JPS5918424A - Line sensor driving device - Google Patents

Abstract

PURPOSE:To suppress the fluctuation of the output signal with respect to the fluctuation of input light, by detecting the range of the maximum value of a signal in a specified section from a line sensor, and changing the timing of scanning start pulses. CONSTITUTION:An output signal 15 from a line sensor 3 is amplified and applied to a sample and hold circuit 5. A signal 16 from the circuit 5 or a signal 17, which is obtained by converting the signal 16 into a digital quantity by an AD converter 6, is inputted to a control circuit 19. The signal 17 is also inputted to a memory 18. The output of the circuit 19 is applied to a timing generating circuit 2 for the sensor 3. At first, a pulse P1 of a scanning start signal 8 from the circuit 19 is inputted. After a storing time T1, a pulse P2 is inputted. The circuit 19 judges whether the peak of the signal 16 from the circuit 5 is within a specified level or not. When the peak is too small, the next storing time T2 is made longer than the time T1. In this way, the signal from the circuit 5 can be suppressed to a specified level.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a line sensor driving device, and more particularly to a line sensor driving device suitable when the level of human power light changes.

In conventional line sensor drive devices, the accumulation time of the line sensor is either fixed or set to an optimal value by humans observing the output waveform.

Here, the accumulation time is the time during which charges caused by input light and the like are stored in the senna. A block diagram of a conventional example is shown in FIG. In the same figure, accumulation time setting circuit 1
A scanning clock signal 8 for the line sensor 3 is output from the line sensor 3. From the timing generation circuit 2, various scanning signals 9 (for example, 2-phase or n-phase clock signals, reset signals, etc.) for the line sensor 3, sample/halt circuit trigger signals 10. Trigger signal 1 for analog-digital conversion
1. Output circuit trigger signal 12.

The line sensor 3 consists of a part in which a plurality of sensors are arranged in an array, and a part that scans and extracts signals from each sensor. For example, the optical sensor may be a photodiode or phototransistor, and the scanning section may be a combination of a MOS gate and a shift register, or a COD (
A well-known example is one based on a charge coupling element.

The output of the line sensor 3 reduces scanning signal noise,
The signal is input to an amplifier circuit 4 for amplifying the signal, and after being converted into a digital quantity through a sample hold circuit 5 and an analog-to-digital conversion circuit 6, the data is outputted through a data output circuit 7.

When the accumulation time T is changed, the level of the output signal from the lie/sensor 3 changes as shown in FIG. That is, as the accumulation time T increases, the output signal level also increases,
It becomes constant at the saturation value. Even if the power of the input light P is increased while keeping the accumulation time T constant, a region of monotonous increase and a region of saturation occur.

Usually, the accumulation time is set so that the signal value does not saturate and reaches a certain value. In commercial applications, there is little change in the human-powered light P, so once the storage time is set to the optimum value, there is little need to change it frequently thereafter (References Bispectroscopy Research, 30.3 PP177)
-184 ('81) 1°By the way, if the level of the human-powered light P changes frequently (for example, every N1m5 or every 108m), or even if the level of the input light P changes infrequently, the measurement When performing this automatically, known devices have limitations, and some kind of countermeasure is desired.

Therefore, an object of the present invention is to prevent the output signal level from changing much even if the human power light level fluctuates widely,
Another object of the present invention is to provide a sensor array driving device that does not significantly reduce the signal-to-noise ratio of the output signal.

To this end, the present invention detects the maximum value of the output signal from the line sensor, calculates the optimal accumulation time based on that value, and determines the timing to start the next scan, so that the human power light level changes. Also, a good output signal is obtained and the value is stored in the memory.

An embodiment of the present invention will be described below with reference to FIG. Compared to the conventional example shown in FIG.
output 16 or output 17 of analog-to-digital converter 6
A control circuit 19 is added that calculates the optimum accumulation time T based on the .

Further, a scan start signal 8 for the line sensor 3 is inputted from the control circuit 19 to the timing generation circuit 2 .

In FIG. 3, an example of the signals of each part when an element that performs COD scanning is used as the line sensor 3 is shown in the fourth section.
As shown in the figure.

The pulse P1 of the scanning start signal 8 is manually input, and the accumulation time T1
After that, P2 is manually operated. The line sensor 3 is applied with a phototransfer gate clock 9-1, two-phase COD register clocks 9-2 and 9-3, a reset transistor gate clock 9-4, and the like.

The sensor signals accumulated during the time T1 are sequentially output as the line sensor output signal 15 after the pulse P2. A control circuit 19 determines whether the peak of the sample-and-hold output signal 16 is too small, appropriate, or large compared to a predetermined level range. If it is too small, the accumulation time T is used as the next scan start pulse P3.
2 is set to be larger than T1 and output. In this way, the accumulation-scanning is repeated one or more times, and when the peak of the output signal 16 reaches a predetermined level range, the scanning is completed and the measurement end signal 14 is output.

The memory 18 receives a write enable signal 1 in synchronization with the scanning signal 9.
2' and the write address signal 13 are input manually, and the digital data 17 is stored at the desired address. In this way, after the measurement end signal 14, digital signals of a good level are stored in the memory 18, so that the digital signals can be sequentially read out by adding the readout address signal 13'.

Assuming that the period of the two-phase COD register clock is constant,
The time t required to scan the desired number of sensor arrays. is uniquely determined. The above accumulation time T needs to be determined to be larger than to.

The present invention automatically determines the start timing of the next scan, and the period of the scan clock signal (for example, t in FIG. 4).
c) is kept constant. If the cycle of the scanning clock signal is changed to change the accumulation time, in the frame where the cycle is changed, the accumulation time will differ depending on the location of the cell of the line sensor, and a normal signal will not be obtained. However, it becomes normal from the next frame onwards. As the accumulation time becomes longer, the time loss in frames where a normal signal cannot be obtained becomes more severe. On the other hand, if the period of the scanning clock signal is kept constant and the timing of the start of scanning is changed to change the accumulation time, the above-mentioned problem does not occur.

One embodiment of the control circuit 19 is shown in FIG. 5, and the timing thereof is shown in FIG.

When the uncut measurement start signal 40 is input, the scan start signal 8
is output. The first one or several scans are performed to clear the charge on the sensor array (in FIG. 6, the sensor array is cleared in one scan). After 1o, the scanning start signal 8 is outputted again. When the sensor array is scanned,
Analog data 16 or digital data 17 is manually input.

A comparator 22 compares these data with the level setter 21, and if the amplitude of the data is larger than the output of the level setter 21, it outputs 1. The latch circuit 23 is connected to the comparator 2
This circuit latches the output of 2 in synchronization with the clock 20, and when the output of the comparator 22 becomes ``1'', it has the function of holding 11'' until the next set signal 29 is input manually.

The latch circuit 23 is also reset by the measurement start signal 4o. Note that there may be cases where it is desired to limit the waveforms to be subjected to automatic range switching to a part of the signals obtained by scanning the sensor. In that case, instead of the clock 20, a signal obtained by gating the clock 2o so that a pulse is generated only in the target portion may be used.

FIG. 11 shows an example of a configuration for generating a gated clock signal 20-1 by gating the clock 20. A gate signal 41 is generated by manually inputting a gate instruction signal 43 to a gate signal generation circuit. FIG. 12 shows an example of the timing of FIG. 11. FIG. 13 shows an example of the configuration of the gate signal generation circuit 42. The delay time τ1 is set by the gate instruction signal 43-1, and the gate pulse width τ is set by the gate instruction signal 43-2.

The latch circuit 23 outputs a stop signal 26 indicating that the maximum value of the target waveform amplitude has exceeded the output of the level setter 21. The accumulation time designation circuit 24 is composed of a counter and a decoder. The counter is reset by the measurement start signal 4o, and counts up if the stop signal 26 is ``OI'' at the rise of the reset signal 29.The counter value is 0.1, 2, 3, 4.5.
Correspondingly, 24 built-in decoders are configured so that the accumulation time designation signals are 1.1, 2, 4, 8°16.

The timer 25 outputs the scan start signal 8 in response to the measurement start signal 40 and latches the accumulation time designation signal 27 at the same time, and starts the reference scan period t. After a time corresponding to the product of , and the accumulation time designation signal, the scan start signal 8 is output again. Note that when each scan is completed, a reset signal 29 is output, and at the rising edge of this reset signal 29, the accumulation time designation signal is latched again, and the same operation is performed thereafter. Then, the stop signal 26 is manually input and the timer 25
stops working. The end signal generating circuit 28 is a circuit that generates the end signal 14 which becomes 0" along with the measurement start signal 40 and becomes 1" at the falling edge of the stop signal.

Here, a case has been described in which the accumulation time is changed every two times, but it goes without saying that it may be changed every three times or every ten times (9).

Furthermore, if the light input level becomes weaker and the storage time increases significantly, the dark current of the line sensor will increase, which will have an adverse effect. In this case, it is effective to cool the line sensor to reduce dark current.

Another embodiment of the control circuit 19 is shown in FIG. 7, and the timing thereof is shown in FIG. It consists of a peak holding circuit 30 that holds the peak value of the digital input data 17, an accumulation time designation circuit 24' that specifies the accumulation time based on the peak value 31, and a timer 25'. The peak holding circuit 30 is reset by the measurement start signal 40 and the reset signal 29,
The clock 20 sequentially outputs the peak values of the human input signals.

The accumulation time designation circuit 24' latches the peak value signal 31 at the rise of the reset signal 29 and outputs the accumulation time designation signal 33. An example of the relationship between the peak value signal 31 and the accumulation time designation signal 33 is shown in FIG.

In the case of Figure 5, the accumulation time designation signal is
In the example of Fig. 7, (10) XI/2. X2. X4. X8. X16. Changes to one of X32. Therefore, the optimum range is reached quickly. For example, to reach 32to, five scans are required in the example of FIG. 5, while two scans are required in the examples of FIGS. 7 and 9. As mentioned earlier, when the measurement start signal 40 is input manually, the sensor array is first scanned once or several times to clear the charge, but this scan is not included in the above comparison. There are no people.

The timer 25' is reset by the measurement start signal 40 and set to the reference signal t0. After that, the time that is the product of the accumulation time designation signal 33 and the previous setting value of the timer is
The timer 25' is set at the rising edge of the scan start signal 8. Then, the scanning start signal 8 is output again after a set time.

In the example shown in Fig. 9, excluding the period for clearing the sensor charge, only 3 scans are required and relatively slow operation from 1o to 1024Xto is sufficient, so operation by the software of the microcomputer (11) can be used instead. .

FIG. 9 shows an example of a configuration when the wavelength of the laser diode 35 is measured at high speed and outputted to the display 39 using the present invention. The light from the laser diode 35 enters the slit 37 through the optical fiber 36, is separated by the grating 38, and then forms an image on the line sensor 3. The image corresponds to the emission wavelength of the laser diode and is dispersed onto the line sensor. At this point, a measurement start signal 4o is sent.

Reading the contents of the memory 18 after receiving the end signal 14;
Data processing such as peak detection and data display on the display 39 are performed by a one-chip microcomputer 34 having a large number of human output boards.

When trying to measure the wavelengths of laser diodes with various output powers, with conventional equipment, it is necessary to manually set the accumulation time for each laser diode and measure, making it difficult to increase the speed. By adopting the present invention, it has become possible to automatically set the accumulation time, and it has become possible to measure wavelengths (12) at intervals of 1 second or less or every few seconds, eliminating the need for manpower.

According to the invention, all signals from the line sensor or
The range of the peak value of the signal in the desired section is detected, and the next scan start timing is changed in accordance with the detected range, and the optimum accumulation time is automatically set. Therefore, a signal with a good signal-to-noise ratio can be obtained even when the human power light level changes significantly. Further, the configuration is simple because it is only necessary to change the timing of starting the next scan based on the signal from the line sensor.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing a conventional example, Fig. 2 is a diagram showing the relationship between accumulation time and output signal level, Fig. 3 is a diagram showing the basic configuration of the present invention, and Fig. 4 is a timing example of Fig. 3. Figure 5 showing
The figure shows an example of the configuration of the control (wealth) circuit 19, and FIG.
7 is a diagram showing another example of the configuration of the control circuit 19. FIG. 8 is a diagram showing a timing example of FIG. 7. FIG. 9 is an example of the algorithm of the accumulation time designation circuit. 10 is a diagram showing a system configuration using the present invention. (13) FIG. 11 is a diagram showing an example of a clock gating method.
The figure shows an example of the timing of FIG. 11, and FIG. 13 shows an example of a clock gate circuit. DESCRIPTION OF SYMBOLS 1... Accumulation time setting circuit, 2... Timing generation circuit, 3... Line sensor, 4... Amplification circuit, 5...
- Sample hold circuit, 6... Analog-to-digital converter, 7... Data output circuit, 8... Scanning clock signal, 9... Various scanning signals for line sensor, 18...
-Memory, 19...control circuit. Agent Patent Attorney Toshiyuki Susuda 1 Figure 3 Eye 4 Figure zb 1 Ifl (T/Gen C-"3c;, \ ~ → Sun Excuse me further heat; Pickled lθ Figure 11 Figure 1z Figure Y 13 figure

Claims (1)

[Claims] 1. In a line sensor driving device consisting of a line sensor in which sensors are arranged in an array and a scanning circuit for scanning the line sensor, all signals output from the line/upper/side or a desired section are output. A line sensor driving device comprising: a detection means for detecting a maximum value range of a signal; and a changing means for changing the timing of a scan start pulse based on the detected signal value.