JP4656214B2 - Image reading apparatus and image sensor discrimination method - Google Patents

Description

  The present invention relates to an image reading apparatus and an image sensor discrimination method.

Conventionally, when a CMOS type image sensor is connected, a high (H) level signal is input to the CPU, while when a CCD type image sensor is connected, a low (L) level signal is input to the CPU. There is known an image reading apparatus that determines whether a CMOS type image sensor or a CCD type image sensor according to a signal input in a CPU (for example, see Patent Document 1).
JP 2001-358998 A

However, according to the conventional image processing apparatus, although it can be determined whether it is a CMOS type image sensor or a CCD type image sensor, for example, when there are a plurality of types of CMOS type image sensors, those types are determined. There is a problem that you can not.
The present invention has been completed based on the above-described circumstances, and an object thereof is to provide an image reading apparatus and an image sensor discrimination method capable of discriminating more types of image sensors.

The first invention is an image reading apparatus, an image sensor that outputs a pixel signal corresponding to the electric charge accumulated in a light receiving element, an acquisition unit that acquires a pixel signal output from the image sensor, and the acquisition Determining means for determining a type of the image sensor based on a length of an acquisition period for acquiring the pixel signal from the image sensor, and the determining means is configured to read the image during a reading operation for one line. you determine the type of the image sensor based on the signal level of said acquisition means into a predetermined timing difference occurs in the signal level obtained from the image sensor across type of sensor.
According to the present invention, since the type of the image sensor is determined based on the length of the acquisition period, it is possible to determine the types of a plurality of image sensors having different acquisition periods.
Therefore, according to the present invention, more types of image sensors can be discriminated.
Furthermore, according to the present invention, since the type of the image sensor is determined based on the signal level acquired at a predetermined timing, it is not necessary to specifically specify the length of the acquisition period, and the type determination process is simplified. it can.
A second invention is an image reading apparatus, wherein a light source that irradiates a document, an image sensor that outputs a pixel signal corresponding to a charge accumulated in a light receiving element, and a pixel signal output from the image sensor are acquired. And a determination unit that determines the type of the image sensor based on a length of an acquisition period during which the acquisition unit acquires the pixel signal from the image sensor. The reference signal is added and output, and the determination unit determines the type of the image sensor based on the length of the acquisition period of the pixel signal output from the image sensor with the light source turned off.
If the type of image sensor is determined based on the pixel signal output from the image sensor while the light source is turned on, a certain amount of waiting time is required until the brightness stabilizes after the light source is turned on. It takes. On the other hand, when the determination is made with the light source turned off, such a waiting time becomes unnecessary.
However, when the light source is turned off, the charge accumulated in the light receiving element becomes almost zero, so the signal level of the pixel signal becomes almost zero. In this case, if the signal level other than the pixel signal is 0, it is difficult to specify whether the pixel signal is output. For this reason, it is difficult to determine the type of the image sensor.
According to this invention, since the signal level for the reference signal is acquired during the acquisition period even if the charge accumulated in the light receiving element is 0, it is specified whether the pixel signal is output even when the light source is turned off. it can. Therefore, the waiting time described above can be eliminated, and the type can be determined in a shorter time.

A third aspect of the invention is the image reading apparatus according to the second aspect of the invention, wherein the determination means obtains the acquisition at a predetermined timing at which a difference in signal level occurs between the types of the image sensors during a reading operation for one line. The means determines the type of the image sensor based on the signal level acquired from the image sensor.
According to the present invention, since the type of the image sensor is determined based on the signal level acquired at a predetermined timing, it is not necessary to specifically specify the length of the acquisition period, and the process for determining the type can be simplified.

A fourth invention is the image reading apparatus according to any one of the first to third inventions, wherein the image sensor outputs a pixel signal in parallel from each section obtained by partitioning the image sensor in the main scanning direction, The discrimination means discriminates the type of the image sensor based on the length of the acquisition period of the pixel signal output from any one of the sections.
According to the present invention, it is possible to reduce the time required for discrimination as compared with the case of discriminating the type based on the length of the acquisition period of the pixel signal output from the entire image sensor, and it is possible to discriminate the type in a shorter time.

A fifth invention is the image reading device according to the fourth invention, wherein the determining means is configured to obtain the image sensor based on a length of an acquisition period of the pixel signal output from the section having the smallest number of light receiving elements. Determine the type.
According to the present invention, since the determination is made based on the length of the acquisition period of the pixel signal output from the section having the smallest number of light receiving elements, the type can be determined in a shorter time.

A sixth invention is the image reading device according to any one of the first to third inventions, and is the image reading device according to any one of claims 1 to 3,
The number of light receiving elements varies depending on the type of image sensor.
If the number of light receiving elements differs depending on the type of image sensor, the length of the acquisition period differs between the types of image sensor, so that the type of image sensor can be determined.

A seventh invention is the image reading apparatus according to any one of the first to sixth inventions, wherein the image sensor includes an effective light receiving element and an invalid light receiving element, and the determination means includes the effective light receiving element. The type of the image sensor is discriminated based on the length of the acquisition period of the pixel signal output from.
In general, an image sensor has an ineffective light receiving element in addition to an effective light receiving element. However, it is not always guaranteed that a pixel signal is output from the invalid light receiving element, and it may be considered that a pixel signal is not output depending on the type of the image sensor.
On the other hand, it is guaranteed that a pixel signal is output from the effective light receiving element. Therefore, if the type of the image sensor is determined based on the length of the acquisition period of the pixel signal output from the effective light receiving element, the type of the image sensor can be more reliably determined.

An eighth invention is the image reading apparatus according to the first or third invention, wherein the determining means determines the type of the image sensor based on an average value of the signal levels at a plurality of different predetermined timings. Determine.
According to the present invention, the influence of electrical noise can be reduced by averaging the signal level, and the determination can be made more accurately.

A ninth invention is the image reading apparatus according to the first or third invention, wherein the determining means is configured to use the image sensor based on a maximum value and a minimum value of the signal level at a plurality of different predetermined timings. Determine the type.
According to the present invention, more types can be discriminated by the combination of the maximum value and the minimum value.

A tenth aspect of the invention is the image reading apparatus according to any one of the first to ninth aspects, wherein the image sensor is capable of reading a document at different resolutions, and the discrimination means is the image at any one resolution. The determination is made based on the length of the acquisition period of the pixel signal output from the sensor.
According to the present invention, since the resolution does not change during the process of determining the type of the image sensor, it can be determined with a simple process.

An eleventh aspect of the invention is an image reading apparatus, which is output from each image sensor during a reading operation for one line due to a difference in the number of light receiving elements constituting the image sensor and each of the different types of image sensors. An acquisition unit that acquires the signal level at different timings of the signal level, and a determination unit that determines the type of the image sensor based on the signal level acquired by the acquisition unit.
If there is a difference in the number of light receiving elements depending on the type of image sensor, there is a timing at which a difference in signal level occurs between the types. Therefore, the type of the image sensor can be determined based on the signal level at that timing. When there are three or more types of image sensors, for example, the signal level is acquired at a timing when the signal level differs between the A-type image sensor and the B-type image sensor. It is possible to determine whether the B type or the C type is obtained by acquiring the signal level at different timings at which the B type image sensor and the C type image sensor have different signal levels. Thus, according to the present invention, it is possible to discriminate more types of image sensors.

A twelfth aspect of the invention is an image sensor discrimination method, wherein an acquisition step of acquiring a pixel signal output from an image sensor that outputs a pixel signal corresponding to an electric charge accumulated in a light receiving element, and in the acquisition step, seen including a discrimination step of discriminating a type of the image sensor on the basis from the image sensor to the length of the acquisition period for acquiring the pixel signal, a, in the determining step, of the image sensor during a read operation for one line The type of the image sensor is determined based on the signal level acquired by the acquisition unit from the image sensor at a predetermined timing when the signal level differs between the types .
According to the present invention, more types of image sensors can be discriminated.
A thirteenth aspect of the present invention is a method for discriminating an image sensor in an image reading apparatus including a light source that irradiates a document, and a pixel signal output from an image sensor that outputs a pixel signal corresponding to a charge accumulated in a light receiving element. An acquisition step of acquiring, and a determination step of determining a type of the image sensor based on a length of an acquisition period in which the pixel signal is acquired from the image sensor in the acquisition step, wherein the image sensor includes the pixel signal. A reference signal is added to and output, and in the determination step, the type of the image sensor is determined based on the length of the acquisition period of the pixel signal output from the image sensor with the light source turned off.

  According to the present invention, more image sensor types can be discriminated.

<Embodiment 1>
A first embodiment of the present invention will be described with reference to FIGS.
(1) Outline of Image Reading Apparatus FIG. 1 is a schematic diagram of an image scanner 1 (an example of an image reading apparatus). The image scanner is a flat bed type image reading apparatus that reads a document M placed on the platen glass 12 by a CIS (Contact Image Sensor) method.

The casing 11 is generally formed in a box shape, and a platen glass 12 serving as a document table is provided on the top.
The platen glass 12 is a colorless and transparent glass plate on which a document M such as a printed document, a photograph, or a book is placed.
The document cover 13 is connected to the housing 11 so as to be rotatable between a closed position covering the platen glass 12 and an open position opening the platen glass 12. When the document cover 13 is in the closed position, the platen glass 12 is covered with the document cover 13 and the outside light is prevented from entering the housing 11.

  The document reading unit 14 includes an image sensor 15, a light source 16 formed of RGB light emitting diodes, a rod lens array 17 that forms an image of the reflected light reflected by the document M on each light receiving element 19 of the image sensor 15, and a carriage. 18 and a stepping motor (not shown) for driving the carriage 18. As shown in the figure, the image sensor 15, the light source 16, and the rod lens array 17 are mounted on a carriage 18. The carriage 18 is driven by a stepping motor to reciprocate in the sub-scanning direction (X direction in the figure).

  The image sensor 15 includes a plurality of light receiving elements 19 arranged in a line in the main scanning direction (perpendicular to the paper surface), an output unit (not shown) that outputs pixel signals corresponding to the charges accumulated in each light receiving element 19, and the like. ing. The image sensor 15 is an image sensor. When each light receiving element 19 receives the reflected light reflected by the original M, the image sensor 15 accumulates charges according to the light intensity (brightness) of the received reflected light, and the image sensor 15 is accumulated. The converted charge is converted into an electrical signal (pixel signal) and output. The image sensor 15 may be a COMS type image sensor, a CCD type image sensor, or an image sensor instead of these. The structure of the image sensor 15 will be described later.

  The image sensor control circuit 20 (an example of an acquisition unit and a determination unit) is configured as an ASIC, and is connected to the document reading unit 14 via a flexible flat cable (not shown). The image sensor control circuit 20 includes an A / D conversion unit 21 and an image processing unit 22. The A / D converter 21 converts the analog pixel signal output from the image sensor 15 into a digital pixel signal. The image processing unit 22 performs various corrections such as shading correction and gamma correction on the pixel signal output from the A / D conversion unit 21 and outputs the result to the control unit 23. The A / D conversion unit 21 may be provided independently of the ASIC.

  Further, when the image scanner 1 is turned on, the image sensor control circuit 20 performs reading with the light source 16 turned off, and at this time, a period in which a pixel signal is output from the image sensor 15 to the image sensor control circuit 20. The type of the image sensor 15 is determined based on the length of (an example of the acquisition period), and various settings are performed according to the determined type.

  The control unit 23 (an example of an acquisition unit and a determination unit) includes a CPU, a ROM, a RAM, an NVRAM, and the like (not shown). The control unit 23 controls each part of the image scanner 1 when an instruction to read a document is given via an interface unit 24 from an external device such as a so-called personal computer or an operation panel (not shown) provided in the housing 11. Based on the read pixel signal output from the image processing unit 22, image data in a predetermined format such as a JPEG format or a TIFF format is generated. Then, the generated image data is transmitted to the external device.

  The interface unit 24 includes a USB interface, a network interface, an operation panel, and the like.

(2) Structure of Image Sensor In this embodiment, any one of different types of image sensors is selected at the time of manufacture and incorporated as the image sensor 15. In the present embodiment, either an A-type image sensor 15A or a B-type image sensor 15B described below is incorporated.

FIG. 2A is a schematic diagram of an A-type image sensor 15A. The image sensor 15A is configured by arranging 11 sensor units having 480 light receiving elements in the main scanning direction, and has a total of 5280 light receiving elements. The sensor unit is a so-called small image sensor. By selecting the number of sensor units, an image sensor having the number of light receiving elements corresponding to the purpose can be obtained.
One signal line for outputting a pixel signal from the image sensor 15A to the image sensor control circuit 20 is provided for two sensor units. In the present embodiment, two sensor units that output pixel signals using the same signal line correspond to one section. However, for the sensor unit A11, one signal line is provided only for the sensor unit A11, and only the sensor unit A11 corresponds to one section.

  The plurality of signal lines can output pixel signals in parallel with each other, and therefore, the pixel signals can be output in a shorter time than when one signal line is provided for the entire image sensor. In the following description, each signal line is referred to as a first channel to a sixth channel in order from the left in FIG.

  FIG. 2B is a schematic diagram of a B-type image sensor 15B. The image sensor 15B is configured by arranging 12 sensor units each having 440 light receiving elements, and has a total of 5280 light receiving elements. Similarly, the image sensor 15B is provided with one signal line for two sensor units and has six channels.

(3) Signals sent and received between the image sensor and the image sensor control circuit The interface of each type of image sensor 15 is made common, via a flexible flat cable having 16 signal lines. Connected to the image sensor control circuit 20.
FIG. 3 shows the number of the signal line connecting the image sensor 15 and the image sensor control circuit 20 (specifically, the pin number of the connector connecting the flexible flat cable and the image sensor control circuit 20) and the function of the signal. Show.

Signals 1 to 6 are analog pixel signals output from the image sensor 15 to the image sensor control circuit 20. One signal line for outputting a pixel signal is provided for each channel, and a total of six signal lines are provided.
Signals Nos. 7 to 16 are all input to the image sensor 15 from the image sensor control circuit 20 side, and a resolution switching signal (MODE) for switching the resolution during the reading operation and a GND potential are input. A GND signal for driving, a drive power supply signal (Vcc) for driving the image sensor 15, a reference voltage signal (Vref) for inputting a reference voltage at the time of output, and a drive start that gives a drive start timing for each line Pulse signal (SP), drive clock signal (CLK) for inputting a reference clock, current supply common signal supplied in common to the anode side of each light emitting diode of RGB which is the light source 16, cathode side for each light emitting diode of each color It consists of a current supply signal supplied to.

(4) Signal Level Obtained from Image Sensor Here, the signal level obtained from the sixth channel will be described as an example of the signal level obtained from the image sensor 15.

FIG. 4 is a timing chart of signal levels of signals (No. 6 signal) acquired from the sixth channel of each type of image sensor 15 during the reading operation for one line.
Here, it is assumed that the resolution setting does not change during the reading operation for one line. The fact that the resolution switching signal (MODE) in the figure is constant indicates that the resolution does not change during the reading operation for one line.
As shown in the figure, the reading operation for each line of the image sensor 15 is divided into an initial setting period, a data output period, and a standby period.

  The initial setting period is a certain period started based on the drive start pulse signal (SP) (in the figure, each type of image sensor is also 1 to 16 clocks). In the initial setting period, a pixel signal corresponding to the electric charge accumulated in each light receiving element in the image sensor 15 is transferred to the output unit, and subsequently, the electric charge accumulated in each light receiving element is released to be in a reset state. Further, the Vcc, GND, and Vref voltages are taken into the image sensor 15 and set as reference potentials. During the initial setting period, the reference voltage signal (Vref) is output for each type of image sensor 15.

  In the subsequent data output period, charges are accumulated in each light receiving element of the image sensor 15. On the other hand, the charges transferred to the output unit (accumulated in each light receiving element during the operation period of the previous line) are sequentially read out at the timing synchronized with the drive clock (CLK) for each light receiving element, A voltage (pixel signal) corresponding to the accumulated charge is superimposed on (added to) the reference voltage signal (Vref) and output. The reference voltage signal (Vref) is an example of the “reference signal” in the present invention.

  The length of the data output period of the sixth channel differs between the A type and the B type because the A type image sensor 15A has 480 light receiving elements in the sixth channel, and the B type image sensor. In 15B, since the number of light receiving elements in the sixth channel is 880 (= 440 × 2), the B type requires a longer time for output than the A type.

  In the standby period following the data output period, charge accumulation is continued in each light receiving element of the image sensor 15 and a standby state in which the input of the drive start pulse signal (SP) for the next line is on standby. During this standby period, the output of the light reception signal is stopped for each type of image sensor 15, and any type of image sensor 15 always outputs the GND value. When the image sensor 15 receives the next drive start pulse signal (SP) during the standby period, the image sensor 15 starts the operation during the above-described initial setting period.

(5) Determination of Type of Image Sensor Hereinafter, determination of the type of the image sensor 15 will be described with reference to FIG.
(5-1)
It can be said that the data output period described above is a period during which the image sensor control circuit 20 acquires a pixel signal from the image sensor 15. Therefore, in the following description, the above-described data output period is referred to as an acquisition period.

As described above, the length of the data output period (acquisition period) of the sixth channel differs between the A-type image sensor 15A and the B-type image sensor 15B. Therefore, based on the length of the acquisition period of the sixth channel, it is possible to determine whether the image sensor is the A-type image sensor 15A or the B-type image sensor 15B.
It should be noted that any channel may be used as the channel used for type discrimination as long as it is a channel in which the number of light receiving elements is different between A type and B type, in other words, a channel having a different acquisition period length. For example, in the case of the present embodiment, the number of light receiving elements is different between the A type and the B type in any channel, and therefore the type of the image sensor 15 can be determined using any channel.

  However, since the A-type image sensor 15A has a smaller number of light-receiving elements in the sixth channel than other channels, the use of the sixth channel shortens the acquisition period and shortens the time required for using the other channels. The type can be discriminated.

(5-2)
When determining the type of the image sensor 15 based on the length of the acquisition period, the length of the acquisition period is not specifically specified, and is determined based on whether the length of the acquisition period is equal to or longer than a predetermined length. You can also
For example, the B-type image sensor 15B has an acquisition period and the A-type image sensor 15A has a non-acquisition period (a period of 497 to 896 clocks) outside the acquisition period. A pixel signal is output from the image sensor 15B, and no pixel signal is output from the A-type image sensor 15A.

  Therefore, if the pixel signal is output at an arbitrary timing during the period (497 to 896 clock period), it can be determined that the pixel is B type, and if the pixel signal is not output, it can be determined that the pixel signal is A type. This determination is made by determining whether or not the length of the acquisition period is equal to or longer than the length (an example of a predetermined length) from the pixel signal output start timing (17 clocks) to the arbitrary timing. It can be said that As described above, when the determination is made based on whether or not the length of the acquisition period is equal to or longer than the predetermined length, it is not necessary to specify the specific length of the acquisition period, and thus the determination can be performed with simple processing.

(5-3)
In the determination method described above, whether or not a pixel signal is output can be determined by comparing the signal level of the sixth signal with a predetermined threshold. Specifically, it can be determined that the pixel signal is output if the signal level of the No. 6 signal is equal to or higher than a predetermined threshold, and that the pixel signal is not output if the signal level is less than the threshold.

  However, the signal level acquired from the image sensor 15 may be affected by electrical noise, and there is a risk of erroneous determination if the signal level is acquired and determined only once. Therefore, in this embodiment, during the period (497 to 896 clock periods) that is an acquisition period for the B-type image sensor 15B and is a non-acquisition period (standby period) outside the acquisition period for the A-type image sensor 15A. The signal level is acquired at a plurality of timings during an arbitrary period (period from “DETECT_1 START” to “DETECT_1 END” in the figure), and the average value is compared with a threshold value. As a result, the influence of noise can be reduced and the determination can be made more accurately. In this case, the influence of noise can be further reduced by removing the upper predetermined number and the lower predetermined number of signal levels of the acquired signal level and obtaining the average value.

(5-4)
In general, an image sensor has spare light receiving elements (invalid light receiving elements) that output pixel signals that are not used for generating image data at both ends in the main scanning direction. The number of invalid light receiving elements is not always the same even with the same type of image sensor, so another image sensor of the same type is also invalid during the period when one image sensor outputs a pixel signal from the invalid light receiving element. The pixel signal is not always output from the light receiving element.

  Therefore, in this embodiment, “DETECT_1 START” and “DETECT_1 END” are set during the effective light receiving element output period of the B-type image sensor 15B. Since all the image sensors of the same type output pixel signals regardless of the individual during the effective light receiving element output period, erroneous determination due to individual differences can be prevented.

(5-5)
In the present embodiment, the type of the image sensor 15 is determined with the light source 16 turned off. If the determination is made with the light source 16 turned on, it takes a long time to make a determination since a certain amount of waiting time is required until the luminance is stabilized after the light source 16 is turned on. On the other hand, if it discriminate | determines in the state which turned off the light source 16, such waiting time becomes unnecessary.

  However, when the light source 16 is turned off, the charge accumulated in the light receiving element becomes almost zero. In this case, if the signal level other than the pixel signal is approximately 0, it is difficult to specify whether or not the pixel signal is output. However, in this embodiment, since the reference signal is added to the pixel signal and output as described above, the signal level corresponding to the reference signal is acquired even if the accumulated charge is 0, thereby outputting the pixel signal. It can be specified whether or not.

(6) Discrimination Processing FIG. 5 is a flowchart of processing for discriminating the type of the image sensor 15. This process is started when the image scanner 1 is turned on.

In S <b> 101, the image sensor control circuit 20 inputs the above-described signals to the image sensor 15 and performs various settings.
Specifically, the resolution at the reading operation of the image sensor 15 is set by the resolution switching signal. Here, in each type of image sensor 15, the resolution at the time of reading operation can be set to any one of three types of 1200 dpi, 600 dpi, and 300 dpi based on the resolution switching signal. The resolution of 15 is set to 600 dpi.
Further, the light source 16 during the reading operation is set to be turned off by the current supply signal (see (5-5) described above).
Further, a value such as 1.1 [V] is input to the image sensor 15 as a reference voltage by the reference voltage signal (Vref).
Further, the operation cycle of one line of the image sensor 15 is set to a predetermined number of clocks (for example, 5456 clocks) by the drive start pulse signal and the drive clock signal.

  In S <b> 102, the image sensor control circuit 20 executes the reading operation of the image sensor 15.

  In S103, the image sensor control circuit 20 acquires the signal level from the sixth signal at a plurality of different timings during the period from “DETECT_1 START” to “DETECT_1 END” described above (described above (5-1) to “5-1”). (Refer to (5-4)).

  In S104, the image sensor control circuit 20 removes the upper predetermined number and lower predetermined number of signal levels from the signal levels acquired at a plurality of timings, and calculates the average value for the remaining signal levels (described above (5- 3)). Here, the predetermined number is 10, for example.

In S105, the image sensor control circuit 20 determines whether or not the average value is less than a predetermined threshold value (AD_THRESH) (see (5-3) described above). Here, the threshold value (AD_THRESH) is a value (voltage) larger than GND and smaller than Vref, for example, 0.25 [V].
If the average value is less than the threshold value (AD_THRESH), the image sensor control circuit 20 determines that it is A type and proceeds to S106, and if it is equal to or greater than the threshold value (AD_THRESH), determines that it is B type and proceeds to S107.

In S106, the image sensor control circuit 20 reads various setting information related to the A-type image sensor 15A stored in the ROM, and performs settings for the A-type.
More specifically, for example, the gamma table corresponding to the A-type image sensor 15A is set to be used when performing gamma correction on the acquired image data. For example, the signal level acquisition timing (sampling point) is set to a timing according to the characteristics of the A-type image sensor 15A. Specifically, for example, it is set to the eighth clock from the rising edge of the drive clock (CLK).

  In S107, the image sensor control circuit 20 reads various setting information related to the B-type image sensor 15B stored in the ROM, and performs settings for the B-type.

(7) Effects of the Embodiment According to the image scanner 1 according to the first embodiment of the present invention described above, the type of the image sensor 15 is determined based on the length of the acquisition period. The type of sensor 15 can be determined. Therefore, according to the present invention, more image sensor types can be discriminated.

  Furthermore, according to the image scanner 1, since it is determined whether or not the acquisition period is equal to or longer than a predetermined length, there is no need to specify the length of the acquisition period, and the type determination process can be simplified. .

Furthermore, according to the image scanner 1, since the type of the image sensor 15 is determined with the light source 16 turned off, the type can be determined in a shorter time.
Further, if the light source 16 is turned off, the signal level during the data output period becomes constant (Vref), so there is no need to finely control the sampling point, and the type of the image sensor 15 can be achieved with simple processing. There is also an effect that can be determined.

  Furthermore, according to the image scanner 1, since the type of the image sensor 15 is determined based on the length of the acquisition period of the pixel signal output from any one channel, the acquisition period of the pixel signal output from the entire image sensor Compared with the case of discriminating the type based on the length, the time required for discrimination can be reduced. Therefore, the type can be determined in a shorter time.

  Furthermore, according to the image scanner 1, since it discriminate | determines based on the length of the acquisition period of the pixel signal output from the channel with the minimum number of light receiving elements, a kind can be discriminate | determined in a short time.

  Furthermore, according to the image scanner 1, since the type of the image sensor 15 is determined based on the length of the acquisition period of the pixel signal output from the effective light receiving element, erroneous determination due to individual differences can be prevented.

  Furthermore, according to the image scanner 1, since the determination is made using the average value of the signal level, the influence of electrical noise can be reduced and the determination can be made with higher accuracy.

  Furthermore, according to the image scanner 1, since the resolution does not change during the process of determining the type of the image sensor 15, the determination can be made with a simple process.

<Embodiment 2>
Next, Embodiment 2 of the present invention will be described with reference to FIG.
FIG. 6 is a timing chart of signal levels acquired from the sixth channel of each type of image sensor. In the illustrated example, there are three types of image sensors, A type, B type, and C type, and the length of the data output period of each image sensor is different from each other.

  In FIG. 6, the period from “DETECT_1 START” to “DETECT_1 END” is outside the data output period for the A-type image sensor, and is set during the period that is the data output period for the B-type image sensor. The period from “DETECT_2 START” to “DETECT_2 END” is outside the data output period for the B-type image sensor and is set during the period that is the data output period for the C-type image sensor. In this case, it is possible to determine which of the three types is made by determining each period in the same manner as in the first embodiment.

  For example, if the average value of the signal level in the period from “DETECT_1 START” to “DETECT_1 END” is less than the threshold value (AD_THRESH), it can be determined as the A type. If the average signal level from “DETECT_1 START” to “DETECT_1 END” is greater than or equal to the threshold (AD_THRESH), the average signal level from “DETECT_2 START” to “DETECT_2 END” If it is less than (AD_THRESH), it can be determined that it is the B type, and if it is greater than or equal to the threshold value (AD_THRESH), it can be determined that it is the C type.

  If there is a difference in the number of light receiving elements depending on the type of image sensor, there is a timing at which a difference in signal level occurs between the types. Therefore, the type of the image sensor can be determined based on the signal level at that timing. When there are three or more types of image sensors, for example, the signal level is acquired at a timing when the signal level differs between the A-type image sensor and the B-type image sensor. It is possible to determine whether the B type or the C type is obtained by acquiring the signal level at different timings at which the B type image sensor and the C type image sensor have different signal levels. As described above, according to the image sensor according to the second embodiment, it is possible to determine more types of image sensors.

<Embodiment 3>
Next, Embodiment 3 of the present invention will be described with reference to FIG.
FIG. 7 is a timing chart of signal levels acquired from the sixth channel of each type of image sensor. In the second embodiment described above, the three types are determined based on the average value of the signal level, but in the third embodiment, the determination is made based on the maximum value and the minimum value of the signal level.

  In FIG. 7, “DETECT_3 START” is set outside the data output period for the A-type image sensor and during the data output period for the B-type image sensor, and “DETECT_3 END” is set for the B-type image sensor. For the C-type image sensor, it is set during the period that is outside the data output period.

In this case, by acquiring the maximum value and the minimum value of the signal level during the period from “DETECT_3 START” to “DETECT_3 END”, it is possible to determine which of the three types. For example, a signal level is acquired at a plurality of timings during the period, and if the maximum value and the minimum value of the acquired signal level are both less than a threshold value (AD_THRESH), it can be determined that the type is A. Further, if the maximum value is equal to or greater than the threshold (AD_THRESH) and the minimum value is less than the threshold (AD_THRESH), it can be determined as B type, and if both the maximum value and minimum value are equal to or greater than the threshold (AD_THRESH), type C Can be determined.
As described above, if the determination is made based on the maximum value and the minimum value of the signal level, more types can be determined by the combination of the maximum value and the minimum value.

<Other embodiments>
The present invention is not limited to the embodiments described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention.

  (1) In the above embodiment, the length of the acquisition period is not specifically specified, but an example in which the type of the image sensor is determined based on whether or not the acquisition period is a predetermined length or more will be described. However, the length of the acquisition period may be specifically identified and determined.

  (2) In the above embodiment, the case where the image sensor is configured by a plurality of sensor units has been described as an example. However, if the number of light receiving elements varies depending on the type, in other words, the length of the acquisition period varies depending on the type. If so, the entire image sensor may be configured as one unit.

  (3) In the above embodiment, the case where the type of the image sensor is determined with the light source 16 turned off has been described as an example. However, the determination may be made with the light source 16 turned on.

  (4) In the above embodiment, the case where the reference signal is added to the pixel signal and output is described as an example, but the reference signal may be output without being added. However, in that case, since it cannot be determined whether or not a pixel signal is output when the light source 16 is turned off, it is necessary to make a determination while the light source 16 is turned on.

  (5) Although the case where the image sensor control circuit 20 determines the type of the image sensor has been described as an example in the above embodiment, the control unit 23 may determine the type. However, in this case, since the control unit 23 acquires the pixel signal after the processing in the image sensor control circuit 20, a time difference exists between the data output period of the image sensor and the acquisition period of the pixel signal in the control unit 23. Will occur.

  (6) Although the image scanner has been described as an example of the image reading apparatus in the above embodiment, the present invention may be applied to a so-called multi-function machine having a scanner function, a printer function, a copy function, and a facsimile function.

1 is a schematic diagram of an image reading apparatus according to an embodiment of the present invention. 1 is a schematic diagram of an image sensor according to an embodiment of the present invention. 1 is a schematic diagram of an image sensor according to an embodiment of the present invention. The schematic diagram which shows the signal of the image sensor which concerns on one Embodiment of this invention. 4 is a timing chart of an image sensor according to an embodiment of the present invention. The flowchart which concerns on one Embodiment of this invention. 4 is a timing chart of an image sensor according to an embodiment of the present invention. 4 is a timing chart of an image sensor according to an embodiment of the present invention.

1. Image scanner (image reading device)
15, 15A, 15B ... image sensor 16 ... light source 19 ... light receiving element 20 ... image sensor control circuit (acquisition means, determination means)

Claims (13)

An image sensor that outputs a pixel signal corresponding to the charge accumulated in the light receiving element;
Obtaining means for obtaining a pixel signal output from the image sensor;
Determining means for determining the type of the image sensor based on the length of an acquisition period in which the acquisition means acquires the pixel signal from the image sensor;
Equipped with a,
The discriminating unit determines the type of the image sensor based on the signal level acquired from the image sensor by the acquiring unit at a predetermined timing when a difference in signal level occurs between the types of the image sensor during the reading operation for one line. image reading apparatus determine. A light source for illuminating the document;
An image sensor that outputs a pixel signal corresponding to the charge accumulated in the light receiving element;
Obtaining means for obtaining a pixel signal output from the image sensor;
Determining means for determining the type of the image sensor based on the length of an acquisition period in which the acquisition means acquires the pixel signal from the image sensor;
With
The image sensor adds and outputs a reference signal to the pixel signal,
The image reading device that determines the type of the image sensor based on a length of an acquisition period of the pixel signal output from the image sensor with the light source turned off. The image reading apparatus according to claim 2 ,
The discriminating unit determines the type of the image sensor based on the signal level acquired from the image sensor by the acquiring unit at a predetermined timing when the signal level differs between the types of the image sensor during the reading operation for one line. Is determined. An image reading apparatus according to any one of claims 1 to 3,
The image sensor outputs a pixel signal in parallel from each section obtained by partitioning the image sensor in the main scanning direction,
The discrimination means discriminates the type of the image sensor based on the length of the acquisition period of the pixel signal output from any one of the sections. The image reading apparatus according to claim 4,
The discriminating unit discriminates the type of the image sensor based on the length of an acquisition period of the pixel signal output from the section having the smallest number of light receiving elements. An image reading apparatus according to any one of claims 1 to 3,
The number of light receiving elements varies depending on the type of image sensor. The image reading apparatus according to claim 1, wherein:
The image sensor has an effective light receiving element and an ineffective light receiving element,
The discrimination means discriminates the type of the image sensor based on the length of the acquisition period of the pixel signal output from the effective light receiving element. The image reading apparatus according to claim 1 or claim 3,
The determination means determines the type of the image sensor based on an average value of the signal levels at a plurality of different predetermined timings. The image reading apparatus according to claim 1 or 3 ,
The determination unit determines the type of the image sensor based on a maximum value and a minimum value of the signal level at a plurality of different predetermined timings. An image reading apparatus according to any one of claims 1 to 9,
The image sensor can read a document at different resolutions,
The discriminating unit discriminates based on the length of the acquisition period of the pixel signal output from the image sensor at any one resolution. An image sensor;
An acquisition means for acquiring the signal level at a timing when the signal level output from each image sensor is different during a reading operation for one line due to a difference in the number of light receiving elements constituting each of the different types of image sensors;
Determining means for determining the type of the image sensor based on the signal level acquired by the acquiring means;
An image reading apparatus comprising: An acquisition step of acquiring a pixel signal output from an image sensor that outputs a pixel signal corresponding to the electric charge accumulated in the light receiving element;
A determination step of determining a type of the image sensor based on a length of an acquisition period for acquiring the pixel signal from the image sensor in the acquisition step;
Only including,
In the determination step, the type of the image sensor based on the signal level acquired from the image sensor by the acquisition unit at a predetermined timing when a difference in signal level occurs between the types of the image sensor during the reading operation for one line. A method for discriminating image sensors. An image sensor discrimination method in an image reading apparatus having a light source for irradiating a document,
An acquisition step of acquiring a pixel signal output from an image sensor that outputs a pixel signal corresponding to the electric charge accumulated in the light receiving element;
A determination step of determining a type of the image sensor based on a length of an acquisition period for acquiring the pixel signal from the image sensor in the acquisition step;
Including
The image sensor adds and outputs a reference signal to the pixel signal,
An image sensor discrimination method in which, in the discrimination step, the type of the image sensor is discriminated based on a length of an acquisition period of the pixel signal output from the image sensor with the light source turned off.

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