JP2000069237A - Control method for image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect home position without erroneously detecting the gap between a pressing plate and a case as a border between a white board and a black board by moving an image sensor for a prescribed distance after the output of an image sensor at a black level is darker than the level for deciding a prescribed black level. SOLUTION: Each of R, G, B color LEDs 202 is integrated with a line sensor 201 or the like to configure a close contact image sensor, and an LED drive control voltage 203 selects to any of the LEDs 202 of each color and to light it, while causing this image sensor to move to read an R, G, B line sequential color image. This image scanner detects the border between a white board and a black board, by using an image signal when the line sensor 201 reads the white board and the black board to detect a home position which is a read reference position of the image sensor. Then when the output of the image sensor at a black level is obtained darker than the level for discriminating a prescribed black level, the image sensor is moved by a prescribed distance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image sensor for converting a read image into an electric image signal, and digitizing the image signal by an A / D converter to an external device. The present invention relates to a control method of an image reading device capable of performing the control.

[0002]

2. Description of the Related Art Conventionally, in an image reading apparatus (hereinafter referred to as an "image scanner"), a boundary between a white plate and a black plate is detected by an output of an image sensor.
Home position detection (hereinafter referred to as "HP detection")
Had gone.

[0003]

However, in the above-described detection method, the gap between the pressure plate and the housing is erroneously detected as the boundary between the white plate and the black plate.
There was a problem that detection was not possible.

An object of the present invention has been made in view of the above-mentioned problems, and it is possible to detect an HP without erroneously detecting a gap between a pressure plate and a housing as a boundary between a white plate and a black plate. It is an object of the present invention to provide an image reading apparatus capable of performing the following.

Further, as described above, in order to avoid erroneous detection of the gap between the pressure plate and the housing at the boundary between the white plate and the black plate,
When detecting a black plate after moving a contact image sensor (CIS) by a predetermined amount after detecting black, a method of detecting a boundary between a white plate and a black plate during scanning (scanning) may be considered. Control of the image reading apparatus capable of shortening the scan time by detecting the boundary between the black plate and the white plate immediately after detecting the black plate and performing the home position detection as in the present invention shown in FIG. It is to provide a method.

[0006]

Therefore, in the present invention, the above object is achieved by providing a method of controlling an image reading apparatus described in any of the following items (1) to (3). It is assumed that.

(1) An image sensor for converting a read image into an electric image signal, a transfer means for transferring the image signal to an external device, and an image reading device having a white portion and a black portion outside the image reading area A method of controlling an apparatus, wherein an output of the image sensor is detected when a reading reference position of the image sensor is detected by detecting a boundary between the white portion and the black portion using the image sensor. The image sensor is moved by a predetermined length when a black output is obtained at a level higher than the level for determining that the image is black.

(2) In the control method of the image reading device according to the above (1), after the image sensor is moved by the predetermined length, the output of the image sensor and the black determination level are compared again, and A method for controlling an image reading device, comprising detecting a black plate.

(3) In the control method of the image reading device described in (2) above, when the black plate is detected, the image sensor is moved toward the white plate, and the output of the image sensor and a predetermined value are detected. A control method for an image reading apparatus, comprising: comparing a level for determining white and detecting a boundary between the black plate and the white plate.

[0010]

According to the structure of the present invention as described above, it is possible to prevent the gap between the pressure plate and the housing from being erroneously detected as the boundary between the white portion and the black portion.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings based on an embodiment: (Structure) FIGS. FIG. 2 is a diagram illustrating the configuration of an embodiment of an image scanner. FIG. 2A is a perspective view of the outer shape of the image scanner, and FIG. 2B is a side view of a main part of the image scanner.

In FIG. 1, reference numeral 101 denotes a contact-type image sensor (hereinafter, “CIS”), which is an LED (not shown).
The emitted light flux is converted into a linear shape by the light guide 102 and illuminates the document surface. The reflected light from the illuminated document is
The light is focused on the line sensor by the lens array 103.

By driving the drive motor 104, the CIS 101 can be moved in the reading direction via the wire 105, and the image on the document can be read.

In FIG. 1, reference numeral 106 denotes a contact glass, 107 denotes a pressure plate, 108 denotes a read original, and arrow 109 denotes
Represents the reading direction.

(Control Circuit) FIG. 2 is a block diagram showing the configuration of the control circuit in the embodiment of the present invention. Figure 2 below
The circuit operation of this embodiment will be described with reference to FIG. 2. In FIG. 2, reference numeral 201 denotes a line sensor. Reference numeral 202 denotes LEDs of R, G, and B colors, which are light sources.
3. The CIS 101 is integrated with the line sensor 201. Then, while moving the CIS 101 (FIG. 1), the LED driving circuit 203 controls the LE of each color line by line.
By switching D to light it, it is possible to read a color image of R, G, B lines in order.

Reference numeral 204 denotes an amplifier (AMP) for amplifying a signal output from the line sensor 201.
An A / D converter 205 performs A / D conversion of the amplified output to obtain an 8-bit digital output, for example.
The shading RAM 206 stores shading correction data by reading a calibration sheet in advance, and the shading correction circuit 207 stores the shading correction data in the shading RAM 206.
Performs shading correction on the read image signal based on the data stored in the. The peak detection circuit 208 is a circuit that detects a peak value in the read image data for each line.

A gamma conversion circuit 209 performs gamma conversion of image data read according to a gamma curve preset by a host computer (not shown).

The buffer RAM 210 is a RAM for temporarily storing image data in order to match the timing of an actual reading operation with the communication with the host computer, and the packing / buffer RAM control circuit 211 is provided with a host computer. After performing a packing process in accordance with a more preset image output mode (binary, 4-bit multi-level, 8-bit multi-level, 24-bit multi-level), a process of writing the data into the buffer RAM 210 and an interface circuit 212 Buffer RAM 21
Processing for reading and outputting image data from 0 is performed.

The interface circuit 212 sends and receives control signals and outputs image signals to and from an external device 213 serving as a host device of the image reading apparatus according to the present embodiment, such as a personal computer.

Reference numeral 215 denotes a microcomputer-type CPU, for example, a ROM 215A storing processing means.
And a work RAM 215B, and controls each unit according to a procedure stored in the ROM 215A.

Reference numeral 216 denotes a crystal oscillator (OSC), 214
Is an oscillator (OSC) 21 according to the setting of the CPU 215.
6 is a timing signal generation circuit that divides the output of 6 and generates various timing signals serving as operation references.

FIG. 3 shows a view from above the inside of the image scanner: 301 is an image reading area. 302 denotes a white plate, 303 denotes a black plate, and detects a boundary using an image signal when these are read by a line sensor.
A home position HP, which is a reading reference position of the image sensor, is detected.

(Operation Control) Next, an operation control method according to the embodiment of the present invention will be described with reference to the operation control sequence flowchart of FIG.
The accumulation time of the home position (HP) detection CIS 101 (FIG. 1) is set. Next, in step S2,
The light amount of the LED is set, and the LED is turned on in step S3. In step S4, the movement of the CIS 101 toward the home position is started, and in step S5, the CIS 10
1 is obtained.

Next, in step S6, the output of the CIS 101 is compared with the black determination level. If the output of the CIS 101 is smaller than the black determination level, the process proceeds to step S7, otherwise, the process proceeds to step S3.

At step S7, the CIS 101 is stopped. At step S8, the CIS 101 is moved by a specified amount. At step S9, the output of the CIS 101 is obtained.

In step S10, the output of CIS 101 obtained in step S9 is compared with the black determination level, and
If the output of 101 is smaller than the black determination level, the process proceeds to step S11, otherwise, the process proceeds to step S3.

In step S11, the CIS 101 is moved by one line in the direction opposite to the home position HP, and in step S12, the output of the CIS 101 is obtained.

In step S13, the output of the CIS 101 obtained in step S12 is compared with the white determination level,
If the output of S101 is larger than the white determination level, the process proceeds to step S14, otherwise, the process proceeds to step S11.

In step S14, each LED 202 (FIG. 2) is turned off, and in step S15, the CIS 101 is moved by a predetermined amount in the direction of the home position HP.

(Other Embodiments) In this embodiment, the contact type image sensor CIS10 using CMOS is used.
Although 1 is used, it is also an effective method when a CIS using a CCD (Charge Coupled Device) or the like is used.

[0031]

As described above, according to the present invention,
In the image reading apparatus, the home position can be detected without erroneously detecting the gap between the pressure plate and the housing as the boundary between the white portion and the black portion.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the configuration of an image scanner according to an embodiment (a).
External perspective view, (b) Side view of main part

FIG. 2 is a block diagram of a control circuit configuration according to an embodiment;

FIG. 3 is a view of the image scanner as viewed from above from the inside;

FIG. 4 is a flowchart of an operation control sequence according to the embodiment.

[Explanation of symbols]

 Reference Signs List 101 Contact image sensor (CIS) 106 Contact glass 107 Pressure plate 108 Reading document 202 LED (R, G, B) 205 A / D converter 207 Shading correction circuit 208 Peak detection circuit 213 External device 215 CPU 301 Image reading area 302 White Plate 303 Black plate

Claims (3)

[Claims] An image sensor for converting a read image into an electric image signal; a transfer unit for transferring the image signal to an external device; and an image reading device having a white portion and a black portion outside an image reading area. Detecting a boundary between the white portion and the black portion by using the image sensor, when detecting the reading reference position of the image sensor, the output of the image sensor is a predetermined A method for controlling an image reading apparatus, comprising: moving an image sensor by a predetermined length when a black output is obtained from a level for determining black. 2. The method according to claim 1, wherein after the image sensor is moved by the predetermined length, an output of the image sensor is compared with the black determination level again, and the black plate is read. A method for controlling an image reading apparatus, comprising: 3. The method for controlling an image reading device according to claim 2, wherein when the black plate is detected, the image sensor is moved toward the white plate, and an output of the image sensor and a predetermined white color are output. A method for controlling an image reading apparatus, comprising: comparing a level for determination with a threshold value; and detecting a boundary between the black plate and the white plate.