JPH0212492A - Photoelectric converter - Google Patents

Abstract

PURPOSE:To detect the edge and contaminated state by dust, etc., of an object to be read out by providing a reference light reflecting plate in the scanning area of an image sensor. CONSTITUTION:A light reflecting film 12 which is provided in the scanning area in an image sensor 13, arranged so that the plate can reflect reference light when no object to be detected exits in the visual field, and constituted to reflect light having a different wavelength at a specific scanning position is provided. Since a voltage can be obtained to all scanning signals of each wavelength in the area other than the specific scanning area, the part is sampled and used as a reference for AGC. The scanning signal of the wavelength to which no voltage is obtained in the specific scanning area can be used for detecting the edge of the object to be read out. Therefore, the scanning signal having a specific wavelength is obtained over the visual field and the signal can be used for detecting a contaminated part of the object by dust, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Field of Application) The present invention relates to a photoelectric conversion device that photoelectrically converts and reads images on objects to be read, such as paper sheets.

(Prior Art) Conventionally, for example, there has been a photoelectric conversion device as shown in FIG. 7 whose purpose is to detect a printing pattern of a printed matter and determine the type of the printed matter.

In FIG. 7, an illumination unit 71 illuminates a certain field of view, and the reflected light image is transmitted to a color line sensor 7 through an imaging lens 72.
The image is focused on 3.

The printed matter 74 is held between belts 75 and moved in the X direction at a constant speed, and in conjunction with the scanning of the color line sensor 73 in the Y direction, a signal obtained by two-dimensionally scanning the printed matter is obtained.

The output signal of the color line sensor 73 includes RGB color components, and undergoes signal processing (not shown) necessary for determining the print pattern.

Here, in order to obtain highly reliable detection and discrimination performance, the following matters are required of the photoelectric conversion device.

That is, (1) detect and correct changes in signal amplitude due to deterioration of the illumination lamp or dust;

■There is dust on the imaging system or sensor! If so, it will be automatically detected.

■Detect edges of printed matter for signal processing.

Such functionality is required. Therefore, conventionally, a reference light reflection plate 74 is placed in the reading field.

That is, the reference light reflecting plate 74 shown in FIG. 8 is one that has been commonly used in the past, and has a central portion 74a in the y-direction scan indicated by the arrow made of, for example, opal glass, which has a high reflectance, and both end portions 74b are made of opal glass. In order to lower the reflectance, black plating treatment is applied, for example.

The scanning signal in this case becomes a signal as shown in FIG. 10(a). The above-mentioned required function (2) can be satisfied by sampling the voltage at the central portion I and using it for AGC when there is no printed matter. For request ■, scan signal at both ends■,■
Edges can be detected by detecting that the voltage increases (dotted line). In addition, according to requirement (2), dirt such as dust can be detected in the center of the scanning field of view by detecting a voltage drop in the scanning signal, but there is no original signal voltage at either end of the field of view, so there is a problem that dirt cannot be detected. .

On the other hand, a reference light reflector 74' as shown in FIG. 9 is also used, and this reference reflector is made of, for example, opal glass 74C, which has a high reflectance for the entire field of view in the y direction. The required functions ■ and ■ are satisfied, but for ■, the voltage is diverse over the entire field of view, as shown in Figure 10 (b).
There is a problem in that it is not possible to detect edges of printed matter as shown in FIG.

(Problems to be Solved by the Invention) Conventionally, it was not possible to automatically detect the edges of printed matter, changes in the read signal, adhesion of dust, etc. The problem was that it could not be obtained.

[Structure of the Invention] (Means for Solving the Problems) In order to solve the above problems, the present invention uses a photo image sensor that is sensitive to a plurality of wavelengths and has a scanning function, and uses reflected light to scan printed matter, etc. In a photoelectric conversion device that detects a pattern, the photoelectric conversion device is provided in the scanning area of the image sensor, is arranged to reflect the reference light when the object to be detected is not within the field of view, and is arranged to reflect different wavelengths at a specific scanning position. A reference light reflecting plate configured as shown in FIG.

(Function) With the above configuration, since a voltage is obtained for all the scanning signals of each wavelength in a region other than a specific scanning position, this portion is sampled and used as a reference signal for AGC. Scanning signals of wavelengths for which voltage cannot be obtained at specific scanning positions can be used to detect edges of the object to be read. Furthermore, since a scanning signal of a specific wavelength can be obtained over the entire field of view, this signal can be used to detect dirt such as dust.

(Example) An example of the present invention will be shown using FIGS. 1 to 6. 1st
In the figure, an illumination unit 11 illuminates a fixed field of view, and a reflected light image thereof is formed on a color line sensor 13 via an imaging lens 12. The printed matter 14 is held between belts 15 and moved in the X direction at a constant speed, thereby obtaining a two-dimensional scanning signal of the printed matter in conjunction with the scanning of the color line sensor 13 in the Y direction. The output signal of the color line sensor 13 includes RGB color components, which are amplified to a constant voltage by the amplifier 14, and then R and G are separated by the color separation circuit 15.

The signal is separated into B color signals, and the discrimination section 16 performs signal processing necessary for discrimination of the print pattern.

Further, a timing sensor 17 for detecting the arrival of printed matter is arranged on the conveyance path of the printed matter, and the output of the timing sensor 17 is supplied to a timing control circuit 18. The timing control circuit 18 is the timing sensor 1
Line sensor 131 color separation circuit 1 based on the signal from 7
5 controls the operation of the control circuit 16.

The control circuit 16 detects the edges of the printed matter, detects the pattern, determines the type of the printed matter, and determines whether dust has adhered to the optical system or the like. That is, the discrimination circuit 16 is connected to a reference signal generating section 17, and the reference signal generating section is connected to the reference signal generating section for a certain period of time from when the arrival of the printed matter is detected by the timing sensor 17 (until the printed matter arrives in the reading field of view and finishes passing through). Printed matter is discriminated based on the reference signal from 17.

Further, based on the output of the timing sensor 17, when there is no bill present, it is determined whether there is dust or the like attached to the optical system.

2 and 3 are diagrams for explaining the configuration of the reference light reflecting plate 21. The spectral sensitivities R (red F), G (green), and B (blue) of the color line sensor shown in FIG. ) Opal glass 23 that reflects all wavelengths
Place. Further, a sharp cut filter 24 having a transmission characteristic A shown by the chain line in FIG. 4 is attached to the opal glass 23.
The central part of the y-direction scanning field indicated by the arrow reflects light of all R, G, and B wavelengths.

On the other hand, both ends of the scanning field of view in the y direction are connected to the color line sensor R.
, G, and B, only the light of wavelength R is reflected.

Therefore, when the scanning signal of the color line sensor is separated into RlG and B color signals, signals as shown in FIGS. 5 and 6 are obtained.

FIG. 5 shows the signal when there is nothing in the visual field, and FIG. 6 shows the signal when the printed matter P is in the visual field as shown by the dotted line in FIG.

That is, when there is no printed material, an R (red) signal can be obtained over the entire scanning area as shown in FIG.
Green) and (B (blue)) signals can be obtained only in the center of the scanning area.

Also, as shown in FIG. 6, when there is a printed matter, R,
Signals for both G and B can be obtained.

Next, the operation of the above-described configuration will be explained.

Based on the output of the timing sensor 14, the timing control circuit 18 instructs the amplifier 14 to perform gale control. As shown in FIG. 1, when there is no printed material in the field of view, the central part of each color signal is sampled and detected during the AGC sampling (AGT) period of '1' in the AGC circuit 18.Then, the SGC circuit 17 The gain of the amplifier 14 is controlled so that the output of the amplifier 14 is kept at a constant voltage.

Similarly, in detecting the presence of dirt such as dust, as shown in FIG. Signal and reference signal generator 17
The dirt detection level (L d) is compared with the dirt detection level (L d) from dirt detection section 1. II, when R<Ld in m, it is determined that there is dirt.

The edge detection of the printed matter is performed when the bill arrives in the scanning area based on the instruction from the timing control circuit 18 in the same way as described above, and the discrimination circuit 16 receives the B (blue) scanning signal from the reference signal generation section 17. Binarization is performed using the output edge detection level (L e), and if the binary signal Bα changes from "0" to "1" or from "1" to "0' in the edge detection sections ■ and ■, the printed matter It is determined that it is Etsuji.

As described above, the functions required of the above-mentioned photoelectric conversion device can be obtained by the reference light reflection plate having a simple configuration.

Furthermore, in the edge detection, in the above embodiment, the B signal was used and a printed matter with relatively high reflectance and no printing on the edge was assumed. The R signal may be used instead of the signal.

Further, in the embodiment, the reflected light at both ends of the field of view is configured to be only R, but other wavelengths may be used.

In addition, a sharp-cut filter was placed on top of the opal glass, and the transmission characteristics of the filter were used to reflect specific wavelengths. .

[Effects of the Invention] As described above, according to the present invention, it is possible to reliably detect the edges of the object to be read with a simple configuration, and it is also possible to detect dirt such as dust.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing the photoelectric conversion device of the present invention, FIG. 2 is a front view of the reference reflector shown in FIG. 1, FIG. 3 is a side view of the reference reflector shown in FIG. The figure is a characteristic diagram to explain the characteristics of the sharp filter, Figures 5 and 6 are diagrams showing output signals to explain the operation of the photoelectric conversion device, and Figure 7 is a diagram showing output signals to explain the operation of the photoelectric conversion device.
This figure shows a conventional photoelectric conversion device, FIGS. 8 and 9 are front views of a conventional reference reflector, and FIG. 10 is a diagram showing output signals for explaining the operation of the conventional device. 11... Illumination section, 13... Color line sensor 12
...Reference reflector

Claims (1)

[Claims] In a photoelectric conversion device that uses a photo image sensor that is sensitive to multiple wavelengths and has a scanning function to detect patterns on printed materials etc. using reflected light, it is installed in the scanning area of the image sensor and detects objects within the field of view. 1. A photoelectric conversion device comprising a reference light reflecting plate arranged to reflect reference light when the reference light is not present and configured to reflect different wavelengths depending on the scanning position.