JPS62130478A - Driving system for one-dimensional image detector - Google Patents

Abstract

PURPOSE:To improve the reliability and the resolution of a system without increasing the frequency of a driving pulse at a detector by dividing a detection element to two groups, and performing simultaneously a scanning at every group in parallel. CONSTITUTION:The detection element consisting of a line sensor 4 is divided into two groups, at least, of one element or more alternately, and the scanning at every group is performed simultaneously with a driving circuit 5 in parallel. Signals outputted from each group are quantized at an odd bit side quantization circuit 6 and an even bit side quantization circuit 7 repectively. Quantized two signals are synthesized at a synthesis circuit 8, and one scanning signal can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a driving method for a one-dimensional image detector used in, for example, an optical character reader (OCR) and a barcode reader.

[Conventional technology]

2. Description of the Related Art One-dimensional image detectors in which a plurality of photodetecting elements are arranged in a straight line are used as image detectors in optical character reading devices, barcode readers, and the like.

A conventional driving system for this type of one-dimensional image detector has the configuration shown in FIG. Here, a charge-coupled device (COD) line sensor 2 is used as the -dimensional image detector. This line sensor 2 is composed of a plurality of photodiodes as photodetecting elements arranged on a straight line and a shift register that temporarily stores optical information from the photodiodes. These multiple photodiodes correspond to one bit of the shift register, and the optical information of each photodiode is temporarily stored in the shift register, and then
Serial output from shift register.

The drive circuit 1 generates pulses for driving the line sensor 2. This pulse is a clock pulse that causes the shift register to perform a temporary storage operation and then causes the shift register to perform a shifting operation. Still, the clock pulse is used to control the operation of the quantization circuit 3 and the line sensor 2.
The quantization circuit 3 is supplied to a quantization circuit 3 for synchronizing output signals from the quantization circuit 3.

Line sensor 2 outputs optical information to quantization circuit 3 using pulses from drive circuit 1 .

Therefore, in the quantization circuit 3, the analog signal as optical information from the line sensor 2 is sampled and held, and then binarized into a binary signal.

Here, if one scanning time of the line sensor 2 is T, one period of the drive pulse is t, and the number of photodetecting elements of the line sensor 2 is N, then -scanning time T is It is equal to the time during which information is output from the shift register, and is expressed as T = Nt.

Further, the frequency f of the drive pulse is expressed as f=N/T.

[Problem that the invention seeks to solve]

Therefore, in order to improve resolution, that is, increase the number of photodetecting elements per unit length, it is necessary to increase one scanning time as the number of photodetecting elements increases. However, without increasing the scanning time,
In order to improve the resolution, it is necessary to increase the scanning speed.

In this conventional driving method, it is necessary to increase the frequency of the driving pulse in order to increase the scanning speed.

However, by increasing the frequency, each circuit element will no longer be able to track, and the time for accumulating optical information in the photodiode of the photodetection element will become shorter, making it difficult for the image detector made up of the photodetection element to follow. The problem was that I couldn't do it.

Another method has been considered - dividing the scanning line into multiple parts, detecting each part with multiple line sensors, and composing the detected signals, but this method involves adjusting the optical system at the connection part of the line sensor. And there were problems with complicated mechanical precision.

The present invention was made based on the above circumstances, and an object of the present invention is to provide a driving method for a one-dimensional image detector that improves reliability and resolution without increasing the frequency of the driving pulse of the image detector. do.

[Failure to solve the problem]

In order to achieve the above object, the present invention uses a one-dimensional image detector that alternately divides at least one detection element into two groups and outputs detection information for each group. Scanning is performed in parallel at the same time, the signal output for each group is quantized by a quantization circuit provided for each group, and the two quantized signals are combined to obtain a -scanning signal. be.

[For production]

Using a one-dimensional image detector that alternately divides at least one detection element into two groups and outputs them, the area to be scanned is divided into two in order to simultaneously scan each group in parallel. , there is no need to increase the frequency of the drive pulse. As a result, it is possible to prevent the frequency of the drive pulse from becoming high, so that it becomes possible to follow the elements of each circuit and the one-dimensional image detector.

〔Example〕

Hereinafter, the present invention will be explained with reference to an illustrated embodiment.

FIG. 1 shows a block diagram of an embodiment according to the invention. In this example, a charge-coupled device (C
OD) line sensor 4 is used.

The drive circuit 5 supplies pulses for driving the line sensor 4 to the line sensor 4, and clock pulses for synchronizing each signal to each circuit.

In response to the drive pulse, two detection signals are output from the line sensor 4 to the odd bit side quantization circuit 6 and the even bit side quantization circuit 7.

FIG. 2 shows the line sensor 4 used in this embodiment.

The line sensor 4 is composed of photodiodes 9, which are photodetecting elements, and shift registers 10 and 11 arranged on a - straight line. The photodiodes 9 are divided into two groups for each element: an odd bit side and an even bit side.

Then, the detection information of the photodiodes 9 on the odd-numbered bit side and the even-numbered bit side by the driving pulse from the driving circuit i is
It is temporarily stored in each shift register 10.11. After that, by the clock pulse from the drive circuit 8,
The information of the odd bit side shift register 10 is serially output from the output terminal 6, and the information of the odd bit side shift register 1 is outputted serially from the output terminal 6.
The information of 1 is serially output from the output terminal 7. Since this photodiode 9 is divided into two groups, one on the odd bit side and one on the even bit side, the line sensor 4 scans the two groups in parallel at the same time. output simultaneously as a signal.

The driving method will be explained below using FIGS. 1 and 2. The drive circuit 8 supplies the line sensor 4 with a pulse necessary for driving the line sensor 4. At this time, the odd bit side and the even bit side of the lie/sensor 4 are simultaneously scanned in parallel. Then, the optical information on the odd bit side is sent from the output terminal 12 to the odd bit side quantization circuit, and the optical information on the even bit side is sent from the output terminal 13 to the quantization circuit 7 on the even bit side. It is converted into information. For this reason, it is impossible to synchronize the signals on the odd bit side and even bit side, and the quantization circuit suddenly
Sample holding such as sampling is performed, and then binarization is performed. Then, the signals on the odd bit side and the even bit side, which have become binary information, are combined in a combining circuit 11 to become the original signal of one scanning line. A clock pulse is supplied to the combining circuit 8 from the driving circuit 5 in order to synchronize the signals on the odd-numbered bit side and the even-numbered bit side during synthesis.

The synthesis in this synthesis circuit 11 will be explained below with reference to the time chart shown in FIG.

The odd bit side quantization circuit output signal shown in FIG. 3a is an output signal obtained by processing the odd bit side output signal of the line sensor 4 by the odd bit side quantization circuit 9. The even bit side quantization circuit output signal shown in FIG.
Even bit side output signal of even bit side quantization circuit)0
This is the output signal processed by . The odd bit side clock pulse shown in FIG. 3C is a signal generated in the drive circuit 8 and supplied to each circuit and the line sensor 4. The even bit side clock pulse shown in FIG. 3d is a signal generated in the drive circuit B and supplied to each circuit and the line sensor 4. The odd-numbered bit side clock pulse and the even-numbered bit side clock pulse are out of phase by 180 degrees. The combining circuit output signal shown in FIG. 3e is an output signal obtained by combining the odd bit side quantizing circuit output signal and the even bit side quantizing circuit output signal in the combining circuit 11.

The synthesis circuit 11 receives the output signals of the odd-numbered bit side scaling circuit, the even-numbered bit side quantization circuit output signal, the odd-numbered bit side clock pulse, and the even-numbered bit side clock pulse as shown in FIG. 3 a, b, c, and d. do.

Then, in accordance with each clock pulse, the odd-numbered bit side quantization circuit output signal or the even-numbered bit side quantization circuit output signal is selected, and double-signal synthesis is performed. Therefore, the output of the combining circuit 11 has the waveform shown in the combining circuit output signal shown in FIG. 3e. In this way, the optical information extracted separately on the even-numbered bit side and the odd-numbered bit side are combined into the original signal of one scanning line.

Since the line sensor 4 is divided into an odd bit side and an even bit side, it is possible to scan the odd bit side and the even bit side simultaneously in parallel. Therefore, the number of photodetecting elements can be doubled without increasing the frequency of the drive pulse of the lie/sensor 4, and high resolution can be obtained with this increase in the number of photodetecting elements. However, by alternately dividing odd numbers and even numbers, signal deviations caused by optical system adjustment and mechanical precision can be reduced, and reliability can also be improved because signals are combined in terms of time and distance.

In addition, by dividing the quantization circuit into odd-numbered bits and even-numbered bits, it is possible to prevent the driving pulse from being too high for the elements constituting the circuit to follow.

〔Effect of the invention〕

As explained above, according to the present invention, the elements constituting the -dimensional image detector are divided into two groups, and processing is performed by the quantization circuit provided in each group, thereby eliminating the need to increase the frequency of the drive pulse. By improving the resolution and separating the photodetecting elements for the odd-numbered side and the even-numbered side, adjustment of the optical system and mechanical precision are facilitated, and the reliability of the obtained information is improved.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention, and FIG.
The figure shows a line sensor that outputs information on the even-numbered bit side and the odd-numbered bit side used in one embodiment, and FIG. 3 shows a time chart of each signal in the synthesis circuit shown in FIG. 1.
FIG. 4 is a block diagram of a conventional drive system. 4...Line sensor 5...Drive circuit 6...Odd bit side quantization circuit 7...
・Even bit side quantization circuit 8...Synthesizing circuit agent Patent attorney Noriyuki Noriwa Norio Obetsu Figure 1 Figure 2 Figure 8 Figure 3 2] Figure 4

Claims (1)

[Claims] (1) A plurality of photodetecting elements are alternately divided into first and second sets for each of at least one element, and detection information of the photodetecting elements is temporarily stored for each of the first and second sets. first and second shift registers for shifting, and a first for quantizing signals output corresponding to the first and second sets from the first and second shift registers;
and a second quantization circuit, a synthesis circuit for synthesizing the outputs of the first and second quantization circuits, and a first and second quantization circuit for temporarily storing and shifting the detection information from the photodetection element to the shift register. Equipped with a generation circuit that generates drive pulses to cause the shift register to perform operations in parallel,
A primary method characterized in that detecting elements divided into first and second sets are simultaneously scanned in parallel, alternately for each at least one element, and output signals outputted by this scanning are simultaneously quantized and synthesized. Original image detector driving method.