JPH04292064A - Picture reader - Google Patents

Abstract

PURPOSE:To simplify an adjustment mechanism between a document edge detection position and a reference position by providing a means holding distance information between the document edge detection position and the reference position. CONSTITUTION:A holding means A (for document edge detection position adjustment amount), a reading means B and a correction means C (each for the document edge detection position adjustment amount) are provided in the picture reader. Thus the distance information between the document edge detection position and the reference position are measured in advance, the holding means A holds arbitrary distance information between the document edge detection information and the reference position proper to the automatic document feeding device with simple construction. The correction means C corrects the reading starting timing of the picture reader automatically based on the distance information read by the reading means B results in keeping the constant reading starting position of the picture reader when an arbitrary automatic document feeding device and the picture reader are connected.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a document reading device to which an automatic document feeder can be connected, and more particularly to a document reading device capable of detecting the leading and trailing edge positions of a document.

0002

2. Description of the Related Art Conventionally, a conventional method for detecting a document in an automatic document feeder is to use a document leading edge detection sensor 37, as shown in FIG. FIG. 10 is a sectional view of a main part showing a document feeding path in a conventional automatic document feeder.

As shown in this figure, conventionally, a document is conveyed in the direction of arrow B in the figure, and the leading edge is detected when the leading edge detection sensor 37 of the document is turned on, and then the leading edge of the document is detected when the leading edge detection sensor 37 is turned off. In many cases, a method of detecting the rear end is adopted.

[0004] Here, a distance b (indicated by a broken line in the figure) between the document leading edge detection sensor 37 and the document reading position is set in advance, and reading is performed by the document leading edge detection sensor 37.
starts after the document has been conveyed for line b after is turned on,
Even after the document leading edge detection sensor 37 is turned off, line b
Read for minutes and then exit.

In this method of detecting the leading edge and trailing edge of a document, the reading start position may vary from machine to machine due to the delicate ON/OFF timing of the sensor and variations in the distance between the leading edge detection sensor 37 and the document reading position. Because of the difference in
Volumes such as variable resistors were installed and adjustments were made when assembly was completed.

[0006]

[Problems to be Solved by the Invention] However, in the above conventional example, it is necessary to provide a volume such as a variable resistor only for adjustment at the time of completion of assembly, and also for adjustment of the reading start position. The adjustment has to be made while reading several times, which is a problem in that it is extremely wasteful in terms of cost and man-hours.

The present invention has been made to solve the above-mentioned problems, and is configured to hold and set distance information between the measured document leading edge detection position and the reference position, which is unique to the automatic document feeder, in the automatic document feeder. By doing so, it is an object of the present invention to provide an image reading device that can reliably recognize distance information between a document leading edge detection position unique to an automatic document feeder and a reference position, which is measured and unique to the device, with a simple configuration.

[0008]

[Means for Solving the Problems] An image reading device according to the present invention is provided with a holding means for holding distance information between a document leading edge detection position unique to an automatic document feeder and a reference position, which is measured in advance. be.

[0009] Further, a reading means is provided for reading distance information between a reference position and a document leading edge detection position of the automatic document feeder held by the holding means.

Further, a correction means is provided for correcting the reading start timing of the image reading means based on the distance information between the document leading edge detection position of the automatic document feeder and the reference position read by the reading means.

[0011]

[Operation] In the present invention, when the distance information between the document leading edge detection position unique to the automatic document feeder and the reference position is measured in advance, the holding means is moved between the document leading edge detection position unique to the automatic document feeder and the reference position. and retain any distance information.

[0012] Furthermore, when the automatic document feeder is connected to the image reading means, distance information between the document leading edge detection position and the reference position, which is unique to the automatic document feeder in which the reading means is held, is automatically read out. is possible.

Furthermore, the correction means automatically corrects the reading start timing of the image reading means based on the distance information between the document leading edge detection position of the automatic document feeder and the reference position read by the reading means, and the correction means automatically corrects the reading start timing of the image reading means. When the image reading means and the image reading means are connected, it is possible to always keep the reading start position of the image reading means constant.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing the configuration of an image reading apparatus according to an embodiment of the present invention. In the figure, A is a holding means for the document leading edge detection position adjustment amount provided in the automatic document feeder, B is a reading device for the document leading edge detection position adjustment amount provided in the image reading device, and C is inside the image reading device. This is a correction means for the amount of adjustment of the document leading edge detection position.

In an image reading device connected to an automatic document feeder (ADF), the reading device B reads out the adjustment amount of the document leading edge detection position held by the holding device A, and the correction device C reads the document leading edge detection position adjustment amount in the image reading device. Correct the position adjustment amount.

In the image reading device configured as described above, when the distance information between the document leading edge detection position unique to the automatic document feeder and the reference position is measured in advance, the holding means A detects the distance information unique to the automatic document feeder. To hold arbitrary distance information between a document leading edge detection position and a reference position with a simple configuration.

[0017] Furthermore, when the automatic document feeder is connected to the image reading device, the reading means B automatically reads distance information between the document leading edge detection position and the reference position, which is unique to the automatic document feeder in which the document feeder is held. make it possible.

Furthermore, the correction means C automatically corrects the reading start timing of the image reading device based on the distance information between the document leading edge detection position of the automatic document feeder and the reference position read by the reading device B, To always keep a reading start position of an image reading device constant when a feeding device and an image reading device are connected. Embodiments of the present invention will be described below with reference to specific device configurations. FIG. 2 is a perspective view showing the external configuration of an image reading device according to the present invention, and FIG.
3 is a sectional view showing the internal configuration of the image reading device shown in FIG. 2. FIG.

In these figures, 1 is an image reading device (reader), 2 is a reader main body, and an original on a platen glass 27 (the image is facing downward) is irradiated with an original illumination unit 24, and a reflective mirror is used. -25, and a lens 26 to form an image on a plurality of light receiving elements (for example, charge coupled devices (CCD)) 22 arranged in the main scanning direction. The original illumination unit 24 and the reflection mirror 25 are movable in the sub-scanning direction perpendicular to the main-scanning direction by a drive system (not shown). Reference numeral 3 denotes an ADF, in which a sheet-like original (image facing upward) on an original placing table 31 is conveyed in the direction of an arrow b shown by a broken line in FIG. Reference numeral 33 denotes a holding means, in which the jumper wire is cut according to the measured adjustment amount as shown in FIG. 7, which will be described later. It is configured to be able to read adjustment amount data.

Further, 21 is a control unit, 23 is a CCD
It's a driver. The image reading process will be described below with reference to the control block diagram shown in FIG. 4 and the timing chart shown in FIG. [Operation of the reader 1] The reader 1 has a "sheet (through) mode" in which the ADF 3 reads images while transporting general paper (sheet) originals without binding in the sub-scanning direction. For example, a book mode is used to read an image by placing a book (a bound document like a book) on the platen glass 27 and moving the document illumination unit 24 and reflective mirror 25 in the sub-scanning direction. It has two modes: In the present invention, the "book mode" is not applicable and will therefore be omitted, and only the "sheet through mode" will be explained.

The reader 1 is always connected to external devices (for example, a digital printer, a personal computer, etc.), and is capable of communicating control signals with these external devices and transmitting image information signals to the external devices. The output is the interface circuit 20
7. With a document placed on the document table 31 of the ADF 3 (with the image facing upward), instructions for various modes are input from an external device. For example, set the image density to 40
For example, whether to use 0 dpi, 300 dpi, or 200 dpi, or whether to make the image signal a binary signal or a multi-value signal. After receiving these instructions, the CPU 208
The timing signal generation circuit 209 and selector 2
06 to set the image density and image signal. Here, when a document reading start command is input from the outside, the CPU 208 outputs a lamp control signal to turn on the lamp of the document illumination unit 24, and the optical system document illumination unit 24 starts reading the document with the ADF 3. It is confirmed whether the original illumination unit 24 is in the position (shown in FIG. 10), and if the original illumination unit 24 is not set at the position, the original illumination unit 24 is moved to a predetermined position. Then, an original document feeding start command is output, and the original placed on the original placing table 31 of the ADF 3 is conveyed in the direction of arrow b toward the path indicated by the broken line shown in FIG.

[0022] In the reader 1, the motors used to transport the ADF 3 and drive the scanning optical system are stepping motors, so the pulse frequency for driving these motors can be changed. By doing so, the speed of conveyance and scanning can be changed freely. Until the document reaches the document illumination position, the image formed on the light receiving element 22 is
As will be described later, it is converted into a digital value and input to the interface circuit 207, but since this is not the original image, the CPU 208 sets the output to the interface circuit 207 as "disabled" so as not to output the image signal. gives the control signal.

Next, when the document reaches the illumination position,
The CPU 208 outputs a control signal indicating that the image signal is "allowed" to the interface circuit 207, and the read image signals are sent one after another to an external device. Then, when the trailing edge of the document has finished passing through the document illumination position, the interface circuit 207 is again instructed to issue a control signal indicating that image signal output is not possible.
The interface circuit 207 stops outputting the image signal. After the paper has been ejected, the CPU 208 outputs a document reading completion signal to the external device, and turns off the lamp of the document illumination unit 24 to complete the series of operations.

The light receiving element 22 on the CCD driver 203 shown in FIG. , are driven through a CCD driver 23. The image analog signal output from the light receiving element 22 is sent to the amplifier 201.
The signal is amplified and input to an analog/digital (A/D) converter 202. This A/D converter 2
In step 02, the image signal is converted from an analog signal to an 8-bit digital signal by the timing φAD generated by the timing signal generation circuit 209, and is output to the control unit 21.

The control unit 21 adjusts the image signal level of the input digital image signal due to the non-uniformity of the light amount of the original illumination unit 24, the non-uniformity of the transmission of the lens 26, and the non-uniformity of the sensitivity of the light receiving element 22. Non-uniformity (called shading) is corrected by a shading correction circuit 211.
Remove it electrically. FIG. 6 is a block diagram of the internal configuration of the shading correction circuit 211 shown in FIG. 4. In the figure, 212 is a storage device for storing one line of reference white signals obtained by reading a white reference plate for shading correction by the light receiving element 22, and 213 is a reference white signal stored in the storage device 212. By the reference signal, C
This is a divider that corrects shading of image information by dividing the original image information sent from the CCD drive circuit 203 of the CD driver 23 for each pixel.

In this manner, the shading-corrected digital signal is converted into the above-mentioned mode, that is, the binary mode.
It can be output to an external device in either mode or multi-value mode. Whether to output in either of these two modes is determined by a command from an external device, and the CPU 208 selects the selector 206.
A control signal will be output to. In the case of the multi-value mode, the 8-bit image signal is inputted as is to the selector 206, selected, inputted to the interface circuit 207, and outputted to an external device. In addition, in the case of binary mode, depending on the slice level output by the CPU 208, the binarization circuit 205 converts the 8-bit image signal into 1 bit.
It is converted into bits and input to the selector 206. There are two types of slice levels; one is a level specified by an external device; in this case, the CPU 208 directly outputs the slice level specified by the external device to the binarization circuit 205; The other one is a slice level based on background density detection. In the background detection performed by the image reading device of this embodiment, the background density detection circuit 204 detects the maximum density value (the brightest value) for each line in the main scanning direction of the original, and the CPU 208 takes this in, and detects the maximum density value (the brightest value) for each line in the document main scanning direction. The binarization circuit 205 uses the averaged result as a slice level.
A method is used to output the data to .

The image signal binarized by the above method is input to the selector 206, which selects it and inputs it to the interface circuit 207. In the case of the binarization mode, the interface circuit 207 compresses 8 pixels at once and outputs it as 8 bits to an external device. [Example of Document Leading Edge and Trailing Edge Detection Processing] FIG. 7 is a circuit block diagram showing an example of a holding circuit for the document leading edge detection position adjustment amount in the image reading device of the present invention. Components that are the same as those in FIG. is attached.

In the figure, JP1 to JP3 are jumper wires on the board, which are cut according to the document leading edge detection position adjustment amount for each machine at the time of factory shipping adjustment. Note that one end of jumper wires JP1 to JP3 is connected to C through a diode.
The voltage is input to input ports 1 to 3 of the PU 208, and a predetermined potential (+5V) is applied to port 4 via a resistor. Therefore, a code signal corresponding to the document leading edge detection position adjustment amount is input to the CPU 208 by the jumper wires JP1 to JP3, which are cut according to the document leading edge detection position adjustment amount.

As for the adjustment procedure, first, read the original in sheet mode, and remove the leading edge registration part of the output image (if there is information before the leading edge of the original, such as margins, + data or missing parts of the image). The amount (-data) R (mm) is measured (that is, the measurement of the document leading edge detection position adjustment amount), and the amount (-data) R (mm) of this image missing portion is taken as the adjustment amount. The cutting combinations of the jumper wires JP1 to JP3 are determined based on the amount (-data) R (mm) of this image missing portion based on a predetermined cutting combination (see FIG. 8). The reader 1, which is the main body, checks input ports 1 to 4 when the ADF 3 is connected or when the power is turned on, reads out the adjustment amount, and sets a counter for the amount of image missing portion (-data) R (mm). Adjust it. The checking procedure is to first check whether input port 4 follows changes in input port 1, and if it does, connect jumper wire JP1 to
Turn on each jumper wire JP1 to JP, and if it does not follow, turn off jumper wire JP1.
Check 3 and decide the amount of adjustment. FIG. 9 is a flowchart showing an example of the document reading processing procedure in the image reading apparatus according to the present invention. Note that (1) to (12) indicate each step.

First, when a reading start instruction is input from an external device (1), the CPU 208 conveys the document until the document leading edge detection sensor 37 is turned on (2). Next, when the document leading edge detection sensor 37 is turned ON, a counter (timer counter or motor pulse number counter) of (b + R) (mm), which has been set in advance with consideration to the amount of adjustment, is loaded. Then (3), continue to transport the document and decrement the counter until the counter reaches "0" (4), (5), and when the counter reaches "0", the leading edge of the document reaches the reading position. It is determined that the data has been read, and reading is started (6). Then, when it is confirmed that the document leading edge detection sensor 37 is OFF (7), the counter is set to "0" again.
Continue decrementing the counter until it reaches ``(8)
, (9) When the counter reaches "0", it is determined that the trailing edge of the document has passed the reading position (10), the reading is finished (11), and the document is ejected (12). , ends the document reading process.

[0031] In the above embodiment, a case has been described in which the increments of the adjustment amount are constant, but the increments of the adjustment amount do not have to be constant, and other numerical values are of course possible. Further, in the above embodiment, a case has been described in which the adjustment amount is instructed by a combination of input ports 1 to 4 of the CPU 208, but other methods may be used. Further, in the above embodiment, as a method for holding the document leading edge detection position adjustment amount, a case has been described in which the amount is held by cutting a jumper wire, but it may be configured using other storage circuits.

[0032]

As explained above, the present invention is provided with a holding means for holding the distance information between the document leading edge detection position and the reference position, which is unique to the automatic document feeder and is measured in advance. The mechanism for adjusting the document leading edge detection position and the reference position, which is unique to the device, can be greatly simplified.

Furthermore, since a reading means is provided for reading distance information between the document leading edge detection position of the automatic document feeder held by the holding means and the reference position, the document leading edge detection position and the reference position specific to the automatic document feeder are provided. The image reading device itself can automatically recognize the position adjustment information.

Furthermore, since a correction means is provided for correcting the reading start timing of the image reading means based on the distance information between the document leading edge detection position of the automatic document feeder and the reference position read by the reading means, each document is automatically Document reading can be started at any timing depending on the amount of adjustment between the document leading edge detection position and the reference position specific to the feeding device.

Therefore, the conventional adjustment amount adjustment work is simplified, and the cost of the adjustment mechanism can be reduced.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of an image reading device according to an embodiment of the present invention.

FIG. 2 is a perspective view showing the external configuration of an image reading device according to the present invention.

FIG. 3 is a sectional view showing the internal configuration of the image reading device shown in FIG. 2;

FIG. 4 is a circuit block diagram showing a control configuration of an image reading device according to an embodiment of the present invention.

FIG. 5 is a timing chart explaining the operation of the circuit shown in FIG. 4;

FIG. 6 is a block diagram of the internal configuration of the shading correction circuit shown in FIG. 4;

FIG. 7 is a circuit block diagram showing an example of a document leading edge detection position adjustment amount holding circuit in the image reading apparatus of the present invention.

FIG. 8 is a diagram showing a combination relationship between the document leading edge detection position adjustment amount and jumper wire cutting.

FIG. 9 is a flowchart showing an example of a document reading process procedure in the image reading apparatus according to the present invention.

FIG. 10 is a sectional view of a main part showing a document feeding path in a conventional automatic document feeder.

[Explanation of symbols]

A Holding means B Reading means C Correction means 1 Image reading device 2　Reader body 3 ADF

Claims (3)

[Claims] Claim 1: An image reading device equipped with an image reading means capable of reading a document image fed from an automatic document feeder, wherein a document leading edge detection position and a reference position unique to the automatic document feeder are measured in advance. An image reading device characterized in that a holding means for holding distance information is provided in the automatic document feeder. 2. The image reading apparatus according to claim 1, further comprising reading means for reading distance information between a reference position and a document leading edge detection position of the automatic document feeder held by the holding means. 3. A claim characterized by comprising a correction means for correcting the reading start timing of the image reading means based on the distance information between the document leading edge detection position of the automatic document feeder and the reference position read by the reading means. Item 1. Image reading device according to item 1.