JPH066525A - Picture reader - Google Patents

Abstract

PURPOSE:To reduce time required for reading and to improve the throughput of reading an original by stopping thinning processing in the subscanning direction when an occupied area of an original is shorter than a read request area, allowing the reader to read a reference face by a prescribed quantity as it is and terminating the picture reading. CONSTITUTION:A read optical system of the main body is moved to a read position for an ADF 50. An original is fed by a motor 13 of the ADF 50. Since the original reaches a read position P by L lines after paper feed sensor 15 senses the tip of the original, the original reading is started at that point of time. Since the read density is set to be 1/3, only one line among three lines is read and data by two lines are thinned. When the paper feed sensor 15 senses a tail end of the original, the reading of the original is continued while implementing 1/3 thinning similarly to the case with that so far for succeeding L lines. Since the tail end of the original passes through the read position P after the read by L lines, a white level of a platen roller 17 is read thereafter. In this case, the thinning is stopped, data for each line are validated and the picture is read.

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 for reading and scanning an original by moving it.

[0002]

2. Description of the Related Art As a conventionally known image reading apparatus, for example, an optical system and a sensor array are arranged over one line of an original to be read, and when the original is read, the optical system is fixed and the original is read. There is a method in which an image is read line by line while moving in the scanning direction. In such an image reading apparatus, the conversion of the reading density in the sub-scanning direction is performed by thinning the read image on a line-by-line basis.

Further, when the length of the original is shorter than the reading range required by an external device such as a personal computer or a workstation, the white reference plane in the paper path is read. Even when the white data outside the original range is read, the reading density is converted by the thinning process.

[0004]

As described above, conventionally, the thinning control is performed even during the reading of the white data outside the range of the original document, so that it has the following drawbacks.

That is, for example, when an image is read at half the normal density, data for one storage time is skipped and data is not transmitted until the next storage is performed, so that image is displayed in the original range. Even if the white data is outside, reading cannot be completed regardless of the length of the original document until a predetermined time elapses.

Therefore, there has been a drawback that the reading throughput is lowered.

Therefore, in view of the above points, an object of the present invention is to provide an image reading apparatus which shortens the reading time when reading an image other than a document (for example, an unnecessary white image) and improves the overall throughput. To do.

[0008]

In order to achieve such an object, the present invention is an image reading apparatus for reading a document image line by line by photoelectric conversion while moving the document in a predetermined direction. If there is a thinning means for performing reading for each specific line and a reading area beyond the trailing edge of the document, the operation of the thinning means is stopped after the trailing edge and the image reading processing is performed after reading a predetermined amount. And a control means for stopping.

[0009]

According to the above configuration of the present invention, when the reading area exists beyond the trailing edge of the original, the reading area after the trailing edge of the original is read in each line regardless of the density in the sub-scanning direction. Each time the unnecessary white image or the like is read by a predetermined amount and the image reading is completed, the reading time of the unnecessary image data is shortened.

[0010]

EXAMPLES Examples of the present invention will be described in detail below.

Embodiment 1 FIG. 2 is an electrical block diagram of an image reading apparatus according to an embodiment of the present invention. In the figure, reference numeral 1 denotes a line image sensor such as a CCD, which converts the luminance information for one line of the original image formed by a reading optical system (not shown) into an electric signal for each pixel. 2 is a sensor drive circuit for generating a signal for driving the image sensor 1, 3
Is an amplifier for amplifying the output electric signal of the image sensor 1,
Reference numeral 4 is an A / D conversion circuit for converting the amplified amplifier output analog signal into a digital signal, and 5 is an image processing circuit for performing gamma conversion correction, binarization processing, enlargement / reduction processing, etc. on the pixel information after digital conversion. , 6 are timing signal circuits for generating various synchronizing signals in the apparatus.

Reference numeral 7 is an internal ROM (read only memory)
The CPU controls the image reading apparatus according to the control procedure stored in 7a. Reference numeral 8 is an interface circuit for performing command communication and image data communication with external information equipment such as a personal computer and a printer. A motor drive circuit 9 generates a signal for driving the step motor 10. Reference numeral 10 denotes a reading optical system included in the main body (see FIG.
(See) is a step motor for moving.

Reference numeral 12 is a drive circuit for driving a step motor 13 of an automatic document feeder (hereinafter referred to as ADF). A step motor 13 conveys an ADF document. Reference numeral 14 is a sensor for detecting the presence or absence of a document on the ADF paper feed tray. Reference numeral 15 denotes a document feed sensor that detects the leading edge and trailing edge of the document, and the leading edge or trailing edge of the document is moved to the reading position P (see FIG. 3) by feeding L lines after the detection output of this sensor. Reach Reference numeral 16 is a paper discharge sensor for detecting the state of paper discharge after reading.

FIG. 3 is a diagram showing a cross-sectional structure of the image reading apparatus according to this embodiment. Reference numeral 50 in the figure is an ADF (automatic document feeder). The document 26 on the paper feed tray 27 of the ADF 50 is sent to the reading position P by the paper feed roller 24 and the platen roller 17. The platen roller 17 is
It also serves as a white reference plate, and when the original is not on P, the white color on this surface is read.

The original image at the reading position P is illuminated by the light source 22 and the reflection type 24, passes through the first mirror unit 22 and the second mirror unit 21 including these, and is imaged on the image sensor 1 by the imaging lens 20. It Further, the original after reading is discharged by a discharge roller 25 to a discharge tray 28.
The paper is ejected to the top.

Next, the operation of the present embodiment will be described with reference to the diagram showing the operation timing shown in FIG.

The external device sets a reading area having a length of 24 units and requests reading at a density of 1/3. When the length of the original is 18 units, the white reference plate on the platen roller 17 is read in the area of 6 units in the latter half of the reading area.

Reading proceeds in the following order. First, the reading optical system of the main body moves to the reading position by the ADF 50 (see FIG. 3). After this, the ADF50 motor 1
The document is fed by the method 3. After the paper feed sensor 15 detects the leading edge, the document reaches the reading position P on the L line.
At that time, the document reading is started. In the present embodiment, the read density is set to 1/3, so only one of the three lines is read and the data for two lines is thinned out.

When the paper feed sensor 15 detects the trailing edge of the original during reading, the reading of the original is continued while the L line is thinned out by one-third in the same manner as before. After reading the L lines, the trailing edge of the document passes through the reading position P, and hence the white color of the platen roller 17 is read thereafter. However, in that case, since the image is always white, the thinning is stopped and the data of each line is validated to read the image. In other words, for the remaining 6 units of reading area, 2 is obtained subsequently.
The white data for the line is used as the image data for 6 units.

Therefore, as compared with the case where the thinning-out is performed to the end (the operation timing of the conventional example is shown in FIG. 5), the actual reading line in the white image portion becomes 1/3, and the reading is completed faster by the time ΔT. . After that, the operation shifts to the paper discharge operation, and the document is discharged onto the paper discharge tray 28 by the paper discharge roller 25.

Embodiment 2 FIG. 4 is a block diagram showing a schematic circuit configuration of an image reading apparatus according to another embodiment. In the figure, reference numeral 11 is an image buffer memory for temporarily storing image data and transmitting it via the interface circuit 8 in response to a request from an external device. The other configuration contents are the same as those in the first embodiment.

In this embodiment, all the image data are stored in the temporary buffer memory 11 and then transmitted. Therefore, when the white image area to be read is long, the buffer memory 11 is filled with the white data. Therefore, it is possible to replace the reading and sending of the white data only by reading from the buffer memory 11 without newly reading the white image. it can.

[0023]

As described above, according to the present invention, when the original occupying area is shorter than the reading request area, the thinning process in the sub-scanning direction is stopped and the reference surface is read by a predetermined amount as it is. By ending the image reading, the time required for image capturing can be shortened, and the throughput of document reading can be improved.

[Brief description of drawings]

FIG. 1 is a diagram showing an operation timing of an embodiment of the present invention.

FIG. 2 is a diagram showing a schematic circuit configuration of an embodiment of the present invention.

FIG. 3 is a diagram showing a cross-sectional configuration of an example of the present invention.

FIG. 4 is a diagram showing a schematic circuit configuration of another embodiment of the present invention.

FIG. 5 is a diagram showing operation timing of a conventional example.

[Explanation of symbols]

 1 Image Sensor 5 Image Processing Circuit 7 CPU 13 ADF Step Motor 15 ADF Paper Feed Sensor 17 Platen Roller 24 Paper Feed Roller 50 Automatic Document Feeder (ADF) 51 Image Reader Main Unit

Claims (1)

[Claims] 1. An image reading apparatus for reading an original image by photoelectric conversion line by line while moving an original in a predetermined direction, thinning means for performing image reading in an original feeding direction for each specific line, and a trailing end of the original. When there is a reading area beyond the range, the operation of the thinning means is stopped for the rear end and thereafter,
An image reading apparatus comprising: a control unit that stops the image reading process after reading a predetermined amount.