JP3973667B2 - Image reading device - Google Patents

Description

  The present invention relates to an image reading apparatus that reads and scans an original with a predetermined scanning optical system and receives an image of the original by receiving light that has been read and scanned by a photoelectric conversion element.

  In recent years, environmental protection and energy saving have been screamed, and standards such as Energy Star and ZESM have been defined for copying machines. These standards are intended to save energy and limit energy consumption during standby of copying machines.

In response to this, when the copying machine is on standby, the power source of the operation panel and the like, including the fixing heater with high power consumption, is turned off or switched to low power operation. In an image scanner mounted on a copying machine, it is common to turn off the power collectively.
JP-A-6-326867

  In the prior art as described above, when using a copier in a standby state, turn the power back on or return from a low power operation to a normal operation state until the copier becomes usable. The user waited for this waiting time to be felt longer than the actual time for the user, leading to stress.

As disclosed in JP-A-6-326867, in an image scanner of a copying machine, after the power is turned on so that the obtained analog image signal is converted into a digital image signal with high accuracy, the following: Adjustments are being made.
(1) Adjustment of the amplification factor for amplifying the analog image signal to an appropriate size.
(2) Adjustment of the reference level so that the black level becomes an optimum value.

  That is, in the conventional copying machine, since the above adjustment is performed at the time of return from the standby state, it takes a long time to return from the standby state as described above, which leads to a result of making the user wait longer. was there.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image reading apparatus that does not cause the user to feel uncomfortable because the return time from the standby state is not longer than necessary.

  Another object of the present invention is to obtain stable characteristics even when the light source for exposure scanning and the white reference plate for shading correction are replaced when the image reading apparatus is in a standby state, and stable image reading is achieved. Is to be able to do it.

  The invention according to claim 1 is an image reading apparatus that reads and scans an original with a predetermined scanning optical system, receives light of the read and scan with a photoelectric conversion element, and reads an image of the original. The pre-processing device that performs pre-processing for A / D conversion of the analog image signal output from the analog image signal, a power supply unit that supplies power to the pre-processing device, and the main power switch of the device main body are turned on. A first control unit that controls the power supply unit to supply power to the pre-processing device, and a predetermined time has elapsed without the image reading operation being performed after the start of power supply. When the second control means for controlling the power supply unit to stop the supply of power to the pre-processing device and a predetermined operation to be performed when the image reading is resumed after the power supply is stopped And a third control means for controlling the power supply unit so as to resume the supply of power to the preprocessing device when the detection is made, and Storage means for storing a value set in the preprocessing device for executing preprocessing, and setting means for setting the stored value in the preprocessing device when the supply of power is resumed An image reading apparatus characterized by the above.

  Therefore, the value set for executing the preprocessing at the start of the supply of power to the preprocessing device is stored in advance, and the preprocessing is performed because a predetermined time has passed without performing the image reading operation thereafter. When power supply to the preprocessing device is resumed in order to resume image reading after the power supply to the device is stopped, the prestored value is set in the preprocessing device. It is not necessary to re-determine the value to be set in the preprocessing device in order to execute the preprocessing, the return time from the standby state of the image reading device does not become longer than necessary, and the user is not uncomfortable.

  According to a second aspect of the present invention, in the image reading apparatus according to the first aspect, whether or not the value set in the pre-processing device by the setting unit is appropriate is determined for the A / D conversion after the power supply is resumed. It is characterized by comprising inspection means for judging by detecting necessary characteristics.

  Therefore, since it is determined after resuming the power supply whether the value stored in advance and set in the preprocessing device is appropriate or not, the light source for exposure scanning and the white for shading correction when the image reading device is in a standby state. Even when the reference plate is replaced, characteristics corresponding to the reference plate can be obtained, and stable image reading can be performed.

  According to a third aspect of the present invention, in the image reading device according to the first or second aspect, the preprocessing device uses the adjustment of the amplification factor of the analog image signal and the adjustment of the reference DC level as the preprocessing. It is characterized by performing.

  Therefore, as preprocessing for A / D conversion of the analog image signal, adjustment of the amplification factor of the analog image signal and adjustment of the reference DC level can be performed.

  According to a fourth aspect of the present invention, in the image reading apparatus according to any one of the first to third aspects, the sensor includes an opening of a pressure plate for pressing the original on the contact glass and the original on the contact glass. At least the former of the set of documents on the ADF that supplies the document is detected as the predetermined operation.

  Therefore, when the pressure plate for pressing the original on the contact glass is opened or when the original is set on the ADF that supplies the original on the contact glass, the supply of power to the preprocessing device can be resumed.

  According to the first aspect of the present invention, a value set for executing preprocessing at the start of power supply to the preprocessing device is stored in advance, and then a predetermined value is obtained without performing an image reading operation. When the supply of power to the preprocessing device is stopped because time has passed and the power supply to the preprocessing device is restarted to resume image reading, the previously stored value is Since it is set in the processing device, it is not necessary to determine again the value to be set in the preprocessing device in order to execute the preprocessing, and the return time from the standby state of the image reading device is not unnecessarily long, which is inconvenient for the user. Does not give pleasure.

  According to the second aspect of the present invention, in the image reading apparatus according to the first aspect, since it is determined after the resumption of power supply whether the value stored in advance and the value set in the preprocessing apparatus is appropriate or not is determined. Even when the light source for exposure scanning and the white reference plate for shading correction are exchanged while the apparatus is in a standby state, characteristics corresponding to the light source can be obtained and stable image reading can be performed.

  According to a third aspect of the present invention, in the image reading apparatus according to the first or second aspect, as a preprocessing for A / D conversion of the analog image signal, adjustment of the amplification factor of the analog image signal and a reference DC Level adjustment can be made.

  According to a fourth aspect of the present invention, there is provided the image reading apparatus according to any one of the first to third aspects, wherein the pressure plate for pressing the original on the contact glass is opened or the original to the ADF that supplies the original on the contact glass. When the setting is made, the supply of power to the pretreatment device can be resumed.

Embodiment 1 of the Invention
FIG. 1 is a conceptual diagram showing a schematic configuration of an image reading apparatus according to Embodiment 1 of the present invention. A contact glass 3 on which the document 2 is placed and a white reference plate 4 for shading correction are provided on the upper surface of the casing of the image reading apparatus 1. The white reference plate 4 is a substantially white member having a uniform density provided in the main scanning direction in order to obtain correction data at the time of shading correction. The document 2 is suppressed from being lifted from the contact glass 3 by a pressure plate (not shown) from above. Further, the image reading apparatus 1 is provided with a well-known ADF (auto document feeder) (not shown). The light source 5 irradiates light at a certain angle with respect to the reading surface of the white reference plate 4 or the contact glass 3, and the light reflected by the white reference plate 4 or the document 2 is composed of three mirrors 6 serving as scanning optical systems. The light enters the CCD 10 that is a photoelectric conversion element via the lenses 7 and 8 and the lens 9.

  The light source 5 and the mirrors 6, 7, and 8 form first and second traveling bodies (not shown), and the motor 13 is driven to keep the distance between the reading surface of the document 2 and the CCD 10 in the sub-scanning direction. Move to.

  The CCD 10 outputs a voltage corresponding to the amount of incident light as an analog image signal. The analog image signal is digitally processed after a predetermined process such as A / D conversion is performed by a circuit on the sensor board 11 on which the CCD 10 is provided. The image signal is transferred to the image processing unit 12 as an image signal.

  FIG. 2 is a block diagram showing an electrical connection of the image reading apparatus 1. As shown in FIG. 2, the CCD 10 converts the reflected light from the original into an analog image signal. Although only one line of output from the CCD 10 is shown in FIG. 2, there are two or four output types of high-speed type CCDs, and these CCDs may be used.

  The analog image signal is driven by the buffer 14 and sampled and held by the sampling circuit 15 to remove high frequency components such as reset noise. The gain amplifier 16 that is a preprocessing device is an amplifier that can control the gain with the voltage Vg applied to the control terminal (showing the relationship between the voltage Vg and the gain in FIG. 3), and is also an offset setting unit that is a preprocessing device. 17 has a function of providing an offset with the voltage Vof applied to the control terminal (the relationship between the voltage Vof and the offset amount is shown in FIG. 4).

  The A / D converter 18 converts the analog image signal into a digital image signal with a predetermined resolution (for example, 8 bits) based on the upper limit reference value and the lower limit reference value. In order to fully demonstrate the accuracy of the A / D converter 18, the gain in the gain amplifier 16 is changed so that the analog image signal changes widely between the upper limit reference value and the lower limit reference value of the A / D converter 18. It is necessary to adjust the amount and the offset amount in the offset setting unit 17.

  The black level detection circuit 19 has a function of capturing and storing the output level during a period corresponding to the OPB pixel of the CCD 10 indicated by the range designation signal xopb. The stored black level is an average value obtained by capturing a plurality of OPB pixels, and is stored for each output channel of the CCD 10 (an example of timing is shown in FIG. 5).

  The black level subtraction circuit 20 is a circuit that subtracts a value stored in the black level detection circuit 19 when an effective pixel of the CCD 10 is input.

  The white peak detection circuit 21 is a circuit that stores the peak value of the output level within the range designated by the range designation signal xlgate (a timing example is shown in FIG. 5).

  The shading data FIFO 22 is a memory that sequentially stores values obtained by reading the white reference plate 4 in a known manner while performing processing such as averaging on a pixel-by-pixel basis. The shading correction circuit 23 is also a digital image obtained by reading an image in a known manner. This is a circuit for performing a correction operation on the image data and the reference white plate data stored in the shading data FIFO 22.

  The power supply unit 24 is mainly composed of two types of systems. One is a power supply system Vcnst whose output is turned on / off by a main power switch (not shown), and the other is a power supply system Vtemp whose output is cut off by a control signal Voff from the outside. The opening / closing sensor 25 is a sensor that detects opening / closing of the pressure plate (not shown). The document sensor 26 is a sensor that detects that the document 2 is set on the ADF (not shown). The microcomputer 27 centrally controls the entire image reading apparatus 1. The voltage Vg and the voltage Vof are output from the microcomputer 27, D / A converted by the D / A converters 28 and 29, and supplied to the gain amplifier 16 and the offset setting unit 17. The output of the shading correction circuit 23 is sent to the image processing unit 12 for predetermined image processing.

  FIG. 6 is a block diagram illustrating a power supply configuration of the image reading apparatus 1. A power source Vcnst (see FIG. 2) is supplied to the open / close sensor 25, the document sensor 26, and the microcomputer 27. The power source Vcnst is a power source that is output when the main power switch of the image reading apparatus 1 is turned on. In this embodiment, the open / close sensor 25, the document sensor 26, the microcomputer 27, the open / close sensor 25, and the document sensor 26 are used. Is supplied to an element necessary for transmitting the output of the above to the microcomputer 27.

  On the other hand, Vtemp (see FIG. 2) is supplied to the scanner unit 30. The power supply Vtemp is a power supply system in which the output is turned off by the Voff signal if the image reading apparatus 1 is not operated for a predetermined time even when the main power switch is turned on. The scanner unit 30 referred to here includes the light source 5, the motor 13, the circuit on the sensor board 11 (the circuit in FIG. 2), the image processing unit 12, and the like.

  Next, the operation of the image reading apparatus 1 will be described with reference to the flowchart of FIG. As shown in FIG. 7, when the main power switch is turned on (Y in step S1), the power supply unit 24 supplies the power supply Vconst and the power supply Vtemp to each unit of the image reading apparatus 1 (step S2). By this step S2, the first control means is realized. First, the microcomputer 27 performs initial setting of the image reading apparatus 1 (step S3). The typical contents of the initial settings are as follows.

  -Timing settings for various pulses to drive the CCD 10.

  • Pulse timing setting for sampling by the sampling circuit 15.

  • Initial gain of gain amplifier 16.

  The initial offset amount of the offset setting unit 17

  Next, the light source 5 is turned on, and homing for determining the home positions of the first and second traveling bodies (not shown) is performed, and the first and second traveling bodies are moved to the home positions (step S4).

  Thereafter, reference level E / O difference adjustment is performed (step S5). In this adjustment, when the output of the CCD 10 is two systems, the even and odd reference levels when the processing system is divided and processed for each even and odd pixel are adjusted to the same value. Next, the DC level serving as a reference for the analog image signal is adjusted to an arbitrary value (step S6). The reference level value to be adjusted is generally set to a value that does not interrupt 0 even if there is an influence of noise, considering that black level subtraction is performed later.

  Then, the first and second traveling bodies (not shown) are moved so that the reflected light of the reference white plate 4 enters the CCD 10 (step S7), and the output value when the reference white plate 4 is read becomes an arbitrary value. The gain is adjusted (step S8). As the gain value to be adjusted, the performance of the A / D converter 18 can be improved by increasing the output value of the A / D converter 18 within a range that does not overflow even when the variation factor such as the light amount of the light source 5 is taken into consideration. .

  The reference level adjustment value and the gain adjustment value are stored in the RAM or the like of the microcomputer 27 (step S9), the light source 5 is turned off, and the first and second traveling bodies (not shown) are set to the home position in preparation for reading the document. Move (step S10). The storage means is realized by step S9.

  Thereafter, when the image reading apparatus 1 is not used for a predetermined time and an image forming operation is not performed (Y in Step S11), the microcomputer 27 validates the Voff signal for cutting off the output of the power source Vtemp (Step S12). ). The second control means is realized by this step S12. Thereby, the power supply to the main part of the image reading apparatus 1 is turned off, and the power consumed by the image reading apparatus 1 is significantly reduced.

  However, the power supply Vcnst is supplied to the open / close sensor 25 that detects that the pressure plate that is opened and closed when the document 2 is placed on the contact glass 3 is opened and the document sensor 26 that detects that the document 2 is set on the ADF. When the sensor state changes, the microcomputer 27 can recognize it. If the outputs of the open / close sensor 25 and the document sensor 26 have changed (Y in Step S13), the microcomputer 27 operates the Voff signal so as to output Vtemp to the power supply unit 24, and supplies power to each unit of the image reading apparatus 1. Is supplied (step S14). The third control means is realized by step S14.

  At this time, the reference level adjustment value and gain adjustment value stored in step S9 are set in the gain amplifier 16 and the offset setting unit 17 (step S15). Setting means is realized by this step S15. Therefore, the image reading apparatus 1 can be used with an unnecessary waiting time being minimized.

  [Second Embodiment] The image reading apparatus 1 according to the second embodiment of the present invention differs from the first embodiment in that the process shown in the flowchart of FIG. 8 is replaced with the process shown in the flowchart of FIG. Is in the point of doing. Since other matters are the same as those in the first embodiment, the same reference numerals as those in the first embodiment are used in the following description, and the detailed description is omitted.

  In FIG. 8, steps S1 to S15 are the same as those in the flowchart of FIG. In FIG. 8, after step S15, the light source 5 is turned on and homing is performed to determine the home positions of the first and second traveling bodies (not shown), and the first and second traveling bodies are moved to the home positions. (Step S16), and the reference level value is read (Step S17). If the reference level value is not within the allowable value (N in step S18), the process returns to step S5 and starts again from the reference level adjustment when the main power switch is turned on.

  If the reference level value is within the allowable value (Y in step S18), the first and second traveling bodies are moved to the position of the reference white plate 4 (step S19), and the white plate data is read (step S20). If the value of the white board data is not within the allowable value (N in step S21), the process returns to step S8 and starts again from the gain adjustment when the main power switch is turned on. When the value of the white board data is within the allowable value (Y in step S21), the process returns to step S10. Note that the inspection means is realized by steps S18 and S21.

  As described above, since it is confirmed whether or not the reference level and the white board data are values within the required range (steps S18 and S21), the light source 5 and the white reference board 4 are in a state where the image reading apparatus 1 is in a standby state. Even when the camera is replaced, characteristics corresponding to it can be obtained, and stable image reading can be performed.

1 is a conceptual diagram illustrating a schematic configuration of an image reading apparatus according to a first embodiment of the present invention. FIG. 2 is a block diagram showing electrical connection of the image reading apparatus. 4 is a graph showing a relationship between a voltage Vg and a gain in a gain amplifier of the image reading apparatus. It is a graph which shows the relationship between the voltage Vof in the offset setting part of the said image reading apparatus, and offset amount. 4 is a timing chart of the output of a CCD, a sampling circuit, and an A / D converter of the image reading apparatus. FIG. 2 is a block diagram showing electrical connection of the image reading apparatus. 3 is a flowchart illustrating an operation of the image reading apparatus. It is a flowchart explaining operation | movement of the image reading apparatus which is Embodiment 2 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image reader 2 Original 3 Contact glass 5-9 Scanning optical system 10 Photoelectric conversion element 24 Power supply part 25, 26 Sensor

Claims (4)

In an image reading apparatus that scans and scans an original with a predetermined scanning optical system, receives the read and scanned light with a photoelectric conversion element, and reads an image of the original,
A pre-processing device that performs pre-processing for A / D converting the analog image signal output from the photoelectric conversion element;
A power supply for supplying power to the pretreatment device;
First control means for controlling the power supply unit to supply power to the pre-processing device when a main power switch of the apparatus main body is turned on;
Second control means for controlling the power supply unit to stop the supply of power to the pre-processing device when a predetermined time has elapsed without starting the image reading operation after the start of the power supply; ,
A sensor for detecting that a predetermined operation performed when restarting the image reading after the power supply is stopped;
Third control means for controlling the power supply unit so as to resume the supply of power to the pre-processing device when this detection is made;
Storage means for storing a value set in the preprocessing device to execute the preprocessing when the main power switch is turned on;
Setting means for setting the stored value in the preprocessing device when the supply of power is resumed ,
The pre-processing device is a gain amplifier that amplifies a signal output from the photoelectric conversion element according to a set gain amount and / or an offset setting unit that provides an offset according to a set offset amount, value set in the pretreatment apparatus, an image reading apparatus which is a said gain amount and / or the offset.   Inspecting means for determining whether or not the value set in the pre-processing device by the setting means is appropriate by detecting characteristics necessary for the A / D conversion after resuming the supply of power is provided. The image reading apparatus according to claim 1. The image reading apparatus according to claim 1, wherein the preprocessing apparatus performs adjustment of an amplification factor of the analog image signal and / or adjustment of a reference DC level as the preprocessing.   The sensor detects at least the former as the predetermined operation among opening of a pressure plate for pressing the document on the contact glass and setting of the document on the ADF that supplies the document on the contact glass. The image reading apparatus according to claim 1.

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