JPS5942355B2 - optical reader - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical reading device for reading, for example, postal codes.

This type of device, for example, an optical character reading device that reads characters by scanning them on a form on which characters are written, uses a self-scanning image sensor made of an array of multiple solid-state image sensors. .

However, this type of imaging device has the following problems. In other words, for example, if an image is formed optically so that 1 bit of the image sensor of an imager corresponds to 1 bit of the minimum resolution of a character, one scanning period for imaging the character is fixed, and the character entry area is is specified by a form, and as the character entry area increases in the scanning direction of the imager, an imager with a large number of bits (number of image sensors) is required. If an imager with a large number of bits is used, the frequency of the pulses used to scan and drive it will inevitably become higher. Generally, the scanning frequency of an imager uses each image sensor in a charge accumulation mode, so as the scanning frequency increases, the accumulation time decreases. Further, since the lower limit of the output signal level of each image sensor is determined by noise, the higher the scanning frequency is, the larger the lower limit of the amount of incident light is. That is, when it is desired to scan an imager at high speed, a strong amount of light is required, which increases lighting power consumption and requires a large lighting device. Furthermore, when an imager scans at high speed, the frequency bandwidth of the signal amplification circuit and signal processing circuit that amplify each output signal of the imager increases, and the IC circuits, transistors, and other components used also inevitably operate at high frequencies. This has resulted in the inconvenience of having to use an expensive and adaptable device, and also being unable to increase the conveyance speed of the form. This invention was made in view of the above points, and is intended to reduce the size and power consumption of the illumination device in a reading device that reads characters etc. by irradiating light, and also to reduce the size and power consumption of the illumination device. An object of the present invention is to provide an optical reading device that can also simplify the process. An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a recording medium, such as a form, used in the present invention, and the form 1 is provided with a character entry area 2 having a predetermined pattern, e.g., a width of 1. Second
The figure shows the configuration of an optical reading device according to an embodiment of the present invention, in which 11 is the main body of the reading device, 12 is a first reading section,
13 is a second reading section, and the first reading section 12 includes an imager 14, an imaging lens 15, an irradiation lamp 16, and a reflecting mirror 17.
, a first optical system 20 consisting of condensing lenses 18 and 19, and the like. The image pickup device 14 is of a self-scanning type in which, for example, a large number of solid-state image pickup devices are arranged in a straight line, and is orthogonal to the transport direction a of the form 1, as shown by the two-dot chain line in FIG. It is arranged as follows. The second reading unit 13 also includes an imager 21, a galvanic mirror 22, and an irradiation lamp 23.
, an optical system 2 consisting of condensing lenses 24, 25, and a reflecting mirror 26.
7, etc. Further, 28 is a coordinate specifying circuit, 1 is a form as mentioned above, and this form 1 is indicated by the arrow a.
It is designed so that it is transported in the direction. The above coordinate designation circuit 2
Reference numeral 8 controls the galvanic mirror 22 using a signal from the imager 14. Further, the imaging lens 15 is connected to the imager 14.
is installed so as to image the lower half of the character entry area 2 having a width of 1 in a direction orthogonal to the transport direction a of the form 1. Then, in the first reading unit 12, the lower half of the character entry area 2 of the form 1 is detected by the imager 14, and this detection signal is
The signal is sent to a coordinate specifying circuit 28 that specifies coordinates, and controls the galvanic mirror 22 that sets the field of view position of the image pickup device 21 in the second reading section 13. Also, Figure 3 shows the second
3 is a diagram schematically showing the reading section 13 of FIG. 2, viewed from the right side of FIG. 2. Next, the operation of the present invention configured as described above will be explained.

First, in FIG. 1, the width of the character entry area 2 is l, and 1 bit, which is the minimum resolution of a character, corresponds to n (Mm), and 1 bit of the character corresponds to 1 bit of the image sensor of the imager 14. The image shall be optically formed as shown in FIG. The first reading unit 12 reads the lower half of the character entry area 2 on the form 1, and as a result, the number of bits (number of image pickup elements) N of the image pickup device 14 is determined as N=l/2n (pits). It becomes necessary. Now, if the form 1 is conveyed in the direction of arrow a at a speed V (m/Sec), one scanning period T of the imager 14 is T=n/
(Sec) is determined. Furthermore, the scanning period Tn per 1 bit of the imager 14 is Tn=T/N-2Tn/l(
Sec). Of course, the scanning frequency Fn is Fn-N/
T (Hz). The first reading unit 12 detects character information on the form 1 by scanning the imager 14 at the scanning frequency Fn, sends the character information to the coordinate specifying circuit 28, and sends the character information to the coordinate specifying circuit 28. This is to control the galvanic mirror 22, which is an optical scanning control device. That is, when there is character information in the lower half (1/2) of the character entry area 2 of the form 1 in the first reading unit 12, the coordinate designation circuit 28
Therefore, the galvanic mirror 22 is connected to the second reading section 13 as shown in FIG.
The center of the optical axis is set on point b with respect to the scanning direction of the imager 21 of the second reading unit 13, and the imager 21 of the second reading unit 13 is located on the first
Similarly to the reading section 12 of the , the lower half of the character entry area 2 of the form 1 (
1/2). In addition, the first reading unit 12 reads the form 1.
When there is no character information in the lower half of the character entry area, the coordinate specifying circuit 28 causes the galvanic mirror 22 to move as shown in FIG. Read the top half. By having the first reading section and the second reading section as described above, the scanning frequency per pit of the imager can be reduced to 1/2 compared to the conventional optical reading device. The lighting device can be downsized and its power consumption can be reduced, and subsequent signal amplification circuits, signal processing circuits, etc. do not require a high frequency bandwidth. Therefore,
There is no need to use expensive high-frequency components such as ICs and transistors, and the conveyance speed of the form 1 can be increased. In addition, the first and second
By using dichroic mirrors on the optical path in the reading units 12 and 13, it is possible to separate two colors and detect, for example, a red frame in a postal code frame.

Further, in the above embodiment, the first reading section 12 reads the lower half of the character entry area 1 of the form 1 at the same character resolution as the second reading section. It is also possible to read the entire character entry area of a form at twice the reading resolution, detect character information within the field of view, and specify coordinates. Further, in the above embodiment, the field of view of the second reading section 13 is divided into two with respect to the character entry area of the form based on the information from the first reading section 12, but the field of view is not limited to this and may be divided into two or more. Of course. As described above, according to the present invention, it is possible to reduce the size and power consumption of the lighting device, simplify the subsequent signal amplification circuit and signal processing circuit, and increase the speed of conveyance of objects to be read such as forms. It is possible to provide an optical reading device that can obtain various excellent effects, such as being able to measure

[Brief explanation of the drawing]

Fig. 1 is a diagram showing an example of a form, Fig. 2 is a configuration diagram showing an embodiment of the present invention, and Fig. 3 is a schematic view of the second reading section as seen from the right side of Fig. 2. FIG. 1...Form, 11...Reading device body,
12...First reading section, 13...Second
reading section, 14, 21...imaging device, 20, 27
...Optical system, 22 ... Galvanic mirror, 28
...Coordinate designation circuit.

Claims (1)

[Claims] 1. A first reading section having a first image pickup device that reads and scans a character writing area to be read on a recording medium being conveyed in a direction orthogonal to the direction of conveyance, and a second reading unit that has a second image pickup device that reads and scans the character entry area to be read in a direction orthogonal to the direction of conveyance, and that sets a reading field of view in the direction orthogonal to the direction of conveyance by rotating a rotating mirror; and determining the positional coordinates of the character information in the character writing area to be read based on the output signal of the first reading section, and varying the reading field of the second reading section by rotating a rotating mirror accordingly. and a coordinate specifying circuit for controlling the second
An optical reading device characterized in that an output of a reading section of the invention is used as a reading signal.