JPH0199187A - Optical character reader - Google Patents

Abstract

PURPOSE:To eliminate the influence of dusts and stains and to improve the reliability by providing a mechanism to hold a white plate and to move the plate in rotation from the first position in which a white level is fetched in front the plate stationary in the read line position of an image sensor to the second position in which a read is possible from a medium. CONSTITUTION:With a solenoid in an attracting state, the white reference plate 3 for shading correction is so positioned that its flat surface part comes parallel with a read surface 5 and that the read line of the sensor 7 is covered by the entire flat surface part of the white plate; in this state, the sensor 7 fetches the white level. After fetching of white level, the attraction by the solenoid is released, the flat surface part of the white plate is lifted by the force of a spring to a position so that the plate does not hinder the direct beam or reflecting beam of light from a light source 6, and held therein. Also, the white reference plate 3 has end-wound parts at its both ends, and is pierced by a shaft, and held on the both side surfaces of the block of a sensor unit rotatably via a bearing. As a result, the plate 3 can be mounted in the sensor unit 1 is sealed enclosure, therefore, the sensor unit 1 provided with shading correction mechanism can be improved of its reliability.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an optical character reading device, and particularly to a structure of a shading mechanism suitable for manufacturing a compact and highly reliable contact sensor unit. be.

[Conventional technology]

The conventional optical character reading device is disclosed in Japanese Patent Application Laid-Open No. 61-253588.
As described in the above publication, a device is known in which a light source, a lens array, and a contact sensor are sealed and mounted in a housing so that they are not affected by scattered dust from the surroundings.

This contact sensor unit improves reliability to some extent, but in optical character reading devices, the reading accuracy changes due to changes in the light source and the like over time.

It is necessary to perform shading correction. In this case, either correct the shading using a white reference provided at the leading edge of the reading medium outside the contact sensor unit, or place a white reference plate at the reading position before setting the slip, capture the white level, and perform shading. Corrections will be made.

[Problem that the invention seeks to solve]

In the above conventional technology, since the white reference (white reference plate) for shading correction is located outside the sensor unit, there is a problem that the white reference fluctuates due to the influence of surrounding dust, etc., reducing reliability. . Furthermore, no consideration has been given to miniaturizing the sensor unit and creating a sealed structure to prevent staining of the white reference plate, resulting in the problem that the reading quality of the sensor cannot be maintained.

The purpose of the present invention is to solve these conventional problems and provide a highly reliable optical character reading device that is small and unaffected by various factors that adversely affect the quality of shading capture, such as dust and dirt. Our goal is to provide the following.

[Means for solving problems]

In order to solve the above-mentioned problems, the optical character reading device of the present invention has a reading sensor unit having a structure in which an image sensor, a lens, a light source, etc. are sealed. a first position in which a white plate serving as a reference for capturing the level is housed in the reading sensor unit, and the white plate is stopped at a reading line position of the image sensor to capture the white level; The feature is that a mechanism is provided for rotationally moving and holding the image to a second position where it can be read.

That is, the above-mentioned white plate (hereinafter referred to as a white reference plate for shading) has a bent portion at both ends, a round hole for the shaft to pass through the bent portion, and a white plate portion serving as a reference in the flat portion. A shaft for rotating the driving force of the solenoid via a transmission link is passed through the round hole. The mechanism that rotates and holds the white reference plate includes a drive source such as a solenoid that rotationally drives the white reference plate, a drive transmission link that transmits the driving force from the drive source, and a spring attached to one end of the link. configured.

[Effect]

In the present invention, the white reference plate for shading is such that, when the solenoid is in a suction state, the white plate flat part is located parallel to the reading surface, and the reading line of the sensor is covered by the entire white plate flat part. , the sensor captures the white level.

After capturing the white level, the suction of the solenoid is released, and the flat surface of the white plate is lifted and held by the force of the spring in a position where it does not interfere with the direct light from the light source and the reflected light.

As a result, the medium to be read can be transported in a predetermined manner, and normal reading can be performed without blocking the light from the light source.

Further, the white reference plate has bent portions at both ends, allows the shaft to pass through the white reference plate, and is rotatably held on both side surfaces of the block of the sensor unit via bearings. Therefore, the flat surface of the white plate is almost hermetically sealed (
The area other than this part is usually covered with glass or the like so that there is no risk of scratches, so that it can be protected against dust from the outside and can also avoid adhesion of dirt to the white reference.

〔Example〕

An embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a partial cross-sectional structural diagram of an optical reading device showing one embodiment of the present invention. This shows a side view of the mechanism including the conveyance path near the reading sensor unit.

In FIG. 1, 1 is a reading sensor unit with a sealed structure;
2 is a conveyance path for conveying the reading medium (for example, slip 4); 3
4 is a white reference plate for shading correction; 4 is a slip to be read; 5 is a reading position read by an image sensor 7; 6 is a fluorescent lamp serving as a light source; 7 is an image sensor for reading the white level of the white reference plate 3 and the slip; 8 is a lens through which the reflected light passes; 11 is a rotating shaft for rotating the white reference plate 3; and 12 is a reflecting plate for reflecting the light from the fluorescent lamp 6.

In a normal state, the shading correction white reference plate 3 housed in the reading sensor unit 1 is.

The reading sensor unit 1 detects the upper end of the slip 4 to be read, and the light source of the fluorescent lamp 6 is not obstructed at all by the reading position 5 of the slip 4 being conveyed, as shown by the broken line in FIG. When extracting the image information of the characters to be recognized, the video signal (shading waveform) is
The white level reference of the image sensor 7, the fluorescent lamp 6, and the like are captured in advance so that when the top edge of the slip 4 reaches the reading position, it can be optically detected. In order to correct shading distortion caused by the lens 8 and the like, shading is captured.

FIG. 2 is a perspective view of the white reference plate 3 for shading correction in FIG. 1. As is clear from this figure, the single-mounted reference plate 3 has bent portions at both ends.

The bent part has a round hole for the shaft to pass through,
It has a white plate part as a reference on the plane part, and a rotating shaft 11 for rotating the driving force of the solenoid via a transmission link is passed through a round hole.

This rotating shaft 11 has a rotating shaft D-cut portion 11' at one end.

FIG. 3 is a diagram showing a drive system such as a solenoid for rotating the white reference plate 3 for shading correction in FIG. 1. Here, reference numeral 9 denotes a solenoid, 10a, 10b, which serves as a driving source for the white reference plate 3.

10c is a link for driving the solenoid 9; 12 is a predetermined position (first
The spring 13.13' that lifts up the white reference plate 3 (see the broken line in the figure) is a stopper.

The stopper 13 functions to hold the white reference plate 3 at a reading position, and the stopper 13' functions to hold it at a predetermined position where the medium can be read.

FIG. 4 is a processing flowchart of shading capture in this embodiment. The operation of this embodiment will be explained below according to the flowchart of FIG.

First, shading capture is performed when the fluorescent lamp 6 is turned on by powering on the device (301). When the fluorescent lamp 6 lights up (302), the solenoid 9 is activated (
303), links 10a to 10 connected to solenoid 9
c is pulled in the direction of arrow A, the rotating shaft 11 fixing the white reference plate 3 rotates in the direction of arrow B, and the white reference 3 moves to the solid line position (see FIG. 3). At this time, the white reference plate 3 is positioned at the reading position 5 of the image sensor 7. In this state, the video signal (shading waveform) is captured (304), the peak value of the white level is memorized, and the image information of slip 4 is binarized into white and black using this special shading waveform as a reference. I do.

As a result, the image sensor 7, lens 8. It is possible to recognize the distortion of the shading waveform of the sensor unit 1 caused by the quality characteristics of optical system parts such as the fluorescent lamp 6, and judge the black and white level of the slip 4 accordingly, thereby reducing the variation in the characteristics of the optical system parts. Reading can be performed without being affected.

After the acquisition is completed, the solenoid 9 is set to 0FFL, and the white reference plate 3 is returned to the position indicated by the broken line in FIG. 1 (305). As a result of the above, the slip can be set (306). When the slip is set (
307), and enters a read operation (308).

〔Effect of the invention〕

As explained above, according to the present invention, since the white reference plate for shading correction can be hermetically mounted inside the sensor unit, not only the white reference plate itself but also the dust on each component inside the sensor unit can be removed. Since it is also possible to guard against shading, it is possible to realize a sensor unit with an extremely reliable shading correction mechanism. Further, since the mechanical parts for taking in the white level are composed of solenoids, links, springs, etc., a simple structure and a compact design can be realized.

[Brief explanation of the drawing]

FIG. 1 is a partial cross-sectional structural diagram of an optical reading device showing an embodiment of the present invention, FIG. 2 is a perspective view of a white reference plate for shading correction in FIG. 1, and FIG. 3 is a shading correction in FIG. 1. FIG. 4, which is a cross-sectional structural diagram of the drive system of the white reference plate, is a shading waveform acquisition flowchart in an embodiment of the present invention. 1: Reading sensor unit, 2: Conveyance path, 3: White reference, 4
: Slip, 5: Reading position, 6: Fluorescent lamp, 7: Image sensor, 8: Lens, 9: Solenoid, 10a to 10c: Link, 11: Rotating shaft, 11': Rotating shaft D
Cut part, 12: Reflector, 13.13': Solenoid link stopper. Patent applicant: Hitachi, Ltd. Figure 1 Figure 2 Figure 3 Figure 3

Claims (1)

[Claims] 1. In an optical character reading device having a reading sensor unit with a sealed structure including an image sensor, a lens, a light source, etc., a white plate serving as a reference for capturing a white level according to the light intensity of the light source is attached to the reading sensor unit. At the same time, the white plate is rotated between a first position where the white level is captured by keeping it stationary at the reading line position of the image sensor, and a second position where the medium can be read. An optical character reading device characterized by being provided with a holding mechanism.