KR860000456B1 - The apparatus for measuring distance - Google Patents

Abstract

This appts. for measuring distance and detecting object presence with ultrasonic sensor transmits signal wave periodically and evaluates received signal changes. A source emitting a signal wave periodically contains two scillators operating at different frequencies and in a fixed phase relationship. The received signal is sampled and stored during a transmission period. The sampled signal is compared by the evaluation device with the previously stored signal. The scanning pulse width is no larger than the duration of operation of the higher frequence oscilation.

Description

Distance measuring device

1 is a schematic diagram illustrating a principle for explaining a distance measuring method by ultrasonic reflection.

Fig. 2 (a) and Fig. 2 (b) are signal waveform diagrams illustrating a distance measuring method by ultrasonic reflection.

3 is a block diagram illustrating problems in appearance and distance measurement of a television receiver equipped with a distance measuring device.

4 is a block diagram showing an embodiment of the distance measuring device of the present invention.

5 (a)-5 (s) and 6 (a)-6 (o) are signal waveform diagrams illustrating the operation of FIG.

* Explanation of symbols for main parts of the drawings

25: speaker 26: microphone

30: initializing circuit 31, 32: flip-flop circuit

33, 60, 64: NAND circuit 34, 35: counter

36: memory address counter 37: memory circuit

38: memory start switch 39: memory start circuit

40, 42, 47: oscillator 43: amplifier

41, 54, 55, 61, 62: monostable far vibrator 44: rectifier

45: sample holder circuit 46: timing pulse generation circuit

48: threshold circuit 49: A / D conversion circuit

50, 53: inverter 51, 52: AND circuit

56, 57: latch circuit 58: comparator

59: OR circuit 63: judgment circuit

65: threshold addition circuit 67: buffer

The present invention relates to a distance measuring device for emitting an ultrasonic wave and measuring the distance of the object by the reflected wave.

In general, a method of measuring the object distance by the reflection of ultrasonic energy is well known. That is, as shown in FIG. 1, the speaker 12 of the transmitter 11 emits an ultrasonic pulse and reflects the reflected waves from the objects 13 and 14 for the ultrasonic pulse. Receive and amplify by (16). 2 (a) and 2 (b) show a transmission wave S _A , a reception wave S _B1 , and S _B2 , respectively. If the distance to objects 13 and 14 is l ₁ , l ₂ , the reflection time t ₁ , t ₂ is

[C: sound speed (340 m / sec at 15 ° C in air)] That is, if the reflection times t ₁ and t ₂ are known, the distances to the objects 13 and 14 can be measured.

Thus, the method of measuring the distance of an object by transmitting the ultrasonic pulse and measuring the time until the first reflected wave after transmission is technically simple. However, as shown in FIG. 1, when there are a plurality of objects 13 and 14, and for example, to measure the distance to the object 14, the reflected wave returns to the number of objects 13 and 14 as well. Therefore, it is difficult to measure the distance of the target object because the reflected wave corresponding to the target object is determined from the plurality of reflected waves. This is especially a problem when the target object moves.

SUMMARY OF THE INVENTION The present invention has been studied in response to the above situation, and an object thereof is to provide a distance measuring device that accurately determines only a moving object and accurately measures the distance even if a plurality of stationary objects exist around the moving object.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, the case where the distance measuring device of the present invention is used for distance measurement between a person watching television broadcast and a television receiver is described as an example.

In order to reduce eye strain when watching TV broadcasts, the distance between people and the screen is generally 5 to 7 times the width of the screen. For example, when you see a 20-inch screen, 1.5m-2m is a reasonable distance. However, when watching a broadcast, it is often unknowingly approaching the screen.

Thus, in this embodiment, the distance measuring device is installed in the television receiver so that the distance between the person and the television receiver is always monitored. FIG. 3 is a schematic perspective view of such a television receiver. In FIG. 3, reference numeral 22 denotes a water pipe of the television receiver 21, 23 a speaker for voice output, 24 a keyboard for program selection, and 25 The reference numeral 26 denotes an ultrasonic transmitting speaker and an ultrasonic receiving microphone installed on the front of the television receiver 21, respectively. In addition, the main body of the distance measuring device of the present invention is installed inside the cabinet of the television receiver 21.

In such a configuration, the speaker 25 transmits an ultrasonic pulse, receives the reflected wave from the person 27 with respect to the ultrasonic pulse to the microphone 26, detects the reflected time of the reflected wave, and detects the reflected sound from the person 27 and television. The distance from the receiver 21 is measured. When the measurement result is less than or equal to a predetermined value, that is, when the person 27 approaches the television receiver 21 too much, the voice response device (not shown) installed in the television receiver 21 is driven to speak. From echo 23, it generates a message like "too close. Let's go further."

However, there are many stationary objects such as desks, chairs, bookshelves, etc. in addition to the person watching the broadcast, and the television receiver 21 is placed in the vicinity. many.

The reflected wave of the ultrasonic pulse from the object returns as soon as the object is closer to the distance measuring device as described above. Therefore, when there are several stationary objects 28 around the television receiver 21 as described above, in the conventional distance measuring device, the reflected wave received from the microphone 26 is a reflected wave from a person or from the stationary object 28. Because of the difficulty of distinguishing the reflected wave, it was difficult to accurately measure the distance between a person and a television receiver.

Therefore, the present invention makes it possible to distinguish the stationary object 28 from the person 27 by storing the stationary object 28 around the television receiver 21 in advance.

4 is a block diagram showing the configuration of an embodiment of the present invention.

In Fig. 4, the same parts as those in Fig. 3 are denoted by the same reference numerals. Hereinafter, the configuration and operation of FIG. 4 will be described in detail with reference to the signal waveform diagrams of FIGS. 5 and 6. In addition, the signal waveform shown in FIG. 6 enlarges and shows the signal waveform shown in FIG. Initially, when the television receiver 21 is powered on, the initializing circuit 30 is operated, and the initializing signal is the first flip-flop 31, the second flip-flop 32, and the second counter, respectively. (35) and supplied to the first counter 34, the memory address counter 36, and the memory circuit 37 through the NAND circuit 33, respectively, and these circuits are reset. At this time, the stored contents of each address of the memory circuit 37 are all at the "L" level.

Next, when the memory switch 38 is pressed to store the stationary object 28 (see FIG. 3) around the television receiver 21, the signal S _{1 of} FIG. Is approved. As a result, the memory start-up circuit 39 sends the signal S ₂ shown in FIG. 5 (b) to the initializing circuit 30 to test the initializing circuit 30 again. Immediately thereafter, the memory start-up circuit 39 sends the signal S ₃ shown in FIG. 5C to the flip-flop 31 to set this flip-flop 1 31. Thereby, the oscillator 40 of the first start of the oscillation, and by the first output terminal 5 (d) and Fig claim 6 (a) is derived the oscillation output (S ₄₎ shown in Fig.

The oscillation output S ₄ of the oscillator 40 is supplied to a first monostable multivibrator (hereinafter referred to as MM1) 41. In this way MM1 (41) is to derive the oscillation output (S ₄₎ the signal (S ₅₎ having a predetermined pulse width such as shown in Fig, claim 6 (b) degree of claim 5 (e) synchronized with the rise of the. The second oscillator 42 is driven only when the output of the MM1 41 is at the " H " level, and the ultrasonic wave S ₆ shown in the fifth (f) and the sixth (c) degrees in the speaker 25 is shown. To fire). Therefore, the period in which the ultrasonic wave S ₆ is emitted from the speaker 25 is the same period as the pulse width of the output pulse S ₅ of the MM1 41.

However, the resolution for detecting the object is good to narrow the launch period of the ultrasonic wave. In this case, the ultrasonic firing period of the speaker 25 is set, for example, around 1 m sec in consideration of the response characteristic of the microphone 26.

Ultrasonic pulses emitted by the speaker 25 and reflected by the object are amplified by the microphone 26 to a predetermined level in the amplifier 43. The fifth output of the amplifier (43) (g) also, the 6 (d) is also shown as the S _7. The output of the binary amplifier 43 is rectified by the rectifier 44, and is derived as the defining component S ₈ shown in the fifth (h) and the sixth (e) diagrams at the output terminal thereof. The output of this rectifier 44 is supplied to the sample holder circuit 45, and the sampling pulse supplied from the timing pulse generator circuit 46 to the sample holder circuit 45 (FIGS. 5i and 6f is shown in FIG. The peak value of the reflected wave is detected using the " ₉ "

The sampling pulse S ₉ is obtained as follows. That is, the output S ₄ of the oscillator 40 is also supplied to the third oscillator 47. In this case, the oscillation frequency of the oscillator 40 is set to a sufficiently low value compared to the oscillation frequency of the oscillator 47. Therefore, the oscillator 47 oscillates only when the output of the oscillator 40 is at the "H" level, and derives the signal S ₁₀ shown in FIG. 5 (j). The oscillation output S ₁₀ of the oscillator 47 is divided by the first counter 34. The timing pulse generation circuit 46 generates a sampling pulse S ₉ having a pulse width equal to or greater than the pulse width of the output pulse S ₅ of the MM1 41 according to the output of the counter 43. The sample holder circuit 45 is supplied. The peak detection output (shown as S ₁₁ in FIGS. 5k and 6g) of the sample holder circuit 45 is supplied to the threshold circuit 48 to remove only the reflected waves having an amplitude or higher than a predetermined level. The reason why the threshold circuit 48 is provided is to prevent detection of severe movement such as small toys or cups. The output of the threshold circuit 48 is supplied to an analog / digital (A / D) conversion circuit 49. The A / D conversion operation is started by the A / D conversion start pulse S ₁₂ (see FIG. 5L and FIG. 6I) from the timing pulse generation circuit 46 after the sample is honed, and when it is finished, A The A / D conversion termination pulse S ₁₅ (see FIGS. 5O and 6J) is derived from the / D conversion circuit 49. In this way, the output of the oscillator 40 obtains the data G ₂₃ obtained by A / D conversion of the sampled data S ₁₁ using the sampling pulse S ₉ during the period of the "H" level (see also FIG. 6o). Are written to corresponding addresses of the memory circuit 37, respectively. In this case, the memory operation for the memory circuit 37 is repeated several times, and the largest data is written to each address of the memory circuit 37 during the repetition of this memory operation. This is to prevent the wrong data from being stored in the memory circuit 37 because of the large fluctuations in the reflected waves of the ultrasonic waves.

This operation will be described below. The second counter 35 determines the number of times of storage of the memory circuit 37 based on the output S ₄ of the first oscillator 40. That is, when the counter 35 counts the output S ₄ of the first oscillator 40 by a predetermined number, the counter 35 supplies the pulse S ₁₆ shown in FIG. 5 (p) to the flip-flop 32. As a result, the pulse S ₁₇ shown in FIG. 5 (g) is derived from the flip-flop 32. The above-described memory operation is repeated for the period in which the output of the flip-flop 32 is at the "L" level, and the details in the period in which the output of the flip-flop 32 is at the "H" level will be described later. The distance measurement between a person and a television receiver is performed using the stored data of ") and the output data of the A / D conversion circuit 49.

The output of the flip-flop 32 is supplied to the AND circuit 51 via the inverter 50 and directly to the AND circuit 52. Therefore, the signal which has passed the A / D conversion end pulse S ₁₅ through the inverter 53 is supplied to the second monostable multivibrator (hereinafter abbreviated as MM2) 54 via the AND circuit 51. . The output of this MM2 54 is supplied with the third MM3 55, and from this MM3 55, the pulse S ₂₀ shown in FIG. 6 (k) is derived and this pulse S ₂₀ is the first. The second latch circuits 56 and 57 are supplied as clock pulses. At this timing, the latch circuit 57 stores and stores the memory data of the memory circuit 37, and the latch circuit 56 stores and stores the A / D converted data. The data X ₂ (X ₁ ) of the latch circuits 56 and 57 are compared in the comparator 58. When the comparator 58 X ₁ <X ₂ , X ₁ = X _{2, an} output is derived and supplied to the NAND circuit 60 through the OR circuit 59, and the data of the latch circuit 56 is stored in the memory circuit 37. Do not fill in). The X _1> In X ₂ is when the comparator 58 can not be obtained the output pulse to receive the output of the MM4 (61) or MM5 (62) shown in Fig NAND circuit (60) of claim 6 (l) (S ₂₁ ). Since the output pulse S ₂₁ is a timing pulse, the data X ₁ of the latch circuit 56 is written to the corresponding address of the memory circuit 37 through the buffer circuit 67. When the operation is terminated, the reset pulse S ₁₃ is supplied from the timing pulse generator circuit 46 to the sample holder circuit 45, and the memory data corresponding to the stored data of one address of the memory circuit 37 and this address is supplied. Comparison with the A / D conversion data is completed. Similarly, the above comparison is performed with respect to all addresses of the memory circuit 37. This operation is repeated each time the output of the oscillator 40 becomes the "H" level until the output of the flip-flop 32 becomes the "H" level, and the memory circuit 37 has a maximum of sampling data corresponding to each address. Data is stored. The reset pulse S ₁₃ is supplied as a clock pulse to the memory address counter 36, and the memory address counter 36 sequentially switches the designated address of the memory circuit 37 at this timing. In addition, the determination circuit 63 does not operate when the output of the flip-flop 32 is at the "L" level. This is because the output from the AND circuit 52 cannot be obtained, so that the output of the NAND circuit 64 is always at &quot; H &quot; level.

When the operation of storing the stationary object around only the number of times determined by the counter 35 is repeated in this manner, the output of the flip-flop 32 becomes the "H" level, and the apparatus becomes the ranging mode. That is, when the output of the flip-flop 32 is at " H " level, the AND circuit 51 closes the gate and the AND circuit 52 opens the gate, so that the A / D conversion end pulse S ₁₅ is AND this time. It is supplied to the NAND circuit 64 through the circuit 52. In this case, since the output of the NAND circuit 60, which is the other input of the NAND circuit 64, is always at the "H" level, the NAND circuit 64 pulses at the timing of the A / D conversion end pulse S ₁₅ . (S ₂₂₎ and a derived, and the decision circuit 63, a (first 6 (n), see Fig.) to the "on" state. The determination circuit 63 is supplied with the data S ₂₃ converted by the A / D conversion circuit 49 and the storage data of the memory circuit 37, but the storage data of the memory circuit 37 is added with a threshold value thereto. The data of the circuit 65 is added and then applied. The reason why the threshold addition circuit 65 is provided is to further allow data stored in the memory circuit 37 to prevent malfunction. The address data is supplied to the NAND circuit 64 which controls " on " off " of the decision circuit 63 again from the memory address control counter 36. That is, the operation of the decision circuit 63 also works with the address data. a can be controlled. the decision circuit 63 is compared to Y _1> Y ₂ is the output data (Y ₂₎ of the output data (Y ₁₎ and the threshold value adder circuit 65 of the a / D conversion circuit 49 When it does, the address data at that time corresponds to the position of the person.

Each address data of the memory address counter 36 is related to the distance from the television receiver. Therefore, the distance between the television receiver and the person is detected by the address data and the output of the determination circuit 63 which put the determination circuit 63 in the " on " state. When a person gets too close to the television receiver, the voice response circuit 66 is driven to generate a proximity warning.

In addition, since the oscillation frequency of the oscillator 40 corresponds to the reflected wave reception time, you may select suitably according to the distance to detect. In addition, as a so-called sensor of ultrasonic waves, the speaker 25 and the microphone 26 may be integrated.

According to the present embodiment described in detail above, the position of the stationary object around the television receiver is stored in the memory circuit 37 in advance, and the memory data of the memory circuit 37 and the position of the object around each other are sampled and then A / Compared with the D-converted data, the position of the person is detected. Therefore, only the person can be reliably determined regardless of the presence of the stationary object, and the distance between the person and the television receiver can be measured reliably.

In addition, when the position of the surrounding stationary object is stored in the memory circuit 37 in advance, the memory operation is repeated several times to store only the largest data, thereby preventing malfunction due to the level variation of the reflected wave of the ultrasonic wave. . In addition, since the threshold addition circuit 65 is provided to allow a margin to the data stored in the memory circuit 37, the malfunction of the distance measurement can be made extremely small.

The present invention is not only applied to distance measurement between a television receiver and a person, but also when a plurality of stationary objects exist around a device and a position of a moving object existing therein is to be detected.

Moreover, it is possible to implement not only an ultrasonic pulse but also a distance measuring device using infrared rays as a transmission wave.

As described above, according to the present invention, even if a plurality of stationary objects exist around the moving object, only the moving object can be reliably determined and accurate distance measurement can be performed.

Claims (1)

A transmitter for periodically generating a (correction) signal in the surveillance region, a receiver for receiving a signal generated by the transmitter and reflected in the region, and storage means for storing a reference signal for forming the received signal; Detecting a moving object in a surveillance area having comparison means for comparing a signal received in each transmission cycle of the transmitter with a stored reference signal to generate a detection signal when the transmission cycles of the transmitter are not matched. 1. An apparatus for a method comprising: sampling means (45, 48, 49) for sampling each pulse indicating the presence of an object at a distance away from a receiver and a signal received at a predetermined time interval to generate a pulse train; Storage means 37 for storing the train as a reference signal, and each pulse of the pulse train from the sampling means; Comparison means 63 for comparing each corresponding pulse of the reference pulse train stored in the means 37 and A / D for periodically converting the pulse train from the sampling means 45, 48, 49 into digital signals. The variable stage 49, the first and second latch circuits 56 and 57 connected to the output terminal of the A / D conversion means 49, and the output signal from the first latch circuit 56 are Digital comparator means 58 for comparing the output signals from the first and second latch circuits 56 and 57 to produce an output signal when the output signal from the second latch circuit 57 is smaller than the output signal from the second latch circuit 57; A memory circuit 38 connected to an output terminal of the second latch circuit 57 and set into a write mode by an output signal from the digital comparator means 58, and given from the transmitters 25 and 42; It is set as non-operational mode until a number of signals are reached and generates a detection signal when the signals are different. To A / D conversion means (49) comparing the comparison signal with the distance measuring apparatus characterized by comprising means (63) for storing the output signal from the memory circuit 37.

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