JPS62128609A - Binarization circuit - Google Patents

Abstract

PURPOSE:To obtain a signal having the exact 1//2 amplitude value compared with an input signal by providing a delay element having its end of one side connected to an input terminal via a matching resistance with the other end kept open and a comparator which compares the voltage between both ends of the delay element. CONSTITUTION:The photodetecting signal given from a photodetecting element is transmitted to a terminal 30 and then an amplifier 31 and turned into an input signal. An end (matching terminal X) of a delay element 32 is connected to the amplifier 31 via an impedance matching resistance R2. While the other end (open terminal Y) is connected to the positive input side of the 1st comparator 33. The negative input side of the comparator 33 is connected to the terminal X. The comparator for voltage between both terminals X and Y is connected to the element 32 to obtain the cross points A and B between the 1st and 2nd delay signals (i) and (j). These points A and B show exactly the 1/2 amplitude value of the input signal. In other words, both points A and B show the edge positions of the objects to be measured when this binarization circuit is used to a scan type optical outer diameter measurement instrument.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a binarization circuit, and in particular to a scanning optical type that measures the outer diameter of an object in a non-contact manner by scanning a light beam of a laser beam. The present invention relates to a binarization circuit that can accurately detect edges of an object to be measured in an outer diameter measuring instrument.

[Conventional technology]

Since a scanning type optical outer diameter measuring device can measure the outer diameter without contact, it is often used when the object to be measured is a moving object, a high-temperature object, or the like. The principle of this scanning type optical outer diameter measuring device will be explained below based on FIG. 4.

The laser beam projected from laser tube 1 is fixed mirror 2
The beam is reflected by the rotating mirror 3 and converted into a scanning beam. The scanning beam is converted into a parallel scanning beam by the collimator lens 4, and scans the object to be measured 6 placed between the collimator lens 4 and the condenser lens 5 at high speed. At this time, the outer diameter of the object to be measured 6 is measured from the length of the dark or bright portion of the parallel scanning beam caused by the shielding of the object to be measured 6.

That is, the brightness or darkness of the parallel scanning beam due to the shielding of the measurement object 6 is detected as a change in the output signal a of the light receiving element 7 placed at the focal position of the condenser lens 5. This output signal a is amplified and binarized by an amplifier 8 and transmitted to a segment selection circuit 9. The segment selection circuit 9 transmits the output signal of the light receiving element 7 to the gate circuit 10 for only t while the measurement target 6 is being scanned. Since the clock pulse CP from the clock pulse oscillator 11 is also input to the gate circuit 10, the gate circuit 10 transmits the clock pulse P at the scanning time t corresponding to the outer diameter of the object 6 to be measured to the counting circuit 12. The counting circuit 12 counts the input clock pulses P and transmits the counted value to the display 13. The display 13 displays the measurement target 6 based on this count value.
Display the outer diameter of

As shown in FIG. 5, there is a problem when using such a scanning type optical outer diameter measuring instrument, as shown in FIG. The question is which part of the object to be measured 6 is recognized as an edge. Conventionally, this problem has been dealt with using the following method.

First, the first method is called a fixed threshold method, in which the threshold value A is fixed and the output signal a of the light-receiving element 7 exceeds the threshold value A, as shown in Figure 6 (al). However, in this method, when the output signal a of the light-receiving element 7 fluctuates due to various factors, as shown in FIG. Nevertheless, the amplitude of the output signal a° of the light receiving element 7 fluctuates, and when this signal a° is binarized, an error Δt may occur, resulting in erroneous measurements.

Next, the second method is called a peak level method, and is usually carried out using a circuit as shown in FIG. In this circuit, an amplifier 15 is connected to a terminal 14 to which the output signal a of the light receiving element 7 is transmitted, and a peak hold circuit 16 and the positive input side of a comparator 17 are connected to the output side of the amplifier 15. The output side of the peak hold circuit 16 is grounded via resistors R+ and R+. Resistance R+,
The midpoint of R+ is connected to the negative input side of comparator 17. The output side of comparator 17 is connected to terminal 18 .

With this configuration, as shown in FIG. 8, the cross point of the signal C of the amplitude value of the output signal of the amplifier 15 (see FIG. 7) is connected to the edge of the object to be measured 6. Assuming this, an output pulse d having a pulse width corresponding to the outer diameter of the object 6 to be measured is obtained. That is, the peak value 2 of the output signal of the amplifier 15 is regarded as the output value at the edge position of the object 6 to be measured. However, in this method, the peak value of the output signal d is not known at the rising edge of the output pulse d. Therefore, it is impossible to specify the signal C, which is the amplitude value of this signal No. 2, and it is impossible to determine the cross point, which is the rising point of the output pulse d. Therefore, the signal C is obtained by assuming that the peak value of the output signal S is constant for each scan. However, this assumption does not hold true due to variations in the light source, etc., variations in background light, etc., and the measurements include considerable errors. This error becomes a fatal defect when precision in measuring the outer diameter of the object to be measured 6 is required to the level of several μm.

As a technology that can meet such requirements,
There is a method called a second-order differential method disclosed in Japanese Patent No. 114456. This method uses the output signal a of the light receiving element 7.
The outer diameter of the object to be measured 6 is measured by second-order differentiating the value and detecting the interval between zero cross points. This method will be explained below.

As shown in FIG. 9, the output signal a of the light receiving element 7 is
4 and is amplified by an amplifier 15, and then differentiated by a first-order differentiator 9 and a second-order differentiator 20.

The zero-crossing point of the second-order differentiated signal is detected by a zero-crossing point detection circuit 21, and based on this, the outer diameter of the object to be measured 6 is determined by a signal processing circuit 22. The zero cross point detection circuit 21 has a circuit configuration as shown in FIG. terminal 2
3 is transmitted with the output signal of the second-order differentiator circuit 20 (see FIG. 9), and this signal is transmitted to the comparator 210. The comparator 210 corresponds to the zero cross points of the second-order differential signal (corresponding to the distance from edge to edge of the measurement object 6).
A pulse f as shown in FIG. 11 (fl) is output. This pulse f and a clock pulse e of the lock pulse generator 211 as shown in FIG.
The ND gate 212 transmits an output pulse g as shown in FIG. 11(g) to the signal processing circuit 22.

Therefore, when the signal processing circuit 22 counts the output pulses g corresponding to the zero-crossing points, the time width between the zero-crossing points can be determined, and therefore the outer diameter of the measuring object 6 can be determined.

[Problem that the invention seeks to solve]

However, this second-order differential scanning type optical outer diameter measuring device requires two devices to detect the zero-crossing point, so two differentiating circuits must be provided, which complicates the circuit configuration. There was a problem.

SUMMARY OF THE INVENTION An object of the present invention is to provide a binarization circuit with a simple circuit configuration, which can accurately measure edges of a measurement object in a scanning type optical outer diameter measuring instrument.

[Means for solving problems]

A specific means for solving the above problems and achieving this objective is to use a delay element whose one end is connected to the terminal through which the input signal is transmitted through a matching resistor, and the other end is open. And, the binarization circuit is configured to include a comparator that compares the voltages across the delay element.

[For production]

The effect brought about by implementing this means will be explained based on FIG. 2. An input signal from a light receiving element or the like transmitted to the terminal is transmitted to the delay element via an impedance matching resistor connected to one end of the delay element. In this case, since the impedance of the other end of the delay element is open and the one end is in a matching state, a transmission signal having an amplitude value of 2 of the input signal is generated at the other end of the delay element. This transmission signal is transmitted for a certain period of time t by a delay element.
The signal is delayed by d and transmitted to the other end (open end) of the delay element which is in the open state. At this time, the transmitted signal is totally reflected at this open end, and a first delayed signal i having an amplitude value twice that of the transmitted signal (the same amplitude value as the input signal) is generated. On the other hand, at one end (matching end) of the delay element in a matching state, the rising edge of the protrusion j°, where the transmission signal totally reflected at the open end and the transmission signal transmitted from the terminal are superimposed, is the first delay. A second delayed signal j is generated which is further delayed by a certain period of time td from the signal i.

Therefore, by connecting a comparator that compares the voltages at the matching end and the open end to the delay element, the first delay signal i and the second delay signal
Cross points A and B of delayed signal j can be obtained. These cross points A and B accurately indicate the amplitude value of A of the input signal. That is, when this binarization circuit is used in a scanning type optical outer diameter measuring instrument, the cross points A and B indicate the position of the edge of the object to be measured.

〔Example〕

This invention will be explained in detail below based on examples. Note that explanations of parts that are the same as those in the conventional example are omitted. 1st
As shown in the figure, the light reception signal from the light receiving element is transmitted to the terminal 30.
After being transmitted to the amplifier 31, it becomes an input signal.

One end (matching@X) of a delay element 32 is connected to the amplifier 31 via a resistor R2 for impedance matching. The other end (open end Y) of the delay element 32 is connected to the positive input end of the first comparator 33, and the negative input side of the first comparator 33 is connected to the matching end X.

The matching end X is also connected to the negative input side of the second comparator 34 and the positive input side of the third comparator 35.

The positive input side of the second comparator 34 and the negative input side of the third comparator 35 are connected to the reference voltage source 36 through a resistor R3 or through resistors R3 and R1, and a resistor R4.
and R1 or is grounded via resistor R3. The output sides of the second comparator 34 and the third comparator 35 are connected to an AND gate 37, and the output side of the AND gate 37 is an A
Connected to ND gate 38.

The output side of the AND gate 38 is connected to an OR gate 40 whose other input connection is an inverter 39 connected to the output side of the second comparator 34. The output side of the OR gate 40 is connected to a terminal 41 for transmitting the output signal of this binarization circuit to an external device.

The operation of this embodiment having the above circuit configuration will be explained based on FIG. 3 while referring to FIGS. 1 and 2.

Incidentally, the alphabets in FIG. 3 correspond to the alpha vents of the signals of each part in FIG. 1.

The input signal, which is a signal obtained by amplifying the light-receiving signal of the light-receiving element, generates a transmission signal h (see FIG. 2) having an amplitude value of 2 of the input signal at the matching end X.

This transmission signal is delayed by a predetermined time td by the delay element 32 and transmitted to the open end Y. At the open end Y,
The transmitted signal is totally reflected, and as shown in FIG.
(same amplitude value as the input signal) occurs.

On the other hand, at the matching end
Therefore, the second delayed signal j further delayed by a certain period of time td
occurs. These cross points A and B of the first delayed signal i and the second delayed signal j accurately indicate the two amplitude values of the input signal.

The first comparator 33 inputs the first delayed signal l and the second delayed signal j, and outputs a pulse signal l as shown in FIG. 3+11. This pulse signal p fluctuates in magnitude at two partial ports where the first delayed signal l and the second delayed signal j are superimposed.
Outputs a noise pulse. Therefore, in order to remove this noise pulse, a circuit other than the circuit according to the present invention described above is required. That is, the second comparator 34 and the third comparator 35 detect the cross point A as shown in FIG.

Thresholds C and 2 are set above and below B, respectively. When the second delayed signal j exceeds the threshold value 2, the output signal n of the third comparator 35 becomes HIGI+, as shown in (n) of the figure. This signal n eliminates the noise pulse in the mouth portion that is output when the first delayed signal l and the second delayed signal j are superimposed without exceeding the threshold value 2. Then, when the second delayed signal j exceeds the threshold value C, as shown in FIG.
The output signal m of the second comparator 34 becomes LO-. The AND gate 37 to which both signals m and n are input ignores the noise pulse of the mouth area that is output when the first delayed signal i and the second delayed signal j exceed the threshold value and are superimposed. An output signal 0 as shown in the same figure (01) for p is transmitted to the OR gate 40. Since the OR gate 40 receives the inverted signal of the output signal m of the second comparator 34 as the other input, the first delay inertia i and the second delay signal j are the thresholds. The output signal q as shown in the same figure (ql) corresponding to the outer diameter of the measurement object 6 from which the noise pulse of the mouth part which is output when superimposed exceeding the value C is output from the terminal 41
to communicate.

〔Effect of the invention〕

As is clear from the above description, the binarization circuit according to the present invention includes a delay element whose one end is connected to a terminal through which an input signal is transmitted via a matching resistor, and whose other end is open. Since a comparator is provided to compare the voltages at both ends of the delay element, a signal having exactly each amplitude value of the input signal can be obtained with an extremely simple circuit configuration. Therefore, if the present invention is applied to a scanning type optical outer diameter measuring instrument, the edges of the object to be measured can be detected accurately, and the accuracy of outer diameter measurement can be improved.

[Brief explanation of drawings]

1 to 3 are explanatory diagrams of the binarization circuit according to the present invention. FIG. 1 is a circuit diagram of one embodiment, FIG. 2 is a diagram explaining the principle, and FIG. 3 is the circuit of FIG. 1. 4 to 11 are explanatory diagrams of the conventional example, Fig. 4 is an explanatory diagram of the principle of a scanning type optical outer diameter measuring instrument, and Fig. 5 is a problem with the conventional example. Figure 6 is an explanatory diagram of the fixed threshold method, Figure 7 is a circuit diagram of the peak level method, Figure 8 is an operating waveform diagram of each part of this circuit, and Figure 9 is a diagram of the second-order differential method. Block diagram. Figure 10 is a circuit diagram of the zero cross point detection circuit in Figure 9.
FIG. 1 is an operational waveform diagram of each part of this circuit. 30...terminal, 32...delay element, 33...comparator, R2...matching resistor. Patent Applicant Reed Electric Co., Ltd. Figure 2j' Figure 3 Figure 7 Figure 8 〆1111111 Figure 9 Figure 10 Figure 11 (q)

Claims (1)

[Claims] (1) Equipped with a delay element whose one end is connected to the terminal through which the input signal is transmitted through a matching resistor and whose other end is open, and a comparator that compares the voltages across the delay element. A binarization circuit characterized by: