JPH0374546B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an information reading device, and an object of the present invention is to provide means for performing shading correction with a simple configuration.

About conventional technology In information reading devices used in digital copying machines, facsimile machines, etc., an original on which images or characters are displayed is illuminated with a rod-shaped light source, and the reflected light from the original is received by a solid-state image sensor through a conversion lens. Converts information into electrical signals. In this line of equipment, the light distribution characteristics of the light source are not uniform, the reflector is dirty, and the brightness of the lens approaches the periphery, resulting in the so-called COS ⁴ θ characteristic (where θ indicates the half angle of view of the lens). ) to decrease according to
It is also necessary to correct the shading characteristics caused by variations in sensitivity between bits of the image sensor. As a means for this purpose, it has been proposed to perform shading correction using a signal received from reflected light when a white plate, which should be the standard for shading correction, is irradiated.

Furthermore, in the above-mentioned information reading device, it has been proposed to arrange a plurality of image sensors side by side in the scanning direction in order to increase resolution and transfer speed. In this case, it is necessary to prevent optical discontinuities from occurring at the boundaries of the areas scanned by each image sensor, and for this purpose, an area is provided that is scanned overlappingly by multiple image sensors, and this area is used as a reference point. It has been proposed to arrange markers and connect the outputs of a plurality of image sensors using signals read from the reference markers.

When applying these means to an actual information reading device, it is desirable that these two means be incorporated into the device with a simple configuration without interfering with each other.

Purpose of the Invention Therefore, the present invention provides an information reading device having a shading correction means and a connection processing means for the outputs of a plurality of image sensors, which has a simple configuration and does not require precise position control of a light source device. ,
It is an object of the present invention to provide a device that can avoid the influence of a marker section provided for connection processing of outputs of a plurality of image sensors during shading correction.

Structure of the Invention The present invention provides first and second image sensors (for example, in the specific example described later, a solid-state image sensor as shown in FIG. Image sensor CCD1 and CCD2)
, a reference optical characteristic section (also the reference optical characteristic section 3 in FIG. 1) for detecting the shading characteristic provided on the document table, and the first and second imaging units provided in the reference optical characteristic section. The overlapping scanning is performed based on a marker section (also the marker section 4 in FIG. 1) for detecting an overlapping scanning area by the element, and an output signal obtained by scanning the marker section with the first and second image pickup devices. a removal unit (also a joint processing unit in FIG. 4) that detects an area and removes an output signal corresponding to the overlapping scanning area from an output signal obtained by scanning the original image with the second image pickup device; a detection means (also the address counter 33', address code switch 35, and address comparison circuit 36 in FIG. 2) for detecting that a location immediately before the marker section has been scanned by the first image sensor; and the detection means Holding means (also a second
Among the output signals obtained by scanning the reference optical characteristic section with the latch circuit 37) and the first and second image pickup devices, the output signal corresponding to the marker portion from the first image pickup device replacing means (selector SEL2 in FIG. 2) for replacing the output signal with an output signal corresponding to the position immediately before the marker portion held in the holding means; The first,
The shading characteristic is detected based on an output signal obtained by scanning the reference optical characteristic section with a second image sensor, and an output signal obtained by scanning the document image with the first and second image sensors. A correction means for correcting the shedding characteristic of (also shown in Fig. 2)
The information reading device is characterized by having a RAM 33 and a multiplication ROM 38).

In the above, the reference to specific examples shown in the drawings to be described later does not limit the scope of the present invention, and the present invention can be modified as appropriate within the scope of the claims.

Further, the information read by the reading device of the present invention includes information contained in documents, photographs, maps, or diagrams displaying images, characters, symbols, etc.
Information such as the pattern of a flat object such as textile fabric or textile products is included. Hereinafter, in this specification, these information carriers will simply be referred to as manuscripts.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An information reading device embodying the present invention will be described in detail below with reference to the drawings, including its optical configuration, a specific example of a shading correction section, and the order of processing for connecting outputs of a plurality of image sensors.

Regarding the optical configuration of an information reading device embodying the present invention (Figure 1) Figure 1A is a side view showing the optical configuration of an information reading device embodying the present invention, and Figure 1B is a plan view as well. be. In these figures, reference numeral 1 indicates a document mounting table, and reference numeral 2 indicates its main scanning area. Reference numeral 3 denotes a reference optical characteristic section, which is fixedly or movably disposed on the mounting table 1, or placed at a predetermined position thereof. In this specification, with respect to the reference optical characteristic section 3 and the marker section 4 described later, these means are collectively referred to as arrangement. In this example, the reference optical characteristic section 3 has a white plate at a portion that comes into contact with the mounting table 1. The position of the reference optical characteristic section 3 corresponds to the home position 25 of the light source device 5 (the position in the resting state of this device). In the reference optical characteristic section 3, characteristics that affect reflected light, such as color, reflectance, and surface smoothness, serve as standards for shading correction. 4 is a marker section, which is a reference optical characteristic section 3;
The light reflected when the marker section 4 is irradiated onto the light source device 5 provides a signal for connection processing, which will be described later. In this example, the marker portion 4 has a thin black line at the portion that contacts the mounting table 1.

In addition, the marker portion 4 has lenses 10 and 1, respectively.
It is provided in a portion that is scanned redundantly by two adjacent optical systems including 1.

Reference numeral 5 denotes a light source device, which includes rod-shaped light sources 6 and 6', and which illuminates the entire area of the reference optical characteristic section 3 in the main scanning direction (in the direction of the broken line 25 in FIG. 1B) and the marker section 4 at its home position 25. It's starting to irradiate. Furthermore, the light source device 5 moves in the sub-scanning direction (X direction in FIG. 1A) and scans the original on the main scanning area 2. Reflecting mirrors 7, 8, and 9 move as the light source device 5 moves so that the optical paths from the point irradiated by the light source device 5 to the lenses 10 and 11 are always equal. Specifically, the reflecting mirror 7 moves together with the light source device 5, and the reflecting mirrors 8 and 9 are allowed to move at a predetermined ratio to the amount of movement of the light source device 5 so as to satisfy the above-mentioned conditions. Reference numerals 10 and 11 denote imaging lenses which, when the reference optical characteristic section 3, the marker section 4, and the original on the main scanning area 2 are irradiated by the light source device 5, reflect light from the light through the reflecting mirrors 7 to 9. , an image is formed on the light-receiving surface of the image sensor. CCD1 and CCD2 are solid-state image sensors that are image sensors, and are charge-coupled devices or
It is composed of MOS transistors and the like, and scanning is performed electrically in the main scanning direction.

Reference numeral 14 in FIG. 1B is a reference mark used when placing a document, and 15 is a sensor for detecting the home position 25 of the light source device 5, and its output is used to control the light source through a control mechanism (not shown). Adjust the position of device 5.

To explain the operation of the device shown in FIG. 1, the light source device 5
is in the home position 25 and illuminates the reference optical characteristic section 3, the marker section 4 is also irradiated, and the reflected light is transmitted to the reflecting mirrors 7 to 9 and the imaging lens 1.
After passing through 0 and 11, solid-state image sensor CCD1 and
The light is received by CCD2. Signals indicating this shading characteristic also include signals due to reflected light from the marker section 4. The present invention is based on the existence of the marker section 4 for shedding correction by replacing the signal due to the reflected light from the marker section 4 with a signal from another section, especially a signal from a point immediately before the marker section 4. It is an attempt to avoid the influence mirror. This will be explained in detail with respect to FIG. Next, the light source device 5 moves to the main scanning area 2,
It advances in the sub-scanning direction (X direction) in FIG. 1A, and scans the original in both the main and sub-scanning directions. Signals from reading the original are output from the solid-state image sensors CCD1 and CCD2, and processed by the circuits shown in FIGS. 2 and 4, which will be described later. When the document scanning is completed, the light source device 5 returns to its home position 25.

Regarding a specific example of the shedding correction section in this invention (FIG. 2) FIG. It shows a circuit configuration for replacing with the immediately previous signal, and shows a case where the output of the image sensor CCD1 is processed. Note that since scanning is performed in the Y direction in FIG. 1B, that is, from the document reference mark 14 toward the center of the document, in this case, the signal from the marker section 4 appears in the latter half of the main scanning cycle.

In FIG. 2, when starting the shading correction, the selector SEL1 is switched to the A side and the selector SEL2 is switched to the C side. image sensor
A pit serial image signal from the CCD 1 is amplified by an amplifier 31 and converted into a digital signal by an AD converter 32, and this digital signal is written into a random access memory 33 (hereinafter referred to as RAM). Address control of this RAM 33 is performed by the clock generator 3 for the image sensor CCD 1.
This is done via the address counter 33' by a clock signal that is in synchronization with the clock signal of No. 4. Then, this address signal and the marker section 4
The address comparison circuit 36 compares the address code of the address code switch 35, which is set with the address corresponding to the location immediately before the address, and when a match is obtained, switches the selector SEL2 to the D side and converts the digital value at that time. The value held by the latch circuit 37 is held, and thereafter, the value held by the latch circuit 37 continues to be written into the RAM 33 until the main scanning cycle is completed.

Following the above-described shading sequence, the light source device 5 irradiates the reference optical characteristic section 3 once again at its home position, and then scans the document. In these cases selector SEL
1 is switched to the B side, and inputs the image data obtained by reading the marker section 4 and the original into one of the multiplication read-only memories 38 (hereinafter read-only memories will be referred to as ROM). The other input of the multiplication ROM 38 is given a signal from the RAM 33 containing the shading value obtained in the above-mentioned shading sequence, and the multiplication ROM 38 receives a signal synchronous with the clock signal of the clock generator 34. via the address counter 38',
Address control is performed. This multiplication ROM
38 is incorporated to output a code m/n when the input value from the RAM 33 is n and the image data is m, and shading is corrected by this logic. The output from the multiplier ROM 38 is compared with the output from the dither ROM 39, which is a threshold value determination circuit, in a comparison circuit 40 to obtain binarized image data, which is stored in the shift memory 1 (4).
1) is input. A main scanning counter 42 for the dither ROM 39 receives a signal that is in synchronization with the clock signal of the clock generator 34. A count pulse is inputted to the sub-scanning counter 43 at every fixed count of the main-scanning counter 42, and the sub-scanning of the light source device 5 is maintained in synchronization with the sub-scanning. Note that the signal read from the marker section 4 is used in a connection processing section to be described later.

As mentioned above, in the apparatus shown in FIG. 2, in the shading sequence, the signal from the marker section 4 provided for connecting the outputs of a plurality of image sensors is replaced with the signal at the point immediately before it.
With a simple configuration, it is possible to avoid the influence of the marker section 4 on the shading correction. If the reading of the shedding characteristic and the reading of the marker section 4 are performed at different positions, when the light source device 5 illuminates the reference optical characteristic section 3, the light reflected by the marker section 4 will be reflected by the image sensors CCD1 and CCD2.
Since it is necessary to prevent the light from being picked up and to separately irradiate the marker section 4, the position control of the light source device 5 becomes complicated, but the device shown in FIG. 2 can simplify this.

Note that the shading correction for the image sensor CCD 2 is executed as follows.

That is, since the signal corresponding to the position of the marker section 4 is removed from the output signal of the image sensor CCD 2 by the linking process described later, there is no need to consider the influence of the presence of the marker section 4 on the shading correction. Therefore, in the configuration shown in FIG. 2, a configuration for replacing the signal corresponding to the marker section 4 with a signal other than the marker section 4, that is, the address code switch 35 and the address comparison circuit 3 is required.
6. A configuration in which the latch circuit 37 and selector SEL2 are removed performs shading correction on the output of the image sensor CCD2.

Concerning the process of connecting the outputs of a plurality of image sensors according to the present invention (FIGS. 3 to 5) Next, a means for automatically connecting the output signals of a plurality of image sensors, for example solid-state image sensors CCD1 and CCD2, will be explained. . In the same way as the output of solid-state image sensor CCD1 is stored in shift memory 1 in FIG. 2, the output of solid-state image sensor CCD2 is stored in shift memory 2 (fourth
(Figure). Figure 3 shows the principle of connection processing, where a is the scanning area of CCD1, and b is the scanning area of CCD2.
The scanning direction Y corresponds to the scanning direction Y of FIG. 1B. When the light source device 5 is at the home position 25 and illuminates the marker section 4,
The last 128 pitto-serial signals from CCD1
The bits are shown in FIG. 3C, and the first 128 bits of the bit serial signal from CCD 2 are shown in FIG. 3D.
Here, 128 bits corresponds to a width of 8 mm on the document surface when the resolution is 16 bits/mm. Then extract each of these 128 bits and expand them to RAM. This state is shown in e and f of the same figure, but if the ranges scanned by the two optical systems are set to overlap as described above,
For 128 bits, white bits always appear before and after,
The black bit corresponding to the marker section 4 described above is now in a state of being pinched. Therefore, when reading from the shift memory the number of bits that is the sum of the number of lower white bits (L, W.) output from CCD1, the number of upper white bits (U, W.) output from CCD2, and the number B of black bits. Then, the output signals of CCD1 and CCD2 are extracted as continuous signals.

Next, FIG. 4 shows the connection processing section that executes the above operation. FIG. Explain. The basics of this sampling process is to take in data from both sides 16 times in 8-bit units, and then
It is located in Extract to RAM. The device operates with a write clock signal _φ2 and a read clock signal _φ3 . First, the central processing unit (hereinafter referred to as CPU) sets write address counter 1 and read address counter 2 to down count mode. Note that the read address counter 1 is always preset to a down count mode.
Then set address 2592 (A20H in hex code) to I/O register 1, and set address 8 to I/O register 3.
Set the street address (also 8H). In this circuit
When the CPU activates the test terminal T of the I/O register 4, a reading circuit (not shown) generates a video enable signal (EN in FIG. 5) indicating one scanning period once, and at the same time, bits from CCD1 and CCD2 are generated. It is designed to send out serial video signals.

The video enable signal EN is input to each set terminal S of flip-flops 1 and 2 in FIG.
The video signal from CCD 1 is sent to shift memory 1 (same as shift memory 41 in FIG. 2) and 8-bit shift register 1, and the video signal from CCD 2 is sent to shift memory 2 and 8-bit shift register 2.
is input. 8-bit shift registers 1 and 2
Both start the shift operation upon activation of the video enable signal, and end the same operation in response to the count completion signal RPC1 from the write address counter 1 and the read address counter 2, respectively. Note that this operation is performed on flip-flops 1 and 2, respectively.
It is done through.

Therefore, when the CPU activates the aforementioned test terminal T, the last 8 bits of the signal from CCD 1 remain in 8-bit shift register 1 when the video enable signal ends, and the last 8 bits of the signal from CCD 1 remain in 8-bit shift register 2. The first 8 bits of the signal from CCD2 remain. The CPU then reads the contents of these shift registers and stores them in the RAM.
Expand on top. To process the next 8 bits,
Set address (2592-8) to I/O register 1, and write the I/O
Set (address 8+8) in register 3 and process in the same way as above. Repeat these steps 16 times
It extracts 128 bits.

When the stitch amount calculation is completed, the document is scanned, but before this, the CPU stores address 2504 in I/O register 2 and address (2592-2592-) in I/O register 3.
connection amount) Set the address. This situation is shown in Figure 3g.
and h, g shows the output of CCD1,
This includes 88 bits for margins from the beginning, 2376 bits equivalent to the amount of information for 148.5 mm, and 2376 bits for stitching.
It consists of 128 bits, a total of 2592 bits, while
shows the output of CCD2, which is also a total of 2592
It consists of bits, and the first CON indicates the amount of connection. Note that the video output is taken out via the OR circuit on the output side of the shift memories 1 and 2.

Figure 5 shows the video enable signal (EN),
Output signal from CCD1 (CCD1), output signal from CCD2 (CCD2) and write clock (φ ₂ )
Indicates the time relationship between. In addition to the above, the I/O register 4 in FIG. 4 is used to switch the modes of the write address counter 1 and read address counter 2 and to select the address selectors 1 and 2. The CPU shown in Fig. 4 also controls the shading correction section shown in Fig. 2.
RAM and ROM can also be used as those shown in FIG.

Although an example in which the present invention is applied to a fixed original/light source moving type device has been described above, this invention can be similarly applied to a fixed light source/document moving type device, and transmitted light can be used instead of reflected light. You can also use Further, the number of image sensors is not limited to two, but may be three or more.

Effects of the Invention Based on the above-described configuration and operation, the present invention provides an information reading device including a plurality of image sensors.
When performing the shedding correction, it is possible to avoid the influence of the presence of the marker section for connecting the output signals of the plurality of image sensors with a simple configuration and without requiring complicated movement control of the light source device.

That is, the first, first and second scanners are arranged side by side in the main scanning direction so that their scanning areas overlap, and share the scanning of the original image.
The second image sensor detects the overlap scanning area based on the output signal obtained by scanning the marker section provided in the reference optical characteristic section, and detects the overlap scanning area from the output signal obtained by scanning the original image. In addition to removing the corresponding output signal, among the output signals obtained by scanning the reference optical characteristic section, the output signal corresponding to the marker section is replaced with an output signal corresponding to the position immediately before the marker section, and The shading characteristic is detected based on the output signal in which the corresponding output signal is replaced with the output signal corresponding to the position immediately before the marker section 4, and the shading characteristic of the output signal obtained by scanning the original image is corrected. be.

As a result, it is possible to correspond to the overlapping scanning area from the output signals of the first and second image sensors without providing a marker section for detecting the overlapping scanning area at a separate position from the optical characteristic section for detecting the shedding characteristic. This makes it possible to perform removal processing on the output signal, and also to perform correction processing on the shading characteristics of the output signals of the first and second imaging elements without being affected by the marker section.

[Brief explanation of drawings]

FIG. 1A is a side view showing the optical configuration of an information reading device embodying the present invention, FIG. 1B is a plan view of the same, and FIG. FIG. 3 is an explanatory diagram of the principle of processing to connect the outputs of a plurality of image sensors according to the present invention, FIG. FIG. 4 is an explanatory diagram of the operation of the connection processing section in FIG. 4; In the figure, 3 is a reference optical characteristic section, 4 is a marker section, 5 is a light source device, 33 is a random access memory, 36
is an address comparison circuit, 37 is a latch circuit, 38 is a multiplication read-only memory, CCD1 and CCD2
indicates a solid-state image sensor that is an imaging device.

Claims (1)

[Scope of Claims] 1. A first and a second scanner which are arranged side by side in the main scanning direction so that their scanning areas overlap, and share the scanning of the original image.
an image sensor, a reference optical characteristic section for detecting shading characteristics provided on the document table, and a reference optical characteristic section for detecting overlapping scanning areas by the first and second image sensors provided in the reference optical characteristic section. detecting the overlapping scanning area based on an output signal obtained by scanning the marker section with the marker section and the first and second image pickup devices; scanning the document image with the second image pickup device; removing means for removing an output signal corresponding to the overlapping scanning area from the obtained output signal; detecting means for detecting that a location immediately in front of the marker section has been scanned by the first image sensor; and the detecting means In response to the detection output of the first
holding means for holding an output signal obtained by scanning a location immediately in front of the marker section with an image sensor; and a holding means for holding an output signal obtained by scanning the reference optical characteristic section with the first and second image sensors. Among them, the first
replacing means for replacing an output signal corresponding to the marker section from the image sensor of the image sensor with an output signal corresponding to a position immediately before the marker section held in the holding means; The shading characteristic is determined based on the output signal obtained by scanning the reference optical characteristic section with the first and second image pickup elements, in which the output signal corresponding to the position immediately before the marker section is replaced with an output signal corresponding to a position immediately before the marker section. An information reading device comprising: a correction means for detecting and correcting a shading characteristic of an output signal obtained by scanning the original image with the first and second image pickup devices.