JPS6217883Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a reading device capable of correcting distortion of the read output that occurs due to the movement of the medium when optically reading and serial output is obtained while moving the medium.

The relationship between this type of optical reading device and the medium is explained with reference to FIG. is received by the light receiving element PH via an optical system (not shown). When the medium MD is moved at a predetermined speed in the direction of arrow AR-A and the line sensor LNS is placed perpendicular to that direction, the switches SW of each light receiving element are sequentially closed by a signal from a read clock source (not shown). Therefore, serial output can be obtained from pin OUT. The arrow AR-B drawn on the medium MD indicates the reading locus of the line sensor LNS on the medium MD, and in this case, an example is shown in which the line sensor LNS is scanned five times during medium movement. If we consider that the line sensor LNS has been moved in the direction of arrow AR-B, it will be enlarged as shown in Fig. 2. That is, the light receiving element PH1 that receives light at the start of reading and the light receiving element PHn that receives light at the end of one reading cycle are shifted by an angle θ. Therefore, the image of the medium read by the line sensor LNS is subject to distortion. The Japanese Standard (JIS) stipulates the value of this θ to be a maximum of 3 degrees, but due to a combination of factors such as skew development of the media during media transport and misalignment when printing characters etc. on the media, As a result, there is a risk that characters and the like may not be recognized correctly. It has also been proposed to tilt the medium by the above angle in advance and then move it in the direction of arrow AR-A and read it to make the above θ zero, thereby widening the margin for medium skew and misalignment during printing. However, because the size and mass of the medium are unstable, the structure of the device that moves it while maintaining a constant tilt angle has become complex and large-scale.

SUMMARY OF THE INVENTION An object of the present invention is to provide a reading device that can correct the distortion of the read output with a simple configuration and improve the above-mentioned drawbacks.

Examples of the present invention will be described below.

The angle θ in FIG. 2 is given by θ=tan ⁻¹ /L. Here, L is a plurality of light receiving elements
The length of both ends of PH (i.e. line sensor LNS),
is a value obtained by multiplying the time required to scan all the light receiving elements once by the moving speed of the medium. Therefore, in the embodiment of the present invention, the side of the light receiving element PHn in the line sensor LNS may be shifted in the direction of the medium movement direction AR-A with respect to the light receiving element PH1, as shown in FIG. . line sensor
An example of a specific method for mounting the LNS by shifting it is shown in FIG. 4. In Figure 4, GB is a gauge block, and RL is a guide line that sets the deviation position of the line sensor.
A line is drawn by etching the surface so that it is deviated by θ from a line drawn perpendicular to GD and reflects strongly and diffusely the light emitted from the light source. When reading this gauge block GB as a medium, it can be seen that the set position of the line sensor LNS is accurate when all of the light receiving elements can strongly receive reflected light. If the amount of received light is initially weak and later becomes strong, or vice versa, it can be seen that the setting of the deviation position is not accurate and that correction is necessary.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the relationship between an optical reading device and a medium, Fig. 2 is an explanatory diagram of a light receiving element when considering a fixed medium, Fig. 3 is an embodiment of the present invention, and Fig. 4 3 is an explanatory diagram of a method for checking the mounting position shown in FIG. 3. FIG. PH1, PH2...PHn...Photodetector, LNS...
Line sensor, SW...Switch, GB...Gauge block, GD...Guide, RL...Setting reference line.

Claims (1)

[Claims for Utility Model Registration] Serial output is obtained by sequentially scanning each element with a reading clock while moving the medium relatively to a line sensor in which a plurality of light-receiving elements are arranged in contact with each other in a direction crossing the direction of movement of the medium. An optical reading device using a line sensor, characterized in that the line sensor is mounted with a deviation in the medium movement direction by an angle θ given by the following formula with respect to a line perpendicular to the medium movement direction. Device. θ=tan ^-1 /L Here, L is the length of the line sensor on the medium, which is the value obtained by multiplying the time it takes to scan all the light receiving elements once and the moving speed of the medium.