JPS60193083A - Drive method of optical reader - Google Patents

Abstract

PURPOSE:To read at the same intervals without fail even when the period of a read start signal changes by setting an integral period independently of the period of the read start signal. CONSTITUTION:A signal 13 which is delayed by a constant period T's from a read start signal 10 is generated. A signal 14 obtained by ORing the signal 13 with the start signal 10 is set to a read start signal of an optical reader. Since the delaying period T's is a sum (T's=T+t) of an access time (t) (constant) and an integral time T, the latter is always constant. Thus an object to be read can be read out with the same sensitivity without fail because the integral time T becomes always constant independently of a read start period Ts. A dummy output A is distinguished from a normal output B by sampling an output B after the period T's from the read start signal 10 or by sampling the output B at the moment the shifted signal 13 is received.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for driving an optical reading device that makes full use of IC circuit technology to optically read information with high accuracy.

Conventional configurations and their problems In recent years, technologies related to information processing and storage have been developed as offices become more automated.

Information input units are no exception, and optical reading devices, which are the input units for copying machines, facsimile machines, optical character readers, etc., have basic performance such as high resolution, high sensitivity, and high speed, as well as high performance depending on the application. New driving methods are required to meet these demands.

Higher resolution requires a smaller light-receiving area of the optical sensor (phototransistor, photodiode).
Sensitivity decreases. To solve this problem, high-resolution optical reading devices commonly use a method in which the optical sensor is operated in a charge accumulation mode. In conventional COD optical reading sensors, the accumulated carriers generated by optical excitation in the optical sensor while the transfer gate is closed are transferred to the potential well of the CCD shift register by opening the transfer gate, and then synchronized with the shift clock from the CCD shift register. is read out. In other words, the output is the amount of generated carriers integrated over the time the transfer gate is closed, and is (light intensity x integration time).
is proportional to. A conventional driving method for an optical reading device will be described below with reference to the drawings.

FIG. 1 is a block diagram of an optical reader that reads out the charge stored in a photosensor array by a CCD shift register. 1 is a photosensor array, 2 is a transfer gate, 3 is a CCD shift register, 4 is a transfer gate terminal, 5 is a shift clock terminal, 6 is a video output terminal, and 7 is a charge detector. FIG. 2 is a timing diagram of signals applied to the optical reading device. 10
is the transfer gate signal, 11 is the shift clock (
(shown as a two-phase clock in the figure), and 12 is a video output. T is the period of the reading start signal, t is the time when the transfer gate opens, T is the time when the transfer gate closes, ie, T is the integration time. As described above, the video output is proportional to (light intensity x integration time), and if the integration time (T in FIG. 2) is constant, it is proportional to the light intensity. Assuming that the time t for the transfer gate to open is constant,
The integration time T (Ts-t) changes depending on the reading start period T8. If the reading start period Ts changes, the integration time T also changes, and the sensitivity changes even if the same object is read.

That is, when the reading period Ts is made longer, the sensitivity increases and the output becomes whitish, while when it is made short, the sensitivity decreases and the output becomes blackish. In particular, when obtaining a reading start signal by a second scan, it is impossible to keep the scanning speed constant manually, resulting in a significant error in sensitivity. In addition, the video output after the reading start signal is the information of the previous reading start signal in time, and is output with a one-line delay in time, so that the position of the reading start signal generation position and the output are the same. Another drawback was that it was not guaranteed.

OBJECT OF THE INVENTION The object of the present invention is to provide an optical system that enables a hand scan reading device or the like to maintain constant sensitivity even when the reading start cycle changes and to obtain an output that coincides with the reading start signal in time or position. It is an object of the present invention to provide a driving method for a digital reading device.

Composition of the Invention The method for driving an optical reading device of the present invention uses an optical reading device composed of a plurality of photosensors operating in a charge accumulation mode and a CCD shift register for reading out the charges accumulated in the photosensors. When reading the optical sensor, the transfer gate opens in response to the reading start signal, and the carriers accumulated in the optical sensor are discharged. After that, the transfer gate is closed and the integration operation begins. Then, the transfer gate is opened by a signal delayed by a fixed time Ts' from the reading start signal, and the carriers accumulated in the optical sensor by optical excitation are transferred to the CCD shift register, and the carriers are transferred and read out in synchronization with the lock after Ts' from the reception of the reading start signal. By using such a driving method, even when the reading start period changes such as in hand scanning, a faithful output with a constant sensitivity error can be obtained. is used as a reading start signal, the positional information and the document information of the line corresponding to the positional information can be obtained at the same time.

Description of examples Embodiments of the present invention will be described below with reference to the drawings.

FIG. 3 shows a timing diagram of one driving method for an optical reading device in an embodiment of the present invention. By using such a driving method, all the problems of the conventional example can be solved. Third
In the figure, a certain period of time (Ts
) is generated with a delay of signal 13. The signal 14 obtained by ORing the signal 13 and the reading start signal 1° is used as the reading start signal of the optical reading device.

In this way, the delay time T5' remains constant despite the 100 cycles TB of the read start signal. This delay time Ts is the sum of the access time 1 (constant) and the integration time T ('rs='r+t), so the integration time T is constant. In this way, the integration time T is always constant independent of the reading start period Ts, so that it is possible to always read the object with the same sensitivity. Third
In the figure, the video output is 12 during the reading start period 780.
is output twice as A and B. However, A is a dummy output, and B is a normal output with the same sensitivity.

Therefore, by sampling the B output TB after the reading start signal 10 or by sampling the B output from the time when the shifted signal 13 is received, it is possible to distinguish between the large dummy output and the regular output B. 16 is a differentiated regular output. Therefore, since the integration operation starts after receiving the reading start signal 10, the video output 120B or the output 16 coincides with the information on that line in time. The delayed signal 13 in FIG. 3 can be generated using a monostaple multivibrator 16 triggered by the read start signal 10, as shown in FIG. 4, but it can also be generated using other digital circuits. It can be easily produced. The video output described below will be designated by the differentiated regular output 16 in FIG. FIG. 5 shows the relationship between the reading start signal 10 and the video output 2o according to the conventional driving method, and FIG. 6 shows the relationship between the reading start signal 10 and the video output 2o according to the driving method of the present invention. According to the driving method of the present invention, the video output sensitivity is constant regardless of the reading start period, and it is clear that the sensitivity is consistent even in time.

FIG. 7 outlines a practical application of the invention.

It is also possible to always read with the same sensitivity with the optical reading device 32 only when receiving a reading request signal from the signal processing section 31 at any time.

33 is a read request signal line, and 34 is a video output line. FIG. 8 shows the timing diagram.

A and b are timing diagrams using the conventional driving method, and C is a timing diagram using the driving method of the present invention. 36 is a read request signal from the signal processing section 31, 36 is a read start signal within the optical reading device 32, and 37 is a video output. In FIG. 8a, a reading start signal 36 is generated in an optical reading device 32 in a self-propelled manner. In this case, it is necessary to synchronize the reading request signal 35 from the signal processing unit 31 and the reading start signal 36 in the optical reading device 32, and the video output 37 is also output one line later [Is it necessary to read part J of A? be. It is necessary to generate the read start signal 36 in the optical reader 32 at least twice in synchronization with the read request signal 36 from the signal processing unit 31 using an external trigger type in FIG. It is necessary to read the output (mouth part) after the line.

The above is an example using the conventional driving method, but FIG. 8C shows an example using the driving method of the present invention which solves these problems. Since a shift signal is generated by mono-staple multi-by-break, the read request signal from the signal processing unit 31 can be directly used as the read start signal 36 of the optical reader 32, and the video output 37 is also output immediately after the read start signal 36. It is possible to read out the output [)・part]. By using the optical reading device driving method of the present invention, the signal connection between the signal processing unit 31 and the optical reading device 32 becomes much easier, and it is still possible to easily obtain the video output 37 with the same sensitivity at any time. be able to.

Figures 9 and 1o also give an overview of the practical application.

41 is an object to be read, 42 is an optical reading device, 4
3 is a position detection pattern, 44 is a light emitting element, and 45 is a light receiving element, and these 43, 44, and 45 constitute a position detector. 46 is a rotary potentiometer, which is also used as a position detector. The optical reading device 42 moves manually or automatically as shown by arrow 2,
The information on that line can be optically read by taking No. 15 from the position detector and using it as a start signal. Even if there is a change in the scanning speed in the direction of arrow 2, such as in the case of manual operation, according to the first driving method, the integration time is constant as described above, so reading can be performed with the same sensitivity.

Furthermore, it becomes possible to read information corresponding to the position detected by the position detector. In this example, the position detector is configured with a position detection pattern, a light emitting element, a light receiving element, or a rotary potentilon meter. It is fine as long as it can be obtained.

In addition, in Fig. 3, it was explained that the integration for a certain period of time T is executed immediately upon receiving the reading start signal, but depending on the specifications of the device connected to the optical reading device, etc., the reading signal may be received. A similar effect can also be obtained in a device in which integration for a certain period of time is performed after a certain period of time.

As described in the detailed description of the invention, according to the driving method of the present invention, since the integration time is set independently of the cycle of the read start signal, it is possible to always read at the same interval even if the cycle of the read start signal changes. This excellent effect can be obtained.

Furthermore, the integration operation is started when a reading start signal at any time is received from the signal processing section, and the video signal is output after the desired time (integration time) has elapsed. You can get video output.

In addition, by using the signal from the position detector that detects the position of the object to be read as the reading start signal, even when the scanning speed is not constant such as hand scanning, the video output corresponds to the position detection signal with the same sensitivity. is obtained.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a device that sequentially accesses a plurality of optical sensors, FIG. 2 is a timing diagram of a conventional driving method for an optical reading device, and FIG. 3 is a timing diagram of an embodiment of the driving method of the present invention. , FIG. 4 is a timing diagram and block diagram of an embodiment for creating a shifted read start signal having an integration time independent of the period of the read start signal, and FIG.
6 and 6 are diagrams for explaining the temporal relationship between the reading start signal and the video output according to the conventional driving method and the driving method of the present invention, respectively, and FIG. 7 is the connection between the signal processing section and the optical reading device. Figures 8 and 8 are diagrams showing the temporal relationship between the reading start signal in Figure 7 and the video output, Figures 9 and 10.
The figure is a diagram showing an outline of a device that uses a position detector to read a start signal. 1... Optical sensor array, 2... Transfer gate, 3... COD shift register, 4... Transfer gate terminal, 6...
...Shift clock terminal, 6...Video output terminal, 10...Reading start signal, 31...
...Signal processing unit, 33...Reading request signal line, 41...Reading object, 43...
...Position detection pattern, T...Constant integration time. Name of agent: Patent attorney Toshio Nakao and others
1 Figure 2 Figure 3 Figure 4 DaS 5 Figure 6 Figure 7 Figure 9 Figure 10

Claims (3)

[Claims] (1) In an optical reading device consisting of a plurality of photosensors operating in a charge accumulation mode, a charge-coupled device shift register for reading out the charges accumulated in the photosensors, and a transfer gate for transportation, a voltage is applied to the transfer gate. driving an optical reading device that performs integration for a certain period of time that is set independently of the period of the read start signal after receiving a read start signal, and then reads carriers from the charge-coupled device shift register; Method. (2) A method for driving an optical reading device according to claim 1, characterized in that a reading request signal from a signal processing section provided upstream of the optical reading device is used as the reading start signal. (3) A method for driving an optical reading device according to claim 1, characterized in that a scanning position detection signal on an object to be read is used as a readout start signal.