other light emitting element 21 exists on the left and right of each light emitting element 21 in the figure.

The laser light emitted from each light emitting element 21 of such a VCSEL is used to scan the left and right in the drawing as the main scanning direction, and the images of a plurality of main scanning lines can be written on the photosensitive member at once. . Then, the photosensitive member is advanced in the sub-scanning direction by the width (band width) that can be written by one main scanning, and the sub-scanning is performed. By repeating such an operation, it is possible to write an image or an electrostatic latent image on the photosensitive member.

FIG. 10 is an explanatory diagram showing an example of a problem when the VCSEL is used. As described above, when writing is performed on the photosensitive member using the VCSEL, there is a problem that black stripes are generated at the seams of the bands. That is, as shown in FIG. 10, after writing for one band by a certain main scan, writing for one band by the next main scan is performed at a position shifted by the bandwidth.
At that time, the laser light at the rear end portion of the previous main scanning and the laser light at the front end portion of the next main scanning are partially irradiated at the same position on the photosensitive member. Therefore, the photosensitive amount of the photosensitive member is increased in the portion where the laser light is overlapped and the density of the image is higher than that in the other portions, and the black stripes appear as described above.

In order to prevent the occurrence of such black stripes, it is conceivable to increase the movement distance during the sub-scan to some extent.
However, this time, there is also a problem that "white stripes" partially occur due to not being irradiated with the laser beam, and the image quality is deteriorated.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and is a problem peculiar to the use of a plurality of light-emitting elements in which uneven density, unevenness in color and the like are improved. An object of the present invention is to provide an image forming apparatus that suppresses the generation of black stripes and white stripes and realizes high-quality image formation.

[0011]

SUMMARY OF THE INVENTION The present invention is an image forming apparatus for forming an image or an electrostatic latent image according to an image signal on a photosensitive member, and a plurality of two-dimensionally arranged at a predetermined density. A light emitting source such as a vertical cavity surface emitting laser, which is composed of a light emitting element, a light emitting control means for controlling light emission of each light emitting element in the light emitting source according to the image signal, and a light emitted from the light emitting source. The light emission control means has a scanning means for performing a main scanning in one direction and a driving means for driving a photosensitive member in a sub-scanning direction in a direction substantially orthogonal to the main scanning, and the light emission control means includes at least one of the plurality of light emitting elements. It is characterized in that light emission is controlled by using a book or more as a light emitting element for an auxiliary image.

As described above, in the present invention, a part of the plurality of light emitting elements is used as a light emitting element for auxiliary image. Then, for example, by causing a certain amount of light to be emitted from the auxiliary image light emitting element in the low density portion, it is possible to increase the irradiation light amount to the photosensitive member and increase the density. As a result, it is possible to reduce uneven density and uneven color tone over the entire image and form a high quality image.

For example, the light emitting elements for the auxiliary image are evenly distributed so that it is possible to deal with unevenness at any position in the image.
The unevenness in the sub-scanning direction can be dealt with by distributing to the upper or lower part or both upper and lower ends, or the unevenness in the main scanning direction can be dealt with by distributing to both left and right ends.

At this time, for example, the light quantity of the light emitting elements for the auxiliary image, the light emission time (cycle), the number of light emitting elements are variably controlled, or the arrangement pattern of the light emitting elements for the auxiliary image is changed, so that the density unevenness or the color unevenness is caused. It is possible to control according to the degree. Further, such emission control of the auxiliary image light emitting element can be performed based on the output image information, the input image signal, or the user's instruction.

Further, the light emission control of the light emitting element for the auxiliary image can be performed based on the auxiliary image different from the image signal or both the image signal and the auxiliary image. For example, an image for density unevenness correction or an image for overall auxiliary exposure can be used as an auxiliary image.

Further, for example, an auxiliary image light emitting element is used to embed an embedded image for suppressing illegal copying in an image signal, or a copy prevention image such as a bill or an image control pattern image is superimposed on the image signal. You can also let it.

[0017]

1 is a schematic configuration diagram showing an embodiment of an image forming apparatus of the present invention. In the figure, 1 is VC
SEL, 2 is an optical system, 3 is a rotary polygon mirror, 4 is a rotary polygon mirror drive unit, 5 is an image carrier, 6 is an image carrier drive unit, and 7 is a control unit. The VCSEL 1 is a light emitting source in which a plurality of light emitting elements are two-dimensionally arranged at a predetermined density on one surface, as shown in FIG. 9 described above. By using such a VCSEL 1, a plurality of main scan lines can be formed by one main scan. As described above, since a plurality of main scanning lines can be formed by one main scanning, it is possible to reduce the number of rotations of the rotary polygon mirror described later, or conversely, it is possible to form an image at high speed. . Furthermore, each light emitting element can be arranged so that each light emitting element forms an image of a different main scanning line, and in this case, as shown in FIG. Main scanning lines can be formed with high density, and high-resolution image formation is possible. In the present invention, a part of the plurality of light emitting elements is used as the auxiliary image light emitting element by the control unit 7 as described later.

An optical system 2 and a rotary polygon mirror 3 are arranged on an optical path from a plurality of light emitting elements provided in the VCSEL 1 to the image carrier 5. In this example, the optical system 2 is arranged before and after the rotary polygon mirror 3. The optical system 2 can be configured by using an arbitrary optical element at the time of designing. The rotary polygon mirror 3 is a member having a polygonal cross section with a mirror surface arranged around it, and reflects the laser light emitted from the VCSEL 1 to the image carrier 5. At this time, the rotary polygon mirror 3 is rotationally driven by the rotary polygon mirror drive unit 4. By this rotation, the direction in which the laser light emitted from the VCSEL 1 is reflected is changed, and main scanning is performed.

A photosensitive layer is provided on the surface of the image carrier 5, and an electrostatic latent image can be written by irradiating a laser beam. On the image carrier 5, the spots of the plurality of laser beams emitted from the VCSEL 1 linearly move in the axial direction by the main scanning by the rotary polygon mirror 3 as described above. As a result, a belt-shaped electrostatic latent image having a predetermined width is written by one main scan. The image carrier 5 is rotationally driven by the image carrier driving unit 6, and thereby performs sub scanning.

The control unit 7 controls the VCSE based on the image signal.
It functions as a light emission control means for controlling the light emission of L1. In this example, the drive control of the rotary polygon mirror drive unit 4 and the image carrier drive unit 6 is performed, and main scan and sub-scan control is also performed. Of course, these controls can be performed separately.

When the control unit 7 controls the light emission of the VCSEL 1, a part of the plurality of light emitting elements provided in the VCSEL 1 is controlled to emit light as an auxiliary image light emitting element, and the other light emitting elements are image-drawn. The light emission is controlled according to the image signal for use. VCSEL as a light emitting element for auxiliary image
Which position of the light emitting element 1 is used will be described later using a specific example. The light emission control of the light emitting element for the auxiliary image can be performed according to the auxiliary image prepared separately and according to the image signal input with the auxiliary image. Also, as the light emission control itself, in addition to the lighting control,
It is possible to variably control the amount of light, the light emission time (cycle), the number of light emitting elements, the position of the light emitting elements to emit light, and the like. Also,
It is also possible to control the image formation while appropriately changing the light emitting element used as the auxiliary image light emitting element.

Some arrangement patterns of auxiliary image light emitting elements will be shown below. In the drawings of the array patterns shown below, it is assumed that the VCSEL 1 is provided with 6 × 6 light emitting elements, and for simplification of the illustration, the light emitting elements are arranged in a matrix without taking into consideration the deviation of each light emitting element. Shows. Further, in the figure, indicates a light emitting element for image drawing,
Indicates a light emitting element for auxiliary image.

FIG. 2 is an explanatory diagram of a typical example of an array pattern when the light emitting elements for auxiliary image are evenly distributed. Figure 2
In (A), an example in which rows of light emitting elements for image drawing and rows of light emitting elements for auxiliary image are alternately arranged is shown. Figure 2
(B) shows an example in which rows of light emitting elements for image drawing and rows of light emitting elements for auxiliary image are alternately arranged. Further, FIG. 2C shows an example in which light emitting elements for image drawing and light emitting elements for auxiliary images are arranged alternately in the column direction and the row direction. FIG. 2D illustrates an example in which columns in which the light-emitting elements for auxiliary images are arranged are alternately arranged and the light-emitting elements for auxiliary images are arranged every other row in the column in which light-emitting elements for auxiliary image are arranged. There is.

In such an array pattern of the light emitting elements for the auxiliary image, the light emitting elements for image drawing and the light emitting elements for the auxiliary image are mixed, so that the density can be adjusted at the level of each pixel position. Therefore, it is possible to finely adjust the density. For example, when it is known that the density becomes low in a partial area in the image, the auxiliary image light emitting element may be controlled to emit light when drawing the area.
This makes it possible to reduce uneven density over the entire image. In the case of color, color unevenness can be reduced by performing such emission control of the auxiliary image light emitting element for each color material color.

In adjusting the density, for example, a sample image may be formed in advance, data of density unevenness may be acquired from the sample image, and the data may be used as an auxiliary image. When using the auxiliary image, for example, regardless of the input image signal, the auxiliary image light-emitting element emits light in accordance with the density in a portion having a low density according to the auxiliary image so that the density can be made uniform. . Alternatively, it is possible to perform light emission control by using an auxiliary image together with an image signal and increasing the density adjustment amount for a dark image portion and decreasing the density adjustment amount for a light image portion.

FIG. 3 is an explanatory view of a typical example of an array pattern in the case where the light emitting elements for auxiliary image are distributed at both lateral ends. Figure 3
The array pattern shown in FIG. 9A shows an example in which the left and right columns are used as auxiliary image light emitting elements. As a modified example, the array pattern shown in FIG. 3B shows an example in which one column at the left end and one column at the center are used as auxiliary image light emitting elements. Of course, the same applies when the rightmost and central columns are used as auxiliary image light emitting elements. Also, 1
Not limited to the number of columns, the number of columns used as the auxiliary image light emitting elements can be set.

Such an array pattern of the light emitting elements for the auxiliary image is effective when, for example, the density of the formed image is different on the right and left sides. As shown in FIG. 3C, when the density is low on the left side and the density is high on the right side, the auxiliary image light emitting element is turned on to increase the density in the left area, and the density shifts to the right area. The amount of irradiation of the image carrier 5 by the light emitting element for auxiliary image is gradually reduced, and the light emitting element for auxiliary image is turned off in the right area to suppress an increase in density. In this way, the left and right densities can be kept uniform. Of course, when the density on the right side is low and the density on the left side is high, the light emission amount of the auxiliary image light emitting element may be controlled to increase in the right side region. The same applies to the case where the density increases or decreases in the central portion, and the auxiliary image light emitting element may be turned on in the low density portion.

FIG. 4 is an explanatory view of a typical example of an array pattern when the light emitting elements for auxiliary image are vertically distributed. Figure 4
The array pattern shown in FIG. 7A shows an example in which the upper and lower rows are used as auxiliary image light emitting elements. As a modified example, the array pattern shown in FIG. 4B shows an example in which one row at the upper end and one row at the center are used as the light emitting elements for auxiliary images. Of course, the same applies when the rows at the lower end and the central portion are used as the light emitting elements for the auxiliary image. Also, 1
Not limited to the rows, it is possible to set the number of rows used as the light emitting elements for the auxiliary image.

Such an array pattern of the light emitting elements for the auxiliary image is effective, for example, when the densities of the formed image are different above and below. As shown in FIG. 4C, when the density is low on the upper side and high on the lower side, the auxiliary image light emitting element is turned on to increase the density in the upper area (at the beginning of image formation). Then, the amount of irradiation of the auxiliary image light-emitting element to the image carrier 5 is gradually reduced as it moves to the lower area (the image formation is advanced), and the lower area (at the end of the image formation). Then, the light emitting element for auxiliary image is turned off to suppress the increase in density. In this way, the upper and lower densities can be kept uniform. Of course, when the lower density is low and the upper density is high, the amount of light emitted from the auxiliary image light emitting element may be controlled to increase in the lower region. The same applies to the case where the density increases or decreases in the central portion, and the auxiliary image light emitting element may be turned on in the low density portion.

FIG. 5 is an explanatory view of an application example of an array pattern in which the auxiliary image light emitting elements are vertically distributed. Figure 4 above
By using the arrangement pattern of vertical both ends distribution as shown in FIG. 9A, it is possible to prevent the generation of black stripes as shown in FIG. Specifically, the light amount of the auxiliary image light emitting element surrounded by a broken line in FIG. 5 is reduced. The black streak shown in FIG. 10 occurs at the joint portion of each scan.
In the VCSEL 1, each auxiliary image light emitting element actually draws a different line as shown in FIG. 9, and an image of a band-shaped area can be drawn by one main scan. It is the upper left auxiliary image light emitting element in FIG. 5 that irradiates the upper end portion of the band-shaped region with the laser light, and the lower right portion of FIG. 5 irradiates the lower end portion with the laser light. Is. At the seam of the band-shaped areas drawn by the main scanning, in the same main line drawn by the auxiliary image light-emitting element on the lower right in the main scanning of the previous two times of the two main scanning for drawing the adjacent band-shaped areas, A black streak occurs due to the auxiliary image light-emitting element on the upper left drawing by one main scan. Therefore, as shown in FIG. 5, the light amounts of the auxiliary image light emitting element on the upper left (that is, the upper end of the strip-shaped area is drawn) and the lower right (that is, the lower end of the strip-shaped area is drawn) By suppressing, the total light amount is suppressed even when the laser light is overlapped and irradiated on the image carrier 5, so that the generation of the black stripes as shown in FIG. 10 can be prevented. For example, in FIG.
By reducing the light amount of the six auxiliary image light emitting elements surrounded by the broken line in the figure by 25%, it was possible to improve the black stripes to a level at which they cannot be visually recognized.

Conventionally, when drawing is performed using a large number of light emitting elements such as the VCSEL 1, black streaks or white streaks are generated unless sub-scanning is accurately performed. However, according to the present invention, as described above, when the black stripes are generated, the occurrence of the black stripes can be suppressed by adjusting the light emission amount of the auxiliary image light emitting element. On the contrary, it is also possible to provide an overlap in advance so that white stripes do not occur and to adjust by the light emission amount of the auxiliary image light emitting element.

In the example shown in FIG. 5, three light emitting elements for the upper left and lower left are provided as auxiliary image light emitting elements for suppressing the amount of light in order to prevent black streaks. The number of light emitting elements for image can be arbitrarily set according to the number of overlapping lines in each main scan. Further, it is also possible to control so that the light amount is greatly suppressed only in the upper left or only the lower right. Further, the amount of reducing the light amount is also arbitrary.

FIG. 6 is an explanatory view of a typical example of an array pattern when the light emitting elements for auxiliary image are vertically distributed. Figure 6
The array pattern shown in FIG. 9A shows an example in which the lower half is used as a light emitting element for auxiliary image. In addition, FIG. 6 (B)
In the array pattern shown in (1), the right half is used as a light emitting element for auxiliary image. These arrangement patterns can correct the density change in the vertical direction of the image in the same manner as the vertical both end distribution shown in FIG. 4 in FIG. 6A, for example. Of course, it is also possible to use several light emitting elements from the right of the lower end to prevent black stripes. In addition, in FIG.
Similar to the lateral both-ends distribution shown in (1), it is possible to correct the density change in the horizontal direction of the image.

Further, in the case of the array pattern shown in FIG. 6A, the speed of sub-scanning (or the distance of one sub-scanning) is halved, and the sub-scanning is performed in each half of the width that can be drawn in one main scanning. By performing the above, it is possible to perform two exposures at the same position on the image carrier 5 by the light irradiation by the auxiliary image light emitting element and the light irradiation by the other light emitting elements. As a result, the density can be adjusted in pixel units. For example, it is possible to correct even manufacturing variations in light emitting elements. In the arrangement pattern shown in FIG. 2A, for example, one in two main scanning lines is exposed by the auxiliary image light emitting element, and the resolution is lowered. But this Figure 6
By using the array pattern shown in (A), it is possible to adjust the density in pixel units without lowering the resolution.

The arrangement pattern of the auxiliary image light emitting elements has been described above by showing some examples. However, the present invention is not limited to these examples, and it is possible to provide the auxiliary image light emitting element by an arbitrary array pattern. Further, the array pattern of the auxiliary image light emitting elements as described above is not fixed, and only a part of the light emitting elements provided in the VCSEL 1 in the control unit 7 is controlled as the auxiliary image light emitting element. Therefore, it is possible to appropriately change the array pattern of the auxiliary image light emitting elements. For example, it can be switched according to the characteristics of the whole or part of the input image signal. Further, for example, it is possible to change the array pattern and control the number of auxiliary image light emitting elements, the amount of light, and the like according to a user's instruction such as density adjustment.

As described above, according to the present invention, it is possible to reduce the density fluctuation by the auxiliary image light emitting element.
Various density fluctuations can be easily dealt with, and dedicated hardware for preventing density fluctuations is not required. Further, it is possible to easily deal with a change with time by changing the auxiliary image for controlling the light emission of the auxiliary image light emitting element. Further, as described above, it is possible to change the arrangement pattern of the auxiliary image light emitting elements as appropriate to change the density fluctuation adjusting method. Furthermore, it is possible to balance the performance and accuracy of the functional component alone, the accuracy of assembly adjustment, and the like to cover these accuracy, and further improve and stabilize the image quality.

In the above description of the array pattern of the light emitting elements for the auxiliary image, it is assumed that 6 × 6 light emitting elements are arranged in the VCSEL 1 as shown in FIG.
However, the arrangement of the light emitting elements in the VCSEL 1 usable in the present invention is not limited to this, and for example, 8 ×
The number and arrangement of light emitting elements such as four are arbitrary. Even in the arrangement of light emitting elements other than 6 × 6, the auxiliary image light emitting elements can be arranged and used in various arrangement patterns as described above.

By using the auxiliary image light emitting element as described above, it is possible to reduce the density unevenness and suppress the generation of black stripes. In addition to this, the auxiliary image light emitting element is positively used. It is also possible to use. Figure 7
FIG. 8 is an explanatory diagram of an application example of the embodiment of the image forming apparatus of the present invention, and FIG. 8 is an explanatory diagram of image formation in various application examples. In the figure, 11 is a main image and 12 is an auxiliary image. Note that FIG. 7 shows only part of the configuration shown in FIG.

In this application example, as shown in FIG. 7, the main image 11 to be formed in the control unit 7 and the auxiliary image 12 as another image are input. The control unit 7 causes the auxiliary image 12 to be formed by the auxiliary image light emitting element. At this time, the light emitting element for the auxiliary image is driven to emit light only by the auxiliary image 12, and the main image 11 can be used together with the auxiliary image 12 to perform light emission control according to the contents of the main image 11.

As described above, since the light emitting element to be used as the auxiliary image light emitting element is provided in the array of the plurality of light emitting elements provided in the VCSEL 1, the auxiliary image light emitting element is used to display the auxiliary image 12 and others. By controlling the light emission so that the main image 11 is drawn by each of the light emitting elements, the main image 11 and the auxiliary image 12 are combined on the image carrier 5. By applying this, various functions can be realized.

For example, it is possible to register a commonly used standard image as the auxiliary image 12. For example, if an image including a company name, a mark, a frame line, a ruled line, etc. is registered, an image including the company name, the mark, the frame line, the ruled line, etc. can be obtained by forming the image by giving the main image 11. . For example, in the example shown in FIG. 8 (A), a description indicating "for internal use" is automatically added together with the company name.

In order to prevent illegal copying, a method has been developed in which a printed matter is inconspicuous when viewed, but an image for preventing illegal copying, which appears when the image is read, is printed on the background. Conventionally, a special paper called "Sakura paper" was used to form the main image on which the illegal copy prevention image was printed in advance, but recently, the illegal copy prevention image itself was also combined with the main image. Image formation is starting to take place. In such an application, by using an unauthorized copy prevention image as the auxiliary image 12, for example, the main image 1
1 and the illegal copy prevention image can be overlapped to form an image. For example, as shown in FIG. 8B, by using an illegal copy prevention image as the auxiliary image 12 in which the character “copy” appears when read by the image reading device,
An image in which an unauthorized copy prevention image is added to the main image 11 is formed, and unauthorized copy can be suppressed.

Further, in order to prevent forgery of banknotes utilizing color copying, a function has been developed for modifying the image of the entire image or a part of the banknote when the document itself or a banknote exists in the document. In such a technique, when the entire image or a part of the image is modified, another image can be superposed to be apparently distinguished from the bill. The superimposed image used at this time is set as the auxiliary image 12,
The auxiliary image light emitting element may be driven to emit light in accordance with a recognition result from an image recognition unit such as a banknote (not shown). As a result, the main image 11 and the auxiliary image 12 used for modification are formed in an overlapping manner.
Can be modified to forge bills and the like. For example, in the example shown in FIG. 8 (C), an image having a high density is prepared as the auxiliary image 12, and an image including banknotes is uniformly changed to a black image. Note that, for convenience of illustration, the banknote portion is described as "banknote" to indicate the existence of a banknote image.

Further, various information is added to the formed image. For example, there is also a system in which parameters and the like used during image formation are embedded as an image of which image quality does not deteriorate so that the parameters at the time of image formation can be known when read later by an image reading device or the like. In such a case, the parameters at the time of image formation are coded, and the auxiliary image 1 is coded from the code.
2 may be generated and input to the control unit 7 together with the main image 11. For example, in the example shown in FIG. 8D, an example is shown in which a code indicating a parameter at the time of image formation is embedded as an image depending on the direction of the diagonal lines. Of course, in addition to the parameters at the time of image formation, various information can be added to the main image 11 using the same method.

Of course, if information indicating density unevenness is given as the auxiliary image 12, the density unevenness can be controlled. In addition to this, it can be used for various purposes.

[0046]

As is apparent from the above description, according to the present invention, among the plurality of light emitting elements provided in the light emitting source,
Since it is configured to use a part of it as a light emitting element for auxiliary image, it is not necessary to separately provide dedicated hardware as in the past, and there is also density unevenness that cannot be completely removed by the accuracy of the individual parts or assembly. Can be dealt with, and the image quality can be improved. Also,
The generation of black streaks and white streaks that occurred when a plurality of light emitting elements were used was suppressed, and it was possible to improve the image quality in this respect as well. Further, it can be applied to various fields such as prevention of illegal copying and forgery, composition with various template images, and embedding of various information.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of an image forming apparatus of the present invention.

FIG. 2 is an explanatory diagram of a representative example of an array pattern when the light emitting elements for auxiliary images are evenly distributed.

FIG. 3 is an explanatory diagram of a typical example of an array pattern when the auxiliary image light emitting elements are distributed at both lateral ends.

FIG. 4 is an explanatory diagram of a typical example of an array pattern when light emitting elements for auxiliary image are vertically distributed.

FIG. 5 is an explanatory diagram of an application example of an array pattern in which auxiliary light emitting elements are vertically distributed.

FIG. 6 is an explanatory diagram of a representative example of an array pattern when light emitting elements for auxiliary image are vertically distributed.

FIG. 7 is an explanatory diagram of an application example of the embodiment of the image forming apparatus of the invention.

FIG. 8 is an explanatory diagram of image formation in various application examples.

FIG. 9 is an explanatory diagram of an example of an array of light emitting elements in a VCSEL.

FIG. 10 is an explanatory diagram of an example of a problem when a VCSEL is used.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... VCSEL, 2 ... Optical system, 3 ... Rotating polygon mirror, 4 ... Rotating polygon mirror drive part, 5 ... Image carrier, 6 ... Image carrier drive part,
7 ... Control part, 11 ... Main image, 12 ... Auxiliary image, 21 is a light emitting element.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G03G 21/00 560 G03G 15/04 120 H01S 5/18 (72) Inventor Yasuyuki Tanaka 2274 Hongo, Ebina, Kanagawa Prefecture Address In Fuji Xerox Co., Ltd. (72) Inventor Shigeru Tsukada 2274 Hongo, Ebina City, Kanagawa Prefecture F-Term in Fuji Xerox Co., Ltd. (reference) 2C362 AA03 AA10 AA13 AA15 AA16 AA17 AA26 AA31 AA52 AA54 AA63 BA56 BA58 BA66 BA67 CB45 EA07 2H027 DA02 DA09 DB01 EA02 EC03 EC06 EC11 EC20 2H076 AB06 AB12 AB16 AB74 AB76 DA07 DA08 DA31 EA03 2H134 NA20 NA24 NA28 5F073 AB27 BA07 GA24 GA37

Claims (19)

[Claims] 1. An image forming apparatus for forming an image or an electrostatic latent image according to an image signal on a photosensitive member, the light emitting source comprising a plurality of light emitting elements arranged two-dimensionally at a predetermined density, A light emission control means for controlling light emission of each light emitting element in the light emission source according to the image signal, a scanning means for main scanning the light emitted from the light emission source in one direction, and a direction substantially orthogonal to the main scanning An image characterized by having driving means for driving the photosensitive member in the sub-scanning direction, wherein the light emission control means controls light emission by using at least one or more of the plurality of light emitting elements as auxiliary image light emitting elements. Forming equipment. 2. The image forming apparatus according to claim 1, wherein the light emission control unit controls the light emission of the auxiliary image light emitting element based on an auxiliary image different from the image signal. 3. The light emission control means controls light emission of the light emitting element for the auxiliary image based on both the image signal and an auxiliary image different from the image signal. Image forming apparatus. 4. The light emission control means controls light emission so that the auxiliary image light emitting elements are evenly distributed in an array pattern of the plurality of light emitting elements. The image forming apparatus according to claim 1. 5. The light emission control means controls light emission so that the auxiliary image light emitting elements are distributed to an upper portion or a lower portion in an array pattern of the plurality of light emitting elements. The image forming apparatus according to claim 3. 6. The light emission control means controls the light emission so that the auxiliary image light emitting elements are distributed to the left and right ends of the array pattern of the plurality of light emitting elements. The image forming apparatus according to claim 3. 7. The light emission control means controls light emission so that the auxiliary image light emitting elements are distributed to the upper and lower end portions in the array pattern of the plurality of light emitting elements. The image forming apparatus according to claim 3. 8. The light emission control means controls light emission of the light emitting element for the auxiliary image by using an image for correcting unevenness in density as the auxiliary image. The image forming apparatus according to item. 9. The light emission control means controls the light emission of the light emitting element for the auxiliary image by using an image for full surface auxiliary exposure as the auxiliary image. The image forming apparatus according to item. 10. The light emission control means controls the light emission of the light emitting element for the auxiliary image by using an embedded image embedded in the image signal as the auxiliary image. 2. The image forming apparatus according to item 1. 11. The light emission control means controls the light emission of the light emitting element for the auxiliary image by using a copy prevention image such as a bill as the auxiliary image.
The image forming apparatus according to claim 7. 12. The light emission control means controls the light emission of the light emitting element for the auxiliary image by using an image control pattern image as the auxiliary image. The image forming apparatus according to item 1. 13. The image forming apparatus according to claim 1, wherein the light emission control unit variably controls a light amount of the auxiliary image light emitting element. 14. The image forming apparatus according to claim 1, wherein the light emission control unit variably controls a light emission time (cycle) of the auxiliary image light emitting element. . 15. The image forming apparatus according to claim 1, wherein the light emission control unit variably controls the number of light emitting elements of the auxiliary image light emitting elements. 16. The light emission control means variably controls the arrangement pattern of the light emitting elements used as the auxiliary image light emitting elements in the arrangement pattern of the plurality of light emitting elements. The image forming apparatus according to claim 12. 17. The light emission control unit controls the auxiliary image light emitting element based on output image information or an input image signal.
The image forming apparatus according to claim 16. 18. The image forming apparatus according to claim 8, wherein the light emission control unit controls the auxiliary image light emitting element based on a user's instruction. apparatus. 19. The light emitting source is a vertical cavity surface emitting laser, according to claim 1.
The image forming apparatus according to claim 1.