JPH1073682A - Time measuring device and ultrasonic wave transmitter receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a time measuring device capable of accurately measuring transmission time and the like using clock signal with low frequency. SOLUTION: Provided are a main oscillation circuit 11 generating main clock signal CKL1 with a period of τ 1 and a sub oscillation circuit 21 generating sub clock signal CKL2 with a period of τ 2 slightly different from the period τ1. By multiplying the period τ1 of the main clock signal CKL1 to the pulse number of the main clock signal CKL1 in the term from the time a transmission timing generator circuit 12 outputs a transmission signal RS to the time an ultrasonic wave receiver 14 outputs a reception signal R, a rough primary time is calculated, and the pulse number of the sub clock signal CLK2 is counted with a sub counter circuit 23 for the term from the time the reception signal R is output to the time the phase of the main clock signal CLK1 and the phase of the sub clock signal CLK2 coincide, and to this pulse number, the period difference πτ between the main clock signal CLK1 and the sub clock signal CLK2 is multiplied to obtain a secondary time. The primary and the secondary times are added to calculate transmission time T.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a time measuring device and an ultrasonic wave transmitting / receiving device, and more particularly, to a time measuring device having improved time resolution by using two clock signals having slightly different frequencies, The present invention relates to an ultrasonic transmission / reception device having improved measurement time resolution.

[0002]

2. Description of the Related Art As a conventional ultrasonic wave transmitting / receiving apparatus, for example, the one shown in FIG. 3 is known. In the figure,
11 is an oscillation circuit, 12 is a transmission timing generation circuit, 13
Is an ultrasonic wave transmitter having a transmission circuit 13a and an ultrasonic transducer 13b, 14 is an ultrasonic wave receiver having a reception circuit 14a and an ultrasonic transducer 14b, 15 is a counting circuit, and 16 is a microcomputer (arithmetic circuit). .

In this ultrasonic wave transmitting / receiving apparatus, an oscillation circuit 11 outputs a clock signal CLK1 having a predetermined frequency f to a transmission timing circuit 12, and the transmission timing circuit 12 outputs the clock signal CLK1.
The transmission timing signal RS is transmitted from the ultrasonic transmitter 13 based on CLK1.
Output to When the transmission timing signal RS is input to the transmission circuit 13a, the ultrasonic transmitter 13 emits an ultrasonic wave S from the ultrasonic transducer 13b, and the ultrasonic receiver 14 transmits the ultrasonic wave (reflected wave or the like) S to the ultrasonic transducer. 14b
And the receiver 14a outputs the received signal R.

The counting circuit 15 receives a clock signal CLK1 at a clock input terminal (CLK) and a start terminal (START).
The number of pulses of the clock signal CLK1 input during the period from when the transmission timing signal RS is input to when the reception signal R is input when the transmission timing signal RS is input to the stop terminal (STOP) and the reception signal R is input to the stop terminal (STOP) And outputs a count signal C1 indicating the count value C1 to the microcomputer 16.
The microcomputer 16 multiplies the period tau ₁ in the pulse number C1 of the clock signal CLK1 based on the count signal C1 calculates the propagation time T of ultrasonic S.

[0005]

However [0007], in the conventional ultrasonic transmitter device described above, in order to calculate by multiplying the period tau ₁ the propagation time T of ultrasonic pulse number C1 of the clock signal CLK1 In addition, the time resolution of the propagation time T is also limited to the period τ ₁ of the clock signal CLK1, and there is a problem that high-precision measurement is impossible. Although this problem can be solved by using the clock signal CLK1 having a high frequency, a new problem arises in that power consumption is increased and wiring and the like are required to be fine. The present invention has been made in view of the above problems, and has a time measuring circuit having an excellent time resolution of measurement, and an ultrasonic wave transmitting / receiving apparatus capable of measuring an ultrasonic wave propagation time with high accuracy without using a high-frequency clock signal. The purpose is to provide.

[0006]

To achieve the above object, a time measuring circuit according to the present invention comprises: a main oscillation circuit for outputting a main clock signal of a predetermined frequency; A measurement start command circuit that outputs a measurement start command signal in synchronization with a signal, a measurement end command circuit that outputs a measurement end command signal, and a sub clock signal having a different frequency from the main clock signal at the input of the received signal. A sub-oscillator circuit for outputting, and a sub-clock signal and a main clock signal, and a phase-coincidence detection circuit for outputting a phase coincidence signal when the phase difference between the sub-clock signal and the main clock signal becomes equal to or less than the period difference. And a period from when the measurement start command signal, the measurement end command signal, and the main clock signal are input and when the measurement start command signal is input to when the measurement end command signal is input. The main counting circuit that counts the number of pulses of the main clock signal and outputs a main count signal, the measurement end command signal, the phase match signal, and the main clock signal or the sub clock signal are input, and the measurement end command signal is input. A sub-counting circuit that counts the number of pulses of the main clock signal or the sub-clock signal during a period from time to the input of the phase matching signal and outputs a sub-count signal; and the main count signal and the sub-count signal are input. And an arithmetic circuit for calculating a time from when the measurement start command signal is output to when the measurement end command signal is output based on the main count signal and the sub count signal.

Further, an ultrasonic wave transmitting / receiving apparatus according to the present invention includes a main oscillation circuit for outputting a main clock signal of a predetermined frequency, a main clock signal input thereto, and a transmission timing signal synchronized with the main clock signal. A transmission timing generating circuit to output, an ultrasonic transmitter to which the transmission timing signal is input, and to transmit an ultrasonic wave at the input of the transmission timing signal, and an ultrasonic wave output by the ultrasonic transmitter or a reflected wave thereof An ultrasonic receiver that receives a signal and outputs a received signal at the time of reception, a sub-oscillator circuit that outputs a sub-clock signal having a different frequency from the main clock signal at the input of the received signal, and the sub-clock signal When the main clock signal is input and the phase difference between the sub clock signal and the main clock signal is smaller than the period difference (hereinafter, when the phases match), a phase match signal is output. The transmission timing signal, the reception signal, and the main clock signal are input, and the number of pulses of the main clock signal in a period from when the transmission timing signal is input to when the reception signal is input is counted. A main counting circuit that outputs a main counting signal, and a period from when the received signal, the phase matching signal and the main clock signal or the sub clock signal are input and the received signal is input to when the phase matching signal is input. A sub-counting circuit that counts the number of pulses of the main clock signal or the sub-clock signal and outputs a sub-count signal; the main count signal and the sub-count signal being input; And an arithmetic circuit for calculating the time from when the transmitter transmits the ultrasonic wave to when the ultrasonic receiver receives the ultrasonic wave.

[0008] The time measuring apparatus and the ultrasonic transducer according to the present invention determine the absolute value of the difference between the frequency of the main clock signal and the frequency of the sub clock signal by about 1% to 10% of the main clock signal. For example, it is possible to adopt a configuration in which a signal having a frequency of 1 MHz is used as a main clock signal and a signal having a frequency of 1.01 MHz is used as a sub clock signal.

[0009]

In the time measuring device according to the present invention, the number of pulses C1 of the main clock signal CLK1 counted by the main counting circuit, that is, the measurement end command signal R is output from when the measurement start command signal RS is output. The period τ ₁ of the main clock signal CLK1 to the number of pulses C1 of the main clock signal CLK1
To obtain a first time (τ ₁ * C1). Further, the number of pulses C2 of the main clock signal CLK1 (or the sub clock signal CLK2) during the period from when the measurement end command signal R is output to when the phase coincidence signal P is output is counted by the sub counter circuit. The period τ of the main clock signal CLK1 is added to the pulse number C2.
₁ and the period τ ₂ of the sub clock signal CLK2 Δτ (Δτ =
τ ₁ −τ ₂ ) to obtain a second time (Δτ * C1) that is not included in the first time (τ ₁ * C1). Then, to calculate the propagation time by adding the first hour (tau ₁ * C1) and the second time the (Δτ * C1). Therefore, the time resolution is determined by the period difference Δ
It can be reduced to τ, and the propagation time can be measured with high accuracy.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 show an ultrasonic wave transmitting / receiving apparatus (time measuring apparatus) according to an embodiment of the present invention. FIG. 1 is a circuit block diagram, and FIG. 2 is a timing chart. The same parts as those of the ultrasonic wave transmitting / receiving apparatus of FIG. 3 described above are denoted by the same reference numerals, and a part of the description will be omitted.

In FIG. 1, reference numeral 21 denotes a sub oscillation circuit, 22 denotes a phase coincidence detection circuit, and 23 denotes a sub counting circuit. The sub-oscillation circuit 21 receives the received clock signal R and receives the main clock signal described above.
And outputs the sub-clock signal CLK2 of a high frequency f ₂ than the frequency f ₁ of the CLK1. The frequencies f ₁ and f ₂ of the clock signals CLK 1 and CLK ₂ are values satisfying the following inequality of Equation 1, and more preferably, the frequency f ₁ of the main clock signal CLK ₁ is 1M.
Hz, the frequency f ₂ of the sub-clock signal CLK2 1.01MH
z.

[0012]

(Equation 1)

It should be understood that it is needless to say that it is possible to arbitrarily select which of the frequencies f ₁ and f ₂ of the clock signals CLK 1 and CLK ₂ should be the high (low) frequency. Also, the level of the frequencies f ₁ and f ₂ of the clock signals CLK 1 and CLK ₂ and their difference, that is, the difference Δτ between the periods τ ₁ and τ ₂ (Δτ = τ ₁ −
The time resolution improves as τ ₂ ) decreases, but the value defined by the above inequality is desirable from the viewpoint of circuit manufacturing and from the viewpoint of improving the time resolution. Further, the above-mentioned sub-oscillation circuit 21 may be provided with a well-known gate in an output part to control the output of the sub-clock signal CLK2 (G in FIG. 2).
reference).

The phase coincidence detection circuit 22 outputs the clock signal CL
When K1 and CLK2 are input and the phase of these clock signals CLK1 and CLK2 becomes equal to or less than the difference Δτ between the periods τ ₁ and τ ₂ , the phase matching signal P is output to the sub-counting circuit 23. Sub-counting circuit 23
Means that the sub clock signal CLK2 is input to the clock input terminal (CLK),
Received signal R is applied to start terminal (START) and stop terminal (S
TOP) receives the phase match signal P. The phase coincidence detection circuit 22 starts the phase coincidence signal P from the time when the reception signal R is input.
Counts the number of pulses C2 of the sub-clock signal CLK2 during the period until the input is performed, and a count signal indicating the counted value C2
C2 is output to the microcomputer 16.

The microcomputer 16, the main counting circuit 15 counts the signal C1 from the count signal C2 is input from the sub-counter circuit 23, these count signals C1, C2, the period tau ₁ and the sub-clock signal CLK2 of the main clock signal CLK1 The propagation time T is calculated from the period τ _{2 of} . That is, the number of pulses of the main clock signal CLK1 counted by the main counting circuit 15
A rough first time T ₁ (T ₁ = τ ₂ * C 1) is obtained by multiplying C 1 by the period τ ₂ of the main clock signal CLK 1, and the number of pulses of the sub clock signal CLK 2 counted by the sub counting circuit 23
C2 is multiplied by the difference Δτ between the periods τ ₁ and τ ₂ to obtain a second time T ₂ (T
₂ = Δτ * C2), and the first and second times T ₁ and T ₂ are added to calculate the propagation time T (T = T ₁ + T ₂ ).

In this embodiment, the transmission timing generation circuit 12 corresponds to the measurement start command circuit according to the first aspect, and similarly, the transmission timing signal RS corresponds to the measurement start command signal, and the reception circuit 14a corresponds to the measurement start command signal. In the measurement end command circuit, the received signal R corresponds to the measurement end command signal.

In this embodiment, as shown in the timing chart of FIG. 2, the transmission timing generation circuit 12 outputs the transmission timing signal RS in synchronization with the main clock signal CLK1 at the time of measurement (t ₀ ). . Then, the ultrasonic wave transmitter 13 transmits the ultrasonic wave S with the output of the transmission timing signal RS, and the main counting circuit 15 outputs the main clock signal CL.
Start counting the number of pulses of K1. Thereafter, when the ultrasonic wave S is reflected by the measurement target or the like, the ultrasonic wave receiver 14 receives the ultrasonic wave S reflected by the ultrasonic transducer 14a,
Reception circuit 14a outputs the received signal R (t _1).

The received signal R is transmitted to the main counting circuit 1
5, input to the sub-oscillation circuit 21 and the sub-counter circuit 23, the main counter circuit 15 finishes counting the number of pulses of the main clock signal CLK1, outputs a count signal C1 to the microcomputer 16, Starts outputting the sub clock signal CLK2, the sub counter circuit 23 starts counting the sub clock signal CLK2, and the phase coincidence detection circuit 22 detects the phase difference between the main clock signal CLK1 and the sub clock signal CLK2. In addition, as described above, as shown by G in FIG.
The control of the sub-clock signal CLK2 of the sub-oscillation circuit 21 is a reception signal.
It is also possible to use a gate or the like that responds to R.

Thereafter, when the phase difference between the main clock signal CLK1 and the sub clock signal CLK2 input to the phase coincidence detection circuit 22 becomes smaller than the difference Δτ between the periods τ ₁ and τ ₂ , the phase coincidence detection circuit 22 Is output to the sub-counting circuit 23. Therefore, the sub-counter circuit 23 terminates the pulse number counting sub clock signal CLK2, and outputs a count signal C2 to the microcomputer 16 (t _2).

[0020] That is, as shown in FIG. 2, the phase difference of the phase and the main clock signal CLK1 of the sub-clock signal CLK2 sub oscillation circuit 21 outputs gradually decreased from time t _1, when t
₂ , the phase difference becomes equal to or smaller than the period difference Δτ, and at time t ₂ , the phase coincidence detection circuit 22
Output to Therefore, the sub-counter circuit 23, the sub-clock signal CLK2 to be input in the period until the time t ₂ from time t ₁
The number of pulses (GC in FIG. 2) is counted, and a count signal C2 representing the number of pulses of the sub clock signal CLK2 is output to the microcomputer 16.

Then, the microcomputer 16 calculates the propagation time T based on the count signals C1 and C2. That is, the period of the main pulse number C1 of the clock signal CLK1 by multiplying the period tau ₁ of the main clock signal CLK1 calculating a rough first hour T _1, The sub clock signal CLK2 to the pulse number C2 of the sub-clock signal CLK2 multiplying by τ ₂ to calculate a second time T ₂ ,
The propagation time T is obtained by adding the first and second times T _{1 and} T ₂ .

[0022] Thus, high frequency of the main clock signal CLK1, i.e., the main oscillation circuit 11 is high resolution obtained even large period tau ₁ of the main clock pulse signal to be output, without causing an increase in power consumption The propagation time T can be measured with high accuracy.

[0023]

As described above, according to the time measuring device of the present invention, from the time when the measurement start command circuit outputs the measurement start command signal to the time when the measurement end command circuit outputs the measurement end command signal. Multiplying the number of pulses of the main clock signal in the period of the period by the period of the main clock signal to obtain a rough first time, and the phase of the main clock signal coincides with the phase of the sub clock signal from when the measurement end command signal is output. The number of pulses of the main or sub clock signal in the period up to the time when the counter is counted is counted by the sub counting circuit, and the number of pulses is multiplied by the period difference between the main clock signal and the sub clock signal to obtain the second pulse.
Since the propagation time is calculated by calculating the time and adding the first and second times, the time resolution can be reduced to the difference between the periods, and the propagation time can be measured with high accuracy.

[Brief description of the drawings]

FIG. 1 is a block diagram of an ultrasonic wave transmitting / receiving apparatus according to one embodiment of the present invention.

FIG. 2 is a timing chart of the ultrasonic wave transmitting / receiving apparatus.

FIG. 3 is a block diagram of a conventional ultrasonic wave transmitting / receiving device.

[Description of Signs] 11 Main oscillation circuit 12 Transmission timing generation circuit (measurement start command circuit) 13 Ultrasonic wave transmitter 14 Ultrasonic wave receiver 14a Receiving circuit (measurement end command signal) 15 Main counting circuit 16 Microcomputer (calculation) Circuit 21 Sub-oscillation circuit 22 Phase coincidence detection circuit 23 Sub-counter circuit CLK1 Main clock signal CLK2 Sub-clock signal R Received signal (measurement end command signal) RS Transmission timing signal (measurement start command signal) S Ultrasound

Claims (3)

[Claims] 1. A main oscillation circuit for outputting a main clock signal of a predetermined frequency; a measurement start command circuit for receiving the main clock signal and outputting a measurement start command signal in synchronization with the main clock signal; A measurement end command circuit that outputs a command signal, a sub-oscillation circuit that outputs a sub-clock signal having a frequency different from the main clock signal at the input of the received signal, and a sub-clock signal and a main clock signal that are input. A phase coincidence detection circuit that outputs a phase coincidence signal when the phase difference between the phase of the sub clock signal and the phase of the main clock signal is equal to or less than the period difference, and the measurement start command signal, the measurement end command signal, and the main clock signal are input; Main count that outputs the main count signal by counting the number of pulses of the main clock signal during the period from when the measurement start command signal is input to when the measurement end command signal is input A main clock signal or a sub-clock signal during a period from when the measurement end command signal is input to when the phase end signal is input after the measurement end command signal, the phase matching signal, and the main clock signal or the sub clock signal are input. A sub-counting circuit that counts the number of pulses and outputs a sub-count signal; and when the main count signal and the sub-count signal are input, and the measurement start command signal is output based on the main count signal and the sub-count signal. And a calculation circuit for calculating the time from when the measurement end command signal is output. 2. A main oscillation circuit that outputs a main clock signal of a predetermined frequency; a transmission timing generation circuit that receives the main clock signal and outputs a transmission timing signal in synchronization with the main clock signal; A signal is input, an ultrasonic wave transmitter for transmitting an ultrasonic wave at the input of the transmission timing signal, an ultrasonic wave output by the ultrasonic wave transmitter or a reflected wave thereof is received, and a reception signal is output upon reception. An ultrasonic wave receiver, a sub-oscillation circuit that outputs a sub-clock signal having a frequency different from the main clock signal at the input of the received signal, and a sub-clock signal to which the sub-clock signal and the main clock signal are input. A phase coincidence detection circuit that outputs a phase coincidence signal when the phase difference between the phase of the main clock signal and the phase difference of the main clock signal is equal to or less than the period difference; A main counting circuit that counts the number of pulses of the main clock signal during a period from when a transmission timing signal is input to when a reception signal is input and outputs a main count signal; and The number of pulses of the main clock signal or the sub clock signal during the period from when the coincidence signal and the main clock signal or the sub clock signal are input and when the reception signal is input to when the phase coincidence signal is input is counted and the sub count signal is generated. A sub-counter circuit to output, the main count signal and the sub-count signal are input, and the ultrasonic wave receiver transmits ultrasonic waves based on the main count signal and the sub-count signal, and then the ultrasonic receiver An ultrasonic transmission / reception device, comprising: an arithmetic circuit for calculating a time until receiving an ultrasonic wave. 3. The time measuring device according to claim 1, wherein the absolute value of the difference between the frequency of the main clock signal and the frequency of the sub clock signal is about 1% to 10% of the frequency of the main clock signal. Item 3. An ultrasonic wave transmitting / receiving device according to item 2.