JP2021111931A - Image reading device, image forming apparatus, and image reading method - Google Patents

Abstract

To provide an image reading device, an image forming apparatus, and an image reading method that can easily detect an area of a subject from image data obtained through a reading operation regardless of the density of the subject.SOLUTION: An image reading device comprises: a light source that radiates light to a subject; a reading unit that detects reflected light of the light radiated from the light source and reflected on the subject to read the reflected light as image data; a background member that is arranged at a position opposite to the reading unit and has areas with at least two or more densities; and a control unit that switches to any one area of the areas of the background member at the position opposite to the reading unit based on information on the subject to control the quantity of light of the light source.SELECTED DRAWING: Figure 2

Description

The present invention relates to an image reading device, an image forming device, and an image reading method.

In an image reading device that irradiates a subject with light from a light source, receives the light radiated to the subject by an image reading means, and generates image data of the subject based on the amount of the received light, the amount of change in the reading value of the image data. A technique for detecting an area of a subject is known.

As such an image reader, in order to adjust the black level and the white level, a background member having at least two or more surfaces, a black reference surface and a white reference surface, is provided, and highly accurate shading correction is performed in the photographic mode. On the other hand, in the character mode, in order to quickly perform the shading correction, in the photo mode, the shading correction is performed based on the reading result of the white reference plane of the background. A technique for easily performing shading correction based on the reading result of is disclosed (for example, Patent Document 1).

Further, a technique is disclosed in which only a light source in a direction in which a shadow is positively generated is turned on in order to positively generate a shadow on a background member and detect a subject region from the shadow (for example, Patent Document 2).

Further, in order to detect the subject position with high accuracy, a technique is disclosed in which the color of the surrounding background member through which the end portion in the main scanning direction of the subject passes is black (for example, Patent Document 3).

However, the technique described in Patent Document 1 is based on the premise that the background member at the time of transporting the subject is white, and when a subject having a low density is transported, the density difference between the subject and the background member is small. Therefore, there is a problem that it becomes difficult to detect the area of the subject. Further, in the technique described in Patent Document 2, when a shadow is generated on a background member, the density of the subject and the shadow become close to each other depending on the density of the subject, and it becomes difficult to detect only the area of the subject. There is. Further, in the technique described in Patent Document 3, when a subject having a high density is conveyed, the background member around the subject has a high density, and the subject and the background member have a close density. Therefore, only the subject area can be easily covered. There is a problem that it becomes difficult to detect. Further, the vicinity of the center of the sub-scanning of the subject is a white background member, and a shadow is generated on the background member. There is also the problem of becoming.

The present invention has been made in view of the above, and is an image reading device, an image forming device, and an image reading device, an image forming device, which can easily detect a region of a subject from image data obtained by a reading operation regardless of the density of the subject. It is an object of the present invention to provide an image reading method.

In order to solve the above-mentioned problems and achieve the object, the present invention detects image data by detecting a light source that irradiates a subject with light and the reflected light that is reflected by the subject from the light emitted from the light source. The background member is arranged at a position facing the reading unit and has a region having a density of at least 2 or more, and the background member is located at a position facing the reading unit based on the information of the subject. It is characterized in that it is provided with a control unit that switches to any of the above regions and controls the amount of light of the light source.

According to the present invention, the area of the subject can be easily detected from the image data obtained by the reading operation regardless of the density of the subject.

FIG. 1 is a diagram showing an example of a schematic structure of an image reading device according to a first embodiment. FIG. 2 is a diagram showing an example of a block configuration of the image reading device according to the first embodiment. FIG. 3 is a diagram for explaining a shadow generated from the positional relationship between the light source and the subject P. FIG. 4 is a diagram for explaining image data obtained when the subject has a low density and the background member has a high density. FIG. 5 is a diagram for explaining image data obtained when the subject has a high density and the background member has a low density. FIG. 6 is a diagram for explaining image data obtained when the background member has a high density and the subject has a low density close to a high density. FIG. 7 is a diagram for explaining image data obtained when the amount of light of the light source is increased when the background member has a high density and the subject has a low density close to a high density. FIG. 8 is a diagram for explaining image data obtained when the subject has a high density and the background member has a low density. FIG. 9 is a diagram for explaining image data obtained when the amount of light of the light source is reduced when the subject has a high density and the background member has a low density. FIG. 10 is a flowchart showing an example of the flow of the reading operation of the image reading device according to the first embodiment. FIG. 11 is a diagram illustrating an operation of switching the density of the background member in accordance with the switching of the density of the subject in the image reading device according to the modified example of the first embodiment. FIG. 12 is a diagram showing an example of a schematic structure of the image reading device according to the second embodiment. FIG. 13 is a diagram showing an example of a block configuration of the image reading device according to the second embodiment. FIG. 14 is a diagram illustrating image data obtained when the light amounts of the first light source and the second light source are equalized. FIG. 15 is a diagram illustrating a shadow generated when only the first light source is turned on. FIG. 16 is a diagram illustrating image data obtained when only the first light source is turned on. FIG. 17 is a diagram illustrating a shadow generated when only the second light source is turned on. FIG. 18 is a diagram illustrating image data obtained when only the second light source is turned on. FIG. 19 is a diagram illustrating a shadow generated when the lighting of the first light source and the second light source is switched. FIG. 20 is a diagram illustrating image data obtained when the lighting of the first light source and the second light source is switched. FIG. 21 is a diagram illustrating image data obtained when the subject has a high density. FIG. 22 is a diagram showing an example of a schematic structure of the image reading device according to the third embodiment. FIG. 23 is a diagram showing an example of the block configuration of the image reading device according to the third embodiment. FIG. 24 is a diagram showing an example of the block configuration of the image reading device according to the fourth embodiment. FIG. 25 is a diagram illustrating the operation of the subject area detection unit of the image reading device according to the fourth embodiment. FIG. 26 is a diagram showing an example of a block configuration of the image reading device according to the fifth embodiment. FIG. 27 is a diagram illustrating image data corrected by the image correction unit based on the subject detection result. FIG. 28 is a diagram showing an example of the overall structure of the image forming apparatus according to the sixth embodiment. FIG. 29 is a diagram illustrating image data corrected based on the subject detection result.

Hereinafter, embodiments of an image reading device, an image forming device, and an image reading method according to the present invention will be described in detail with reference to the drawings. Further, the present invention is not limited by the following embodiments, and the components in the following embodiments include those easily conceived by those skilled in the art, substantially the same, and so-called equivalent ranges. Things are included. Furthermore, various omissions, substitutions, changes and combinations of components can be made without departing from the gist of the following embodiments.

[First Embodiment]
(Outline structure of image reader)
FIG. 1 is a diagram showing an example of a schematic structure of an image reading device according to a first embodiment. The schematic structure of the image reading device 10 according to the present embodiment will be described with reference to FIG.

The image reading device 10 shown in FIG. 1 irradiates the subject P and the background member 16, which are recording media on which the image pattern to be conveyed is printed, with light from a light source, and is reflected by the subject P and the background member 16 described later. It is a device that reads an image of the subject P and the background member 16 by detecting the reflected light. FIG. 1 shows a state in which the subject P is conveyed from the right side to the left side when viewed on paper. As shown in FIG. 1, the image reading device 10 includes a reading device 11 and a background member 16.

The reading device 11 is a device that irradiates the subject P and the background member 16 with light from a light source and detects the reflected light reflected by the subject P and the background member 16 to read the subject P and the background member 16 as image data. be. As shown in FIG. 1, the reading device 11 includes a light source 111 and a photoelectric conversion element 112 (reading unit).

The light source 111 is a light source that irradiates the subject P with light in order to read the image pattern printed on the subject P. The light source 111 is, for example, a halogen lamp, a noble gas fluorescent lamp (xenon lamp), an LED (Light Emitting Diet), or the like. In order to realize small size and low power consumption, a single or multiple LEDs that do not require a dedicated inverter required for lighting (light emission) are used as the light source 11a as compared with halogen lamps and rare gas fluorescent lamps. Is desirable. The noble gas fluorescent lamp generally requires several tens of [ms] as the time required for stabilizing the amount of light, whereas the LED has less than 1 [ms], so that the response to the lighting and extinguishing control is fast.

The photoelectric conversion element 112 is an element that receives the reflected light from the subject P and converts the reflected light into an electric signal.

The background member 16 is arranged at a position facing the reading device 11, and is a member that serves as a background when the subject P is read. The background member 16 has a rotatable shape, for example, as shown in FIG. 1, and has at least two or more density regions (high density region and low density region such as black region and white region). Have. The background member 16 is not limited to the rotatable shape as shown in FIG. 1, and may be, for example, a flat plate shape having two or more concentration regions.

(Block configuration of image reader)
FIG. 2 is a diagram showing an example of a block configuration of the image reading device according to the first embodiment. The block configuration of the image reading device 10 according to the present embodiment will be described with reference to FIG.

As shown in FIG. 2, the image reading device 10 includes a reading device 11, a control unit 20, a subject information storage unit 21, a motor control unit 22, a motor 23, and a background member 16.

As described above, the reading device 11 irradiates the subject P and the background member 16 with light from the light source and detects the reflected light reflected by the subject P to read the images of the subject P and the background member 16. As shown in FIG. 2, the reading device 11 includes a light source 111, a photoelectric conversion element 112, and an AFE (Analog Front End) 113. The light source 111 and the photoelectric conversion element 112 are as described above. The AFE 113 is a device that converts an electric signal converted by the photoelectric conversion element 112 into an image signal which is a digital signal.

The control unit 20 is a control device that controls the operation of the entire image reading device 10. The control unit 20 is, for example, a processor programmed to execute each function by software such as a CPU (Central Processing Unit) implemented by an electronic circuit, an ASIC (Application Specific Integrated Circuit), a DSP (Digital Signal Processor), and a DSP (Digital Signal Processor). It is realized by a device such as an FPGA (Field-Programmable Gate Array), an ASIC (System on a Chip), a GPU (Graphics Processor Unit), or a conventional circuit module.

Specifically, the control unit 20 operates the reading device 11 by the drive signal, and performs lighting control including ON / OFF control of the light source 111 of the reading device 11 and control of the amount of light by the light source lighting control signal. Further, the control unit 20 causes the motor control unit 22 to drive the motor 23 by sending a control signal to the motor control unit 22.

The subject information storage unit 21 is a storage device that stores subject information such as density information of the subject, length in the main scanning direction, and length in the sub-scanning direction.

The motor control unit 22 is a drive circuit that generates a drive signal for rotationally driving the motor 23. The motor 23 is a motor for rotationally driving the background member 16 to switch the background region of the subject P.

(About shadows generated from the positional relationship between the light source and the subject)
FIG. 3 is a diagram for explaining a shadow generated from the positional relationship between the light source and the subject P. With reference to FIG. 3, a shadow generated from the positional relationship between the light source 111 and the subject P will be described.

As shown in FIG. 3A, when the front end of the subject P in the sub-scanning direction (hereinafter, may be simply referred to as the front end of the subject P) passes through a position (reading position) directly below the photoelectric conversion element 112. Due to the positional relationship between the front end of the subject P and the light source 111 on the upstream side in the transport direction, a shadow extending from the front end of the subject P to the downstream side on the background member 16 is generated. Further, as shown in FIG. 3B, when the rear end of the subject P in the sub-scanning direction (hereinafter, may be simply referred to as the rear end of the subject P) passes through the reading position, it is referred to as the rear end of the subject P. Due to the positional relationship with the light source 111 on the downstream side in the transport direction, a shadow extending from the rear end of the subject P to the upstream side on the background member 16 is generated.

(Image data obtained when the subject has a low density and the background member has a high density)
FIG. 4 is a diagram for explaining image data obtained when the subject has a low density and the background member has a high density. The image data obtained when the subject P has a low density and the background member 16 has a high density will be described with reference to FIG.

FIG. 4A shows image data obtained when the subject P has a low density and the background member 16 has a high density. FIG. 4B is a graph showing the distribution of signal levels (reading values) in the region 502 in the main scanning direction in the image data shown in FIG. 4A. FIG. 4C is a graph showing the distribution of signal levels (reading values) in the region 501 in the sub-scanning direction in the image data shown in FIG. 4A. As described above in FIG. 3, a shadow of the subject P is generated on the background member 16 due to the positional relationship between the light source 111 and the subject P. However, as shown in FIG. 4A, when the background member 16 has a high density, the signal level of the background member 16 is low, so even if a shadow is generated, the signal level of the shadow portion is the background member. Since it does not fall below the signal level of the 16th part, it is not easily affected by shadows.

(Image data obtained when the subject has a high density and the background member has a low density)
FIG. 5 is a diagram for explaining image data obtained when the subject has a high density and the background member has a low density. The image data obtained when the subject P has a high density and the background member 16 has a low density will be described with reference to FIG.

FIG. 5A shows image data obtained when the subject P has a high density and the background member 16 has a low density. FIG. 5B is a graph showing the distribution of signal levels (reading values) in the region 504 in the main scanning direction in the image data shown in FIG. 5A. FIG. 5C is a graph showing the distribution of signal levels (reading values) in the region 503 in the sub-scanning direction in the image data shown in FIG. 5A. As shown in FIG. 5A, when the background member 16 has a low density, the signal level of the background member 16 portion is high, so that the signal level drops when a shadow is generated, and the image of the shadow SD1 on the front end side of the subject P. , Appears as an image of shadow SD2 on the rear end side of the subject P. That is, as shown by the distribution of the signal level in the region 503 in the sub-scanning direction of FIG. 5C, both ends of the image data in the sub-scanning direction are high values because the signal level of the background member 16 is low. However, the signal level drops stepwise in the shadows SD1 and SD2.

As described above, in the image data shown in FIG. 4A and the image data shown in FIG. 5A, the density of the background member 16 is changed, but the switching of the density of the background member 16 is controlled. This is performed based on the information (subject information) of the subject P read from the subject information storage unit 21 by the unit 20. In this case, for example, density information is used as the subject information.

For example, when the background member 16 has two regions, a low density region and a high density region, the control unit 20 determines the density of the subject P (for example, the average value or the median value of the density of the subject P) according to the subject information. When it is determined that the density is lower than the predetermined density, it is determined that the density of the subject P is low, and the background member 16 switches so that the background becomes a high density region. On the other hand, when the control unit 20 determines that the density of the subject P is higher than the predetermined density based on the subject information, the control unit 20 determines that the density of the subject P is high, and the background by the background member 16 is a region having a low density. Switch to.

(Light source lighting control when the background member has a high density and the subject has a low density close to high density)
FIG. 6 is a diagram for explaining image data obtained when the background member has a high density and the subject has a low density close to a high density. FIG. 7 is a diagram for explaining image data obtained when the amount of light of the light source is increased when the background member has a high density and the subject has a low density close to a high density. With reference to FIGS. 6 and 7, lighting control of the light source 111 when the background member 16 has a high density and the subject P has a low density close to a high density will be described.

FIG. 6A shows image data obtained when the background member 16 has a high density and the subject P has a low density close to a high density. FIG. 6B is a graph showing the distribution of signal levels (reading values) in the region 502 in the main scanning direction in the image data shown in FIG. 6A. FIG. 6C is a graph showing the distribution of signal levels (reading values) in the region 501 in the sub-scanning direction in the image data shown in FIG. 6A. In this case, as shown in FIGS. 6 (b) and 6 (c), a sufficient difference may not be obtained between the signal level of the subject P and the signal level of the background member 16. Further, as described above, in the image data, the light received by the photoelectric conversion element 112 of the reading device 11 is converted into an electric signal, and the electric signal is converted into a digital signal (image signal) by the AFE 113. Due to this conversion, noise components are included in the image data due to the influence of quantization error and the like. As shown in FIGS. 6 (b) and 6 (c) above, when a sufficient difference cannot be obtained between the signal level of the subject P and the signal level of the background member 16, noise included in the image data. Due to the influence of the above, the region of the subject P and the region of the background member 16 in the image data cannot be clearly discriminated, and the accuracy of region detection deteriorates. Therefore, in consideration of the influence of this noise, it is desirable to sufficiently secure the difference between the signal level of the subject P and the signal level of the background member 16. Therefore, when the background member 16 has a high density and the subject P has a low density close to a high density, the control unit 20 controls to increase the amount of light of the light source 111 to be larger than the normal amount of light. Here, the normal light amount is, for example, a light amount preset as a standard light amount when reading the subject P. As a result, image data as shown in FIG. 7A can be obtained.

FIG. 7A shows image data obtained by increasing the amount of light of the light source 111 when the background member 16 has a high density and the subject P has a low density close to a high density. As shown in the image data shown in FIG. 7A, the amount of light emitted to the subject P and the background member 16 increases, so that the signal level increases in the entire region. As a result, the signal levels as shown in FIGS. 7 (b) and 7 (c) are obtained, and image data having a sufficient difference between the signal level of the subject P and the signal level of the background member 16 is obtained. Can be done. FIG. 7B is a graph showing the distribution of signal levels (reading values) in the region 502 in the main scanning direction in the image data shown in FIG. 7A. FIG. 7 (c) is a graph showing the distribution of signal levels (reading values) in the region 501 in the sub-scanning direction in the image data shown in FIG. 7 (a).

For example, in the image data of FIG. 6A, when the signal level of the background member 16 is 10 [LSB] and the signal level of the subject P is 30 [LSB], the difference is 20 [LSB]. On the other hand, when the amount of light of the light source 111 in the case of FIG. 7A is twice the amount of light in the case of FIG. 6A, the signal level of the image data changes proportionally, and the signal of the background member 16 changes. The level is 20 [LSB], the signal level of the subject P is 60 [LSB], and the difference is 40 [LSB]. At this time, since the light received by the reading device 11 is converted into a digital signal in a state where the amount of light is increased, the quantization error remains 1 times, and the signal level of the subject P and the signal level of the background member 16. Is changed twice, while the signal level of noise remains 1 times, and the influence of noise can be relatively reduced, so that the accuracy of region detection can be improved.

In the example shown in FIG. 7, when the background member 16 has a high density and the subject P has a low density close to a high density, the control unit 20 increases the amount of light of the light source 111. When the information (subject information) of the subject P stored in the subject information storage unit 21 indicates that the subject P has a low density, the background member 16 switches the background so that the background becomes a high density region, and the light source 111 Control to increase the amount of light may be performed.

(Light source lighting control when the subject has a high density and the background member has a low density)
FIG. 8 is a diagram for explaining image data obtained when the subject has a high density and the background member has a low density. FIG. 9 is a diagram for explaining image data obtained when the amount of light of the light source is reduced when the subject has a high density and the background member has a low density. The lighting control of the light source 111 when the subject P has a high density and the background member 16 has a low density will be described with reference to FIGS. 8 and 9.

FIG. 8A shows image data obtained when the subject P has a high density and the background member 16 has a low density. FIG. 8B is a graph showing the distribution of signal levels (reading values) in the region 504 in the main scanning direction in the image data shown in FIG. 8A. FIG. 8C is a graph showing the distribution of signal levels (reading values) in the region 503 in the sub-scanning direction in the image data shown in FIG. 8A. In this case, as shown in FIG. 8C, three signal levels are generated, that is, the signal level of the subject P, the signal level of the shadows (shadows SD1 and SD2), and the signal level of the background member 16, and the influence of the shadows. Therefore, the image data may be such that the region of the subject P and the region of the background member 16 cannot be clearly distinguished. In this case, the control unit 20 controls to reduce the light intensity of the light source 111 to be smaller than the normal light intensity when the subject P has a high density and the background member 16 has a low density. As a result, image data as shown in FIG. 9A can be obtained.

FIG. 9A is image data obtained by reducing the amount of light of the light source 111 when the subject P has a high density and the background member 16 has a low density. By reducing the amount of light applied to the background member 16 as in the image data shown in FIG. 9A, the signal level of the background member 16 is equivalent to the shadows SD1 and SD2 shown in FIG. 8A. Can be the signal level of. As a result, the signal levels as shown in FIGS. 9 (b) and 9 (c) are obtained, and the shadow SD1 is provided with a difference between the signal level of the subject P and the signal level of the background member 16. , An image in which the influence of SD2 is suppressed can be obtained. FIG. 9B is a graph showing the distribution of signal levels (reading values) in the region 504 in the main scanning direction in the image data shown in FIG. 9A. FIG. 9 (c) is a graph showing the distribution of signal levels (reading values) in the region 503 in the sub-scanning direction in the image data shown in FIG. 9 (a).

For example, in the image data of FIG. 8A, the signal level of the background member 16 is 200 [LSB], the signal level of the shadows (shadows SD1 and SD2) is 100 [LSB], and the signal level of the subject P is 0 [LSB]. In the case of, three signal levels exist, and it is difficult to discriminate the region between the subject P and the background member 16. On the other hand, when the amount of light of the light source 111 in the case of FIG. 9A is 1/2 times the amount of light in the case of FIG. 8A, the signal level of the background member 16 is 100 [LSB] and the shadow ( The signal levels of the shadows SD1 and SD2) are 100 [LSB], the signal level of the subject P is 0 [LSB], the signal levels of the background member 16 and the shadow are the same, and the regions of the subject P and the background member 16 are discriminated. It becomes easy to do so, and the accuracy of area detection can be improved.

As described with reference to FIGS. 6 to 9 described above, the control unit 20 of the image reading device 10 according to the present embodiment switches the background by the background member 16 according to the density of the subject P, and adjusts the amount of light of the light source 111. By doing so, it is possible to make it difficult to see the shadow generated on the background member 16 regardless of the density of the subject P, and to make the density of the subject P and the background member 16 clearly different. It becomes easy to discriminate the region between P and the background member 16, and the accuracy of region detection can be improved.

(Reading operation of image reader)
FIG. 10 is a flowchart showing an example of the flow of the reading operation of the image reading device according to the first embodiment. The flow of the reading operation of the image reading device 10 according to the present embodiment will be described with reference to FIG.

<Step S11>
Prior to the subject P being conveyed to the reading position of the reading device 11, the control unit 20 reads the subject information of the subject P from the subject information storage unit 21. Then, the process proceeds to step S12.

<Step S12>
The control unit 20 determines whether the density of the subject P is low or high from the read subject information. For example, when the density of the subject P (for example, the average value or the median value of the density of the subject P) is lower than a predetermined density, the control unit 20 determines that the density of the subject P is low. Further, when the density of the subject P is higher than the predetermined density, the control unit 20 determines that the density of the subject P is high. When the density of the subject P is low (step S12: low density), the process proceeds to step S13, and when the density of the subject P is high (step S12: high density), the process proceeds to step S16.

<Step S13>
When the control unit 20 determines that the density of the subject P is low, the control unit 20 switches so that the background formed by the background member 16 becomes a high density region. Then, the process proceeds to step S14.

<Step S14>
The control unit 20 determines whether or not the density of the subject P is a low density close to a high density. For example, the control unit 20 can determine that the density of the subject P is lower than the predetermined density in step S12, but the difference from the predetermined density is less than the threshold value (that is, the density of the subject P). Is closer to the high concentration), it is determined that the concentration is low, which is close to the high concentration. When the density of the subject P is a low density close to a high density (step S14: Yes), the process proceeds to step S15, and when the density is not low close to a high density (step S14: No), the process proceeds to step S18.

<Step S15>
The control unit 20 controls to increase the amount of light of the light source 111 to be larger than the normal amount of light before the subject P reaches the reading position. For example, it is assumed that a detection unit that detects the subject P is provided upstream of the transport path of the image reading device 10, and when the control unit 20 detects the subject P by the detection unit, the light source 111 uses the light source 111 more than the normal amount of light. May be lit with a large amount of light. Then, the process proceeds to step S18.

<Step S16>
When the control unit 20 determines that the density of the subject P is high, the control unit 20 switches so that the background formed by the background member 16 becomes a low density region. Then, the process proceeds to step S17.

<Step S17>
The control unit 20 controls the amount of light of the light source 111 to be smaller than the normal amount of light before the subject P reaches the reading position. For example, it is assumed that a detection unit that detects the subject P is provided upstream of the transport path of the image reading device 10, and when the control unit 20 detects the subject P by the detection unit, the light source 111 uses the light source 111 more than the normal amount of light. May be lit with a small amount of light. Then, the process proceeds to step S18.

<Step S18>
The reading device 11 irradiates the subject P and the background member 16 with light from the light source 111 according to the control of the control unit 20, and detects the reflected light reflected by the subject P and the background member 16, thereby causing the subject P and the background member 16. 16 image data are read.

The reading operation of the image reading device 10 is performed by the flow of the above steps S11 to S18. In the process shown in FIG. 10, the determination of whether or not the density of the subject P in step S14 is low, which is close to the high density, is skipped, and if the density of the subject P is low, the control unit 20 uses the light source 111. The amount of light of may be made larger than the amount of normal light.

As described above, in the image reading device 10 according to the present embodiment, the background by the background member 16 is switched according to the density of the subject P, and the amount of light of the light source 111 is adjusted, so that the density of the subject P does not matter. Since it is possible to make the shadow generated on the background member 16 difficult to see and to make the density of the subject P and the background member 16 clearly different, the image data obtained by the reading operation shows the subject P and the background. The region with the member 16 can be easily discriminated, and the region of the subject P can be easily detected.

(Modification example)
FIG. 11 is a diagram illustrating an operation of switching the density of the background member in accordance with the switching of the density of the subject in the image reading device according to the modified example of the first embodiment. With reference to FIG. 11, the operation of switching the density of the background member 16 in accordance with the switching of the density of the subject P in the image reading device 10 according to the modified example of the present embodiment will be described.

In FIG. 11, a region from the center to the front end side of the subject P in the sub-scanning direction (hereinafter referred to as a front end side region) has a high density, and a region from the center to the rear end side (hereinafter referred to as a rear end side region). Shows image data when is low density. When the front end region having a high density of the subject P shown in FIG. 11 passes through the reading position of the reading device 11, the control unit 20 switches the background member 16 so as to be a low density region. .. Then, when the rear end side region of the subject P, which has a low density, passes through the reading position, the control unit 20 switches the background member 16 so that the background member 16 becomes a high density region. By such control by the control unit 20, the image data shown in FIG. 11 can be obtained. As a result, it is possible to make a state in which there is a clear difference in the density between the subject P and the background member 16 in the image data, it becomes easy to discriminate the area between the subject P and the background member 16, and the area of the subject P can be changed. It can be easily detected.

When reading the high-concentration front end side region of the subject P, a shadow on the front end side of the subject P is generated on the low-density background member 16, so that the control unit 20 has the front end as described in FIG. When the side region passes through the reading position, the light amount of the light source 111 may be controlled to be smaller than the normal light amount. This makes it difficult to see the shadow generated on the background member 16, and makes it possible to make the density of the subject P and the background member 16 more clearly different.

[Second Embodiment]
The image reading device according to the second embodiment will be described focusing on the differences from the image reading device 10 according to the first embodiment. In the first embodiment, the control unit 20 is described on the premise that the light amounts of the plurality of light sources 111 of the reading device 11 are controlled by the same light amount without distinction. In the present embodiment, each light source of the reading device 11 operates independently, and an operation of turning on or off each light source properly will be described.

(Outline structure of image reader)
FIG. 12 is a diagram showing an example of a schematic structure of the image reading device according to the second embodiment. The schematic structure of the image reading device 10a according to the present embodiment will be described with reference to FIG.

As shown in FIG. 12, the image reading device 10a includes a reading device 11a and a background member 16. The reading device 11a includes a first light source 111a, a second light source 111b, and a photoelectric conversion element 112.

The first light source 111a is a light source arranged at a position downstream of the photoelectric conversion element 112 in the transport direction (sub-scanning direction). The second light source 111b is a light source arranged at a position on the upstream side in the transport direction (sub-scanning direction) with respect to the photoelectric conversion element 112. The first light source 111a and the second light source 111b are independently lit and controlled by separate light source lighting control signals output from the control unit 20.

The background member 16 and the photoelectric conversion element 112 are as described above in the first embodiment.

(Block configuration of image reader)
FIG. 13 is a diagram showing an example of a block configuration of the image reading device according to the second embodiment. The block configuration of the image reading device 10a according to the present embodiment will be described with reference to FIG.

As shown in FIG. 13, the image reading device 10a includes a reading device 11a, a control unit 20, a subject information storage unit 21, a motor control unit 22, a motor 23, and a background member 16. The reading device 11a includes a first light source 111a, a second light source 111b, a photoelectric conversion element 112, and an AFE 113.

The control unit 20 controls the lighting of the first light source 111a by the first light source lighting control signal, and controls the lighting of the second light source 111b by the second light source lighting control signal. That is, the control unit 20 can independently control the lighting operation of the first light source 111a and the lighting operation of the second light source 111b.

The operation of the other blocks shown in FIG. 13 is as described above in the first embodiment.

(Image data obtained when the light amounts of the first light source and the second light source are equalized)
FIG. 14 is a diagram illustrating image data obtained when the light amounts of the first light source and the second light source are equalized. With reference to FIG. 14, the image data obtained when the light amounts of the first light source and the second light source are equalized will be described.

The image data shown in FIG. 14 is image data obtained when the light amounts of the first light source 111a and the second light source 111b are equalized and the background member 16 is switched to a low density. As shown in FIG. 14, when the background member 16 has a low density, the signal level of the portion of the background member 16 is high. Therefore, as described above in FIG. 5, the signal level drops when a shadow is generated, and the front end side of the subject P It appears as an image of shadow SD1 and an image of shadow SD2 on the rear end side of the subject P. Due to the generation of the shadows SD1 and SD2, it becomes difficult to distinguish the region of the subject P from the region of the background member 16 in the obtained image data.

(Reading operation when only the first light source is turned on)
FIG. 15 is a diagram illustrating a shadow generated when only the first light source is turned on. With reference to FIG. 15, a shadow generated when only the first light source 111a is turned on will be described.

As shown in FIG. 15, it is assumed that the control unit 20 controls lighting so that the first light source 111a of the reading device 11a is turned on and the second light source 111b is turned off. As shown in FIG. 15A, when the front end of the subject P passes through the reading position directly below the photoelectric conversion element 112, the shadow of the subject P is unlikely to be generated on the background member 16. On the other hand, as shown in FIG. 15B, when the rear end of the subject P passes through the reading position, the subject is viewed from the positional relationship between the rear end of the subject P and the first light source 111a on the downstream side in the transport direction. A shadow extending from the rear end of P to the upstream side on the background member 16 is likely to occur.

FIG. 16 is a diagram illustrating image data obtained when only the first light source is turned on. The image data obtained when only the first light source 111a is turned on will be described with reference to FIG.

As described with reference to FIG. 15 above, when the rear end of the subject P passes through the reading position, a shadow extending from the rear end of the subject P to the upstream side on the background member 16 (shadow SD2 shown in FIG. 16) is generated. It will be easier. However, when the front end of the subject P passes through the reading position, shadows are unlikely to be generated on the front end side of the subject P. Therefore, as shown in FIG. 16, image data in which shadows are suppressed on the front end side of the subject P can be obtained. Be done.

Therefore, in the image data, the region on the front end side of the subject P can be in a state where there is a clear difference in density from the background member 16, and the region on the front end side of the subject P and the region of the background member 16 can be discriminated. This facilitates the process, and the region on the front end side of the subject P can be easily detected.

In the description of FIGS. 15 and 16, the first light source 111a is turned on and the second light source 111b is turned off, but the present invention is not limited to this. That is, on the premise that the second light source 111b is not completely turned off and is smaller than the light amount of the first light source 111a, the second light source 111b may be turned on with a weak light amount in order to reduce noise. good.

(Reading operation when only the second light source is turned on)
FIG. 17 is a diagram illustrating a shadow generated when only the second light source is turned on. With reference to FIG. 17, a shadow generated when only the second light source 111b is turned on will be described.

As shown in FIG. 17, it is assumed that the control unit 20 performs lighting control in which the first light source 111a of the reading device 11a is turned off and the second light source 111b is turned on. As shown in FIG. 17A, when the front end of the subject P passes through the reading position directly below the photoelectric conversion element 112, the positional relationship between the front end of the subject P and the second light source 111b on the upstream side in the transport direction. Therefore, a shadow extending from the front end of the subject P to the downstream side on the background member 16 is likely to occur. On the other hand, as shown in FIG. 17B, when the rear end of the subject P passes through the reading position, the shadow of the subject P is unlikely to be generated on the background member 16.

FIG. 18 is a diagram illustrating image data obtained when only the second light source is turned on. The image data obtained when only the second light source 111b is turned on will be described with reference to FIG.

As described with reference to FIG. 17, when the front end of the subject P passes through the reading position, a shadow extending from the front end of the subject P to the downstream side on the background member 16 (shadow SD1 shown in FIG. 18) is likely to occur. .. However, when the rear end of the subject P passes through the reading position, a shadow is unlikely to be generated on the rear end side of the subject P. Therefore, as shown in FIG. 18, the image in which the shadow is suppressed on the rear end side of the subject P is suppressed. Data is obtained.

Therefore, in the image data, the region on the rear end side of the subject P can be in a state where there is a clear difference in density from the background member 16, and the region on the rear end side of the subject P and the region of the background member 16 can be discriminated. This makes it easy to detect the region on the rear end side of the subject P.

In the description of FIGS. 17 and 18, the first light source 111a is turned off and the second light source 111b is turned on, but the present invention is not limited to this. That is, on the premise that the first light source 111a is not completely turned off and is smaller than the amount of light of the second light source 111b, the first light source 111a may be turned on with a weak amount of light in order to reduce noise. good.

(Reading operation when switching the lighting of the first light source and the second light source)
FIG. 19 is a diagram illustrating a shadow generated when the lighting of the first light source and the second light source is switched. With reference to FIG. 19, a shadow generated when the lighting of the first light source 111a and the second light source 111b is switched will be described.

As shown in FIG. 19A, when the front end of the subject P passes through the reading position directly below the photoelectric conversion element 112, the control unit 20 turns on the first light source 111a of the reading device 11a and turns on the second light source. Lighting control is performed to turn off 111b. In this case, as shown in FIG. 19A, the shadow of the subject P is unlikely to be generated on the background member 16 due to the positional relationship between the front end of the subject P and the first light source 111a on the downstream side in the transport direction.

On the other hand, as shown in FIG. 19B, when the rear end of the subject P passes through the reading position, the control unit 20 turns off the first light source 111a of the reading device 11a and turns on the second light source 111b. Performs lighting control to switch to. In this case, the control unit 20 may switch between the lighting and extinguishing states of the first light source 111a and the second light source 111b, for example, near the center position in the sub-scanning direction of the subject P. At least, when the front end of the subject P passes the reading position, the control unit 20 turns on the first light source 111a and turns off the second light source 111b, and the rear end of the subject P passes through the reading position. In that case, the first light source 111a may be turned off and the second light source 111b may be turned on. Also in this case, as shown in FIG. 19B, the shadow of the subject P is generated on the background member 16 due to the positional relationship between the rear end of the subject P and the second light source 111b on the upstream side in the transport direction. Hateful.

FIG. 20 is a diagram illustrating image data obtained when the lighting of the first light source and the second light source is switched. With reference to FIG. 20, the image data obtained when the lighting control for switching the lighting of the first light source 111a and the second light source 111b is performed will be described.

As described with reference to FIG. 19 above, when the front end of the subject P passes through the reading position, as shown in FIG. 20, the generation of shadows is suppressed on the front end side of the subject P, and the rear end of the subject P is the reading position. Even when passing through, image data in which the generation of shadows is suppressed on the rear end side of the subject P can be obtained.

Therefore, in the image data, there can be a clear difference in density from the background member 16 in both the front end side region and the rear end side region of the subject P, and the front end side region and the rear end of the subject P can be set. It becomes easy to distinguish the side region from the background member 16 region, and the front end side region and the rear end side region of the subject P can be easily detected.

FIG. 21 is a diagram illustrating image data obtained when the subject has a high density. A case where the subject P has a particularly high density will be described with reference to FIG.

As shown in FIG. 21, when a subject P having a particularly high density is conveyed and a shadow is generated on the background member 16, the difference in density between the area of the subject P and the shadow area becomes unclear, and discrimination can be made. It will be difficult. In this case, as described above, when the front end of the subject P passes the reading position directly below the photoelectric conversion element 112, the control unit 20 turns on the first light source 111a of the reading device 11a and turns the second light source 111b into a lighting state. Performs lighting control to turn off the light. Then, when the rear end of the subject P passes through the reading position, the control unit 20 performs lighting control for switching the first light source 111a of the reading device 11a to the off state and the second light source 111b to the lighting state. As a result, the generation of shadows on the background member 16 on the front end side and the rear end side of the subject P can be suppressed, and the background member 16 and the density can be suppressed in both the front end side region and the rear end side region of the subject P. There can be a clear difference. Therefore, it becomes easy to distinguish the region on the front end side and the rear end side of the subject P from the region on the background member 16, and the region on the front end side and the region on the rear end side of the subject P can be easily detected. Can be done.

As described above, in the image reading device 10a according to the present embodiment, a plurality of (for example, two) light sources are independently lit and controlled, and the positional relationship with at least one of the front end side and the rear end side of the subject P. Therefore, the light source capable of suppressing shadows is turned on, and the other light sources are turned off to perform the reading operation. As a result, it is possible to suppress the generation of shadows on the background member 16 on at least one of the front end side and the rear end side of the subject P, and in at least one of the front end side region and the rear end side region of the subject P. , It is possible to make a state in which there is a clear difference in density from the background member 16. Therefore, it becomes easy to distinguish at least one region on the front end side and the rear end side of the subject P from the region of the background member 16, and at least one of the front end side region and the rear end side region of the subject P. The area can be easily detected.

In the description of FIGS. 19 to 21, it is assumed that either the first light source 111a or the second light source 111b is turned off, but the present invention is not limited to this. That is, the light source on the side to be turned off may be turned on with a weak amount of light in order to reduce noise on the premise that the light source on the side to be turned off is not completely turned off and is smaller than the amount of light of the light source on the side to be turned on.

[Third Embodiment]
The image reading device according to the third embodiment will be described focusing on the differences from the image reading device 10 according to the first embodiment. In the present embodiment, an operation of detecting the density of the subject P before the subject P is conveyed to the reading position of the reading device 11 will be described.

(Outline structure of image reader)
FIG. 22 is a diagram showing an example of a schematic structure of the image reading device according to the third embodiment. The schematic structure of the image reading device 10b according to the present embodiment will be described with reference to FIG. 22.

As shown in FIG. 22, the image reading device 10b includes a reading device 11, a background member 16, and a subject information detecting unit 24 (subject detecting unit).

The subject information detection unit 24 is a device that detects the density and the like of the subject P transported on the transport path. As shown in FIG. 22, the subject information detection unit 24 is arranged on the upstream side of the reading device 11.

The other configurations shown in FIG. 22 are as described above in the first embodiment.

(Block configuration of image reader)
FIG. 23 is a diagram showing an example of the block configuration of the image reading device according to the third embodiment. The block configuration of the image reading device 10b according to the present embodiment will be described with reference to FIG. 23.

As shown in FIG. 23, the image reading device 10b includes a reading device 11, a control unit 20, a subject information storage unit 21, a motor control unit 22, a motor 23, a subject information detection unit 24, and a background member 16. And have.

As described above, the subject information detection unit 24 detects the density and the like of the subject P transported on the transport path, and stores the detected information as subject information in the subject information storage unit 21.

The control unit 20 reads out the subject information detected by the subject information detection unit 24 and stored in the subject information storage unit 21, and uses the subject information to control the lighting of the light source 111 and the operation of the background member 16. .. The control using the subject information by the control unit 20 is as described above in the first embodiment described above.

As described above, in the image reading device 10b according to the present embodiment, the control unit 20 determines the density of the subject P detected by the subject information detecting unit 24 arranged on the upstream side of the transport path from the reading device 11. The lighting control of the light source 111 and the operation control of the background member 16 are performed using the subject information. As a result, the subject information is directly detected by the subject information detection unit 24 before the reading operation of the reading device 11, so that the trouble of setting the subject information about the subject P in the subject information storage unit 21 in advance is eliminated. be able to. Further, since the control is performed using the subject information about the subject P directly detected by the subject information detection unit 24, it is more accurate to make it difficult to see the shadow generated on the background member 16 regardless of the density of the subject P. , The density of the subject P and the background member 16 can be clearly different.

The configuration in which the subject information detection unit 24 of the present embodiment is arranged can also be applied to the image reading device 10a according to the second embodiment described above.

[Fourth Embodiment]
The image reading device according to the fourth embodiment will be described focusing on the differences from the image reading device 10 according to the first embodiment. In the present embodiment, the operation of detecting the region of the subject from the image data obtained by the reading operation by the reading device 11 will be described.

(Block configuration of image reader)
FIG. 24 is a diagram showing an example of the block configuration of the image reading device according to the fourth embodiment. The block configuration of the image reading device 10c according to the present embodiment will be described with reference to FIG. 24.

As shown in FIG. 24, the image reading device 10c includes a reading device 11, a control unit 20, a subject information storage unit 21, a motor control unit 22, a motor 23, and a subject area detection unit 25 (area detection unit). And a background member 16.

The reading device 11 outputs the image data (image signal) obtained by the reading operation to the subject area detection unit 25.

The subject area detection unit 25 is a module that receives the image data (image signal) obtained by the reading operation by the reading device 11 and detects the area of the subject P from the image data.

The operation of the other blocks shown in FIG. 24 is as described above in the first embodiment.

(Subject detection operation)
FIG. 25 is a diagram illustrating the operation of the subject area detection unit of the image reading device according to the fourth embodiment. With reference to FIG. 25, an operation in which the subject P is detected from the image data by the subject area detection unit 25 of the image reading device 10c will be described.

As an example of the image data, FIG. 25A shows the image data obtained when the background member 16 has a high density and the subject P has a low density. FIG. 25B is a graph showing the distribution of signal levels (reading values) in the region 502 in the main scanning direction in the image data shown in FIG. 25A. FIG. 25 (c) is a graph showing the distribution of signal levels (reading values) in the region 501 in the sub-scanning direction in the image data shown in FIG. 25 (a).

The subject area detection unit 25 performs a sub-scanning in which the graphs of the signal levels (reading values) of the areas 501 and 502 intersect with a predetermined threshold value in the image data shown in FIG. 25A obtained by the reading operation by the reading device 11. The positions in the direction and the main scanning direction are detected as the boundary positions of the subject P. Then, the subject area detection unit 25 can detect the area inside the detected boundary as the area of the subject P.

As described above, in the configuration capable of acquiring image data suitable for detecting the region of the subject P, the subject region detection unit 25 can detect the region of the subject P from the obtained image data, and is therefore highly accurate. The area of the subject P can be detected. If the image reading device 10c according to the present embodiment is applied to a scanner or the like, it is possible to generate image data of only the area of the subject P based on the information of the area of the subject P detected in the scanned image data. Therefore, the amount of information can be reduced.

The configuration including the subject area detection unit 25 of the present embodiment can also be applied to the image reading device 10a according to the second embodiment and the image reading device 10b according to the third embodiment. be.

[Fifth Embodiment]
The image reading device according to the fifth embodiment will be described focusing on the differences from the image reading device 10c according to the fourth embodiment. In the present embodiment, an operation of correcting the image data of the area of the subject P obtained by the subject area detection unit 25 will be described.

(Block configuration of image reader)
FIG. 26 is a diagram showing an example of a block configuration of the image reading device according to the fifth embodiment. The block configuration of the image reading device 10d according to the present embodiment will be described with reference to FIG. 26.

As shown in FIG. 26, the image reading device 10d includes a reading device 11, a control unit 20, a subject information storage unit 21, a motor control unit 22, a motor 23, a subject area detection unit 25, and an image correction unit. 26 and a background member 16.

The reading device 11 outputs the image data (image signal) obtained by the reading operation to the subject area detection unit 25 and the image correction unit 26.

The image correction unit 26 is a module that geometrically corrects the inclination, size, etc. of the subject P from the detection result of the area of the subject P by the subject area detection unit 25 in the image data received from the reading device 11. The image correction unit 26 may output as image data of only the region of the subject P corrected from the detection result of the region of the subject P.

The operation of the other blocks shown in FIG. 26 is as described above in the fourth embodiment.

(Correction operation of the image correction unit)
FIG. 27 is a diagram illustrating image data corrected by the image correction unit based on the subject detection result. The correction operation for the image data by the image correction unit 26 will be described with reference to FIG. 27.

Depending on the relationship between the width of the transport path and the size of the subject P, or due to factors such as variations in the size of the subject P, the subject P may be transported at an angle or may be transported while floating from the transport path. be. In this case, the subject P may be tilted or may appear in a size other than the original size on the image data obtained by the reading operation by the reading device 11.

FIG. 27A shows image data read by the reading device 11 when the subject P is conveyed at an angle with respect to the sub-scanning direction. In FIG. 27 (b), the inclination is corrected by the image correction unit 26 based on the detection result of the region of the subject P by the subject area detection unit 25 from the image data shown in FIG. 27 (a), and only the region of the subject P is shown. The extracted image data is shown.

As described above, in the image reading device 10d according to the present embodiment, in the image data received from the reading device 11, the inclination, size, etc. of the subject P are determined from the detection result of the area of the subject P by the subject area detecting unit 25. Corrected image data can be obtained. As a result, it is possible to obtain image data corrected for the change from the image data in which the originally undesired geometric change is caused by the inclination or floating of the subject P generated on the transport path. If the image reading device 10d according to the present embodiment is applied to a scanner or the like, image data in which the inclination, size, etc. of the subject P are corrected is generated based on the detection result of the region of the subject P in the image data. Can be provided.

The configuration including the subject area detection unit 25 and the image correction unit 26 of the present embodiment is also applied to the image reading device 10a according to the second embodiment and the image reading device 10b according to the third embodiment. It is possible to do.

[Sixth Embodiment]
The image forming apparatus according to the sixth embodiment will be described. In this embodiment, the image reading device 10d according to the fifth embodiment described above will be provided, but any image of the image reading device according to the first to fourth embodiments described above will be provided. A reading device may be provided.

(Overall structure of image forming apparatus)
FIG. 28 is a diagram showing an example of the overall structure of the image forming apparatus according to the sixth embodiment. The overall structure of the image forming apparatus 100 according to the present embodiment will be described with reference to FIG. 28.

As shown in FIG. 28, the image forming apparatus 100 includes a scanner 101, an ADF (Auto Document Feeder: automatic document feeder) 102, a paper feeding unit 103, and an image forming unit 104. As the image forming apparatus 100 according to the present embodiment, for example, an electrophotographic image forming apparatus or a multifunction device (MFP: Multifunction Peripheral) or the like can be applied. Here, the multifunction device is a device having at least two functions of a printing function, a copying function, a scanner function, and a fax function. Hereinafter, the image forming apparatus 100 according to the present embodiment will be described as being a multifunction device.

The scanner 101 is a device that is arranged between the image forming unit 104 and the contact glass and reads an image of a document supplied on the contact glass. The ADF 102 is a device that automatically sends a document placed on a platen to a contact glass. The paper feeding unit 103 is a portion that sends out a recording medium such as paper and feeds it to the image forming unit 105 via the transport path 107.

The image forming unit 104 is a device that forms an image of an image read by the scanner 101 on a recording medium such as paper. The image forming unit 104 includes an optical writing device 109, an image forming unit 105, a resist roller 108, a double-sided tray 115, an intermediate transfer belt 117, and an image reading device 10d.

The optical writing device 109 irradiates light-modulated laser light based on the image read by the scanner 101 to expose the surface of the photoconductor drum 116 of the uniformly charged image forming unit 105. It is a device that forms an electrostatic latent image on the surface.

The image forming unit 105 is a device that forms an image by transferring the toner image formed on the photoconductor drum 116 to a recording medium. The image forming unit 105 includes four photoconductor drums 116 corresponding to four colors of Y (yellow), M (magenta), C (cyan), and K (black), a charging device, a developer 106, and the like. It includes a transfer device, a cleaning device, and a fixing unit 110.

The photoconductor drum 116 is, for example, a drum-shaped member in which a raw tube made of aluminum or the like is coated with a photosensitive layer made of a photosensitive organic photosensitive material, and is rotationally driven.

The charging device is a charging roller to which an AC voltage is applied, and is strangely charged by sliding contact with the photoconductor drum 116.

The developer 106 is a device that supplies toner to the photoconductor drum 116 on which the electrostatic latent image is formed by the optical writing device 109 to develop the electrostatic latent image and form the toner image.

When the toner image formed on the surface of the photoconductor drum 116 comes to a position opposite to each other due to the rotation of the photoconductor drum 116, the transfer device causes the transfer bias between the photoconductor drum 116 and the photoconductor drum 116 to cause the photoconductor drum 116 and the transfer device. This is a device for primary transfer of a toner image to an intermediate transfer belt 117 conveyed between the two.

The cleaning device is a device that removes and cleans the toner remaining on the surface of the photoconductor drum 116 after the toner image is transferred by the transfer device.

The resist roller 108 is a roller that supplies a recording medium from the paper feeding unit 103 to the image forming unit 104 via the transport path 107.

The double-sided tray 115 is a device that reverses the recording medium printed on one side and supplies it to the resist roller 108 again.

The intermediate transfer belt 117 is a belt stretched between the drive roller and the driven roller while being sandwiched between the nips between the transfer device and the photoconductor drum 116, and the toner image of the photoconductor drum 116 is primary. It is a belt that is transferred. Then, the intermediate transfer belt 117 secondarily transfers the primary transferred full-color toner image to the recording medium.

The fixing unit 110 is a device for fixing the toner image to the recording medium by the action of heating and pressure on the recording medium on which the toner image is secondarily transferred by the intermediate transfer belt 117. When the recording medium (subject P) on which the toner image is fixed by the fixing unit 110 is supplied to the image reading device 10d, the image reading device 10d performs a reading operation.

The image reading device 10d has a reading device 11 that reads image data of the subject P and the background member 16. The image reading device 10d performs a reading operation using the recording medium on which the toner image is transferred as a subject, detects a region of the subject with respect to the read image data, and corrects the inclination, size, etc. of the subject from the detection result. Generate data.

(About the image corrected based on the detection result of the area of the subject)
FIG. 29 is a diagram illustrating image data corrected based on the subject detection result. The image data corrected based on the detection result of the region of the subject P will be described with reference to FIG. 29.

FIG. 29A shows image data obtained by the image reading device 10d when the subject P is tilted and conveyed and the tilt of the image formed by the image forming device 100 is not corrected. It shows that the front end and the rear end in the sub-scanning direction of the formed image and the image data are parallel.

FIG. 29B shows a subject whose image is formed by the image forming apparatus 100, and shows that the formed image is tilted.

FIG. 29C shows an image obtained by the image reading device 10d when the subject P is tilted and conveyed and the tilt correction of the image formed by the image forming apparatus 100 is performed based on the detection result of the region of the subject P. Shows the data. It shows that the image to be formed is tilted.

FIG. 29D shows a subject image formed by the image forming apparatus 100, and shows that the formed image and the front end and the rear end in the sub-scanning direction of the subject are parallel.

As described above, based on the information of the area of the subject detected with high accuracy, the image formed on the subject is corrected to an appropriate inclination and size with respect to the subject, thereby forming the image on the subject. The image can be made to the original desired tilt and size.

It should be noted that each function of each of the above-described embodiments can be realized by one or a plurality of processing circuits. Here, the "processing circuit" is a processor programmed to execute each function by software like a processor implemented by an electronic circuit, or an ASIC or DSP (Digital) designed to execute each function described above. It shall include devices such as Signal Processor), FPGA (Field-Programmable Gate Array), ASIC (System on a Chip), GPU (Graphics Processing Unit), and conventional circuit modules.

Further, in each of the above-described embodiments, when at least one of the functional units of the image reading devices 10, 10a to 10d is realized by executing a program, the program is provided by being incorporated in a ROM or the like in advance. Further, in each of the above-described embodiments, the program executed by the image readers 10, 10a to 10d is a CD-ROM (Compact Disc Read Only Memory) or a flexible disk (Compact Disc Read Only Memory) in an installable format or an executable format file. It may be configured to be recorded and provided on a computer-readable recording medium such as an FD), a CD-R (Compact Disk-Recordable), or a DVD (Digital Versaille Disc). Further, in each of the above-described embodiments, the program executed by the image reading devices 10, 10a to 10d is stored on a computer connected to a network such as the Internet, and is provided by being downloaded via the network. You may. Further, in each of the above-described embodiments, the program executed by the image reading devices 10, 10a to 10d may be configured to be provided or distributed via a network such as the Internet. Further, in each of the above-described embodiments, the program executed by the image reading devices 10, 10a to 10d has a module configuration including at least one of the above-mentioned functional units, and the actual hardware is a CPU. Reads a program from the above-mentioned storage device and executes it, so that each of the above-mentioned functional units is loaded on the main storage device and generated.

10, 10a-10d Image reader 11, 11a Reading device 16 Background member 20 Control unit 21 Subject information storage unit 22 Motor control unit 23 Motor 24 Subject information detection unit 25 Subject area detection unit 26 Image correction unit 100 Image formation device 101 Scanner 102 ADF
103 Paper feed unit 104 Image forming unit 105 Image processing unit 106 Developer 107 Transport path 108 Resist roller 109 Optical writing device 110 Fixing unit 111 Light source 111a First light source 111b Second light source 112 Photoelectric conversion element 113 AFE
115 Double-sided tray 116 Photoreceptor drum 117 Intermediate transfer belt 501-504 area SD1, SD2 Shadow

JP-A-2010-004110 Japanese Unexamined Patent Publication No. 2008-017067 Japanese Patent No. 60444768

Claims (12)

A light source that illuminates the subject and
A reading unit that reads the light emitted from the light source as image data by detecting the reflected light reflected by the subject.
A background member arranged at a position facing the reading unit and having a region having a density of at least 2 or more.
Based on the information of the subject, a control unit that switches to any of the regions of the background member at a position facing the reading unit and controls the amount of light of the light source.
An image reader equipped with. The light source is
A first light source arranged on the downstream side of the reading unit in the transport direction of the subject,
A second light source arranged on the upstream side of the reading unit in the transport direction of the subject,
Including
The image reading device according to claim 1, wherein the control unit controls the amount of light of the first light source to be larger than the amount of light of the second light source. The light source is
A first light source arranged on the downstream side of the reading unit in the transport direction of the subject,
A second light source arranged on the upstream side of the reading unit in the transport direction of the subject,
Including
The image reading device according to claim 1, wherein the control unit controls the amount of light of the second light source to be larger than the amount of light of the first light source. The light source is
A first light source arranged on the downstream side of the reading unit in the transport direction of the subject,
A second light source arranged on the upstream side of the reading unit in the transport direction of the subject,
Including
The control unit
When at least the front end of the subject in the transport direction passes through the reading position of the reading unit, the amount of light of the first light source is controlled to be larger than the amount of light of the second light source.
The image reading device according to claim 1, wherein at least when the rear end of the subject in the transport direction passes through the reading position, the amount of light of the second light source is controlled to be larger than the amount of light of the first light source. When the density of the subject indicated by the information of the subject is higher than a predetermined density, the control unit switches so as to be a low density region of the respective regions of the background member at a position facing the reading unit. The image reading device according to any one of claims 1 to 4. When the density of the subject indicated by the information of the subject is lower than a predetermined density, the control unit switches so as to be a high density region of the respective regions of the background member at a position facing the reading unit. The image reading device according to any one of claims 1 to 4. The control unit
When a region having a density higher than a predetermined density in the region of the subject passes through the reading position of the reading unit, it becomes a region having a low density in each of the regions of the background member at a position facing the reading unit. To switch,
When a region having a density lower than a predetermined density among the regions of the subject passes through the reading position, the region is switched so as to be a region having a high density among the regions of the background member at a position facing the reading portion. The image reading device according to any one of claims 1 to 4. A subject detection unit, which is arranged upstream of the light source and the reading unit in the transport direction of the subject and detects information on the subject, is further provided.
Based on the information of the subject detected by the subject detection unit, the control unit switches to any of the regions of the background member at a position facing the reading unit, and reduces the amount of light of the light source. The image reading device according to any one of claims 1 to 7 to be controlled. 6. Image reader. The image reading device according to claim 9, further comprising an image correction unit that geometrically corrects the subject in the image data based on the detection result of the area of the subject by the area detection unit. An image forming unit that forms an image on a recording medium and outputs it as the subject,
The image reading device according to any one of claims 1 to 10.
An image forming apparatus equipped with. A reading step in which the reading unit reads the light emitted from the light source that irradiates the subject as image data by detecting the reflected light reflected by the subject.
A background member arranged at a position facing the reading unit and having a region having a density of at least 2 or more.
Based on the information of the subject, with respect to the background member arranged at the position facing the reading unit and having a region having a density of at least 2 or more, any one of the above regions at the position facing the reading unit. Switching steps to switch to the area and
A control step that controls the amount of light from the light source based on the information of the subject, and
Image reading method having.

Images