JPH11289421A - Image reading device - Google Patents

Abstract

(57) [Summary] An object of the present invention is to make it unnecessary to re-take correction data due to a change in the combination of an image sensor unit and an image reading device main body, and to facilitate replacement of an image sensor unit. Before an image sensor unit is assembled to an image reading apparatus main body, information unique to the image sensor main body is written into a flash ROM by connecting to a dedicated writing jig device. The image sensor unit 1 is attached to the image reading apparatus main body 2 and data stored in the flash ROM 4 is loaded into the SRAM 7 provided with the image processing circuit 6 of the image reading apparatus main body 2 when the power is turned on.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading apparatus equipped with an image sensor unit including an image sensor, a light source and an optical system, and more particularly to an improvement in maintenance when the image sensor unit is replaced.

[0002]

2. Description of the Related Art An image reading apparatus, such as a facsimile apparatus or an image scanner, having a function of reading an original by an image sensor is required to meet the market needs of high performance, low cost, and space saving at a high level. It has become to. In order to fuse market needs for these image reading devices, it is essential to integrate high performance, low cost, and space saving of the image sensor itself.
As an image sensor aiming at space saving and cost reduction, a contact image sensor unit is recently mounted on many devices. The contact image sensor unit is generally of the type in which a plurality of image sensor elements are arranged in the same width as the original reading width, and since there is no need for a reduction optical system, the image sensor, the light source, and the optical system such as a lens are all one. The reading unit can be compactly assembled as a unit, and is excellent not only in space saving but also in mounting properties.

However, since the image sensor unit is a composite unit in which the image sensor, the light source, and the optical system such as the lens are combined, the image sensor unit includes a variation as a unit in which the characteristic variations of the components such as the image sensor and the light source are stacked. The image signal output from the image sensor unit has inherent distortions and characteristics due to variations in these various components, and the image reading device equipped with the image sensor unit corrects these characteristics of the image sensor unit. Functions and devices that must be provided. For example, various correction methods such as a correction method at an analog level and a correction method at a digital level have been proposed as correction of an output level in darkness, which is an offset on the black side. However, all correction methods are common in that a memory for storing the output level in the dark is required to realize the correction faithful for each pixel. The same is true for the bright output distortion correction by shading correction in that image correction is performed using data stored in the memory.

Generally, a memory for storing correction data is arranged near an image processing unit of an image reading apparatus main body, and has a configuration capable of following an image processing speed and capable of high-speed access. When collecting these correction data, the correction data may be newly acquired every time the original is read.
As described in Japanese Patent Application Laid-Open No. 98017, data may be stored in a nonvolatile memory or a volatile memory backed up by a battery at the stage when an image reading apparatus is manufactured, and the data may always be used. Is determined by the characteristics of the image sensor unit, the configuration of the document reading unit, and the like.

When the correction data of the image sensor unit is stored at the stage of manufacturing the original reading apparatus as described above,
Although it has the advantage of being less susceptible to the influence of dust and the like on the document reading unit that adheres in use, the unit cannot cope with the aging of the characteristic values of the image sensor unit and the unit has correction data stored in the main unit. However, there is a disadvantage in that it is necessary to perform the storage operation again when replacing the device. Although it is possible to predict the effect of the image sensor unit's characteristic value over time, the reloading of correction data when replacing the unit is a burden on the user and service personnel and makes the equipment unusable. Since the effects are wide-ranging, such as prolonged (downtime) and malfunctions due to erroneous operations, there is a possibility that serious failures or complaints may occur. further. The excellent feature of the contact image sensor unit, that is, the good attachment property (exchangeability), is impaired. In addition, the operation of reacquiring the correction data is not limited to when the image sensor unit is replaced, but also when the substrate with the memory for storing correction data on the image reading apparatus main body is replaced.

According to the present invention, such disadvantages are improved, and the re-taking operation of the correction data accompanying the change of the combination of the image sensor unit and the image reading device main body becomes unnecessary, and the image sensor unit can be easily mounted and exchanged. It is an object of the present invention to provide an image reading apparatus which is excellent in maintainability by utilizing the convenience of the above.

[0007]

An image reading apparatus according to the present invention is provided with an image sensor for outputting an electric image signal in accordance with the density of a document, and an image sensor unit including a light source and an optical system. Wherein the image sensor unit is provided with a memory for storing information unique to the image sensor unit, and the main body of the image reading apparatus directly reads out the information stored in the memory of the image sensor unit to perform image correction.

Preferably, the dark output level data of the image sensor is stored in the memory, and the image reading apparatus main body reads the dark output level data stored in the memory to perform black offset correction. Further, it is preferable that the bright output level data of the image sensor is stored in the memory, and that the image reading apparatus main body reads the bright output level data stored in the memory and performs shading correction. Further, the information for specifying the image signal level adjustment gain of the image sensor is stored in the memory, and the image reading apparatus main body reads the information for specifying the image signal level adjustment gain stored in the memory and adjusts the image signal gain. It is good to do.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An image reading apparatus according to the present invention has an image sensor unit and an image reading apparatus main body. The image sensor unit has an image sensor body including an image sensor, an optical system such as a light source and a lens, and an output circuit, and a flash ROM. The image reading apparatus main body has a CPU that controls the operation of the entire apparatus, an image processing unit, and an SRAM that is an image processing memory associated with the image processing unit. The image processing unit has various analog processing functions such as gain adjustment for analog image signals output from the image sensor body, AD conversion functions, various correction functions for digitally correcting image signal distortion, and gradation processing functions. Flash ROM provided in image sensor unit
It also has a function of controlling the data reading.

Before assembling this image sensor unit into the image reading apparatus main body, the flash ROM is connected to a dedicated writing jig device to store information specific to the image sensor main body, for example, dark output level data and bright output level data. Write. This image sensor unit is attached to the image reading device main body. The image reading device is a flash RO
In order to smoothly perform the correction process using the data stored in the M, an SRA provided with the image processing circuit is provided.
Load data into M. When the image sensor unit of the image reading apparatus is replaced with another unit in this manner, the correction data corresponding to the replaced image sensor unit is stored in the image reading apparatus main body without performing any special operation.
It can be stored in RAM.

[0011]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. As shown in the figure, the image reading device has an image sensor unit 1 and an image reading device main body 2.
The image sensor unit 1 includes an image sensor main body 3 including an image sensor, a light source, an optical system such as a lens and an output circuit, and a memory having a nonvolatile function such as a nonvolatile memory or a volatile memory backed up by a battery, for example, a flash ROM 4. . The image reading apparatus main body 2 includes a CPU 5 that controls the operation of the entire apparatus, an image processing unit 6, and an SRAM that is an image processing memory associated with the image processing unit 6.
And an image processing unit 6 and a CPU via a system bus 8.
5 exchange data and commands. The image processing unit 6 and the flash ROM 4 provided in the image sensor unit 1 are connected by a local bus 9. The image processing unit 6 performs various analog processing functions such as gain adjustment, an AD conversion function, various correction functions for digitally correcting image signal distortion, and gradation processing for an analog image signal output from the image sensor body 3. It has a function and the like, and also has a function of controlling data reading from the flash ROM 4 provided in the image sensor unit 1. The start and stop of the data exchange between the image processing unit 6 and the flash ROM 4 are controlled by a command from the CPU 5. The SRAM 7 functions as a line buffer or the like and stores correction data serving as reference data for correction processing. The reason why the SRAM 7 is used as the image processing memory is that high-speed access is required so that image processing can be performed following the image data input speed from the image sensor body 3. Note that any RAM other than the SRAM may be used as long as the RAM can follow the image processing speed.

Before the image sensor unit 1 is assembled to the image reading device main body 2 in the image reading device configured as described above, the image sensor unit 1 is attached to the dedicated writing jig device 10 as shown in FIG. Connect and Flash R
Information specific to the image sensor body 3, such as dark output level data and bright output level data, is written into the OM 4. The dedicated writing jig device 10 has the same interface as the image reading device main body 2, a power supply circuit 11 for supplying power to the image sensor unit 1, a driving pulse generating circuit 12 for supplying a driving pulse to the image sensor main body 3, A light source lighting control circuit 13 of the sensor body 3, an analog circuit 14 and an AD conversion circuit 15 similar to the image processing unit 6,
A line buffer circuit 16 for writing to the OM4,
It has an address generation circuit 17, a strobe generation circuit 18, and a write control circuit 19 for controlling the entire device.

An operation of writing the information unique to the image sensor body 3 to the flash ROM 4 by connecting to the dedicated writing jig device 10 configured as described above will be described with reference to the flowchart of FIG. First, the image sensor unit 1 is mounted on the dedicated writing jig device 10, and power is supplied to the image sensor unit 1 from the power supply circuit 11,
A drive clock is supplied from the drive pulse generation circuit 12 (step S1), and a dark output level signal of all pixels of the image sensor is processed by the analog processing circuit 14 in a state where the light source of the image sensor main body 3 is turned off. In step S15, the data is subjected to A / D conversion and taken into the line buffer circuit 16 (step S3). At this time, the settings of the analog processing circuit 14 and the reference voltage of the AD conversion circuit 15 are matched with the image reading apparatus main body 2. When all the data for one line has been captured, the flash R of the image sensor unit 1
The data of the dark output level of the line buffer circuit 16 is written in the previously specified dark output level data storage area of the OM 4 (steps S5 and S6). Here, the line buffer circuit 16 is provided with a flash RO having a restriction on the writing speed.
It is used to cope with M4, and is not particularly necessary as long as it is capable of simultaneously performing a reading operation and writing to the memory of the image sensor unit 1 at the same time.
When writing of all pixels is completed, the dark output level data of the image sensor main body 3 can be stored in the flash ROM 4 (step S6).

In this state, the light source of the image sensor body 3 is turned on by the light source lighting control circuit 13 (step S7).
The analog image processing circuit 14 processes all white output level signals of all pixels of the image sensor, and the AD conversion circuit 15
The data is converted and taken into the line buffer circuit 16 (step S8). When all the data for one line has been fetched, the data of the bright output level of the line buffer circuit 16 is written to a pre-designated bright output level data storage area of the flash ROM 4 of the image sensor unit 1 (steps S9 and S10). When writing of all pixels is completed, the bright output level data of the image sensor main body 3 can be stored in the flash ROM 4 (step S11).
Thereafter, the light source of the image sensor body 3 is turned off, the supply of the clock signal and the power is stopped, and the flash ROM 4 is turned off.
, The storage of the dark output level data and the light output level data of the image sensor main body 3 for the image data is ended (Step S1)
2).

As described above, the dark output level data and the bright output level data of the image sensor body 3 are stored in the flash RO.
The image sensor unit 1 stored in M4 is attached to the image reading device main body 2. In order for the image reading apparatus main body 2 to smoothly perform the correction process using the data stored in the flash ROM 4, it is necessary to load the data into the SRAM 7 provided along with the image processing circuit 6. This procedure corresponds to the line buffer circuit 1 of the dedicated writing jig device 10.
The reverse operation of the operation of transferring data from the flash memory 6 to the flash ROM 4 may be performed. If the SRAM 7 does not have a backup function, this operation is performed once each time the power is turned on, thereby enabling image processing using the correction data. If the sequence is programmed to be automatically executed at power-on, when the image sensor unit 1 of the image reading apparatus is replaced with another unit, the power is turned on again after the replacement without special operation. The correction data corresponding to the image sensor unit 1 replaced only by the
Can be captured.

In the above embodiment, the case where the dark output level data and the bright output level data of the image sensor body 3 are stored in the flash ROM 4 as the information unique to the image sensor body 3 has been described. Instead of the bright output level data, several levels of analog gain setting information can be stored. For example, when eight levels of gain switching are required depending on the output level of the image sensor, the gain setting unique to the image sensor unit 1 is written by writing 3-bit setting information.
It can be stored in the OM4.

Although a unique control flow is required to determine the gain setting value, a process for setting the dedicated writing jig device 10 according to the variation in the light output level will be described with reference to the flowchart of FIG. . For example, when the light output level can be set to eight levels from the minimum level 1 to the maximum level 8, first, the dedicated writing jig device 10 to which the image sensor unit 1 is attached has the analog gain setting level Gn as the maximum value. With the level 8 set, the light source of the image sensor body 3 is turned on (Steps S21 and S21).
22), fetch the bright output level of the image sensor (step S23). At this time, the A / D conversion value is checked over one line to determine whether there is an overflow pixel (step S24). If there is no overflowing pixel, the level 8 is set as it is (step S
25). If there is an overflowing pixel, the gain setting is reduced by one level to take in the bright output level of the image sensor, and the same confirmation is performed (steps S26 and S2).
7, S24, S24). This process is repeated, and when overflow is not detected at a certain gain level, that level is set as a set value (steps S24 and S2).
5). If the overflow occurs even if the gain is lowered to the minimum level 1, a warning is displayed as an abnormal state of the image sensor main body 3 (step S28).
With this operation, the analog gain according to the variation in the bright output level of the image sensor unit 1 can be appropriately set. The set gain is stored in the flash ROM 4 of the image sensor unit 1 as 3-bit information.
Then, the data is written and stored in the predetermined area, the light source is turned off, and the process ends (step S29).

After the image sensor unit 1 is attached to the image reading apparatus main body 1, the gain setting information stored in the flash ROM 4 of the image sensor unit 1 is read out as an initial operation when the power is turned on. Set the corresponding gain level. By automatically performing these series of operations, even when the image sensor unit 1 is replaced with another unit, an appropriate gain setting value can be obtained by simply turning on the power after replacement without performing any special operation. it can.

After setting the gain level as appropriate in the image reading apparatus main body 1 as described above, the dark output level and the light output level are taken in, so that the correction data corresponding to the image sensor unit 1 can be obtained. SR
It can be imported to AM7.

[0020]

As described above, according to the present invention, the information unique to the image sensor unit is stored in the memory of the image sensor unit, and the stored information unique to the image sensor unit is directly read by the image reading apparatus main body to correct the image. Thus, even when the combination of the image sensor unit and the image reading device main body is changed, the correction data can be updated without special operation from the outside, and the image sensor unit can be easily replaced. it can.

Further, by storing the dark output level data and the light output level data of the image sensor as information unique to the image sensor unit, even if the combination of the image sensor unit and the image reading apparatus main body is changed, it is possible to use the appropriate data. To perform black offset correction processing and shading correction processing.

Further, by storing information specifying the image signal level adjustment gain of the image sensor as information unique to the image sensor unit, appropriate information can be obtained even when the combination of the image sensor unit and the image reading device changes. The gain can be adjusted based on the gain.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a dedicated writing jig device.

FIG. 3 is a flowchart illustrating an operation when saving information unique to an image sensor in a flash ROM.

FIG. 4 is a flowchart showing an operation when saving a level adjustment gain.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image sensor unit 2 Image reading device main body 3 Image sensor main body 4 Flash ROM 5 CPU 6 Image processing unit 7 SRAM 10 Dedicated writing jig device

Claims (4)

[Claims] 1. An image reading apparatus comprising an image sensor for outputting an electric image signal in accordance with the density of a document, and an image sensor unit including a light source and an optical system. An image reading apparatus comprising: a memory for storing information; and a main body of the image reading apparatus for directly reading out information stored in a memory of the image sensor unit and performing image correction. 2. The image reading apparatus according to claim 1, wherein the dark output level data of the image sensor is stored in the memory, and the image reading apparatus main body reads the dark output level data stored in the memory to perform black offset correction. 3. The image reading apparatus according to claim 2, wherein the bright output level data of the image sensor is stored in the memory, and the image reading apparatus main body reads the bright output level data stored in the memory to perform shading correction. 4. An image signal level adjusting gain of the image sensor is stored in the memory, and the main body of the image reading apparatus reads out the information specifying the image signal level adjusting gain stored in the memory and outputs the image signal. 4. The image reading device according to claim 3, wherein the gain adjustment is performed.