JPS6138514B2 - - Google Patents

Description

Detailed Description of the Invention The present invention is a device that optically detects information written on a form, and in order to detect the information, it is necessary to know the coordinate reference by some means. Regarding equipment.

Conventionally, the techniques shown in (a) to (c) below have been used.

(a) There are cases where timing marks are written on the form but there is no means to check the four sides of the form. However, this prior art is inconvenient for users because it imposes restrictions on the layout of the form due to the provision of timing marks.

(b) There is an example in which a separate transmitted light detection converter is installed near the photoelectric converter to detect only the front and rear edges of the form. However, in this kind of method, 2
Both the mechanical accuracy and the accuracy of the form transfer speed between different types of converters require strict verification, which is a hindrance when trying to speed up and generalize the device.

(c) There is an example in which the coloring of the four sides of a form is prohibited, and the circuit that detects the black and white information on the form attempts to detect the four edges of the form as well, hoping for the high reflectance of the blank surface. However, it is common for forms to be colored at specific edges so that they can be sorted and oriented in a stacked state, and in this case detection becomes impossible.

An object of the present invention is to accurately detect the coordinates of the four sides of a form in an optical reading device, so that the inclination and expansion/contraction of the form can be determined in later processing.

The present invention is characterized by a background plate provided in the photoelectric conversion unit and formed so as to reduce its reflectance, and a background plate that is provided in the photoelectric conversion unit and that reflects light from the background plate and the black printed portion of the form. and a circuit for setting a slice level that can identify the slice level.

The embodiment described below is an example of an optical character reading device. As a recent trend in documents used in optical character reading devices, (a) the timing mark is no longer used as the reference position of written characters, and instead the distance from the edge is defined. (b) Other areas, including the four sides, other than the text entry area may be printed or colored in any other way. There are two new trends. In addition, the form feeding device of the optical character reading device is
(a) documents of different sizes, (b) documents with a thickness ratio of more than twice, and (c) documents with various surface treatments, (d) must be mixed, and (e) must be transported at high speed. Because of this, it is difficult to obtain the same paper feeding accuracy as before. In order to solve the above-mentioned problems with document trends and paper feeding accuracy, it is necessary to have means for simultaneously measuring the position of the edge of the document when attempting to read characters. Therefore, it is effective to implement the present invention.

FIG. 1 shows the reflectance characteristics of black printing and black oil-based felt pen. From FIG. 1, in order to detect the four sides of a form whose four sides are colored as described above, it is desirable that the apparent reflectance of the background is 0.08 or less.

By the way, FIG. 2, FIG. 3a, FIG. 3b, and FIG. 3c show the photoelectric conversion section in the present invention. The background plate 14 has an elongated shape, and the one-dimensionally arranged photoelectric conversion elements 13 capture the reflected light, and since the form is conveyed at a constant speed by a motor, the form is This means that a two-dimensional image can be obtained.

FIG. 3a shows a specific example of means for reducing reflected light from the background plate, in which a slit-shaped hole 19 is provided in the background plate 14. The incident light from the lamp 11 passes through the slit obliquely, so it does not illuminate the black felt 16. Therefore, the amount of light that enters the one-dimensional photoelectric conversion element 13 through the imaging lens 12 is smaller than when black felt is attached directly to the background plate 14.

FIG. 3b shows a mirror 17 in the center of the background plate 14.
This is an example of installing the . Since the light from the lamp 11 is specularly reflected by the mirror 17, if the dark box 15 sufficiently closes off the surrounding light, the incident light on the one-dimensional photoelectric conversion element 13 is sufficiently small.

FIG. 3c shows a folded portion 1 at the center of the background plate 14.
This is an example in which 8 is provided. The bent portion 18 is set at an angle that directly faces the lamp 11 on the right side and does not illuminate the lamp 11 on the left side. Thereby, the amount of light incident on the one-dimensional photoelectric conversion element 13 can be reduced.

Regarding the background of Fig. 3, one-dimensional photoelectric conversion element 1
3, when the values corresponding to the reflectance of light entering from the background plate 14 were measured, they were uniformly less than 0.05 (the measurement limit of the measuring device). However, in FIGS. 3b and 3c, discrete noise is observed, but this is because the background plate 14 is within the depth of focus of the lens, so it was determined that paper dust is being imaged. Discrete noise could be removed by using a filter after photoelectric conversion.

Next, a specific example of a circuit system for detecting the four sides of a form, which is one of the requirements of the present invention, will be explained. FIG. 4 shows a circuit for detecting edges of a form. This circuit is characterized in that it includes a form slice level generation circuit 25.

The output of the photoelectric conversion element 13 is amplified by an amplifier 21 and inputted to comparators 23 and 24 and a background level storage circuit 26. The background level storage circuit 26 is connected to the background board 1
The reflected light level (reflectance: 0.05) from 4 is stored and output to the form slice level generation circuit 25. Since the reflected light level 32 of the black frame of the form has a reflectance of 0.08 or more, the form slice level generation circuit 25 sets a level 28 (reflectance of 0.07) that is intermediate between these two values.

The output 28 of the form slice level generation circuit 25 is input to the comparator 24, and the comparator 24 is connected to the amplifier 21.
output 29 and form slice level generation circuit 25,
The outputs of 28 are compared, and a reflected light level 30 exceeding the slice level 29 is detected. On the other hand, comparator 23
is for detecting character level 34, and amplifier 21
The output 29 of the character slice level generating circuit 22 is compared with the slice level 27 of the character slice level generating circuit 22. The comparison output 31 becomes a character signal.

Of course, in terms of circuit technology, the form slice level generation circuit 25 can share a part of the circuit with the character slice level generation circuit 22, or use the same circuit by time sharing, using known technology. This is possible by using Although the form slice level generation circuit 25 receives input from the background level storage circuit 26, it may also receive input from another circuit, such as a semi-fixed volume.

There are various known examples of circuits corresponding to the background level storage circuit 26, but in the case of this embodiment, a simple circuit is used to store the output of the amplifier 21 during a certain period before the start of reading the form. A method was adopted in which the potential at the darkest level is stored as the background level. As mentioned above, the reflected light level 35 of the background board in FIG. 5 corresponds to the reflected light level of the blackboard with a reflectance of 0.05 or less, while the reflected light level 32 of the form black frame has a reflectance of 0.08 or more, so the form slice The level generation circuit 25 may provide the intermediate level between these two values as the form slice level 28.

The form slice level 28 is created by using the output of the background level storage circuit 26 and adding a constant value to it. That is, in this embodiment, the value is 0.02 larger than the reflected light level 35 of the background plate. As a result, even if a black frame is printed around the document as shown in FIG. 5, the edge of the document can be detected stably.

As described above, according to the present invention, it is possible to accurately detect the coordinates of the four edges even for a form whose four edges are colored. Also for
You can clearly know the position and slope of the information on the form.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing measurement examples of reflectance at each wavelength for black printing and black oil-based felt pen, Fig. 2 is a schematic three-dimensional perspective view of the photoelectric conversion section according to the present invention, and Fig. 3a is Figure 3b is a side view showing an example in which holes are made in the background plate; Figure 3c is a side view showing an example in which the background plate is bent at an obtuse angle; FIG. 4 is a block diagram of an embodiment of the present invention, and FIG. 5 is a timing chart showing waveforms at major points in the circuit of FIG. 11... lamp, 12... imaging lens, 13...
...Photoelectric conversion element, 14...Background plate, 15...Dark box, 17...Mirror surface, 18...Bend portion, 19...
... Hole, 21 ... Amplifier, 22 ... Character slice level generation circuit, 23, 24 ... Comparator, 25 ...
Form slice level generation circuit, 26...Background level storage circuit.

Claims (1)

[Scope of Claims] 1. In an optical reading device, there is a conveyance path in which a portion of the conveyance path that is illuminated by light from a light source has a lower reflectance than black, and a portion of the conveyance path that has a lower reflectance and a portion that is conveyed. a photoelectric conversion unit that receives reflected light from the form and converts it into an electrical signal; a storage unit that stores the level of the electrical signal output from the photoelectric conversion unit and obtained from the low reflectance portion of the transport path; a slice level generation circuit that generates a slice level for detecting the edge of a form from the storage content of the storage means and the level of an electrical signal corresponding to the reflected light from the black colored portion on the form; and the slice level generation circuit. 1. An optical reading device comprising a comparison means for comparing a slice level output from the photoelectric conversion section with an output from the photoelectric conversion section to detect edges of a form. 2. The optical reading device according to claim 1, wherein a hole is formed in a portion of the transport path that is exposed to light in order to reduce the reflectance of the transport path. 3. The optical reading device according to claim 1, wherein the portion of the transport path that is exposed to light is made of a mirror surface to reduce the reflectance of the transport path. 4. The optical reading device according to claim 1, characterized in that in order to reduce the reflectance of the transport path, the portion of the transport path that is exposed to light is bent toward the side opposite to the form. Device.