JPS589985B2 - Mojiyomitrisouchi - Google Patents

Description

[Detailed Description of the Invention] The present invention provides a character reading device, in particular, a system that can obtain a constant character pattern at a stage before a preprocessing section even when the relative speed between the character surface and the observation system for reading the characters is not constant. This invention relates to a character reading device.

In conventional character reading devices, when reading characters optically using a one-dimensional image sensor as a light-receiving element, as shown in FIG. As a result, the light reflected from each part of the character surface forms an image on the one-dimensional image sensor 3 by the optical system depending on the degree of reflectance.

The one-dimensional image sensor 3 converts this image into an electrical signal and transmits it to the next processing circuit.

The one-dimensional image sensor 3 is composed of a number of elements having sufficient resolution to decode character images, and is arranged perpendicularly to the direction of movement of the optical image.

Now, the number of elements of the one-dimensional image sensor 3 is n,
- If the number of scans of this one-dimensional image sensor 3 is M times while the optical image for a character passes through the above-mentioned -dimensional image sensor, then the number of meshes constituting the -character is nXM
It is.

This is transferred to the register of the processing circuit, and scanning of one character is completed.

If the relative speed between the character surface and the observation system that reads it is constant, and the size of the characters is the same, the number of meshes that constitute the above-mentioned characters will be a constant value of nXM, and a constant character pattern will always be obtained. I can do it.

If the relative speed of the character surface and the observation system that reads it is not constant, the number of scans of the one-dimensional image sensor while the optical image for the characters passes through the one-dimensional image sensor is different from M' becomes.

Therefore, the number of constituent meshes for the - character is nXM', and the character pattern obtained varies in various ways due to the change in the relative speed.

In this way, although the characters are the same, the reception patterns vary in various ways, which puts a heavy burden on subsequent processing circuits.

In another method, a very small spot light source is created on the CRT surface and projected onto the character pattern through a lens system, and the reflection from the character portion is detected by a photo multiplier.

Therefore, when the spot light source is moved onto the CRT surface, it is equivalent to scanning the paper surface, and a time-series output signal is obtained from the photo multiplier.

In this way, in conventional character reading devices, either the relative speed between the character surface and the observation system is constant as in the former case, or it is stationary until the scanning of one character is completed, as in the latter case, which treats a literary society as a surface. This was the case.

Now, in the conventional apparatus shown in FIG. 1, if we consider a case where the relative speed between the character surface 1 and the observation system (one-dimensional image sensor 3) changes, the character pattern received by the observation system is as follows.
A constant pattern is obtained in the vertical direction, but various patterns depending on the relative velocity are obtained in the horizontal direction.

That is, when the character surface 1 is stationary, only the same position is scanned, and when the speed is relatively slow,
As shown in Fig. 2a, when the character surface 1 is scanned at short intervals and at a small oblique angle, and when it moves at a high speed, it is scanned at wide intervals and at a large oblique angle as shown in Fig. 2a. The number of meshes constituting one character is n−
M is no longer constant because M changes.

Therefore, in conventional devices, when the relative speed between the character surface and the observation system changes, the processing method becomes extremely complex in the subsequent identification processing process, and the processing circuitry and processing program are both scaled up. It is inevitable that the

In order to eliminate such drawbacks, the present invention maintains the character pattern obtained from the observation system in the preprocessing stage in a constant form in response to changes in the relative speed between the character surface and the observation system, and For the purpose of simplifying the identification process, a relative speed detection means is provided, and speed information from the means is used to change the scanning period of the observation system or when compressing information of input character patterns in a preprocessing section. The present invention is characterized in that a means for varying the degree of compression is provided to obtain a constant character pattern that is not affected by changes in speed.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIGS. 3 and 4 are block diagrams showing an embodiment in which the relative speed is detected and the scanning period of the observation system is changed, and a relationship curve between the scanning period and the relative speed.

In FIG. 3, 1 is a character surface, 2 is a light projector, 3 is a one-dimensional image sensor, 4 is an image sensor drive circuit, 5 is a preprocessing circuit, and 6 is a speed detection section.

As the speed detection section 6, there is one that detects the speed using two photoelectronic switches having a constant interval, or one that uses the principle of Doppler radar.

The speed detection section 6 detects the relative speed between the character surface 1 and the observation system, and sends the detected speed information to the image sensor drive circuit 4.

If scanning is performed at the same intervals and at the same oblique angle, the relationship between relative velocity and scanning period is expressed by the straight line in FIG.

Therefore, the image sensor drive circuit 4 only needs to change the scanning period according to FIG. 4 based on the relative speed information from the speed detection section 6.

In FIG. 3, the preprocessing circuit 5 and subsequent parts are not changed in the same manner, and only a scanning period variable means is provided in the image sensor drive circuit 4, and a relative velocity detection means 6 is provided in addition to the observation system, and a constant form is maintained. You can get the character pattern of

FIG. 5 and FIG. 6 are block diagrams showing an example of a case where relative velocity is detected and the degree of information compression of an input character pattern is made variable in the preprocessing section, and an explanatory diagram of variable compression degree. be.

When transferring the character image signal obtained by scanning character surface 1 to the subsequent stage, the data is compressed by taking advantage of the property that there is a strong correlation between pixels in adjacent scanning lines, reducing redundancy and improving efficiency. is planning to change.

In the preprocessing circuit 5, data compression is performed, and by making the degree of compression variable according to the relative speed, the character pattern can be transferred to a subsequent stage in a fixed form.

When the scanning period is kept constant, the change in relative velocity is
In order to send the scanned character pattern in a constant form to the next identification processing circuit, it is necessary to establish a linear relationship between the number of samples N and the relative speed as shown in FIG.

If a scanning period is set that allows sufficient reading when the moving speed of the character surface 1 is maximized, and the moving speed of the character surface 1 is reduced to 1/N within this period, the scanning interval can also be shortened to 1/N.

At this time, if N pieces of scanning information are compressed and sent as one piece of scanning information, the same pattern information can be transferred without degrading the quality of the character image.

The case where N=3 will be explained with reference to FIGS. 5 and 6a.

A is 1 bit information, mouth is 1 scanning line width, and c. 2 is scanning line information that is combined into one, A is scanning information, B is compressed information, and the other symbols are the same as those used in FIG. 3.

When the character surface 1 passing through is illuminated by the light projector 2, the light reflected from the character surface 1 is read by the one-dimensional image sensor 3.

At the same time, the speed detection section 6 measures the relative speed between the character surface 1 and the observation system.

Characters are scanned by the image sensor drive circuit 4 at a constant scanning cycle, and the scanned character pattern information A is sent to the preprocessing circuit 5 at the next stage.

The preprocessing section 5 receives speed information from the speed detection section 6, and determines the number of samples N for data compression as a function of speed, as shown in FIG.

When the number of samples is N-3, three pieces of scanning line information are sent together as one piece of information, and at this time, each bit of scanning line information is determined by the majority rule or a threshold value determined by the number of samples N.

For example, if two bits are black out of three corresponding bits, it will be black, so A will be black, and two will be black.
The data is compressed into two and then transferred.

In FIG. 5, the components other than the preprocessing circuit 5 are not changed, and the preprocessing circuit 5 is simply provided with means for changing the degree of data compression based on the output from the relative speed detection means. A character pattern of the shape can be given.

As described above, according to the present invention, even if the relative speed between the character surface and the observation system changes, a constant pattern can be obtained through preprocessing, so there is an advantage that the identification processing circuit does not become complicated.

Further, since the present invention compresses the information of the input character pattern using speed information, it has the advantage that the influence of noise caused by dirt on the paper on which the characters are written can be reduced.

[Brief explanation of the drawing]

Figure 1 is a block diagram of a conventional character reading device, Figure 2a,
b is an explanatory diagram of the scanning pattern when the relative speed is changed; FIG. 3 is a block diagram showing an embodiment of the present invention in which the scanning period is variable; FIG. 4 is an explanatory diagram of the relationship between the scanning period and the relative speed; The figure is a block diagram showing an embodiment of the present invention in which the degree of data compression is variable, and FIGS. 6a and 6b are explanatory diagrams of the relationship between the data compression method, the number of samples, and the relative speed. 1... Character surface, 2... Floodlight, 3... One-dimensional image.
Sensor, 4... Image sensor, drive circuit, 5... Preprocessing circuit, 6... Speed detection section, A... Scanning information, B...
Compressed information, N: Number of samples, A: 1 bit information, H: 1 scanning line width, C, 2: Scanning line information that is grouped into one.

Claims (1)

[Claims] 1. In a character reading device that optically reads characters using a one-dimensional image sensor, when the relative speed between the character surface and the observation system that reads the characters is not constant, a means for detecting the relative speed is provided, and The relative speed can be adjusted by means of changing the scanning period of the one-dimensional image sensor based on the speed information from the detection means, or by means of changing the degree of compression when compressing the information of the input character pattern in the preprocessing section. A character reading device characterized by eliminating deformation of character patterns due to changes.