JPH031710B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention particularly relates to an optical character reading device with an improved scanning mechanism.

[Technical background of the invention and its problems] In recent years, optical character reading devices (hereinafter referred to as OCR) have a reading function for kanji characters in addition to alphanumeric characters and kana characters. By the way, in the case of kanji reading, assuming reading of handwritten kanji recorded on a form to be read, reading of printed kanji, etc.
There is a big difference in the size of the characters compared to alphanumeric characters and kana characters.

Therefore, in conventional OCR, the scanning control of the scanning mechanism is fixed when reading a form, so the reading resolution may be insufficient depending on the size of the Kanji characters recorded on the form. Therefore, with conventional OCR, depending on the size of Kanji characters,
This method had the disadvantage that the number of rejects increased and the reading efficiency decreased.

[Purpose of the invention]

This invention was made in view of the above circumstances, and its purpose is to perform scanning control according to the size of characters recorded on a form to ensure reliable reading operation. An object of the present invention is to provide an optical character reading device that can perform the following steps.

[Summary of the invention]

According to the present invention, a scan control section outputs both a document transport speed designation signal based on the size of characters recorded on the document in advance and a conversion signal designating the scanning density. Then, the speed of the driving means for transporting the form is controlled based on the transport speed designation signal. Further, a digital signal obtained by scanning a form is converted into a predetermined scanning density by a scanning density converter using the conversion signal.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a partial configuration of an OCR according to the present invention. In the figure, reference numeral 1 denotes a reflecting mirror that provides reflected light from a form 2 to be read to a line sensor 4 via an optical lens 3. The line sensor 4 is a photoelectric converter that converts character information obtained by optically scanning the form 2 into electrical signals and outputs the electrical signals. The electrical signal output from the line sensor 4 is amplified by an amplifier 5 and given to an analog-to-digital converter (hereinafter referred to as an A/D converter) 6. This A/D converter 6 converts the analog video signal, which is the electric signal, into a digital signal and outputs it to the scanning density converter 7. Based on a scanning density conversion signal (hereinafter referred to as a conversion signal) S sent from a scanning control section 8, this scanning density converter 7
The scanning density for the analog video signal obtained by the scanning density of the line sensor 4 is converted, and a digital signal corresponding to the converted analog video signal is output. The scan control unit 8 is a circuit that outputs the conversion signal S based on the size of characters recorded on the form 2 in advance and a speed signal V specifying the transport speed of the form 2.

Here, the form 2 is conveyed in a certain direction (arrow in the figure) and scanned by the conveyance motor 9. This transport motor 9 is connected to a transport motor drive circuit 1.
The drive is controlled by 0. Conveyance motor drive circuit 1
0 is a conveyance speed set by the control signal V _C of the conveyance speed control circuit 11, and drives and controls the conveyance motor 9 to convey the form 2. The conveyance speed control circuit 11 outputs a control signal V _C corresponding to the speed designation signal V mentioned above.

The operation of this configuration will be explained. For example, as shown in Figure 2, Form 2 has the following information:
Entry area 2a where handwritten numbers or kana characters are entered, entry area 2b where handwritten kanji characters are entered, entry area 2 where printed kanji characters are entered.
c, and a writing area 2d in which characters are printed by a printer or the like.

When such a form 2 is read by the OCR shown in FIG. 1, the form 2 is first conveyed in a certain direction (the direction indicated by the arrow) by the drive of the conveyance motor 9. The characters recorded in each area 2a to 2d of the form 2 are optically scanned, and the reflected light is applied to the line sensor 4 via the reflecting mirror 1 and the optical lens 3 to form an image. The analog video signal photoelectrically converted by this line sensor 4 is amplified by an amplifier 5 and then given to an A/D converter 6. In this case, the scanning time of the line sensor 4 is kept constant, and the scanning density is, for example, 8 lines/mm (or 8 pixels/mm) in the case of handwritten characters or printed characters, or 16 lines/mm in the case of printed characters. mm (or 16 pixels/
mm). The transport speed of the form 2 when being scanned is as shown in FIG.
In the case of 2b, the speed is V ₁ , and in the case of writing areas 2c and 2d, the speed is V ₂ . These speeds V ₁ and V ₂ are expressed as “V ₁ =
2V ₂ ” relationship. Therefore, the scan control section 8
In this case, a speed designation signal V corresponding to the transport speeds V ₁ and V ₂ as described above is output to the transport speed control circuit 11 in advance. As a result, the transport speed control circuit 11 sends a control signal V _C to the transport motor drive circuit 10.
is output, and the form 2 is conveyed at the speeds V ₁ and V ₂ as described above. Here, the scan control section 8
is given information (format data) for each type of character written on the form 2, for example, from a control circuit (not shown) that controls the entire OCR.

On the other hand, the analog video signal given to the A/D converter 6 as described above is given to the scanning density converter 7 after being converted into a digital signal. In this case, the scanning density converter 7 is supplied with a video signal of the line sensor 4 having a scanning density of, for example, 16 lines/mm (see Fig. 4A).
) is always provided. Then, the scanning density converter 7 performs scanning density conversion using the conversion signal S from the scanning control section 8 as described above. That is, the digital signals of characters corresponding to the entry areas 2a, 2b, and 2d of the form 2 are converted into digital signals corresponding to a video signal (shown in FIG. 4B) with a scanning density of 8 lines/mm. In this case, the scanning density converter 7 may e.g.
16 lines/mm video signal (digital signal) is extracted every 2 pixel signals, and judgment is made based on the average value or their waveforms and the video signals before and after them, and 1 pixel signal is generated from 2 pixel signal components. It works like that. Therefore, the scanning signals corresponding to the entry areas 2a, 2b, and 2d of the form 2 are output from the scanning density converter 7 as digital video signals with a scanning density of 8 lines/mm. Furthermore, the scanning signal corresponding to the entry area 2c of the form 2 is 16
As a digital video signal with a scanning density of lines/mm,
It will be output as is. The scanning control section 8
outputs the converted signal S to the scanning density converter 7 based on the format data given from the overall OCR control circuit as described above. Then, the output signal of the scanning density converter 7 is sent to, for example, a character recognition processing section, where character reading processing is performed.

In this way, a reliable read image can be obtained by setting the conveyance speed of the form 2 during scanning and converting the scanning density according to the characters recorded on the form 2. That is, in the present invention, a video signal with a scanning density for print characters, Chinese characters, etc. that requires high resolution is always supplied to the scanning density converter 7. Then, for video signals such as handwritten alphanumeric characters, handwritten kanji characters, and printed characters that are larger than printed kanji characters (i.e. characters with lower resolution), the scanning density is converted and output as a video signal. . Therefore, regardless of the type of characters, such as small printed Chinese characters and large handwritten characters, a high quality video signal can always be output and reliable reading processing can be performed. Furthermore, since the conveyance speed and scanning density are changed depending on the size of the characters, there is an effect of increasing the reading processing speed and improving the memory efficiency of the video signal. Note that the present invention can be applied not only to character reading but also to image processing of graphics and the like.

〔Effect of the invention〕

As detailed above, according to the present invention, when characters recorded on a form are scanned and read, the transport speed and scanning density of the form are adjusted depending on the size of the character, that is, the resolution required for reading. Can be set. Therefore, a reliable reading operation can be performed regardless of the size of the characters on the form. Therefore, it is possible to improve the reading efficiency of Kanji characters that have a large difference in size due to handwritten characters, printed characters, etc., for example.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a partial configuration of an OCR according to an embodiment of the present invention, FIG. 2 is a diagram showing an example of the structure of a form, and FIG. 3 is a diagram for explaining the transport speed of the form. , FIG. 4 is a diagram showing video signals according to scanning density for explaining the operation of the above-mentioned OCR. 4... Line sensor, 6... Analog-digital converter, 7... Scanning density converter, 8... Scanning control section, 1
1... Conveyance speed control circuit.

Claims (1)

[Scope of Claims] 1. Photoelectric sensor means that converts information obtained by optically scanning a form into an electrical signal and outputs it, and an analogue that converts the electrical signal output from the photoelectric sensor means into a digital signal.・Digital conversion means, and a speed designation signal for designating the transport speed of the form and a scanning density conversion signal for designating the scanning density, depending on the size of the characters to be scanned recorded on the form. a scanning control means for outputting the digital signal outputted from the analog-to-digital conversion means based on the scanning density conversion signal outputted from the scanning control means; scanning density conversion means for converting into a digital signal; and control of a conveying speed at which the form is conveyed when the photoelectric sensor means scans the form, based on the speed designation signal output from the scanning control means. What is claimed is: 1. An optical character reading device characterized by comprising: speed control means for controlling speed;