JP3642389B2 - Image reading device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image reading apparatus.
[0002]
[Prior art]
In an image reading apparatus such as a digital copying machine or a digital facsimile, the read image information is converted into an electrical signal and subjected to electrical processing by a predetermined electrical circuit. As disclosed in Japanese Patent No. -150622, there is a case in which a device for automatically adjusting the amplification factor of an amplifier in an electric circuit and the reference voltage of an A / D converter is provided. These apparatuses have an advantage that an image output in which a certain quality is guaranteed can be obtained without depending on individual differences or changes in characteristics over time of parts used in an electric circuit and parts used in a light source.
[0003]
[Problems to be solved by the invention]
However, in recent image reading apparatuses, reading resolution has been increased and reading speed has been increased due to advances in semiconductor miniaturization technology and market requirements.
[0004]
In these devices, as the number of components increases and the degree of circuit integration per component increases, the electrical circuit becomes more complex and the probability of occurrence of device failures tends to increase. In addition, when a failure occurs, the number of parts that can cause the failure is large, which leads to the time required for identifying the cause and repairing / recovering. Furthermore, when the image reading device is a digital facsimile, the operator cannot check the result of the read image on the spot. It may also lead to a serious disadvantage in use due to failure to transmit an accurate image.
[0005]
The object of the present invention is to use a self-adjusting device originally provided to obtain higher image quality, and to inform the operator of the situation when a device failure occurs, thereby causing a serious disadvantage in use. The purpose is to reduce the time and cost of repair and recovery by avoiding in advance and identifying the fault location.
[0008]
[ Means for Solving the Problems ]
According to the first aspect of the present invention, there is provided a light source that irradiates light on a document, a solid-state image sensor that receives reflected light of the light and converts it into an electrical signal, and an electrical process for analog signals output from the solid-state image sensor A signal processing circuit to which the processing coefficient of the electrical processing performed by the signal processing circuit is adjusted to an appropriate coefficient, and the electrical processing described above after the processing coefficient is adjusted to the appropriate coefficient. When the analog signal to which the signal is added is not within a predetermined numerical range, a notification means for notifying an operator of the occurrence of a system abnormality is provided , and the notification means sets the processing coefficient to an appropriate coefficient. After the adjustment, the maximum value of the analog signal after the electrical processing is performed when the solid-state imaging device reads the image of the black dummy pixel and the image of the white reference plate is compared. And both analogies When the difference between the signals is smaller than a predetermined value and the analog signal after the electrical processing when the image of the black dummy pixel is read is smaller than the predetermined value, the abnormality of the system is detected by the light source. The operator is notified of the failure .
[0009]
Therefore, when a failure occurs in the apparatus, the location of the failure can be automatically identified and notified to the operator, so that the time and cost required for repair and repair of the apparatus can be reduced.
[0010]
According to a second aspect of the present invention, there is provided a light source for irradiating a document with light, a solid-state image sensor that receives reflected light of the light and converts it into an electrical signal, and an electrical process for analog signals output from the solid-state image sensor A signal processing circuit to which the processing coefficient of the electrical processing performed by the signal processing circuit is adjusted to an appropriate coefficient, and the electrical processing described above after the processing coefficient is adjusted to the appropriate coefficient. When the analog signal to which the signal is added is not within a predetermined numerical range, a notification means for notifying an operator of the occurrence of a system abnormality is provided, and the notification means sets the processing coefficient to an appropriate coefficient. After adjustment, the maximum value of the analog signal after the electrical processing is performed when the solid-state imaging device reads the image of the black dummy pixel and the image of the white reference plate is compared. And both analogies When the difference in signal is smaller than a predetermined value and the analog signal after the electrical processing when the image of the black dummy pixel is read is larger than the predetermined value, the abnormality of the system is detected in the solid-state imaging The operator is notified that the element is faulty .
[0011]
Therefore, when a failure occurs in the apparatus, the location of the failure can be automatically identified and notified to the operator, so that the time and cost required for repair and repair of the apparatus can be reduced.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a diagram showing a schematic configuration of an image reading apparatus according to an embodiment of the present invention. The image reading apparatus 1 includes a contact glass 2, a pressure plate 3 covering the contact glass 2, a light source 4 for exposing a document, mirrors 5, 6, and 7, a lens 8, a CCD camera 9, and signal processing. Circuit 10. The light source 4 and the mirror 5 are attached to the traveling body 11 and travel in the arrow direction by the motor 13 via the wire 12. The original placed on the contact glass 2 is irradiated on the light source 4, and the irregularly reflected light is reflected by the three mirrors 5, 6, 7 and is imaged on the CCD camera 9 through the lens 8. The CCD camera 9 replaces the incident light with an electric signal for each line, and sends an analog electric signal to the signal processing circuit 10. Reference numeral 14 denotes an original size sensor, which is installed below an optical system including the light source 4 to the CCD camera 9.
[0013]
FIG. 2 is a block diagram showing the flow of image information centered on the signal processing circuit 10 of the image reading apparatus 1. Light incident on the CCD camera 9 is replaced with an analog electric signal for each line, and is amplified by an amplifier 21. It is amplified with the amplification factor of. The amplified analog signal is converted into a digital signal by the A / D converter 22. For example, when the A / D converter 22 is an A / D converter that performs 8-bit digital output, the image information is handled as 0 to 255 digital image data. The digitized image information is subjected to electrical image processing by a shading correction circuit 23, an MTF correction circuit 24, a scaling circuit 25, and a γ (gamma) conversion circuit 26, and a controller (not shown) is connected via an interface circuit 27. (Copy controller, facsimile controller or image scanner controller).
[0014]
The output signal of the A / D converter 22 is also input to the peak detection circuit 28. The peak detection circuit 28 is a circuit that detects and holds the maximum value in one line of the input image data, and the held data centrally controls the entire image reading apparatus 1 via the CPU bus 29. Read by the CPU 30. The CPU 30 can change the amplification factor of the amplifier 21 by changing the output of the D / A converter 31 via the CPU bus 29. Similarly, the CPU 30 can change the reference voltage of the A / D converter 22 by changing the output of the D / A converter 32. Here, the reference voltage determines the voltage of the image electrical signal input to the A / D converter 22 and how many volts of the digital data are converted, that is, the density range (= dynamic range) of the original to be read. To decide. Reference numeral 33 denotes NVRAM (nonvolatile RAM), and the data written in the NVRAM 33 by the CPU 30 is retained without loss even when the power of the image reading apparatus 1 is shut off. Further, the CPU 30 is connected to each circuit of the shading correction circuit 23 to the interface circuit 27 via the CPU bus 29, and sets parameters of each arithmetic processing such as an MTF correction coefficient and a scaling factor for each circuit. Can do. Reference numeral 34 denotes a white reference plate, which is an area that is read on the contact glass 2 and coated in a white and uniform density over the entire area of one line. The ROM 35 stores various programs and the like, and the RAM 36 stores various data in a rewritable manner and serves as a work area for the CPU 30.
[0015]
FIG. 3 is a graph for explaining the maximum value in one line detected by the peak detection circuit 28. The horizontal axis indicates the output pixel number of the CCD camera 9, and here, it is assumed that a CCD of 5000 pixels per line is used. The vertical axis represents digitized image data, which is shown here as data normalized to 255 by the 8-bit A / D converter 22, and the closer to 0, the higher the density (close to black) and the closer to 255. The lower the pixel density (close to white) is. The light source 4 is bright in the vicinity of the center of the light source, and has a characteristic that the amount of light decreases as it is at the end. For this reason, even when a uniformly white image is read, the obtained image data is brighter (larger) near the center in one line, and the data at both ends of one line is smaller. Therefore, one line of image data output when the white reference plate 34 is read is as shown in FIG. 4, and the vicinity of the center pixel is the maximum value PKw of the white image.
[0016]
Further, OPBK in FIG. 3 is a signal indicating the output period of the black dummy pixel prepared in the CCD camera 9. The black dummy pixel is a pixel arranged in a portion where the light of the CCD camera 9 is shielded, and the output of this pixel is always a black image output regardless of whether the light source is turned on or the type of the read image. Is obtained. Therefore, as shown in FIG. 3, in the interval in which the OPBK signal is output in Hi active, the image data is substantially constant and high density (close to black) regardless of the light distribution of the light source. In the figure, PKb indicates the maximum value of this OPBK section. The peak detection circuit 28 detects and holds PKw and PKb as the maximum data of each region.
[0017]
Next, details of the automatic adjustment processing will be described with reference to the flowchart of FIG. The automatic adjustment is to automatically adjust the processing coefficient of electrical processing performed in each unit in accordance with the change in mechanical characteristics so that the image reading apparatus 1 obtains an optimal image. Here, the amplification factor of the amplifier 21 is adjusted. An adjustment example will be described. The adjustment of the amplification factor is performed so that a document having a constant density can be read as constant image data even when the light emission amount changes due to the temperature characteristics of the light source 4 or deterioration with time.
[0018]
This automatic adjustment is executed when the power of the image reading apparatus 1 is turned on. As shown in FIG. 4, first, when automatic adjustment is started, the CPU 30 turns on the light source 4 and further moves the traveling body 11 so that the image reading position becomes the white reference plate 34 (step S1). ). Next, the CPU 30 sets an initial value G0 of the amplification factor of the D / A converter 31 (G = G0) (step S2). Then, the value n of a predetermined counter prepared in the RAM 36 is reset to the initial value 1 (n = 1) (step S3).
[0019]
Next, the CPU 30 obtains the maximum value PKw when the white reference plate 34 is read through the peak detection circuit 28 (step S4). Here, PKw is compared with a target value (data that should originally be obtained when the white reference plate 34 is read) Dref (step S5). In this case, if PKw is in the range of “Dref ± 1” ( In step S5, it is determined that an appropriate amplification factor has been set for the amplifier 21, the light source 4 is turned off, and the light source 4 and the mirror 5 are moved to the home position to complete the automatic adjustment (step S6).
[0020]
When PKw is not in the range of “Dref ± 1” (N in step S5), it is determined whether the count value n of the counter is larger than a predetermined value N (step S7). N) From the difference between Dref and PKw, increase / decrease in the amplification factor is determined and set in the D / A converter 31. In this example, the newly set multiplication factor Gn + 1 is
“Gn + 1 = Gn + (Dref−PKw) * K (Gn: current amplification factor, K: predetermined constant)”
(Step S9). Then, the counter is incremented by +1 (step S10). After setting a new amplification factor, the maximum value PKw of the reading area of the white reference plate 34 is read again from the peak detection circuit 28 (step S4), compared with Dref (step S5), and the counter is incremented by +1 (step S4). S10). Hereinafter, the processing of step S4, step S5, step S9 and step S10 is continued until the target PKw is obtained (Y in step S5). When PKw reaches the target value, the CPU 30 stores the amplification factor Gn set in the D / A converter 31 at that time in the NVRAM 33, and then ends the automatic adjustment (step S6).
[0021]
Further, when the target PKw is not obtained (N in step S5) and the counter value n is larger than the predetermined value N, this is indicated on a display (not shown) as a system abnormality (step S8). Then, the automatic adjustment is finished (step S6). The function of the adjusting means of the present invention is realized by the processing shown in FIG. Further, the function of the notification means of the present invention is realized by the processing of step S8.
[0022]
Next, processing executed after the automatic adjustment is performed will be described with reference to a flowchart of FIG. First, the CPU 30 executes the automatic adjustment when the power of the image reading apparatus 1 is turned on (step S11). After completion of the automatic adjustment, the CPU 30 acquires the maximum value PKw at the time of reading the white reference plate 34 and the maximum value PKb of the black dummy pixel via the peak detection circuit 28 (steps S12 and S13). Here, the difference “PKw−Pkb” between PKw and PKb is calculated. If the result is not smaller than the predetermined value Pb (N in step S), it is assumed that no failure has occurred in the system and the normal operation is performed as it is. Continue.
[0023]
If the result is smaller than the predetermined value Pb (Y in step S), PKb is compared with the predetermined value Pb (step S15). If PKb is smaller than Pb (Y in step S15), A display indicating that a system abnormality has occurred due to a failure of the light source 4 is displayed on the display (step S17). In this case, the relationship between PKw, PKb, and Pb is as shown in FIG. 6. In this state, the black dummy pixel portion is normal output, and the reading portion of the white reference plate 34 is abnormal output. The CCD camera 9 and the signal processing circuit 10 in the subsequent stage are operating normally, and it can be determined that the light source 4 is abnormal.
[0024]
If PKb is larger than Db (N in step S15), it is displayed on the display (not shown) that a system abnormality has occurred due to the failure of the CCD camera 9 (step S16). In this case, the relationship between PKw, PKb, and Pb is as shown in FIG. 7. In this state, the black dummy pixel portion and the reading portion of the white reference plate 34 are abnormal outputs, so the CCD camera 9 itself Can be judged as abnormal. Here, Dwb and Pb are set to values such as Dwb = 100 and Pb = 50. Steps S16 and S17 realize the function of the notification means of the present invention.
[0026]
The invention according to claim 1, when the failure of the equipment will automatically identify fault location, it is possible to inform the operator servicing equipment, reducing the time and cost required for repair Can do.
[0027]
The invention according to claim 2, when the failure of the equipment will automatically identify fault location, it is possible to inform the operator servicing equipment, reducing the time and cost required for repair Can do.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a schematic configuration of an image reading apparatus according to an embodiment of the present invention.
FIG. 2 is a block diagram showing a flow of image information centering on a signal processing circuit of the image reading apparatus.
FIG. 3 is a graph for explaining a maximum value in one line detected by a peak detection circuit of the signal processing circuit.
FIG. 4 is a flowchart illustrating details of an automatic adjustment process performed by the signal processing circuit.
FIG. 5 is a flowchart illustrating a process executed by the signal processing circuit after the automatic adjustment is performed.
FIG. 6 is a graph showing a relationship among a maximum value PKw, a black dummy pixel maximum value PKb, and a predetermined value Pb when a white reference plate is read by the image reading apparatus;
FIG. 7 is a graph showing a relationship among a maximum value PKw, a black dummy pixel maximum value PKb, and a predetermined value Pb when a white reference plate is read by the image reading apparatus;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Image reader 4 Light source 9 Solid-state image sensor 10 Signal processing circuit

Claims (2)

A light source for illuminating the document;
A solid-state imaging device that receives the reflected light of this light and converts it into an electrical signal;
A signal processing circuit for applying electrical processing to the analog signal output by the solid-state imaging device;
Adjusting means for adjusting the processing coefficient of the electrical processing performed by the signal processing circuit to an appropriate coefficient;
Notification that informs the operator of the occurrence of an abnormality in the system when the analog signal subjected to the electrical processing is not within a predetermined numerical range after the processing coefficient is adjusted to an appropriate coefficient. Means,
Equipped with a,
The notifying means adjusts the processing coefficient to an appropriate coefficient, and then performs the electrical processing when the solid-state imaging device reads an image of a black dummy pixel and an image of a white reference plate. The maximum values of the analog signals after being performed are compared with each other, the difference between both analog signals is smaller than a predetermined value, and the electrical processing when the black dummy pixel image is read is performed. When the analog signal is smaller than a predetermined value, the image reading device notifies the operator that the abnormality of the system is a failure of the light source . A light source for illuminating the document;
A solid-state imaging device that receives the reflected light of this light and converts it into an electrical signal;
A signal processing circuit for applying electrical processing to the analog signal output by the solid-state imaging device;
Adjusting means for adjusting the processing coefficient of the electrical processing performed by the signal processing circuit to an appropriate coefficient;
Notification that informs the operator of the occurrence of a system abnormality when the analog signal to which the electrical processing is applied is not within a predetermined numerical range after the processing coefficient is adjusted to an appropriate coefficient. Means,
With
The notifying means adjusts the processing coefficient to an appropriate coefficient, and then performs the electrical processing when the solid-state image sensor reads an image of a black dummy pixel and an image of a white reference plate. The maximum values of the analog signals after being performed are compared, the difference between both analog signals is smaller than a predetermined value, and the electrical processing when the black dummy pixel image is read is performed. When the analog signal is larger than a predetermined value, the image reading apparatus notifies the operator that the abnormality of the system is a failure of the solid-state imaging device.

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