JPS6025372A - Optical reader - Google Patents

Abstract

PURPOSE:To optimize reading of original information by providing a light sensor detecting the average lightness of light inputted to a light sensor array and changing the threshold value of the sensor array depending on its output signal. CONSTITUTION:The reader consists of a light sensor array 1 for reading, scanning circuit 2, light sensor 3 for setting threshold valve, amplifier circuit 4 for reading signal, amplifier circuit 5 for threshold value setting signal and a voltage comparator 6. The photodetecting section of the light sensor 3 is placed closely to the light sensor array 1 and also formed over the entire lengthwise region of the light sensor array 1 to detect the average light intensity of the sensor face of the light sensor array 1. After the output of the light sensor 3 is fed to the amplifier circuit 5 possible for gain adjustment, the output is fed to a comparator 6 as a threshold value for binary-coding the reading signal.

Description

DETAILED DESCRIPTION OF THE INVENTION Industrial Field of Application The present invention is directed to CCDII! The present invention relates to an optical reading device α using photoelectric conversion elements such as an il-free image sensor, an M-body 5 solid-state image sensor, and a phototransistor array.

The problem with the structure of the conventional optical reading device is that it illuminates the original, receives the reflected light, converts it into an electrical signal, and converts this into an electrical signal. An important requirement of a reading device is that it can clearly read manuscripts of any type and quality.

For example, the manuscript includes a clear printed manuscript, a 91-yen ink printed manuscript, a pencil-written manuscript, a ball-point pen-written manuscript, and the like. Also, even if the original is of the same type, the print density is high and the whole part is black.
;t There are 4 higher grades. There are manuscripts in which different types of printing (1 (J), printing density 1) coexist on the same page.Also, there are various types of paper, and naturally their reflectances are different.

Conventional optical reading devices irradiate light from a light source onto a surface, guide the reflected light through a J!11 light section consisting of a lens, etc., to a reading sensor L, and then sequentially output a city conversion signal. However, it consists of a part that binarizes this and converts it into a digital signal, etc. +IJ 21 rfi conversion digitizes the output signal with a certain threshold.As a result, the white level and black level may differ depending on the quality of the original. Currently, it is difficult to read various types of originals clearly.For example, originals with thin text have a whitish appearance and have a high black level, so they are easily judged to be white, while originals with dark characters tend to have a high black level. The white level is lowered and the image is more likely to be judged as a black level.

OBJECTS OF THE INVENTION It is an object of the present invention to provide an optical reading device that can clearly read documents regardless of their type or quality.

Structure of the Invention The optical reading device of the present invention sequentially reads out signals from each sensor of an optical sensor array for reading a document, compares this No. 48 level with a threshold value, converts it into a bright/dark binary signal, and converts it into a binary signal of brightness and darkness. Average 1 of the light incident on the photo-recording sensor array
] The present invention is characterized in that an optical sensor for detecting noise is provided, and the threshold value is changed in accordance with the output signal of the optical sensor.

DESCRIPTION OF EMBODIMENTS Hereinafter, an embodiment of the Kibatsu J will be described with reference to the drawings.

The drawing shows an imaging section and a signal processing section in an embodiment of the present invention. (1) Optical sensor array for reading, (2) scanning circuit, (3) optical sensor generating signal for threshold setting, (4) reading signal amplification circuit, (5) threshold setting signal (6) is a voltage comparator that binarizes the read signal according to a set threshold value.

Note that at least the optical sensor circuit (1) and the scanning circuit (2)
) and the optical sensor (3) can be formed on a single silicon chip by IC4 or LSI technology.

CCD solid-state virtual image elements generally use optical t-, I+j arrays (
Suha) Odotiode array, its scanning times FP, (2)
is a CCD (charge transfer device), and in the fO5 solid-state image pickup device, the photosensor array (1) is generally composed of a photodiode array (2) and a ViMOS shift register. The light receiving part of the optical sensor (3) approaches the optical sensor array (1) and is formed over the entire head area in the longitudinal direction of the optical sensor array (1), so that the light receiving part of the optical sensor (3) Detects average light intensity. The optical sensor array (υ) is operated in a charge accumulation mode in terms of sensitivity, but since the optical sensor (3) has a light-receiving section that is cylindrical, it is possible to obtain a sufficiently large signal even with direct current.

Next, I will explain the composition in more detail along with Su's work.

In the case of a CCU image sensor, the start pulse is connected to the terminal (
7), the signal charge accumulated in the photodiodes during the integration time is transferred from each photodiode to the respective C
The signal is guided to the charge well of CI) and sequentially transferred to the output terminal (8) by the output terminal (8), and the read signal is output from the output terminal (8) and converted into an easy-to-use signal by the amplifier circuit (4). Appears on terminal (9).

The operation of this CCD is well known. On the other hand, the output of the optical sensor (3) is passed through an amplifier circuit (5) whose gain can be semi-fixedly adjusted, and then connected to the non-inverting input terminal (13).
No. 14 of 9) is applied to the inverting input terminal e of the voltage ratio device (6). Then, a binary signal is obtained at the output terminal OQ.

In the case of a MOS image sensor, when a start pulse is applied to the terminal, a shift register as a scanning circuit (2) starts a shift operation according to a clock pulse, and sequentially accesses each photodiode of the photosensor array (1). The optical proportional electric signal is outputted to the output terminal (8).

The operation of this MOS image sensor V is well known.

The output of the optical meter (3) passes through an amplifier circuit (5) whose gain can be semi-fixedly adjusted, and then the output of the optical meter (3) is outputted along with the read signal output.
The signal is input to a voltage comparator (6) for 11α conversion, and a binary signal is obtained from its output terminal Ql. Amplification circuit (4)
(5) Vi, invert, amplify, and 1 are connected as a single device, so the polarity of the signal is inverted. The function of the optical sensor (3) is that in the case of an averagely bright document, its reflectance is high and is greater than the absolute value e of the output of the amplifier circuit (5).
The threshold 4Kf of the voltage comparator (6) increases.

On the other hand, the output of optical sensor array (1) IIIJ is also IJ
It is thick because the reflectance of i < 槁 is large. In normal binarization with a constant threshold value, the entire document is determined to be at a white level, making it impossible to read the document information. Since the first threshold is automatically changed to a higher value, appropriate binarization corresponding to the white level and black level is performed. In addition, as described in []0, the optical sensor (3) can be easily arranged in a long shape using a single silicon chip 7 in close proximity to the reading optical sensor array (1) using IC or LSI technology. be able to. Optical sensor (
3) can also be easily formed by forming a p/n junction with the substrate by a diffusion method. Historically, the optical sensor (3) is a single sensor, so only two electrodes are required.
The wiring is simple, the average level of the output signal of the optical sensor array (1) can be outputted from time to time, and the threshold value for binarization can be changed from time to time to an appropriate value for the document.

Due to the effect of +3, according to the optical reading device at the end as shown in J, the readout from the original reading light sensor A is
Since the threshold value for converting the signal into a binary signal is changed taking into account the output ID of the optical sensor that detects the average brightness of the light incident on the optical sensor array, the Regardless of the quality or type of document, it is possible to read and understand the information in the manuscript to the best of our ability.

In addition, if the optical sensor is constructed from a long light-receiving section that is placed close to the optical sensor array on the same board as the optical sensor array, wiring is easy and the optical sensor can be easily configured. The average level of the output of the array (i'J'j) can be obtained from moment to moment, and the above-mentioned ζiI6I can be changed to an appropriate value for the original.

[Brief explanation of drawings]

The drawing is a circuit block diagram of an embodiment of an image sensor for reading a document according to the publication No. 1:114. (1)...Sensor assembly for a storage, (2)...Travelling circuit, (3)...Optical center, (4)(5)...Amplification circuit, (6... 111 pressure comparator agent Yoshi Moriki
Hiroshi

Claims (1)

[Scope of Claims] 1. W. A signal is sequentially read out from each sensor of the optical sensor array for reading, and the signal level is compared with a threshold value to convert it into a binary signal of brightness and darkness, and the optical sensor array An optical reading device is provided with an optical sensor that detects the average brightness of light incident on the optical reading device, and is configured to change the threshold value according to an output signal of the optical sensor. 2. A special IRF claim characterized in that the optical screen is constituted by a long single light-receiving section disposed close to the optical sensor array on the substrate of the optical sensor array for reading a document. An optical reading device according to scope 1.