JPS63285077A - Picture reader - Google Patents

Abstract

PURPOSE:To freely select an original carrier path arrangement by providing a stop original placing means, a carrier original placing means correcting the difference of an output caused by distance from an original radiation means to a CPU so as to obtain a picture with the same density. CONSTITUTION:The distance of a stop original placing means 27 and a carrier original placing means 32 from an original radiation means 24 differs and in reading the original of the same density, the difference of the luminous quantity of a 1st mode and 2nd mode obtained by the luminous quantity detection means 21 is preset and the correction means correcting the maximum density in the binarized density based on the difference is provided to a CPU 208. That is, the luminous quantity difference due to the mode difference by a 1st book mode and a 2nd sheet mode is preset and in the read by the sheet mode, the difference is subtracted from the slice level given to the binarizing circuit 205 at the book mode to correct the binarizing level and the control is applied to obtain the similar density for the picture reproduced from the output signal.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention is an apparatus that reads an original image using an optical sensor and converts it into a density signal, and then digitizes and reads the image using an A/D converter. The present invention relates to an image reading device having a mode for reading a placed original document and a mode for reading an L'2 original document being conveyed.

[Conventional technology]

Conventionally, this type of image reading device has two modes: a mode in which the first reading means scans and reads the surface of the document placed on a glass or the like (hereinafter referred to as "book mode"), and a mode in which the document is conveyed by the conveyance means. has proposed a copying machine having a reading mode using a second reading means (hereinafter referred to as "sheet mode"), and when operating in sheet mode,
Once the document is conveyed to the book mode position ♂t and stopped, the document is read by performing the book mode operation.

However, such a configuration reduces throughput and
Since copying machines are not suitable for high-speed reading, there are also known copying machines that have a mode in which a document is read by a fixed reading means while being conveyed, and a book mode.

[Problem that the invention seeks to solve]

However, the document position in each mode must be placed at the same position with respect to the main body of the reading device.
There was a problem in that the arrangement of the conveyance path in both modes was difficult.

The present invention was developed based on the above-mentioned problem, and even if the document position relative to the first scanning stage is different in both the book and sheet modes, it is possible to output a signal with a constant density. The first objective is to increase the degree of freedom in the arrangement of transport paths in different modes.

[Means for solving problems]

In the image reading device according to the present invention, although the stopped document a placement means and the transport source MA placement device are different in distance from the document irradiation device, when reading documents of the same density, the light M detection device can obtain The CPU is equipped with a correction means for presetting the difference in light q between the first mode and the 7pJ2 mode, and correcting the maximum density of the binarized density based on the difference.

[Effect]

The image reading device of the present invention determines in advance the difference in light amount due to the mode difference between the first book mode and the second sheet mode, and when reading in the sheet mode, the binarization circuit is used in the book mode. The binarization level is corrected by subtracting the difference in data from the slice level to be given, and the image reproduced from the output signal is overlapped so that it has the same density.

(Example〕 Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 shows the image reading device of this embodiment (hereinafter referred to as "Soda J").
FIG.

Reference numeral 2 denotes a reader main body, in which a document irradiation unit (hereinafter referred to as "irradiation unit J") 24 serves as an yl document irradiation means to irradiate Mm on a platen glass 27 serving as a stopping document placement means, and a reflection mirror 25.lens. The original image is formed on the CCD 22 of the light amount detection means 21 via the light source 26.

The light detection means 21 is a COD drive circuit 203 that drives the CCD 22. It consists of an AMP 201 that amplifies analog signals output from the COD driver 23 and CCD 22, and an A/D converter 202 that converts the analog signals into digital image signals and outputs them to the control unit 20.

3 is an automatic document feeder (hereinafter referred to as rADFJ);
The original on the original placing table 31 is conveyed in the direction of the arrow B shown by the broken line, passes through the original reading path 32 as a means for placing the conveying 1M4g on the Mylar film 41, and is ejected to the original ejecting table 33. ing. (See FIG. 2) Next, the operation of the reader 1 will be described.

The reader has a book mode of the first reading means in which a bound original such as a book is placed on the platen glass 27 and the image is read by scanning with an optical system, and a general paper manuscript without a binding is read using the ADF 3. There are two modes: a sheet mode in which the second reading means reads the image while conveying the sheet;

First, regarding seat mode, reader 1 is always connected to an external device (digital, personal computer, etc.)
Communication of control signals with these external devices 5 and output of image signals to the external devices 5 are performed via the interface circuit 207 .

First, with the W and stripes facing upward on the document placement table 31 of the ADF 3, the external device 5, for example,
8 density 400dpi, 300dpi.

200 dpi or set the image signal to 2
When a manual input is given to specify whether to use a value signal or a multi-value signal, the CPU 208 receives the input from the timing signal generation circuit 209 and the selector 20 in advance.
A control signal is output to 6 to set the pixel density and image file number.

In addition, an optical position sensor (
If it is not at the removal position, the irradiation unit 24 is moved to a predetermined position in order to enter the reading operation in response to the next original reading start command. When the start command is input from the external device 5 in this state, the CPU 208 outputs the lamp control signal 303 to turn on the lamp, and
A document feeding start command is output to the ADF 3 using the ADF control signal 302. As a result, the original placed on the original placing table 31 is conveyed in the direction of arrow B along the path indicated by the broken line in FIG.

Note that this reader 1 uses a stepping motor for the motor used to transport the document and drive the optical system scanning, so by changing the frequency of the pulses to drive the motor, You can freely select the rate of perspiration. Also, if the leading edge of the manuscript is
It is well known that whether or not the document illumination position has been reached can be detected by a document leading edge detection sensor (not shown) provided in the ADF 3.

Until the original reaches the original illumination position, the image formed on the CCD 22 is converted into a digital value and input to the interface circuit 207 as described later, but since this is not the original image, the CPU 208 A control signal is given to the interface circuit 207 so as not to output the image signal.

When the document reaches the document illumination position, the CPO 208 outputs a control signal to enable image signal output to the interface circuit 207, and the read image signals are sent one after another to the external device 5. Then, when the trailing edge of the yl light has finished passing the document illumination position, this is detected by the document leading edge detection sensor, and a control chair number indicating that image signal output is not allowed is given to the interface circuit 207 again to stop the output of one image No. 45. At the same time, an fHm reading end signal is output to the external device 5.

After that, if the reading start command does not arrive from the external device 5 within a certain period of time, the CPU 208 sends the lamp 1 to the lamp 1.
The 111 control signal 303 is output and turned OFF to complete the operation.

Next, we will discuss book mode.

In Figure 2, the right end of the % original is placed on the platen glass 27.
' . Note that the pixel density and image signal settings before the start of document reading are the same as in the sheet mode.

When a document reading start command is input from the external device 5, the CP
U208 first outputs the lamp control signal 303 to turn on the lamp, but does not immediately start scanning for reading, and waits approximately 300 to 500 ms until the light intensity of the lamp stabilizes.
ec Wait. During this time, as in the sheet mode, the image signal is input to the interface circuit 207, but is not output to the external device 5 due to the control signal of the CPU 208.

When a document reading start command is input from the external device 5, the irradiation unit 24 immediately starts scanning in the direction of arrow A. The distance from the initial position of the irradiation unit 24 to the leading edge position of the document on the platen glass 27 is about 2 to 3111 Ql, and during this time, the scanning speed of the optical system by the motor is stabilized.
A motor dry pull J# signal 304 is output and controlled. When the irradiation unit 24 reaches the 01 document leading edge position, the CPU 208 outputs a control signal to enable image signal output to the interface circuit 2o7, and the read image signals are sent to the external device 5 one after another. The scanning length of the optical system is
This is because it is uniquely determined by the number of pulses that the CPU 208 uses to drive the motor.

When the required number of pulses are output to the motor, the CPO 208 determines that the document reading is finished, turns off the lamp, disables image signal output, and reverses the motor, and outputs a document reading completion signal to the external device 5. do.

Under the instantaneous inversion IJ control of the CPU 208, the irradiation unit 24. moves in the direction of arrow A and stops when the optical position sensor detects that the initial position has been reached. If the next reading start command does not come from the external device 5 during this optical system return period, it stops at the initial position and the operation ends Y.

Next, the circuit operation of this embodiment will be described using a block diagram of the circuit configuration of the control unit 21 shown in FIG.

The CCD 22 on the COD driver 23 is connected to the control unit 2
The CCD drive circuit 20 is activated by the timing signal 305 generated by the 0-F timing signal generation circuit 209.
Driven through 3.

The analog image signal output from CC'D 22 is A
It is amplified by the MP 201 and converted into a digital image signal by the A/D converter 202, and then sent to the control unit 2.
Output to 0. The control unit 20 can output this digital image signal to the external device 5 in one of two modes, ie, +binary mode and multivalue mode.

In the binary mode, the image signal is converted to 1 bit by the binarization circuit 205 according to the slice level output from the CPU 208 and then inputted to the selector 206 .

The slice level and f slice level include a slice level specified by the external device 5 that is output as is, and a slice level determined by the background density detection circuit 204.

Next, the output operation of the binarization circuit 205 will be explained based on the flowchart shown in FIG.

In the book mode, the document is placed on the platen glass 27 with its reading surface facing the irradiation unit 24, but in the sheet mode, the document moves in the direction of the arrow B along the path shown by the broken line as described above. It passes through the reading path 32.

Since a transparent mylar film 41 is provided between the platen glass 27 and the Il:<HA reading path 32 in sheet mode, the original is irradiated by the irradiation unit 24 through the visiting film 41, and the reflection from the original is The light reaches the CCD 22 along the path shown by the solid line, and a slice level based on the amount of light detected by the light amount detection means 21 is manually input to the binarization circuit 205 (Stapl).

However, the light reflection position in book mode
At the light reflection position S at the time of reading, not only the distance from the irradiation unit 24 to the document differs, but also the amount of light received on the CCD 22 surface differs due to the influence of the Mylar film 41. Therefore, if the same slice level is used in both modes, the output will not be the same even if originals with the same density are read.

Therefore, the tree reader 1 repeatedly determines whether to operate in book or sheet mode, and when reading in sheet mode, the difference in light amount due to the difference in mode is
Set it to PU208. And CPO208 is
The correction means allows the binarization circuit 20 to
Based on the difference in the amount of light, the reference slice level for the sheet mode is set to be reduced from the reference slice level to be given to 5, and is manually input to the binarization circuit 205 (Step 2). Therefore, the binarization circuit 205 compares the human power from the CCD 22 and the human power from the CPO 208.
Output the maximum density of the purulence value at the corrected (Step 4) slice level (Step 5), thereby
Even if the amount of light received differs on the COD 22 surface 1;, it is reproduced as an image with the same density after being binarized.

〔Effect of the invention〕

As explained above, the present invention has a structure in which a correction means is provided in the CPU to compensate for the difference in output that occurs when the stopped original placing means and the conveyed original placing means are located at different distances from the KIA irradiation means. , if the original M4tIA degrees are the same, not only images with the same density can be obtained, but also the arrangement of the document conveyance path can be freely selected.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the internal configuration of an image reading device and the circuit configuration of a control unit in an embodiment of the present invention, FIG. 2 is an enlarged view of the configuration of the document reading portion, and FIG. 5 is a flowchart showing the output operation of the binarization circuit. 21...Light amount detection means 24...Document irradiation unit 27...Platen glass 32-...Document reading path 205--Binarization circuit 208 -...-CPU

Claims (1)

[Claims] A stopped original placing means and a conveyed original placing means having different distances from the original irradiation means, a light amount detection means for detecting the amount of light from each original placed on the original placing means, and a first original reading means for reading the stopped original. An image reading device characterized by comprising a correction means for setting a reference slice level for the second mode to be applied to the binarization circuit based on the difference in light amount between the mode and the second mode for reading the conveyed document. .