JPH01296765A - Image reading device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to, for example, an image reading unit of a facsimile machine or an input device of a computer, or an image reading device existing alone.

(Prior Art) A conventional image reading section of this type includes one shown in FIG. 3, for example. That is, reference numeral 2 denotes a contact type linear image sensor disposed in the reading section, which sequentially reads the original images passing through the reading optical axis 20 of the image sensor 2 while the original 5 is transported by the transport roller 1. On the other hand, a document edge sensor 6 for detecting the edge of the document 5 is arranged on the upstream side in the document conveyance direction with respect to the reading optical axis 20 of the image sensor 2 .

The document edge sensor 6 detects the leading edge of the document inserted into the reading section, and the timing for starting reading the document 5 is determined to read valid image information.

(Problem to be Solved by the Invention) However, in the case of the above-mentioned conventional technology, if the speed at which the original 5 is inserted into the reading section is relatively stable, the reading start timing of the original 5 must be accurately adjusted to the leading edge of the original. However, if the feed speed is not stable, the leading edge of the document cannot be detected accurately.

That is, if there is a document separating device or the like on the upstream side of the reading section, the feeding speed of the document 5 is stable, and the document 5 passes through the distance fil fL 3 between the document edge sensor 6 and the reading optical axis 20. Since the time can be predicted accurately, reading can be started from the time when the tip of the original 1t45 reaches the reading optical axis 20.

However, in cases where a person inserts the document into the reading unit, the leading edge of the JfX document 5 passes through the distance intersection 3 after the leading edge of the document is detected by the document edge sensor 6, and the leading edge of the JfX document 5 is aligned with the reading optical axis 20. It is not possible to accurately predict the time it will take. Therefore, if an image is read based on the point in time when the leading edge of the document is detected, there will be excess or deficiency in the read image information, and missing read information is a hotly debated issue, but invalid information is placed before and after the original valid information. This is also a problem in the case of facsimiles, as it lengthens the transmission time and increases communication costs.

The present invention has been made in order to solve the problems of the prior art described above, and has the following objectives: 1) With a simple configuration, even if the feeding speed of the document to the reading section is unstable, the document can be accurately moved from the leading edge of the document. An object of the present invention is to provide an image reading device capable of reading image information.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides an image reading device that sequentially reads original images passing through a reading optical axis of a reading sensor while conveying the original in a reading section. In the reading unit, sensors for detecting the edge of the document are provided on the upstream side and the downstream side in the document conveyance direction with respect to the reading optical axis of the reading unit, and the sensor detects the edge of the document between the time when the upstream sensor detects the edge of the document and the downstream sensor detects the edge of the document. A memory for temporarily storing a read image of the document is provided, and a reading control means is provided for outputting image information of the leading edge of the document based on a document leading edge detection signal from a downstream sensor among the image information stored in the memory. It is characterized by becoming.

(Function) Image information of the original starts at the same time as the sensor on the upstream side of the reading optical axis detects the leading edge, but this is stored in the memory at - time and is not output to the outside. At the moment when the leading edge of the document passes over the reading optical axis and is detected by a sensor installed downstream of the reading optical axis, the reading control means selects the leading edge of the document from among the image information stored in the memory. , is calculated from the distance between the reading optical axis and the sensor, the interval between seat scans, etc., and the information input into the memory before this point is ignored as it is not an image of the document but invalid information,
The information after that is output to the outside as valid image information.

(Example) The present invention will be described below based on illustrated examples. FIG. 1, which shows an image reading device according to an embodiment of the present invention, shows the entire reading section, and is provided with a contact type linear image sensor 2 similar to the conventional example. The image sensor 2 includes a sensor main body 2a made of a photoelectric conversion element such as a CCD, an illumination light source 2c that illuminates the surface of the document, and an image sensor main body 2a.
The lens array 2d which forms an image on the lens a is integrated into a unit, and is mounted and supported by a main body frame 3 of the main body of the apparatus via a spring 4. The image sensor 2 reads and scans the original image in a line at a magnification of 1:1 in a direction (main scanning direction) perpendicular to the conveying direction.

On the other hand, on the reading section 2d of the image sensor 2, a roller l is arranged as a background member. Such a sensor 2
When using a , the depth of focus is shallow and the depth of focus is shallow so that the image can be read with high resolution and high quality, so a roller l like the one shown in the figure is used as a background member to make it easier for the document to pass through and stabilize the depth of focus as a means of constant speed transport. gaining sex.

The rotation axis of this roller l is arranged on the reading axis 20 of the image sensor 2, that is, on the optical axis of the lens array 2b. The image sensor 2 is pressed against the roller 1 by the spring 4.

On the other hand, an upstream sensor 6 and a downstream sensor 7 are provided on the upstream and downstream sides of the reading optical axis 20 in the document transport direction, respectively, for detecting the edge of the document.

A memory 91 is provided to temporarily store the read image from when the leading edge of the document passes the upstream sensor 6 until it passes the downstream sensor 7. Image information stored in this memory 91 is provided. Among them, a reading control device 9 is provided as a reading control means that outputs image information of the leading edge of the document based on a detection signal from the downstream sensor 7.

The memory 91 includes the reading optical axis 20 and the downstream sensor (
It has a capacity sufficient to store image information of the number of main scanning lines obtained by dividing the distance statement 2 between the detection point 70 of the downstream sensor (hereinafter referred to as a downstream sensor) by the sub-scanning interval. When the original 5 is inserted into the device from the left side in the figure and passes the detection point 60 of the sensor (hereinafter referred to as F upstream sensor) 6 located on the upstream side of the reading optical axis 20, the reading control device 9 detects the morph 8. The background roller 1 is driven to rotate counterclockwise in the figure via a power transmission system (not shown). However, the timing of starting driving of the roller l may be controlled by a signal from the external terminal 92.

When the document 5 reaches the rotating background roller l, it is caught between the roller 1 and the reading surface 2d of the contact type linear image sensor 2. The contact type linear image sensor 2 is
When the upstream sensor 6 detects the leading edge of the document 5, the illumination light source 2c is turned on, and the reading optical axis 20 of the reading surface 2d is placed on the sensor body 2a where the photoelectric conversion elements are arranged in a row via the lens array 2b. Image information is projected, converted into an electrical signal, and sent to the reading control device 9.

In the reading control device 9, the received image information is sequentially organized for each main scanning line and stored in the -H memory 91. The leading edge of the document 5 rolled up by the background roller 1 is the reading optical axis 20
After passing above, the original 5 is transported at a stable speed by the driving force of the background roller l.

When the document 5 further advances downstream and the leading edge of the document 5 passes the detection point 70 of the downstream sensor 7, the reading control device 9 determines the distance between the reading optical axis 20 and the detection point 70 of the downstream sensor 7. The number of main scanning lines of the image information in the memory is incremented in the past by the number obtained by dividing the sentence 2 by the sub-scanning interval, and the image information memory 91 is stored when the leading edge of the document 5 approaches the reading optical axis 20. Find the top position.

The operation on this memory will be explained using FIG. 2. There is an area on the memory 91 that stores image information of n main scanning lines, which is more than 1, and is divided into 1, 2, 3, . . . . address numbers are given as n-1, n.

When image information is sent from the contact linear image sensor 2 to the reading control device 9, the control device 9 sequentially stores the image information in the memory 91 starting from address number 1, with one main scanning line as the middle. When address number n is used, the address returns to address number 1, and the information already stored in address number 1 is invalidated and new image information is stored. Similarly, address numbers 2, 3. . . . The same operation is repeated every time new image information is input to the reading control device 9.

Now, if a signal indicating that the leading edge of the document 5 has been detected from the downstream sensor 7 is inputted to the reading control device 9 while the image information of the address number m is being stored, the control device 9 will store the image information of the address number m. Subtract i copies from m (
The address number m-i+1) is determined to be the address of the main scanning line containing image information at the moment when the leading edge of the document 5 passes over the reading optical axis 2o.

Then, the image information before this is ignored as invalid information that read the background roller l instead of the original 5, and (
The image information after m-i+1) is sequentially sent to other devices via the external terminal 92 as valid information of the document 5.

When the trailing edge of the document 5 is detected by the upstream sensor 6,
The reading control device 9 receives image information corresponding to the number of main scanning lines from the contact type linear image sensor 2. Subsequent image information is ignored as it is assumed that the rear end of the document 5 passes through the reading optical axis 20. Then, the contact type linear image sensor 2 is commanded to stop reading. The driving of the background roller is stopped by an external signal or in synchronization with the above-mentioned reading stop command. Therefore, the smaller statement 1 and statement 2 are, the less memory capacity is required. Further, in a system in which a plurality of documents are sequentially inserted into the reading device 9, a document conveying member for ejection is required downstream of the reading device 9.

However, before the leading edge of the next document touches the upstream sensor 6, this document conveying member transfers the trailing edge of the previous document to the downstream sensor 6.
This is for transporting the paper to the downstream side of the detection point 70, and since the transport speed and the like need only satisfy the above conditions, a very rough configuration is sufficient.

(Effects of the Invention) The present invention has the above-described configuration and operation, and includes sensors for detecting the edge of a document provided on the upstream side and the downstream side in the document conveyance direction with respect to the reading optical axis in the reading section. After the document has passed, the information on the upstream side from the leading edge of the document is cut based on the detection signal of the downstream sensor, so if the document is inserted into the reading section at a speed that cannot be predicted by manual feeding, etc. However, it is possible to accurately determine the leading edge of the document.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of an image reading device according to an embodiment of the present invention, FIG. 2 is an explanatory diagram of addresses of the memory in FIG. 1, and FIG. 3 is a schematic configuration diagram of a conventional image reading device. . Explanation of symbols l...Roller 2...Image sensor 20
...Reading optical axis 3...Body frame '4...
Spring 5... Original 6... Upstream sensor
7...Downstream sensor 60.70...To detection 8.
...Motor 9...Reading control bag 2t 91...Memory 92...Terminal number 1 Figure 2 Section 3

Claims (1)

[Scope of Claims] In an image reading device that sequentially reads original images that pass through a reading optical axis of a reading sensor while conveying the original in a reading section, the image reading apparatus includes: In addition to providing a sensor for detecting the edge of each document, a memory is provided to temporarily store the scanned image between the time when the upstream sensor detects the document edge and the downstream sensor detects the document edge, and the image information stored in the memory is provided. An image reading device comprising a reading control means for outputting image information of a leading edge of a document based on a leading edge detection signal of a downstream sensor.