JPS60102055A - Photoelectric converter - Google Patents

Abstract

PURPOSE:To improve the reading accuracy by switching a background color to a black color when no medium is detected and into a white color when a medium is detected so as to prevent fetching of mis-information of a thin medium. CONSTITUTION:A rotary drum 11 is turned and positioned in the direction of arrow B so as to bring the end of the black part to the reading position until a paper sheet 7 reaches the reading position of an image sensor and the background color is switched into the black color. When the paper sheet 7 is carried in this state, since the background is black and the paper sheet 7 is white, the profile of the paper sheet is detected easily. Furthermore, the rotary drum 11 is turned in the direction of arrow B so as to make the background into white color, then even if the paper sheet 7 is thin, the effect of paper-making of the sheet is not given.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a photoelectric conversion device, and this invention relates to a photoelectric conversion device, which occurs when a thin (inexpensive) medium is used in a facsimile, OCR, image input device, etc. that uses paper sheets as a medium. The present invention relates to a photoelectric conversion device that is effective in preventing deterioration in reading accuracy due to background effects.

[Background of the invention]

Conventionally, in photoelectric conversion devices, the background color has been fixed to either white or black. When the background color is set to white, even when using a thin medium as described above, there is less influence from unevenness in the media, so reading accuracy is stable, which is an advantage! There was a problem in that the image sensor could not distinguish the leading edge of the medium because the color of the landscape and the medium were similar.

On the other hand, if the background/color is set to black, the outline of the medium can be distinguished with high precision, and that information can be used to
While there is an advantage in that the information capture area on the medium can be easily set, when using a thin medium such as the one described above,
There was a problem in that unevenness in the papering of the medium affected the reflectance, resulting in erroneous information being captured, resulting in a decrease in reading accuracy. This will be explained in more detail below.

FIG. 1 is a block diagram of a photoelectric conversion circuit for binarizing an image pattern on a medium. In the figure, 7 is a medium for inputting an image pattern, that is, a sheet of paper, 6 is a light source for illuminating the medium, and 5 is a lens for forming an image of the image pattern on the sheet of paper 7 on an image sensor 1, which will be described later. It is. Also.

2 is an amplifier for amplifying the output signal from the image sensor 1, and 3 is a white level tracking circuit for providing a binarization threshold to a comparator 4 for obtaining a binarized signal.

FIG. 2 shows a photoelectric conversion circuit configured as described above.
This indicates the magnitude of the output signal of the image sensor l for paper sheets 7 of different thicknesses when the coating color of the sheet guide (indicated by symbol 10 in Figure 1), that is, the background color, is black. Yes, curve L1 is curve L1 for thick paper sheets.
2 shows the case of thin paper sheets. As is clear from the figure, when the paper sheet is thin, the output signal becomes low, so there is a problem in that the S/N ratio of the circuit is significantly lowered.

Normally, when there is black information (a) and (c) as shown in Figure 3(a), the binarized output data will be as shown in (a) and (c) as shown in Figure 3(b). . However, as mentioned above,
When the background color is black and the paper leaf 7 is thin.

The influence of the unevenness of the papering appears as shown in (b) of Figure 3 (,), and if the false information leaf is thin as shown in (b) of Figure 3 (b), false information is output. This increases the possibility of this happening and reduces reading accuracy.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and its purpose is to solve the above-mentioned problems in conventional photoelectric conversion devices, to detect the outline of a medium, and to make it possible to detect thin media. It is an object of the present invention to provide a photoelectric conversion device that can prevent erroneous information from being taken in and improve reading accuracy.

[Summary of the invention]

The above-mentioned object of the present invention is to provide a photoelectric conversion device for photoelectrically converting an image pattern on a medium by an image sensor, which includes means for detecting the presence or absence of the medium and means for controlling the background color of the medium; This is achieved by a photoelectric conversion device characterized in that the background color is switched to black when the detection means is not detecting a medium, and the background color is switched to white when the detection means is detecting a medium.

[Embodiments of the invention]

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 4 is a side sectional view showing the main parts of a photoelectric conversion device that is an embodiment of the present invention. In the figure, 7 indicates the paper sheet, 8 a paper presence/absence detector comprising a light emitting element 8A and a light receiving element 8B, and 10 the paper sheet guide. Further, 11 has a white part 11A and a black part (
It is a rotating drum having a hatching part) 11B,
As will be described later, it is located on the rear side of the paper at the opening of the paper guide IO and has the function of controlling the background color.

The rotating drum 11 is controlled by a drive control means (not shown) to rotate the white portion 1, ], in accordance with the position of the paper sheet 7.
A or the black portion 11B is driven so as to be selectively positioned at the reading position of the image sensor. This will be explained below based on FIG. 4 and FIGS. 6(a) to (c).

Figures 6(a) to 6(c) show only the rotating drum 11 in Figure 4, and Figures 4 to 6(a) to 6(c) are for capturing image information. This is for explaining a series of operations including the feeding state of the paper sheet 7 and the change in the position of the rotating drum 11.

First, until the paper sheet 7 reaches the reading position of the image sensor 1 (the position shown in FIG. 4A), the drum 11 rotates once, as shown in FIG. Rotate and position in the direction of arrow B so that the In other words, the background color is set to black.

In this state, when a sheet 7 is fed from the left to the right in the figure, the outline of the sheet can be easily detected because the background color is black and the sheet 7 is white.

Simultaneously with the axis detection, the rotary drum 11 is rotated in the direction of arrow B to make the background color white as shown in FIG. 6(a), even if the paper sheet 7 is thin. , it is possible to avoid being affected by unevenness in paper sheeting.

Thereafter, while capturing the image information on the paper sheet 7, the rotating drum 1
1, the rotating drum 11 is stopped at the position shown in FIG. 6(b), and the paper'! Wait for the rear end of J7 to arrive.

The trailing edge of the sheet 7 is detected by a detector indicated at 8 in FIG. A rotation command is given to the rotary drum 11 a predetermined time after the detector 8 detects the absence of paper sheets. This is because the background color must be black in order for the image sensor 1 to detect the trailing edge of the sheet 7. The trailing edge of the sheet 7 overlaps the black portion of the rotating drum 11. In order not to interfere with the capture of the image information on the paper sheet 7,
As shown in FIG. 6(c), it is desirable to have as little as possible.

According to the device shown in Example 2, the background color changes depending on the state of the paper sheet (starting edge, middle part, trailing edge, etc.), and when detecting the presence or absence of a paper sheet, the background color is changed to black. When reading image information on a sheet of paper, by setting the background color to white, there is an effect that a stable binary output signal can be obtained regardless of the thickness of the sheet of paper.

In the above embodiment, the number of black and white pairs on the rotating drum 11 is one, but there may be multiple pairs, and a structure in which a flat plate is moved left and right instead of the rotating drum 11 may be used. Needless to say, it is fine.

〔Effect of the invention〕

As described above, according to the present invention, in a photoelectric conversion device that photoelectrically converts an image pattern on a medium using an image sensor, a means for detecting the presence or absence of the medium and a means for controlling the background color of the medium are provided, The control means switches the background color to black when the detection means is not detecting the medium and to white when the detection means is detecting the medium, so that the outline of the medium can be detected reliably. It is possible to realize a photoelectric conversion device that can prevent false information from being taken in with thin media and improve reading accuracy. It has a remarkable effect.

[Brief explanation of the drawing]

Figure 1 is a block diagram of the photoelectric conversion circuit, Figure 2 is a diagram showing changes in the output signal of the image sensor depending on the thickness of the paper sheet, Figure 3 is a diagram showing the procedure for obtaining a binary signal, and Figure 4 is a side sectional view showing the main parts of a photoelectric conversion device which is an embodiment of the present invention,
FIG. 4 is a perspective view of the rotary tram, and FIGS. 6(a) to 6(C) are diagrams for explaining the operation of the embodiment. 1: Image sensor, 2: Amplifier, 3: Binarization threshold generation circuit, 4: Comparator, 7: Paper sheet, 8: Paper sheet presence/absence detector, 10: Paper sheet guide, 11: Rotating drum, IIA
: White part, 11B=black part. Fig. 1 Fig. 10 Fig. 2 Fig. 1 Fig. 3 Fig. 4 Fig. 5 Fig. 113 Fig. 6 (a) (b) (c) Procedural amendment (formality) Indication of case 1981 Patent Application No. 209029 Title of the invention
Connection between photoelectric conversion device correction person and decoy Patent applicant Otoya! 5101 Co., Ltd. (11 Hitachi, Ltd.) Subject of amendment Amendment to the brief description of drawings in the specification
Contents: Amend page 8 of the specification as shown in the attached sheet [Effects of the Invention] As described above, according to the present invention, in a photoelectric conversion device that photoelectrically converts an image pattern on a medium into an image sensor, means for detecting the presence or absence of the medium, and means for controlling the background color of the medium, and the control means causes the background color to be black when the detecting means is not detecting the medium, and when the medium is being detected. Since the background color is switched to white, the photoelectric conversion device can reliably detect the outline of the medium, prevent false information from being captured on thin media, and improve reading accuracy. The use of a thinner medium has the remarkable effect of reducing the cost of the medium. 4 Brief explanation of drawings

Claims (1)

[Claims] (1) A photoelectric conversion device that photoelectrically converts an image pattern on a medium using an image sensor, comprising means for detecting the presence or absence of the medium and means for controlling the background color of the medium,
A photoelectric conversion device characterized in that the control means switches the background color to black when the detection means is not detecting a medium, and to white when the detection means is detecting a medium.