JPH04184614A - Tree-dimensional range finder - Google Patents

Abstract

PURPOSE:To measure the distance with high accudacy by receiving the signals transmitted from >=3 time-division intermittently driven oscillation sources, and calculating the distance via a zero-cross detector circuit, a counter circuit, a latch circuit, etc. CONSTITUTION:The ultrasonic sound generator of three oscillation sources, for example, are intermittently driven via an intermittently driven oscillator 12, a divide 13, etc. Thus the ultrasonic waves are transmitted. The reception signal of the reflected ultrasonic wave received from a measured object for the transmission signal of the ultrasonic wave is received by a receiver 14. At the same time, a zero-cross point of the received signal is detected by a zero-cross detector 15, and the time signal of the time counting result is stored in a latch circuit 17 from a signal shaping circuit 17 the delivery time of the ultrasonic wave. Then a distance is calculated from the transmitting/receiving times of the ultrasonic wave. In such a constitution where a zero-cross detector circuit is used, the distance can be measured with high accuracy in a wide virtual space without regulated by the direction-sensitivity dependency of the yltrasonic sound receiver.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a three-dimensional ranging device for computer input.

[Summary of the invention]

In the three-dimensional distance measuring device according to the present invention, the transmitting section has three or more transmitting sources driven intermittently in a time division manner, the receiving section has a sound receiving body, and the transmitting section has three or more transmitting sources that are driven intermittently in a time division manner, It has a zero-cross detection circuit, a counting circuit, and a plurality of latch memory circuits to measure the transfer time of the sound wave from the source to the sound receiver, and sequentially reads out the transfer time data stored in the latch memory circuit. Calculate distance.

[Prior Art 1] Various applications have been filed for ultrasonic distance measuring devices, and it is necessary to accurately determine the delivery time of ultrasonic pulses. One example is a measurement method in which the reception time of the output signal of an ultrasound receiver is detected from a preset level and the delivery time of the ultrasound signal is determined. However, this measurement method has a fatal drawback in that the signal level changes due to changes in the measurement distance, resulting in a large error in the initial delivery time. Therefore, as an example of a device for improving such drawbacks, Japanese Patent Application Laid-Open No. 62-67481 is known. FIG. 5 shows the circuit configuration thereof, and the general operation thereof will be explained below. In this distance measuring device, in order to reduce the influence of signal level fluctuations caused by distance fluctuations, each time is determined from two different signal level values and the reception time is calculated and estimated.

[Problems to be Solved by the Invention] However, as shown in Fig. 6, the sensitivity of the sound receiver has a large azimuth dependence, and the output level fluctuates greatly within an azimuth angle of ±90 degrees. Errors were large depending on the measurement method, and it was not possible to perform highly accurate measurements with excellent distance margins and azimuth margins.

[Means for Solving the Problems] In order to solve the problems, the present invention uses a zero-cross detection method that has a large measurement tolerance margin for signal level fluctuations1 and is excellent in the ability to detect minute levels.

[Implementation Picture 1] The system configuration of the three-dimensional distance measuring device according to the present invention is shown in FIG. It consists of an oscillator 12 and a frequency divider 13 for intermittent driving in the resonance frequency band of the body. The receiving section includes an ultrasonic sound receiver 14, a zero-cross detection circuit 15, and a signal shaping circuit 16. The time signal output from the signal shaping circuit stores the delivery time of the ultrasonic signal in a latch memory circuit 17 that latches and stores the frequency divider output of the first transmitting section. FIG. 2 shows an example of the arrangement of three ultrasonic sounding bodies, which are arranged at three locations on two mutually orthogonal axes within the same plane. Figure 3 shows the operating waveforms of each part of the circuit, a) b) c) shows the driving waveforms of three sounding bodies. One oscillation period Ts is the waveform of the ultrasonic signal assigned to each sounding body. Maximum allowable delivery time Tri, Tr2,
Tr3 (which regulates the maximum value of the measurement distance) and the oscillation time Te1 of each sounding body. It is determined as follows based on Te2 and Te3.

Tri=[maximum measurement distance 1i1]/[sound speed]i=1.2.
3 Ts=(Trl+Tr2+Tr3)+Tel+Te2+Te5)+a Note that the oscillation time Tei is desirably shortened in order to shorten the measurement time.

Next, the ultrasonic pulse from the sounding body generates a pulse signal train (&1 type e) in the ultrasonic sound receiving body. The pulse signal train is highly sensitively amplified by a zero cross circuit (waveform f), then waveform-shaped by a comparator, and the R-S latch circuit determines the delivery time t1. Obtain single pulses (waveform g) at t2 and t3. The single pulse latches a latch memory circuit to store the ultrasound delivery time data.

The data is read into the CPtJ via a data bus or the like, and the position coordinates of the sound receiver are determined through arithmetic processing.

Next, as a specific example of the present invention, FIG. 4 shows the appearance of a keyboardless computer. Here, distance measurement is performed using five sound receivers attached to the fingers of a virtual input glove 44, The signals applied to the six sounding bodies that allow five independent inputs are frequency-divided from the original oscillation of the CPU, the frequency B1 is 40KHz, and the sounding body oscillation time is 1.
00 microseconds, and the maximum allowable time for transmitting ultrasonic signals is 3.1 milliseconds, making it possible to measure distances up to about 1 meter. In order to make the measurement accuracy 8 bits, the output signals from BO to B7 of the frequency divider circuit are input to the latch memory circuit. In this way, the distance data from the three standard sounding bodies to the sound receiving body can be measured in about 10 milliseconds, and distance data can be read out sequentially at high speed even for multiple sound receiving bodies. Distance measurement that fully satisfies the operating speed of a display operating at a frame frequency of 30 Hz is made possible. This measurement method enables distance measurement with a positional accuracy of 4 mm. If measurement with even higher resolution accuracy is desired, it is possible to increase the number of output signal bits of the frequency divider, and as another example, it is possible to limit the measurement range (
For example, the maximum measurement distance may be set to 50 centimeters) and the output of the 8-bit frequency divider may be shifted to the high frequency side.

FIG. 7 shows an example of a distance measuring device in which four sounding bodies are arranged. Here, the ultrasonic sounding bodies are arranged as shown on three orthogonal coordinate axes.

In contrast to the route calculation that was required to calculate the absolute coordinates from the distance measurement using the three sounding bodies, this measurement method eliminates the need for route calculation and simplifies the calculation.

[Effects of the Invention] The present invention uses a zero-cross detection circuit to measure 1@ separation in a wide virtual space and to measure ultrasonic delivery time with high precision without being restricted by the orientation-sensitivity dependence of an ultrasonic sound receiver. enable. Therefore, it can be applied as a virtual input device for computers, games, simulators, etc., which can be operated in a wide spatial area and has multiple functions with high precision.

[Brief explanation of the drawing]

FIG. 1 is a system configuration diagram showing an embodiment of the present invention. FIG. 2 is a layout diagram of the ultrasonic sounding body of the present invention. FIG. 3 is a chart showing operational waveforms of the present invention. FIG. 4 is an external view of a keyboardless computer as an application example of the present invention. FIG. 5 is a circuit block diagram showing the configuration of a conventional ultrasonic measuring device. FIG. 6 is a characteristic diagram showing the sensitivity dependence of the ultrasonic sound receiver depending on the sound source direction. FIG. 7 is a diagram showing another arrangement example of the ultrasonic sounding body of the present invention. 11... Ultrasonic sounding body 12... Oscillator 13... Frequency divider 14... Receiving body 15... Zero cross detector 16... Signal shaping circuit and above Applicant Seiko Epson Corporation Agent Patent attorney Kisanbe Suzuki (and 1 other person) 22 Installation surface Figure 2 Figure 3 41 Main processing unit 46 Screen keychain Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] In a three-dimensional distance measuring device including a transmitting section and a receiving section, the transmitting section has three or more transmitting sources that are driven intermittently in a time division manner, and the receiving section has a sound receiving body, and the transmitting section has three or more transmitting sources that are driven intermittently in a time division manner, and the receiving section has a sound receiving body, and It has a zero-crossing detection circuit, a counting circuit, and a plurality of latch memory circuits to measure the transfer time of the sound wave to the sound receiver, and calculates the distance by sequentially reading out the transfer time data stored in the latch memory circuit. A three-dimensional distance measuring device characterized by: