JPS6211368A - Optical reading device - Google Patents

Abstract

PURPOSE:To reduce noise remaining in output signals and obtain signals of high SN ratio by sending a head in the direction of main scanning at every length of photodetecting elements of an image sensor and repeating reading. CONSTITUTION:Light emitted from a light source 20irradiates the reading face 19 of an original 13 and reflected light is condensed in equivalence in photodetecting elements 24 by a lens 21, scanned at every clock signal and signals of each photodetecting element 24 are outputted to an output signal terminal. Accordingly, reading of one line for the length of the element 24 is performed. Then, an optical head 15 is sent in the direction of main scanning by the length corresponding to the length of reading, and similar reading is performed. Thereby, reading of one line of the original 13 in the direction of main scanning is completed plural times repeatedly. Then a platen 12 is driven and the original 13 is fed by one line and similar reading operation is executed. thus, the original 13 is read in the direction of sub-scanning. As the number of elements 24 of sensor 22 is small and variance at the time of manufacture is small, a probability for one of elements 24 becoming unable to work is small.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an optical reading device that optically reads information on the surface of a document.

2. Description of the Related Art Conventionally, in bar code reading, facsimile, etc., reflected light from the surface of a document is received by a light receiving section, and changes in the amount of reflected light are detected to read information on the surface of the document. The sensor used in such an apparatus uses a CCD or MOS array with a long optical path length, and requires a reduction lens to form an image of reflected light from the document surface onto a light receiving section with high precision. Therefore, it has the disadvantage that the device cannot be miniaturized.

For this reason, in recent years, close-contact image sensors have been used that detect light reflected from the surface of a document by forming a same-magnification image, thereby reducing the size of the apparatus. This close-contact type image sensor includes an "r sandwich type" and a "planar type".

First, as a sandwich-type image sensor, the 5th
It is constructed as shown in FIG. 6 and FIG. That is,
Sputtering onto insulating substrate 1.

A large number of lower electrodes 2 made of Cr are formed by patterning, a photoelectric conversion layer 3 made of a-8i is deposited to a thickness of 1 μm by P-CVD, and a transparent electrode 4 made of an ITO film that acts as a common electrode is formed on this. Deposit a film. In this way, the light receiving elements 5 in which the photoelectric conversion layer 3 is sandwiched between the lower electrode 2 and the transparent electrode 4 are arranged in an array.

However, in this sandwich-type image sensor, if a pinhole occurs in the photoelectric conversion layer 3, the lower electrode 2
If the number of light-receiving elements 5 is increased, it is difficult to manufacture without short-circuiting across all bits, and if the number of pixels is decreased, since this sandwich type is a charge storage type, However, it has the drawbacks that it does not take a long storage time, does not have a large contrast ratio, places a burden on the circuit, and increases cost. That is, in this storage type image sensor, it takes 1.51x-sec to reach the saturation time. Practically, Q,
It is operated at 21x-sec. Since the illuminance irradiated to the sensor part is about 1001x, the driving frequency is 2 m5ec, and the reading speed is 2 m5ec.
/1ine cycle.

For this reason, a planar type has been considered in order to eliminate the drawbacks of the sandwich type described above. As shown in FIG. 7, this planar type has C
The common electrode 7 and a large number of individual electrodes 8 are patterned using r. A photoelectric conversion layer 9 made of A-8I having a thickness of 1 μm is deposited on this patterned area to form a light receiving element 10. This type of planar image sensor is
Since this method detects the magnitude of photocurrent as a signal when the photoelectric conversion layer 9 is irradiated with light, it has the advantage of fast reading time. That is, the background color of the original is white, the text portion is black, the light reflected from the original is bright and dark, and the rising time from bright to dark corresponds to the reading speed. This rise time is Q, about 5 m5 ec, and a period of about 0.5 m5 ec is possible. Therefore, it can be read faster than the sandwich type.

Problems to be Solved by the Invention In such a planar image sensor, an error in the electrode spacing between the individual electrode 8 and the common electrode 7 has a large effect on its output, so it is necessary to use accurate etching technology to manufacture it. is necessary. In other words, it is important in manufacturing to reduce the variation in electrode spacing throughout the arrangement direction.
It is extremely difficult.

For example, when reading the surface of an A4 size document using an image sensor with a sensor array density of 8 dots/ll11, assuming that the document length is 210 mm and a margin of 3 m on the left and right sides is added, 216 x 8 = 1728 (dots). , 1728 light receiving elements 10 are required.

When such a large number of light-receiving elements 10 are provided, if even one of the light-receiving elements 10 becomes defective, the entirety becomes defective, resulting in low reliability, high cost per component, and equipment failure. The problem is that it is expensive.

Furthermore, planar image sensors have a large impedance, which causes noise generation and a decrease in output due to wiring for detection processing.

SUMMARY OF THE INVENTION An object of the present invention is to obtain an optical reading device that is highly reliable and less susceptible to noise.

Means for Solving the Problems An optical head having a planar image sensor equipped with a one-dimensional light receiving element is moved intermittently in the main scanning direction. As a result, the length of the light-receiving element in the main scanning direction can be shortened by the amount of intermittent feeding, and the shielding material including the substrate on which the driving elements are arranged together with such an image sensor can be reduced. It is placed inside a case formed by.

Since the length of the light-receiving elements of the working image sensor in the main scanning direction is short, the number of light-receiving elements is small, and this makes it possible to reduce variations in the number of light-receiving elements, making it easy to manufacture and producing products of stable quality. Since the drive element is also housed inside the case made of shielding material, the influence of noise is small and the SN
It is possible to improve the ratio.

Embodiment An embodiment of the present invention will be explained based on FIGS.
is provided, and a document 13 is guided by this platen 12. A guide shaft 14 parallel to the platen 12 is provided facing the original 13, and an optical head 15 is attached to the guide shaft 14 so as to be able to reciprocate.

A portion of a wire 17, which is passed between pulleys 16 provided on the left and right sides, is connected to the optical head 15, and is driven by a drive section (not shown). This wire 17
The suspended boot 1J16 is connected to a motor (not shown), and the wire 17 serves as a means for feeding the optical head 15. The optical head 15 has a case 18 made of a shielding material, and a light source 20 for illuminating the reading surface 19 of the original 13 is attached to the outside of the case 18 on the original 13 side.

Further, inside the case 18, a lens 21, an image sensor 22, and a substrate 23 are provided. The image sensor 22 has a one-dimensional planar shape, and its al
, a2...a are arranged in a line in the main scanning direction. The length of the light receiving element 24 is 1/n of the length of the reading surface 19 in the main scanning direction. A power source 25 is connected to the light receiving element 24, and T□, T2...
- A drive element 26 labeled T6 is connected. These drive elements 26 have SSs that are sequentially opened in response to a clock signal.

. . . An analog switch 27 labeled S... is connected. These analog switches 27 are connected to one output signal terminal 28.

In such a configuration, the light emitted from the light source 20 illuminates the reading surface 19 of the original 13, and the reflected light is reflected by the lens 2.
1, the light is focused on the light receiving element 24 at the same magnification. The signals from each light receiving element 24 are outputted to the output signal terminal 28 by scanning each clock signal. That is, the light receiving element 24
One line of length is read. Next, the optical head 15 is moved in the main scanning direction by a length corresponding to the reading length, and reading is performed in the same manner. In this way, reading of one line in the main scanning direction of the original 13 is completed by repeating the reading a plurality of times.

Next, the platen 12 is driven to feed the original 13 by one line, and a similar reading operation is performed.

In this way, the original 13 is sequentially read in the sub-scanning direction, but the number of light-receiving elements 24 of the image sensor 22 attached to the optical head 15 is small, and there is little variation in manufacturing, and one of the light-receiving elements 24 is The probability of it becoming inoperable is also low. Therefore, its reliability is high.

Further, the driving element 26 is the light receiving element 2 of the image sensor 22.
4, and is provided inside the case 18 formed of a shielding material, so there is less noise on the output signal and a signal with a high S/N ratio can be obtained.

Effects of the Invention In the present invention, as described above, the light receiving elements of an image sensor are arranged in the main scanning direction to form an optical head, and this optical head is intermittently fed in the main scanning direction, so that the number of light receiving elements is reduced. It is possible to reduce the probability that each light receiving element will be defective, thereby increasing its reliability. By providing these in the optical head, it is possible to prevent noise from entering the optical head, and furthermore, by housing them in a case made of a shielding material, the influence of noise can be further eliminated.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional side view of essential parts showing an embodiment of the present invention, FIG. 2 is a plan view of the whole, FIG. 3 is a front view of the optical head with the light source omitted, and FIG. 4 is an electric circuit diagram. FIG. 5 is a plan view of a sandwich-type image sensor, and FIG. 6 is a cross-sectional view thereof.
FIG. 7 is a plan view of a planar image sensor. 15... Optical head, 17... Wire (feeding means)
, 18... Case, 19... Reading surface, 20... Light source, 21... Lens, 22... Image sensor, 2
3... Board. 24... Light receiving element, 26... Driving element J, 1 Figure 37 Country name 3 J) LL Figure 1 735 Ho J Figure 7 b

Claims (1)

[Claims] 1. A planar image that includes a light source that illuminates the reading surface, a lens that collects the reflected light from the reading surface, and a one-dimensional light receiving element that detects the light from this lens at the same magnification. an optical head mounted with a sensor, the light receiving elements of the image sensor being arranged in the main scanning direction, and a feeding means for intermittently feeding the optical head in the main scanning direction for each length of the light receiving element of the image sensor. An optical reading device characterized by: 2. A planar image sensor equipped with a light source that illuminates the reading surface, a lens that collects reflected light from the reading surface, and a one-dimensional light receiving element that detects the light from this lens at the same magnification, and this image sensor. An optical head mounted with a substrate on which a driving element for light detection of the light receiving element is arranged is provided, the light receiving element of the image sensor is arranged in the main scanning direction, and the optical head is moved along the length of the light receiving element of the image sensor. An optical reading device characterized in that it is provided with a feeding means that feeds intermittently in the main scanning direction. 3. A planar image sensor equipped with a light source that illuminates the reading surface, a lens that collects reflected light from the reading surface, and a one-dimensional light receiving element that detects the light from this lens at the same magnification, and this image sensor. a substrate on which a drive element for light detection of the light receiving element is disposed, and an optical head disposed in a case in which at least the image sensor and the substrate are formed of a shielding material; an optical reading device, characterized in that the optical head is arranged in the main scanning direction, and is provided with a feeding means for intermittently feeding the optical head in the main scanning direction for each length of the light receiving element of the image sensor.