JPS5926075B2 - optical character reader - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical character reading device that uses blank detection as a condition for starting information reading.

Generally, in order for an optical character reading device to correctly read character information written on an object to be read, it is necessary to correctly scan a reading area in which the character information is written with a scanner. 2. Description of the Related Art Conventionally, methods of setting coordinates, methods of reading marks, symbols, etc. are known as methods for correctly scanning a reading area.

In the former case, for example, a reading area is set at a point having a predetermined coordinate value P (x, y) with respect to the reference point of the X-Y axis on the form, and the reading area is set at a point having a predetermined coordinate value P ( This method starts reading scanning from x, y), but it is inconvenient that the coordinate values must be reset each time the document is different. The latter requires the detection of a mark such as ``L'' as a condition for starting reading, and starts reading by detecting a mark, symbol, etc. that has been set in advance. The present invention was made in view of these circumstances, and it uses blank detection as a condition for starting information reading, and it does not require special coordinate setting, There is no need to print marks, etc., and the reading start point can be detected by scanning character information, and the blank detection can be performed accurately with a simple configuration. An optical character reading device is provided.An embodiment of the present invention will be described below with reference to the drawings.As shown in FIG. The character information 2 is scanned by a handheld scanner 3.The scanner 3 includes an illumination lamp 5, a lens 6, a photoelectric conversion element 7, and an amplifier 8 that irradiates light onto the object 1 to be read. It is a built-in, commonly purchased device that images the character information 2 to be read through a lens 6 onto a photoelectric conversion element 7, and outputs an analog character information reading signal from the photoelectric conversion element 7 via an amplifier 8. Then, the analog read signal outputted by the scanner 3 is supplied to a quantization circuit 4 to be quantized into a binary signal, and the binary signal is passed through a character detection circuit 9 for character identification. It is supplied to the circuit 10 and also to the horizontal projection circuit 11 and the vertical projection circuit 12 in parallel.The horizontal projection circuit 11 creates a horizontal projection from the input binary signal for one screen. The vertical projection circuit 12 creates a vertical projection from the input binary signal for one screen.Therefore, the number of bits of black information included in the horizontal projection created by the horizontal projection circuit 11 The control circuit 17 counts the number of bits of black information H and the number W of black information included in the vertical projection created by the vertical projection circuit 12, and the respective counted values H and W are transmitted to the first and second comparison circuits 13,
14.

A constant K1 is set in the first comparison circuit 13, and a constant K2 is set in the second comparison circuit 14. 1st
The comparison circuit 13 outputs a Tv signal when H<K1,
The second comparison circuit 14 outputs the VWlVl signal when W<K2. Then, the first and second comparison circuits 13 and 14
The output of the control circuit 17 and the control signal from the control circuit 17 are input to the AND gate 15.
Blank detection flip-flop (F/F) 16 at the output of
I am trying to set it. The control circuit 17 detects the state of the blank detection flip-flop 16, and if it is not yet set, performs a blank detection operation of periodically counting the number of bits of black information in the horizontal projection and vertical projection described above. After it is set, that is, when a blank is detected, the character detection circuit 9 and the character identification circuit 10 are operated under this condition to perform the character identification operation.

Since the method of character recognition by the character detection circuit 9 and the character identification circuit 10 is the same as usual, its explanation will be omitted here, and blank detection will be explained below.

The surface information obtained from the photoelectric conversion element 7 is usually shown in FIG.
As shown in b, it consists of MXN-bit picture elements, and the maximum number of bits in horizontal projection is M, and the maximum number of bits in vertical projection is N.

On the other hand, if the blank area to be detected is completely white, the number of bits of black information appearing in the horizontal and vertical projections H, W
are H=0 and W=0, respectively. However, the blank part is rarely completely white, and in most cases it has dirt or stains as shown in Figure 2a. Note that FIG. 2b shows a case where there is writing to the extent that it can be recognized as character information. As is clear from comparing Figure 2 A and b, there are differences between horizontal and vertical areas when there is dirt or stains to the extent that they should be recognized as blank areas, and cases where there is writing to the extent that they can be recognized as characters. There is a clear difference in the number of bits H and W of black information appearing in the projection. That is, Figure 2a
In the case of FIG. 2b, H=4 and W=4, whereas in the case of FIG. 2b, H=12 and W=9. Therefore, as a criterion for distinguishing them, for example, a constant K,=5 is set for the horizontal projection,
Set constant K2=5 for vertical projection, H<K,, W<K2
If the blank area is determined to be blank when the following conditions are satisfied, the blank area can be detected with sufficient accuracy even if there is some dirt or stain. Therefore, in the practical example, as shown in the flowchart of FIG. 3, constants Kl and K2 are given to the comparison circuits 13 and 14 in advance,
After horizontal and vertical projections are formed by the horizontal projection circuit 11 and the vertical projection circuit 12, the control circuit 17 counts the number of bits H and W of black information in the horizontal and vertical projections, and the count results are sent to the comparison circuits 13 and 14. Given the husband constant Kl,
Have them compare it with K2.

Then, the comparator circuits 13 and 14 perform H<K1 and W<K2, respectively.
Level 1111 if you meet the conditions! The signal is outputted to the AND gate 15, and when the AND gate 15 establishes a logical product including the control signal from the control circuit 17, the blank detection flip-flop 16 is set by the output of the AND gate 15. ing. As is clear from the above description, according to the present invention, the detection of a blank is the condition for starting reading character information, so the reading start position can be accurately determined by the normal reading operation of scanning the character information part with a scanner. It is possible to detect and read six character information accurately from the beginning, and it is convenient and easy to handle because it does not require setting coordinates or writing marks.

In addition, since blank areas are detected based on the number of bits of black information in horizontal and vertical projections, blank areas can be detected accurately even if there is some dirt or stain, and blank areas and text areas can be accurately detected. It can be clearly distinguished and detected.

[Brief explanation of drawings]

The figures show one embodiment of the present invention, in which Fig. 1 is a block diagram showing the overall configuration, Fig. 2 A and b are schematic diagrams for explaining the principle of blank detection, and Fig. 3 is a block diagram showing the overall configuration. This is a flowchart for detection. 3...Scanner 64...Quantization circuit, 7
......Photoelectric conversion element, 9...Character detection circuit, 10...Character identification circuit, 11...
Horizontal projection circuit, 12...Vertical projection circuit, 13,
14...--Comparison circuit, 15...AND gate. 16...Blank detection F/F, 17...
...control circuit.

Claims (1)

[Claims] 1 A hand-held scanner with a built-in photoelectric conversion element that scans the object to be read, a quantization circuit that quantizes the analog read signal obtained from this scanner into a binary signal, and a a character detection circuit that detects characters from a binary signal for one screen; a character identification circuit that identifies characters from the binary signal detected by the character detection circuit; A horizontal projection circuit that creates a horizontal projection from the binary signal that performs character detection, a vertical projection circuit that creates a vertical projection, and the number of bits H of black information included in the horizontal projection created by the horizontal projection circuit. and a preset constant K_1, and a second comparison circuit that compares the number of bits W of black information included in the vertical projection created by the vertical projection circuit with a preset constant K_2. The comparison result between the circuit and the first comparison circuit is H<K_1, and the comparison result of the second comparison circuit is W<
K_2, a blank detection flip-flop that is set, and a control circuit that is energized by the set output of the blank detection flip-flop and starts the character discrimination operation of the character discrimination circuit. Optical character reader.