Gain adjustment device, signal processing device, imaging device, image reading device, image forming device, and gain adjustment method

Abstract

To prevent the influence between signals due to a variation in load during gain switching in a system having a plurality of processing lines.SOLUTION: A gain adjustment device comprises: gain adjustment means that are provided in a number equal to the number of signals to be input and adjust gain values used for amplification of the signals; and gain reflection control means that, for a signal affecting the signal level of another signal, makes different the switching timing of the gain values in the gain adjustment means so as to switch the gain values in a period different from that for the another signal.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a gain adjustment device, a signal processing device, an imaging device, an image reading device, an image forming device, and a gain adjustment method. [Background technology]

[0002] Conventionally, in image reading devices, when multiple image signals (R / G / B) obtained from a photoelectric conversion element are amplified by a variable gain amplifier (PGA), the gain value is adjusted for each color in a three-channel processing circuit so that each signal level reaches a preset target value to prevent saturation, etc.

[0003] In recent years, a technology has been disclosed in which an AFE adjusts the gain of each of the four channels of color (R / G / B) and monochrome (BW) image signals output from a photoelectric conversion element (see Patent Document 1).

[0004] Furthermore, in recent years, a photoelectric conversion element has been disclosed that outputs invisible information in addition to the visible information of R / G / B by providing a pixel (IR) that receives infrared light as the fourth pixel. Summary of the Invention [Problem to be solved by the invention]

[0005] However, with conventional gain adjustment methods, there is a problem in that GND / power supply fluctuations due to load fluctuations in the processing circuit when the gain is switched cause fluctuations in the image signal level in other channels via the common impedance of the circuit.

[0006] In particular, for the above-mentioned IR pixel, the signal is small because silicon has low sensitivity in the infrared region, and the gain is large, so that the load fluctuation at the time of gain switching has a large effect on other channels.

[0007] The present invention has been made in view of the above, and has an object to prevent influence between signals due to load fluctuations when gain is switched in a system having a plurality of processing systems. [Means for solving the problem]

[0008] In order to solve the above problems and achieve the object, the present invention provides an input Multiple signal Channel A few minutes are provided, Simultaneous acquisition of multiple channels A gain adjustment means for adjusting a gain value used for amplifying a signal, and a gain value switching timing in the gain adjustment means for a signal that has an effect on the signal level of another signal is controlled so that the gain value is switched during a period different from that of the other signal. Selectively per channel and a gain reflection control means for making the gains different from each other. Effect of the Invention

[0009] According to the present invention, it is possible to prevent influence between signals due to load fluctuations when gain is switched in a system having a plurality of processing systems. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram illustrating an example of a configuration of an image forming apparatus according to an embodiment. [Diagram 2] FIG. 2 is a cross-sectional view illustrating an example of the structure of the image reading unit. [Diagram 3] FIG. 3 is a block diagram showing electrical connections of the components constituting the image reading unit. [Figure 4] FIG. 4 is a flowchart showing the flow of the gain adjustment process. [Diagram 5] FIG. 5 is a timing chart showing an example of auto gain control in the gain adjustment process. [Figure 6] FIG. 6 is a timing chart showing an example of auto gain control in the gain adjustment process. [Figure 7]FIG. 7 is a block diagram showing a modified example of the configuration of the gain adjustment device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, with reference to the accompanying drawings, embodiments of a gain adjustment device, a signal processing device, an imaging device, an image reading device, an image forming device, and a gain adjustment method will be described in detail.

[0012] Fig. 1 is a diagram showing an example of a configuration of an image forming apparatus 100 according to an embodiment. In Fig. 1, the image forming apparatus 100 is an image forming apparatus generally called a multifunction machine having at least two functions of a copy function, a printer function, a scanner function, and a facsimile function.

[0013] Image forming apparatus 100 has image reading unit 101, which is an image reading device, and ADF (Automatic Document Feeder) 102, and below that has image forming unit 103. In order to explain the internal configuration of image forming unit 103, the external cover is removed to show the internal configuration.

[0014] The ADF 102 is an original support unit that positions an original, the image of which is to be read, at a reading position. The ADF 102 automatically transports an original placed on a placement table to the reading position. The image reading unit 101 reads the original transported by the ADF 102 at a predetermined reading position. The image reading unit 101 also has a contact glass on its upper surface, which is an original support unit on which an original is placed, and reads the original on the contact glass, which is the reading position. Specifically, the image reading unit 101 is a scanner that has a light source, an optical system, and a photoelectric conversion element such as a CCD (Charge Coupled Device) inside, and reads the reflected light of an original illuminated by a light source through the optical system.

[0015] The image forming unit 103 prints the document image read by the image reading unit 101. The image forming unit 103 has a manual feed roller 104 for manually feeding recording paper, and a recording paper supply unit 107 for supplying recording paper. The recording paper supply unit 107 has a mechanism for feeding recording paper from a multi-stage recording paper feed cassette 107a. The supplied recording paper is sent to a secondary transfer belt 112 via a registration roller 108.

[0016] A toner image on the intermediate transfer belt 113 is transferred to the recording paper conveyed on the secondary transfer belt 112 in a transfer section 114 .

[0017] The image forming unit 103 also includes an optical writing device 109, tandem imaging units (Y, M, C, K) 105, an intermediate transfer belt 113, and the secondary transfer belt 112. Through an image creation process by the imaging units 105, the image written by the optical writing device 109 is formed as a toner image on the intermediate transfer belt 113.

[0018] Specifically, the imaging unit (Y, M, C, K) 105 has four rotatable photoconductor drums (Y, M, C, K), and is provided with imaging elements 106 including a charging roller, a developing unit, a primary transfer roller, a cleaner unit, and a static eliminator around each photoconductor drum. The imaging elements 106 function for each photoconductor drum, and the image on the photoconductor drum is transferred onto the intermediate transfer belt 113 by each primary transfer roller.

[0019] The intermediate transfer belt 113 is stretched across a drive roller and a driven roller in the nip between each photosensitive drum and each primary transfer roller. The toner image primarily transferred onto the intermediate transfer belt 113 is secondarily transferred to the recording paper on the secondary transfer belt 112 by the secondary transfer device as the intermediate transfer belt 113 travels. The recording paper is transported to the fixing device 110 as the secondary transfer belt 112 travels, and the toner image is fixed onto the recording paper as a color image. The recording paper is then discharged to a paper discharge tray outside the machine. In the case of double-sided printing, the front and back of the recording paper are inverted by the inversion mechanism 111, and the inverted recording paper is sent onto the secondary transfer belt 112.

[0020] The image forming unit 103 is not limited to one that forms images by the electrophotographic method as described above, but may be one that forms images by an inkjet method.

[0021] Next, the image reading unit 101 will be described.

[0022] Fig. 2 is a cross-sectional view showing an example of the structure of the image reading unit 101. As shown in Fig. 2, the image reading unit 101 has a sensor board 10 with a photoelectric conversion element 9, a lens unit 8, a first carriage 6, and a second carriage 7 in a main body 11. The photoelectric conversion element 9 is, for example, a CCD or CMOS image sensor. The first carriage 6 has a light source 2, which is an LED (Light Emitting Diode), and a mirror 3. The second carriage 7 has mirrors 4 and 5. In addition, the image reading unit 101 has a contact glass 1 and a reference white plate 13 on the upper surface.

[0023] In the reading operation, the image reading unit 101 irradiates light upward from the light source 2 while moving the first carriage 6 and the second carriage 7 from a standby position (home position) in the sub-scanning direction (direction A). Then, the first carriage 6 and the second carriage 7 form an image of the reflected light from the original 12 on the photoelectric conversion element 9 via the lens unit 8.

[0024] Furthermore, when the power is turned on, the image reading unit 101 sets a reference by reading the reflected light from the reference white plate 13. That is, the image reading unit 101 moves the first carriage 6 to directly below the reference white plate 13, turns on the light source 2, and forms an image of the reflected light from the reference white plate 13 on the photoelectric conversion element 9, thereby performing gain adjustment.

[0025] Fig. 3 is a block diagram showing electrical connections of the components constituting the image reading unit 101. As shown in Fig. 3, the image reading unit 101 includes a light source 2, an imaging device 21, a control unit 23, and a light source driving unit 24. The light source driving unit 24 drives the light source 2.

[0026] A light source 2 irradiates a document (subject) with visible light of visible (Red / Green / Blue) wavelengths and invisible light (infrared light) of infrared (IR) wavelengths.

[0027] The imaging device 21 includes a photoelectric conversion element 9 and a signal processing device 22 .

[0028] The photoelectric conversion element 9 receives incident light that has been separated into visible light (Red / Green / Blue) and invisible light (Infrared light) for each wavelength by a color filter or the like, and converts it into Red / Green / Blue / Infrared electrical signals. The photoelectric conversion element 9 outputs RGB image signals when reading visible images, and IR image signals when reading invisible images, simultaneously for each of the multiple systems to the downstream signal processing device 22.

[0029] In this embodiment, an example in which an infrared (IR) image is used as the invisible image will be described, but an ultraviolet image may be used as the invisible image, and the wavelength range used for the invisible image is not limited. Also, only a visible image may be used.

[0030] The control unit 23 controls each of the light source driving unit 24, the photoelectric conversion element 9, and the signal processing device 22.

[0031] The signal processing device 22 performs various signal processes on the image signal output from the photoelectric conversion element 9 .

[0032] Next, the signal processing device 22 will be described in detail.

[0033] As shown in Fig. 3, the signal processing device 22 includes gain adjustment means 31 for multiple channels (the number of signals) and AD conversion means 32 in order to perform independent gain processing on multiple image signals. The signal processing device 22 also includes a CPU (Central Processing Unit) 33, a register 34, and a level detection means 35. The gain adjustment means 31 for multiple channels (the number of signals) and the level detection means 35 are controlled by the CPU 33 and execute a series of gain processing. The gain adjustment device 20 is realized by the CPU 33, the register 34, the level detection means 35, and the gain adjustment means 31 for multiple channels (the number of signals).

[0034] The level detection means 35 detects the level of the digital data of the signal from the AD conversion means 32 .

[0035] The gain adjustment means 31 includes an amplification means 41, a gain setting means 42, a gain control means 43, and a gain reflection control means 44.

[0036] The gain setting means 42 stores the gain value.

[0037] The amplifier 41 amplifies the input signal by the gain value stored in the gain setting means 42, and outputs the amplified signal as an output signal. The amplifier 41 may be, for example, a switched capacitor, but is not limited to this as long as it is capable of amplifying.

[0038] The gain control means 43 determines a gain value according to the level of the output signal of the AD conversion means 32 detected by the level detection means 35 .

[0039] That is, the level detection means 35 and the gain control means 43 constitute an auto gain control (AGC) function for setting the optimum gain each time depending on the state of the input signal.

[0040] More specifically, the level detection means 35 detects the level of the input signal before the amplification means 41. The gain control means 43 determines the gain according to the level detected by the level detection means 35. The gain setting means 42 switches the gain value of the amplification means 41.

[0041] The gain control means 43 includes a calculation circuit that calculates and derives a target gain value from the detection level.

[0042] The gain adjustment means 31 for a plurality of channels (the number of signals) and the level detection means 35 are controlled by the CPU 33 in FIG. 3 and execute a series of gain processes.

[0043] Incidentally, when the gain adjustment operations are performed simultaneously in the gain adjustment means 31, a load fluctuation in a signal with a large determined gain causes a fluctuation in the input of the adjacent gain adjustment means 31 via a common impedance.

[0044] In this embodiment, the magnitude of the image signal differs between visible light and infrared light, and the image signal of infrared light may have a low value. In fact, the signal amount of the image signal of infrared light is a fraction of the signal amount of the image signal of visible light. This is because the quantum sensitivity of silicon constituting the photoelectric conversion element 9 in the invisible (infrared) range is lower than that in the visible range.

[0045] Therefore, the gain adjustment means 31 of this embodiment includes a gain reflection control means 44. The gain reflection control means 44 is a means for changing the timing of the gain value switching from the gain control means 43 determined by the auto gain control (AGC) function so that an image signal that affects the signal levels of other image signals is subject to gain value switching in a period different from that of the other image signals. More specifically, the gain reflection control means 44 delays the timing of gain reflection of a specific image signal from that of other image signals, or selects whether or not to make the specific image signal subject to gain value switching from the gain control means 43 (whether or not to reflect the gain setting means 42). This prevents the gain adjustment means 31 from simultaneously reflecting the determined gain value in the gain setting means 42, thereby preventing load fluctuations due to gain switching.

[0046] That is, depending on the presence or absence of a channel for which the gain is not desired to be switched at the same time, the gain reflection control means 44 delays the reflection timing for an image signal that affects the signal level of other image signals by a determined time so that the gain value is reflected in a period separate from that of the other image signals. The reflection timing for the gain reflection control means 44 is set in the register 34 via the CPU 33 by the user depending on the situation.

[0047] Alternatively, the gain reflection control means 44 is turned ON / OFF depending on the presence or absence of a channel for which the gain should not be switched at the same time. The ON / OFF of the gain reflection control means 44 is set by the user in the register 34 via the CPU 33 depending on the situation.

[0048] Next, the flow of the gain adjustment process in the signal processing device 22 will be described.

[0049] Here, Fig. 4 is a flowchart showing the flow of the gain adjustment process, and Fig. 5 and Fig. 6 are timing charts showing an example of auto gain control in the gain adjustment process. Note that the examples shown in Fig. 5 and Fig. 6 plot the level fluctuations during AGC of the outputs Dout1 to 4 of each gain adjustment means 31 when four gain adjustment means 31 are arranged.

[0050] 4, first, the signal processing device 22 judges whether there is an image signal that affects the signal levels of other image signals (step S1). If there is an image signal that affects the signal levels of other image signals (Yes in step S1), the signal processing device 22 judges whether the gain reflection control means 44 uses a method of switching by ON / OFF control or a method of shifting the reflection timing, as described above, and branches (step S2). For example, the gain reflection control means 44 refers to a mode (a mode of switching by ON / OFF control, a mode of shifting the reflection timing) previously set by the user, and judges whether the method of switching by ON / OFF control or the method of shifting the reflection timing is used.

[0051] In the case of timing control for the gain reflection control means 44 (No in step S2), the signal processing device 22 turns on the visible light and infrared light of the light source 2 of the image reading unit 101 to adjust the gain in the visible / invisible region (Red / Green / Blue / Infrared). At this time, the signal processing device 22 sets the gain switching setting of Dout4 (infrared light) to "delay" in advance, and sets the gain switching setting of Dout1 to 3 (visible light) to "normal" via a register (step S3).

[0052] 4, when the signal processing device 22 starts an automatic gain control (AGC) operation, it detects an image signal at an initial gain value (step S4). Then, the signal processing device 22 determines the gains (Dout1 to 3) by each gain adjustment means 31 so that the gains become preset target values, and switches the gains (Dout1 to 3) (step S5).

[0053] As shown in FIG. 5, since the gain reflection selection means 44 is set to “delay” for Dout4, the signal processing device 22 does not reflect the gain value from the gain control means 43 to the gain adjustment means 31 corresponding to Dout4 at this timing.

[0054] On the other hand, as shown in FIG. 5, since the gain reflection selection means 44 is set to “normal” for Dout1 to Dout3, the signal processing device 22 reflects the gain values ​​from the gain control means 43 to the gain adjustment means 31 corresponding to Dout1 to Dout3.

[0055] As a result, the signal processing device 22 determines that only the gains of the channels in the visible range (Red / Green / Blue) have been adjusted (step S6).

[0056] As for Dout4, since the gain reflection selection means 44 is set to "normal", the signal processing device 22 reflects the gain value from the gain control means 43 in the gain adjustment means 31 corresponding to Dout4 with a delay.

[0057] That is, the signal processing device 22 determines the gain (Dout4) by each gain adjustment means 31 so that the value becomes a preset target value, and switches the gain (Dout4) (step S7).

[0058] The amount of delay when this "delay" is set is made variable in a register according to the load fluctuation period.

[0059] As a result, the signal processing device 22 determines that only the gain of the channel in the non-visible region (infrared) has been adjusted. Then, the signal processing device 22 ends the auto gain control (AGC) without being affected by noise from Dout4 by shifting the reflection timing between the visible region (Red / Green / Blue) and the non-visible region (infrared) (step S8).

[0060] This enables accurate auto gain control without being affected by noise in high gain channels.

[0061] As described above, according to this embodiment, by delaying gain switching for signals with large gain values ​​among multiple signal levels, it is possible to eliminate the effects of noise on other signals when gain switching occurs. Therefore, in a system having multiple processing systems, it is possible to prevent effects between signals due to load fluctuations when gain switching occurs.

[0062] Furthermore, according to this embodiment, it is not necessary to take into account a long-term wait (more than twice the AGC time) that takes into account variations in the convergence time of the load fluctuation when the load fluctuation occurs.

[0063] In the case of ON / OFF control of the gain reflection control means 44 (Yes in step S2), the signal processing device 22 turns on the visible light and infrared light of the light source 2 of the image reading unit 101 as the first auto gain control operation (AGC(1)) and adjusts the gain in the visible range (Red / Green / Blue). At this time, the signal processing device 22 sets the gain switching setting of Dout4 (infrared light) to "disabled" in advance, and sets the gain switching setting of Dout1 to 3 (visible light) to "enabled" (step S9).

[0064] 4, when the signal processing device 22 starts the first auto gain control operation (AGC(1)), it detects an image signal at an initial gain value (step S10). Then, the signal processing device 22 determines the gain by each gain adjustment means 31 so that the value becomes a preset target value, and switches the gains simultaneously (step S11).

[0065] As shown in FIG. 6, since the gain reflection control means 44 is set to switch OFF (disabled) for Dout4, the signal processing device 22 does not reflect the gain value from the gain control means 43 to the gain adjustment means 31 corresponding to Dout4.

[0066] On the other hand, as shown in FIG. 6, since the gain reflection control means 44 has the switching ON (enabled) set for Dout1 to Dout3, the signal processing device 22 reflects the gain values ​​from the gain control means 43 to the gain adjustment means 31 corresponding to Dout1 to Dout3.

[0067] As a result, after determining that only the gains of the channels in the visible range (Red / Green / Blue) have been adjusted, the signal processing device 22 ends the initial auto gain control (AGC(1)) without being affected by noise from Dout4 (step S12).

[0068] Next, the signal processing device 22 sets the gain switching setting of Red / Green / Blue Dout1 to 3 (visible light) to “disabled” and the gain switching setting of Dout4 (infrared light) to “enabled”, and performs the next auto gain control operation (AGC(2)) (step S13).

[0069] 4, when the signal processing device 22 starts the next auto gain control operation (AGC(2)), it detects an image signal at an initial gain value (step S14). Then, the signal processing device 22 determines the gain by each gain adjustment means 31 so that the value becomes a preset target value, and switches the gains simultaneously (step S15).

[0070] As shown in FIG. 6, since the gain reflection control means 44 is set to switch OFF (disabled) for Dout1 to Dout3, the signal processing device 22 does not reflect the gain values ​​from the gain control means 43 to the gain adjustment means 31 corresponding to Dout1 to Dout3.

[0071] On the other hand, as shown in FIG. 6, since the gain reflection control means 44 has been switched ON (enabled) for Dout4, the signal processing device 22 reflects the gain value from the gain control means 43 in the gain adjustment means 31 corresponding to Dout4.

[0072] As a result, after determining that only the gain of the invisible (infrared) channel has been adjusted, the signal processing device 22 ends the next auto gain control (AGC(2)) without being affected by the noise from Dout1 to Dout3 (step S16).

[0073] This enables accurate auto gain control without being affected by noise in high gain channels.

[0074] As described above, according to this embodiment, by disabling gain switching for signals with large gain values ​​among multiple signal levels, it is possible to eliminate the effects of noise on other signals when gain switching occurs. Therefore, in a system having multiple processing systems, it is possible to prevent effects between signals due to load fluctuations when gain switching occurs.

[0075] Furthermore, according to this embodiment, although AGC is performed twice, there is no need to consider a long-term wait (more than twice the AGC time) in consideration of variations in the convergence time of the load fluctuation when the load fluctuation occurs. Also, for example, when a different control needs to be executed in a scanner, the second AGC timing can be set in consideration of the system configuration and sequence around the imaging device.

[0076] If the optical system being used has a large amount of incident light (a small gain value) or the like, and there is no problem with noise effects between channels, the signal processing device 22 may be implemented at once with all channels set as "enabled."

[0077] 4, assuming that there is no image signal that affects the signal levels of other image signals (No in step S1), the signal processing device 22 detects an image signal at an initial gain value when it starts an initial auto gain control operation (AGC) (step S17), as in the conventional case. Then, the signal processing device 22 determines the gains (Dout1 to 4) by each gain adjustment means 31 so that the value becomes a preset target value, switches the gains all at once (step S18), and ends the auto gain control (AGC) after determining that the gains of each channel have been adjusted (step S19).

[0078] 7 is a block diagram showing a modified example of the configuration of the gain adjustment device 20. As shown in FIG 7, the gain adjustment device 20 may include a level detection means 35 in each gain adjustment means 31. In this case, the level detection means 35 detects the level of the image signal before it is amplified by the amplification means 41.

[0079] In the above embodiment, the image forming apparatus of the present invention is described as being applied to a multifunction peripheral having at least two of the functions of a copy function, a printer function, a scanner function, and a facsimile function. However, the image forming apparatus can be applied to any image forming apparatus such as a copier, a printer, a scanner device, or a facsimile device. [Explanation of symbols]

[0080] 2 light source 9 Photoelectric conversion element 20 Gain adjustment device 21 Imaging device 22 Signal Processing Device 31 Gain adjustment means 32 AD conversion means 44 Gain reflection control means 100 Image forming device 101 Image reading device 103 Image forming section [Prior art documents] [Patent documents]

[0081] [Patent Document 1] Japanese Patent Publication No. 3743401

Claims

1. a gain adjustment unit provided for the number of channels of the input signals, the gain adjustment unit adjusting a gain value used for amplifying the simultaneously acquired signals of the multiple channels; a gain reflection control means for selectively varying a timing of switching the gain value in the gain adjustment means for each channel so that a gain value of a signal that affects the signal level of another signal is switched during a period different from that of the other signal; A gain adjustment device comprising:

2. the gain reflection control means selects not to subject a signal that has an effect on the signal level of another signal to gain value switching in the gain adjustment means; 2. The gain adjustment device according to claim 1.

3. The gain reflection control means delays a timing of switching a gain value in the gain adjustment means for a signal that affects a signal level of another signal.

2. The gain adjustment device according to claim 1.

4. A gain adjustment device according to any one of claims 1 to 3, The signal is an image signal input to each of a plurality of processing systems.

23. A signal processing device comprising:

5. a photoelectric conversion element that converts incident light into an electrical signal and outputs an image signal for each color; A signal processing device according to claim 4 ; Equipped with The signal is an image signal input for each color output from the photoelectric conversion element.

1. An imaging device comprising:

6. The image signals for each color are an image signal obtained by receiving visible light and an image signal obtained by receiving invisible light.

6. The imaging device according to claim 5.

7. A light source that irradiates light; The imaging device according to claim 5 or 6, An image reading device comprising:

8. An image forming unit; The image reading device according to claim 7 ; An image forming apparatus comprising:

9. A gain adjustment method for a gain adjustment device, comprising: a gain adjustment step of adjusting a gain value used to amplify simultaneously acquired signals of a plurality of channels by using gain adjustment means provided for the number of channels of the plurality of signals to be input; a gain reflection control step of selectively varying a timing of switching the gain value in the gain adjustment step for each channel so that the gain value of a signal that has an effect on the signal level of another signal is switched during a period different from that of the other signal; A gain adjustment method comprising:

Images