JPS598859B2 - optical scanning method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical scanning method for scanning characters, symbols, etc. written in a frame.

Conventionally, in postal letters and the like, postal codes are written in a predetermined frame to facilitate classification of delivery destinations.

In addition, there are other types of forms in which characters, symbols, etc. are written within a predetermined frame, and the written characters are automatically read by an optical character reading device. However,
When characters, symbols, etc. written in a predetermined frame are read by an optical character reading device, sheets such as postal letters and forms may become misaligned and tilted while being conveyed to the reading device. , the position of the frame is often tilted from the normal position. If reading scanning is performed with the frame position tilted as described above, the scanning position will shift and correct reading will not be performed. For this reason, conventionally, as shown in FIG. 1, the edge of the sheet 1 is detected by two scans A and B to obtain the inclination of the sheet edge, and this inclination of the sheet edge is directly adopted as the inclination of the frame 2. After correcting the skew, characters are read and scanned while shifting the position of each frame as shown in FIG. In FIG. 1, the broken line indicates the normal position of the sheet 1, and the solid line indicates the inclined state.
However, in the conventional scanning method described above, when performing skew correction, the scanning direction is kept the same but the scanning position is shifted for each frame, so the scanning direction is not parallel to frame 2 and the characters are Unfavorable for identification.

Further, since the inclination of the sheet end is directly used as the inclination of the frame, the end of the sheet 1 and the frame 2 must be parallel to each other.

However, when cutting the sheet 1, there are cases where the position shifts and the sheet edge and the frame 2 are not parallel, and in this case, correct skew correction cannot be performed. The present invention has been made in view of the above points, and even when the sheet is tilted or the sheet edge and the frame ξ are not parallel, it is possible to accurately perform skew correction and perform reading scanning reliably. The purpose is to provide an optical scanning method that can

J The details of the present invention will be explained below with reference to one embodiment of the present invention.

In FIG. 3, numeral 11 is a cathode ray tube for the fly fern spot, and a vertical deflection coil 12a and a horizontal deflection coil 12b are respectively given deflection signals from a vertical deflection circuit 13a) and a horizontal deflection circuit 13b; scanning by the fly fiddle spot is performed. . An object to be read, that is, a sheet 14 on which characters, symbols, etc. are written in a predetermined frame, is arranged opposite to the front part of the cathode ray tube 11, and the character recording surface thereof is optically scanned by the cathode ray tube 11. . This sheet 14
When scanning, first, as shown in Figure 4a,
Point A (Xll, yll) in frame 15 and point B (Xll
, yl2) in the horizontal direction, that is, in the X-axis direction. Then, if the points at which scanning from points A and B reach frame 15 are C(X2l, yll) and D(X22, yl2), respectively, then the slope of frame 15 is slope = master - 1 (X22 - X2l
)/(Yl2-Yll). When the frame 15 of the sheet 14 is scanned by the flying spot, the reflected light is detected by a photoelectric converter such as a photomultiplier tube 16, and its output is sent via an amplifier 17 to a counter 18a. , 18b. The counters 18a and 18b are made to count the number of bits from starting scanning from points A and B within the frame 15 until detecting the frame 15 to obtain X2l-Xll and x22-Xll, respectively. Then, the outputs of the counters 18a and 18b are sent to the subtracter 19, and the value of the counter 18a (X2l-Xl
The value (X22-Xll) of the counter 18b is subtracted from the value (X22-Xll) to obtain (X22-X2l). Next, the subtraction result in the subtracter 19 and the fixed pitch R=Yl2-Yll are added to the divider 20, and the inclination of the frame 15, that is, the amount of skew (X2
2-X2l)/(Yl2-Yll) is obtained, and this skew amount and its positive/negative sign are stored in the register 21.

Then, the skew amount stored in this register 21 is sent to the vertical deflection circuit 13a or the horizontal deflection circuit 13b via the switching circuit 22, and the skew amount is corrected.
Enter scanning within 5. The switching circuit 22 operates according to a switching signal, and supplies the output of the register 21 to the vertical deflection circuit 13a when the cathode ray tube 11 is performing horizontal scanning, and when the cathode ray tube 11 is performing vertical scanning, it supplies the output of the register 21 to the vertical deflection circuit 13a. The output of the register 21 is supplied to the horizontal deflection circuit 13b. The vertical deflection circuit 13a and the horizontal deflection circuit 13b have the same structure, and each has a scanning period equal to that of the other deflection circuit depending on the signals from the main sawtooth wave generation circuits 23a, 23b1 and the register 21, that is, the amount of skew. Sub-sawtooth wave generation circuits 24a, 24b that generate period correction signals; inversion amplification circuits 25a, 25b for inverting and amplifying the output signals of the sub-sawtooth generation circuits 24a, 24b to obtain negative sawtooth-wave signals; Amplifying circuits 25a, 25a, which amplify the output signals of the sub-sawtooth wave generation circuits 24a, 24b as they are to obtain positive sawtooth wave signals;
26b1 Inverting amplifier circuits 25a, 25b and amplifier circuit 2
Selection circuits 27a and 27b1 select and extract output signals of 6a and 26b according to positive or negative information stored in the register 21; output signals of these selection circuits 27a and 27b and the main sawtooth wave generation circuit 23a; , 23b to drive the deflection coils 12a, 12b. But now,
Assuming that the cathode ray tube 11 is horizontally scanned,
The main sawtooth wave generation circuit 23b of the horizontal deflection circuit 13b generates a sawtooth wave signal X with a short period as shown in FIG. 5a to obtain a horizontal scanning line, and the main sawtooth wave generation circuit 23b of the vertical deflection circuit 13a The circuit 23a is shown in FIG. 5b for performing frame scanning.
A sawtooth wave signal Y with a long period is generated as shown in FIG. In this case, the vertical sawtooth signal Y is replaced by the horizontal sawtooth signal X [shown in FIG. 6a], as shown in detail in FIG. 6b. ), and its output waveform is C-corrected based on the output signal of the sub-sawtooth wave generation circuit 24b. As described above, the signal generation period of this sub-sawtooth wave generation circuit 24a is the same as the period of the horizontal sawtooth wave signal X shown in FIG. It changes depending on the amount of skid applied through the. Therefore, as shown in FIG. 4a, the greater the inclination of the frame 15, the greater the output signal of the auxiliary sawtooth wave generating circuit 24a. If the slope of the frame 15 is downward to the right as shown in FIG. The sawtooth wave signal Ya is selected by the selection circuit 27a. The sawtooth wave signal Ya selected by this selection circuit 27a is the sawtooth wave signal Y generated by the main sawtooth wave generation circuit 23a.
are synthesized as shown in FIG. 6d, and vertical deflection is performed based on this synthesized signal. Therefore, the horizontal scanning is skew-corrected and is performed parallel to the upper and lower sides of the frame 15 as shown in FIG. 4b, so that the characters within the frame 15 are accurately scanned. If the frame 15 is tilted upward to the right, the skew amount temporarily stored in the register 21 will be negative, and the scanning line will be tilted to the right, and the upper and lower sides of the frame 15 will be tilted upward and to the right, as in the above case. Scanning is done parallel to the edges. In the above description, the case where the cathode ray tube 11 is horizontally scanned has been described, but the skew correction can be performed in the same manner as in the above case even in the case of vertical scanning. In the above embodiment, a photoelectric conversion means using a flying spot cathode ray tube was shown, but other methods may also be used, such as one using an image pickup tube and a strobe discharge tube or a tungsten lamp, or one in which photosensitive elements are arranged in a matrix and combined with a light source. Various photoelectric conversion means can be considered, such as a photoelectric converter. As described above, according to the present invention, since the skew measurement is performed on the frame itself, the skew measurement is more accurate than the conventional case where the skew measurement is performed at the sheet edge. Accurate skew correction can be performed even when the two are not parallel.

Furthermore, since the scanning after the skew correction is parallel to the upper and lower sides of the frame, extremely good conditions for character identification can be provided.

[Brief explanation of drawings]

1 and 2 are diagrams showing conventional skew correction means;
Figure 3 is a configuration diagram showing one embodiment of the present invention, Figures 4A and b
5A and 6B are diagrams showing the skew amount detection means and the scanning state after skew correction in the same embodiment, FIGS. 5A and 6A,
b is a signal waveform diagram for explaining the operation of the same embodiment. 11... Cathode ray tube for flying spot, 1
3a...Horizontal deflection circuit, 13b...Vertical deflection circuit, 14...Sheet, 15...
・Frame, 16...Photomultiplier tube, 23a, 23b
, 24a, 24b... Sawtooth wave generation circuit.

Claims (1)

[Claims] 1. A means for optically scanning an object to be read, which is equipped with a frame for specifying a reading section, and a means for scanning the frame portion of the object in parallel at a fixed interval, and detecting the distance between the parallel scans and on both scanning lines. means for measuring the amount and direction of inclination of the frame according to the position of the frame respectively corresponding to the positions of the frames; An optical scanning method characterized by comprising means for correcting the skew of the scanning means so as to achieve the following.