JPH0820218B2 - Dimension measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Field of Use of the Present Invention> The present invention relates to a dimension measuring apparatus for sweeping a light beam such as a laser beam to measure the dimension of an object to be measured.

<Prior Art> (FIGS. 6 to 8) In order to measure the outer diameter, edge position, etc. of the object to be measured with high accuracy, a light beam with good directivity such as a laser beam is placed in the space where the object is placed. Conventionally, there has been a dimension measuring device configured to sweep along a measuring direction and receive a light beam blocked by an object to be measured.

 FIG. 6 is a diagram showing the basic configuration of an apparatus of this type.

In the figure, 1 is a light source that outputs a laser beam or the like, 2
Is a deflector for periodically deflecting the light beam from the light source 1 in the direction of the object A to be measured within a range of a predetermined angle φ.

The mirror of this deflector 2 is located at the front focal point of the lens 4, and the light flux reflected by the deflector 2 and passing through the lens 4 is swept parallel to the optical axis of the lens 4 and periodically along the measuring direction Y. Will be done.

Here, when the deflector 2 is a sound or deflector or a vibrating mirror, the position change of the light beam swept in the Y direction changes substantially sinusoidally with respect to time as shown in FIG. 7 (a). .

Therefore, the light reception signal corresponding to the swept light flux that is blocked by the object to be measured A and received by the light receiver 6 through the lens 5 is blocked by the object to be measured A as shown in FIG. 7B, for example. "L" level in the part and "H" level in the unobstructed part.

Therefore, as shown in FIG. 7C, a sine wave signal having the same phase as the position change of the light beam is input from the reference signal generator 8 to the arithmetic unit 7 which subtracts the input voltages of the received light signals at the rising time. If this is done, the outer diameter Ad of the measured object in the Y direction
A subtraction voltage V ₁ −V ₂ corresponding to is obtained.

If the voltage for the object of the standard size is stored prior to this measurement, the outer diameter Ad of the object A to be measured can be obtained from the measurement result subtraction voltage.

Therefore, in the apparatus having such a configuration, particularly when the phase in the actual position change of the light flux and the phase of the reference signal from the reference signal generator 9 do not match, highly accurate measurement cannot be performed.

Therefore, as shown in the main part of FIG. 8, the optical system is configured so that the second swept light flux reflected by the half mirror 11 provided in front of the lens 4 is guided to the light receiver 14 by the lenses 12 and 13. The shield plate 15 for blocking a part of the sweep amplitude of the light beam is provided, and the position change of the light beam coincides with the actual light beam position change in synchronization with the light receiving signal output from the light receiver 14 for each cycle of the position change of the light beam. PLL reference signal generator 16 that outputs a phase reference signal
The applicant of the present application has proposed a dimension measuring device using the above (Japanese Patent Publication No. 63-12523).

That is, the reference signal generator 16 is configured to detect the received light signal and the counter.
The phase from the output from 20 is compared by the phase comparator 17, and the DC voltage corresponding to the phase difference is output from the low-pass filter 18 to the voltage controlled oscillator.
The PLL is configured so that the oscillation pulse is input to the M-ary counter 20 and one pulse output from the counter 20 for each M input pulses is returned to the phase comparator 17, and is referred to in advance. The voltage data is sequentially read by the count value output (for example, 1 to M) of the counter 20 during counting from the memory circuit 21 that stores M voltage data corresponding to one signal period, and is given to the arithmetic unit 7. Is formed.

<Problems to be Solved by the Invention> However, in the reference signal generator 16 configured as shown in FIG. 8, when the measurement resolution is increased, the oscillation frequency of the voltage controlled oscillator 19 and the frequency division of the counter 20 are divided. The ratio must be high.

That is, if the sweep period of the light flux is about 2 milliseconds and two (reciprocal) measured values per period are obtained with a resolution of 1/57000 with respect to the sweep amplitude, the oscillation frequency of the voltage controlled oscillator 19 is about At a frequency of 110 MHz or more, the frequency division ratio of the counter 20 is 2.2 × 10 ⁵ or more. When the frequency division ratio is high and the frequency division ratio is large, it is difficult to obtain good phase followability.

This also applies to the case where the measurement range (sweep amplitude) is expanded with the same resolution.

An object of the present invention is to provide a dimension measuring device that solves such problems.

<Means for Solving the Problems> In order to solve the above problems, the dimension measuring apparatus according to the present invention provides a sweeping light beam that sweeps back and forth in a predetermined direction with a first sweeping light that crosses an object to be measured and a reference object. It is divided into a second sweep light that traverses and is received by the first and second light receiving means, respectively.
Generating a data signal that changes in synchronism with the position change of the first sweep light based on the second light receiving signal output from the first light receiving means of the first light receiving means. A dimension measuring device for measuring the dimension of an object to be measured from a data signal when a state changes, edge detecting means for detecting a state change of the second light receiving signal and outputting an edge pulse, and counting a predetermined clock pulse. A counting circuit that repeatedly performs the clock pulse every time a set number of values are input, and outputs a count value during counting as a data signal that changes in synchronization with the position change of the first sweep light; Each time it receives a count value storage means for temporarily storing the count value of the counting circuit, sequentially receives the count value temporarily stored in the count value storage means, the sweep cycle of the sweep light and its sweep phase are a predetermined phase. To Is obtained, the count output of the counting circuit is initialized at the timing, and a setting value corresponding to the obtained sweep cycle is set in the counting circuit, and the count repetition cycle of the counting circuit is set to the sweep light. A retraction means for synchronizing with the position change of the counter circuit, based on the count value temporarily stored in the count value storage means after the counting repetition cycle of the counting circuit by the retraction means is synchronized with the position change of the sweep light, The phase shift between the counting repetition cycle of the counting circuit and the position change of the sweep light is obtained, and the correction data corresponding to the phase deviation is set in the counting circuit, and the counting repetition cycle of the counting circuit and the position of the sweep light are set. And a correction means for maintaining synchronization with the change.

<Operation> With this configuration, in the dimension measuring apparatus of the present invention, the count value of the counting circuit is changed every time the edge detecting unit outputs an edge pulse corresponding to the state change of the light receiving signal of the second light receiver. The sweep cycle of the sweep light and the timing at which the sweep phase reaches a predetermined phase are obtained from the temporarily stored count value, and the count output of the counting circuit is initialized at that timing and obtained. The set value corresponding to the sweep cycle is set in the counting circuit, and the counting repetition cycle of the counting circuit is synchronized with the position change of the sweep light. Based on the count value temporarily stored in the count value storage means thereafter, the phase shift between the counting repetition period of the counting circuit and the position change of the sweep light is obtained, and the correction data corresponding to this phase shift is stored in the counting circuit. It is set and the synchronization of the counting repetition period of the counting circuit and the position change of the sweep light is maintained.

<Embodiment of the present invention> (Figs. 1 to 4) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of a synchronous data output circuit 30 of one embodiment, and FIG. 2 is a diagram showing the overall configuration of one embodiment, which is the same as the above-mentioned conventional device (FIGS. 6 and 8). The same reference numerals are given to the components and the description thereof will be omitted.

In FIG. 2, a reference object R having a reference size is placed between the half mirror 11 and the lens 12 so as to be crossed by the second sweep light.

The light reception signal from the light receiver 14 as the second light receiving means is
It is input to the synchronous data output circuit 30.

The synchronous data output circuit 30 is based on this received light signal,
It is configured as shown in FIG. 1 so as to output synchronous data synchronized with the sweep light.

In FIG. 1, reference numeral 31 is an edge detection circuit that receives a light reception signal from the light receiver 14 and outputs an edge pulse when its state changes (at the time of rising and falling).

Reference numeral 32 is a frequency divider that divides a predetermined clock pulse by 4, and 33 is a switch circuit that switches between the frequency dividing pulse of the frequency divider 32 and the clock pulse.

34 is a counting circuit that counts the pulses from the switch circuit 33, and the set value set in the cycle register 35 and the counter.
The count output of 36 is compared with the first comparator 37, and when they match each other, the set value set in the phase register 38 is preset as an initial count value of the counter 36 by a load pulse. Has been done.

An initialization circuit 39 receives the first edge pulse from the edge detection circuit 31, switches the switch 33 to the frequency division pulse side, and resets the counter 36 to "0" once.

A latch circuit 40 temporarily stores the count output of the counter 36 each time an edge pulse is received.

Reference numeral 41 is a synchronous operation unit forming the pull-in means and the correction means of this embodiment, and calculates the cycle data and the phase correction data per half cycle of the sweep light based on the count value latched by the latch circuit 40. And register each with the period register 35
And the phase register 38.

The synchronization calculation unit 41 includes a cycle calculation unit 42 that calculates cycle data from the latched count value, a phase calculation unit 43 that also calculates phase correction data from the count value, and also detects a sweep direction of sweep light from the count value. Direction detecting means 44, and out-of-synchronization detecting means 45 for detecting out-of-synchronization by the edge pulse and the load pulse.

The period calculating means 42 is equivalent to a half period of the sweep light obtained based on the four count values C1 to C4 which are continuously latched while the count pulse is started after the counter 36 is reset. And the sync data corresponding to 1/4 cycle, the pull-in data corresponding to the start of synchronization is calculated, and the pull-in mode to be set in the cycle register 35 and the sync mode signal is sent to the initialization circuit 39 at the start of synchronization. Switch 33 to the clock pulse side (the counter 36 is not reset), and every time a predetermined number of count values latched by the latch circuit 40 is received after the start of synchronization, a half cycle and a quarter cycle of the sweep light are received. It has a synchronization mode in which the cycle data is sequentially calculated and set in the cycle register 35.

Further, the phase calculating means 43 sets “0” in the phase register 38 when the surrounding calculating means 42 is in the pull-in mode, and in the synchronous mode, the turning point of the sweep light and the counter from the latched count value. Calculate the phase difference from the repeating point of 36 counts,
The phase correction data corresponding to this phase difference is stored in the phase register 38.
Set to.

The direction detecting means 44 outputs direction data that changes in phase substantially with the phase of the sweep light depending on the interval of the edge pulse or the magnitude of the count value.

The out-of-synchronization detecting means 45 outputs the out-of-synchronization signal to the period calculating means 42 when more than four edge pulses or less than four edge pulses are input while receiving the load pulse from the first comparator 37 twice. Send it out and shift to the pull-in mode.

A direction register 46 stores the direction data from the direction detecting means 44, and the direction data is output from the flip-flop 47 as a direction signal synchronized with the load pulse from the first comparator 37.

The counter 48 stores the cycle data for 1/4 cycle which is sequentially stored in the cycle register 35 together with the synchronization data for half cycle and the counter 36.
The second which outputs a coincidence pulse when the count output of
Is a comparator.

Further, the flip-flop 49 stores the level of the direction signal in synchronization with the coincidence pulse from the second comparator 40, and outputs this stored level as a position signal.

The counter 36 output from the synchronous data output circuit 30 configured as described above is output from the rising edge detector 50 which detects the rising edge of the light reception signal of the light receiver 6 which is the first light receiving means as shown in FIG. Each time a detection pulse is input, it is latched by the latch circuit 51, and the latched count value is a voltage corresponding to the position change along the sweep direction of the sweep light (second sweep light) received by the light receiver 6. The data is output as read data to the reference data storage unit 52 in which, for example, a half cycle of data is stored in advance.

The reference data read from the reference data storage unit 52 is input to the measurement / calculation unit 60, the reference data when the sweep light passes through the edge of the DUT, and the direction signal corresponding to the scanning direction and position of the sweep light. And, for example, the outer diameter of the object to be measured is calculated based on the position signal.

<Operation of the Embodiment> Next, the operation of the dimension measuring apparatus having the above configuration will be described focusing on the operation of the synchronous data output circuit 30.

If the second sweep light output through the lens 12 and received by the light receiver 14 is swept as shown in FIG. 3 (a), and part of the sweep width is blocked by the reference object R. The received light signal changes to "L" level at the position where the reference object R strikes the sweep light as shown in FIG. 3 (b).

Therefore, the edge pulse as shown in FIG. 3C is sequentially output from the edge detection circuit 31.

When the first edge pulse e0 is input to the initialization circuit 39, the counter 36 is reset and the divided pulse is input to the counter 36 as shown in FIG.

At this time (t0), the count value of the counter increases as shown in FIG. 3 (e).

During this counting, the cycle calculating means 42 receives the four count values C1 to C4 continuously latched by the latch circuit 40, and the cycle data D1 corresponding to the clock pulse for half the cycle of the sweep light is 2.C4.
The pull-in data for the divided pulse at the turn-back point of swept light (at the start of synchronization) is calculated by the following formula {(C3 + C4) / 2} + C4 / 2 = C4 + C3 / 2 = D0, and this pull-in count data D0 is calculated. Cycle register 35
Set to.

Therefore, at time t1 when the count value of the counter counting the divided pulses coincides with D0, the load pulse is output from the first comparator 37, and the initial value “0” set in the phase register 38 is changed to the counter 36. And the switch 33 is switched to the clock pulse side.

As a result, the counter 36 starts counting the slock pulse from the initial value “0”.

The first cycle data calculated by the cycle calculation means 42
D1 is set in the period register 35 immediately after the counter 36 starts counting clock pulses.

Therefore, the counter 36 continues counting until D1 clock pulses are input.

On the other hand, the direction detecting means 44 compares the magnitudes of (C4-C3) and (C2-C1) based on the four latched count values C1 to C4 at the beginning, and as shown in FIG. When C3) is larger, at t1, it is at the "L" level, and thereafter, the direction data that is inverted every time two edge pulses are input is output to the flip-flop 47.

For this reason, the direction signal is displayed on the counter as shown in Fig. 3 (f).
It will be inverted in synchronization with 36 counting cycles. Further, the flip-flop 49 outputs a position signal having a phase difference of approximately 90 degrees from that of the direction signal (FIG. 3 (g)).

During this synchronization mode, the cycle calculating means 42 operates the counter 36
Time t3 when the edge pulse e10 is input after the counting cycle for the clock pulse of
Then, check the difference between the count value C6 latched at the time t2 of the first cycle and the count value C10 of the third cycle. If the difference is 0, the cycle data is not changed. If the difference is not 0, it corresponds to the difference. The previous cycle data D1 is corrected with the correction value H to be set, and new cycle data D2 is set in the cycle register 35.

Further, the phase calculating means 43 calculates the time difference from two latched counts sandwiching the turn-around point of the count in the synchronous mode, and the phase of the sweep light and the count cycle is the fourth.
When the time shifts by (td-td ') / 2 as shown in A of the figure, the corresponding phase correction data Td is stored in the phase register 38, and the initial count value of the counter 36 of the pair of counting cycles is changed from 0 to 0. By changing to Td, the phase following of the turning point is performed like B.

In this way, the count value of the counter 36 that changes in synchronization with the second sweep light is latched by the pulse from the rising detector 50, and the reference data corresponding to the latched count value is calculated, for example, by The width is calculated.

If four edge pulses are not received during the two counting cycles of the counter 36 in the synchronous mode,
The signal from the out-of-synchronization detection means 45 enters the pull-in mode operation (operation at t0 to t1 in FIG. 3).

<Other Embodiments of the Present Invention> In the above embodiment, the divided pulse obtained by dividing the clock pulse by 1/4 during the pull-in operation is input to the counter 36,
Although a predetermined number of count data for calculating the period and phase of the sweep light was received, when the number of digits (bit number) of the counter 36 is sufficiently large, the pulling operation is performed with the clock pulse as it is. However, when the frequency division pulse is used, the frequency division pulse is not limited to 1/4 frequency division and any frequency division ratio can be used.

Further, in the above-described embodiment, the counting cycle of the counting circuit 34 corresponds to a half cycle of the sweep light, but this does not limit the present invention, and corresponds to the storage state of the reference data.
It may be a counting cycle corresponding to 1/4 cycle or 1 cycle. Further, unlike the above-described embodiment, the counting circuit 34 may not be set for each turn of the sweep light, but the counting direction of the counter circuit 34 may be inverted for each turn as shown in FIG.

Further, in the above-described embodiment, the synchronous data is obtained by changing the period data and the phase data 2 for the counting circuit 34, but either one is fixed and the period and the phase are set only by setting the other side. May be corrected. In this case, the first comparator 37 can be omitted or a counter without a preset function can be used.

<Effects of the Present Invention> As described above, the dimension measuring apparatus of the present invention is based on the count value of the counting circuit stored in synchronization with the edge pulse of the light receiving signal of the second sweep light that crosses the reference object. , The period and phase of the sweep light are calculated, and the calculated new setting data is sequentially set in the counting circuit to obtain the data signal that changes in synchronization with the position change of the sweep light. The speed can be easily increased without constructing a PLL using a multistage frequency divider, and the resolution of measurement can be significantly increased.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a main part of one embodiment of the present invention, FIG. 2 is a diagram showing an overall configuration of one embodiment, and FIG. 3 is a timing chart for explaining an operation of one embodiment. Is. FIG. 4 is a diagram for explaining the operation of the main part, and FIG. 5 is a diagram showing the operation of the main part of another embodiment of the present invention. FIG. 6 is a diagram showing the basic structure of a conventional device, and FIG. 7 (a).
To (c) are diagrams showing the measurement principle of the conventional device, and FIG. 8 is
It is a figure which shows the principal part structure of the conventional apparatus. 30 …… Synchronous data output circuit, 31 …… Edge detection circuit, 34
...... Counter circuit, 40 …… Latch circuit, 41 …… Synchronous operation unit.

Claims (1)

[Claims] 1. A swept light beam that sweeps back and forth in a predetermined direction is divided into a first swept light beam that traverses an object to be measured and a second swept light beam that traverses a reference object, and these are respectively separated by first and second light receiving means. A data signal that receives light and changes in synchronization with the position change of the first sweep light is generated based on the second light receiving signal output from the second light receiving means, and the data signal from the first light receiving means is generated. A dimension measuring device for measuring a dimension of an object to be measured from a data signal when a state of a first light receiving signal changes, edge detecting means for detecting a state change of the second light receiving signal, and outputting an edge pulse; The clock pulse counting is repeated every time a set number of clock pulses are input, and the count value being counted is output as a data signal that changes in synchronization with the position change of the first sweep light. Circuit and the edge pulse Count value storage means for temporarily storing the count value of the counting circuit each time, and sequentially receives the count value temporarily stored in the count value storage means, the sweep cycle of the sweep light and its sweep phase become a predetermined phase. Is obtained, the count output of the counting circuit is initialized at the timing, and a setting value corresponding to the obtained sweep cycle is set in the counting circuit to set the counting repetition cycle of the counting circuit to the sweep light. A retraction means for synchronizing with the position change of the counter circuit, based on the count value temporarily stored in the count value storage means after the counting repetition cycle of the counting circuit by the retraction means is synchronized with the position change of the sweep light, A phase shift between the counting repetition period of the counting circuit and the position change of the sweep light is obtained, correction data corresponding to the phase shift is set in the counting circuit, and the counting repetition of the counting circuit is performed. A dimension measuring apparatus comprising: a correction unit that maintains synchronization between a scanning cycle and a position change of the sweep light.