JP2007003355A - Instrument for measuring propagation time of pulse light, and application device such as virtual mouse - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To precisely measure a propagation time of a pulse light, even when a measuring object is moved violently. <P>SOLUTION: This instrument for measuring the propagation time of the pulse light capable of making compatible both a pulse transmission light by a light transceiving part 10 and phase difference detection by a frequency conversion circuit 30 and a phase difference detection circuit 50, by interposing a phase lock loop 20, is provided with one more set of a phase lock loop 21, a frequency conversion circuit 31 and a phase difference detection circuit 51, one of the sets is operated in response to leading-up of a pulse signal Bp, the other set is operated in response to tailing of the pulse signal Bp, and phase differences in the both sets are averaged to obtain a phase difference E less affected by a photoreception level. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a pulsed light propagation time measuring apparatus that transmits and receives pulsed light and measures the propagation time or a physical quantity corresponding to the transmitted time, and more particularly relates to an improved technique that contributes to improvement in measurement accuracy and cost reduction.
A pulsed light propagation time measuring device measures the propagation time of pulsed light in a straightforward manner. However, the pulsed light propagation time measuring device performs appropriate signal processing and computations, etc., in which the corresponding physical quantity, that is, the processing content is determined. A physical quantity that can be uniquely associated with the propagation time of light, and those that measure such physical quantity are also applicable. In addition, regarding the propagation state of the pulsed light, the direct propagation of the pulsed light emitted from the light emitting part and reaching the light receiving part is of course measured, as well as refraction, reflection, reproduction by other light receiving and emitting parts, etc. An indirect propagation accompanied by is also included in the measurement object.

Examples of the applied device include various devices such as a distance measuring device, a displacement meter, a speedometer, a position measuring device for obtaining a two-dimensional or three-dimensional coordinate position, and a pointing device.
A hand mouse is also one of pulsed light propagation time measurement application devices. A hand mouse is a 3D mouse (3D position input device) that uses a human hand or finger as a direct input tool. If you place your hand or fingertip in the air in front of the hand mouse or move your hand or fingertip in the air, The three-dimensional position data of the hand or fingertip is input to a computer or the like. By using such a hand mouse, it is possible to easily draw a three-dimensional trajectory. A so-called tongue mouse in which the direct input tool is changed from the hand or finger to the tongue is also a three-dimensional mouse, and is included in the pulsed light propagation time measurement application device. These mice can also be said to be virtual mice or untouched mice from the viewpoint that contact is unnecessary.

Regarding a light propagation time measurement device, a first method that performs pulse light transmission and directly measures the time interval between pulse signals with an electronic circuit, and performs light transmission in which the emission intensity changes in a sine wave shape and is accompanied by frequency reduction. The second method for detecting the phase difference is different. The former first method is used for, for example, a long-distance laser measuring instrument, and the latter second method is suitable for, for example, a short-distance laser rangefinder. Although being used, a phase-locked loop circuit is interposed so that both pulse transmission and phase difference detection are compatible, and a highly accurate and inexpensive pulse light propagation time measuring device is realized and provided ( For example, see Patent Document 1).
Since this apparatus is a premise of the present invention, two embodiments will be described again in detail.

FIG. 9A is a block diagram showing the basic electronic circuit structure of such a conventional pulsed light propagation time measuring device.
This pulsed light propagation time measuring device is a phase-locked circuit that combines the light transmitting / receiving unit 10 of the above-described first-type pulsed light propagation time measuring device and the above-described frequency conversion circuit 30 of the second-type light propagation time measuring device. The loop circuit 20 is interposed and connected.

  That is, in order to drive and control light emission from the oscillation circuit 11, the light emitting unit 12 that receives the pulse signal Ap of the frequency f1 and emits pulsed light at a predetermined period (1 / f1), and the pulse signal Bp based on the presence or absence of light reception The light receiving unit 13 to be generated, the phase lock loop circuit 20 that generates the sinusoidal oscillation signal Bs having the frequency f2 by inputting the pulse signal Bp having the frequency f1, and the signal processing for maintaining the phase state to perform the sinusoidal waveform having the frequency f2. A frequency conversion circuit 30 that generates a sinusoidal oscillation signal Cs having a lower frequency f3 from the oscillation signal Bs, a reference signal generation circuit 40 that generates a reference signal Ds having a frequency f3, a reference signal Ds and a sinusoidal oscillation signal A phase difference detection circuit 50 that detects a phase difference E from Cs is provided.

  The phase-locked loop circuit 20 employs a circuit that fixes the phase of the sinusoidal oscillation signal Bs at the timing of the pulse train in the pulse signal Bp and also multiplies the frequency at that time, thereby the frequency of the sinusoidal oscillation signal Bs. f2 becomes higher than the frequency f1 of the pulse signal Bp. In addition, since the magnification is discrete but has a wide selectable range, the frequencies f1 and f2 can be set and determined with almost no design constraints. Furthermore, the ratio of the frequencies f2 and f3 of the sinusoidal oscillation signals Bs and Cs corresponds to the signal waveform stretching rate, as in the case of the conventional second method, that is, the phase difference detection type optical propagation time measuring device.

  The usage mode and operation of such a pulsed light propagation time measuring device will be described. FIGS. 9B to 9F are signal waveform examples and show typical operation states. The frequency f1 of the pulse signal Ap is designed to be, for example, about several hundred Hz (see FIG. 9B). When this is supplied from the oscillation circuit 11 to the light emitting unit 12, the light emitting unit 12 corresponds to the pulse. Pulse light is emitted. The pulse width is, for example, several ns to several tens ns. Then, every time the pulsed light reaches the light receiving unit 13 directly or after changing to reflected light or reproduction light, a pulse of the pulse signal Bp is output from the light receiving unit 13 by photoelectric conversion (see FIG. 9C). ). The pulse signal Bp is delayed by a time difference G from the pulse signal Ap (see FIGS. 9B and 9C), and the time difference G includes the propagation time of the pulsed light in the light transmitting / receiving unit 10. .

  The pulse signal Bp is input to the phase-locked loop circuit 20, and the phase-locked loop circuit 20 generates a sinusoidal oscillation signal Bs from the pulse signal Bp (see FIG. 9D). In this case, in addition to changing the waveform Frequency multiplication is also performed, and the frequency f2 of the sinusoidal oscillation signal Bs becomes, for example, about several MHz to several GHz. This is a frequency that can be processed by a normal microwave electronic circuit. At that time, the phase of the sinusoidal oscillation signal Bs is fixed to the timing of the pulse train in the pulse signal Bp (see FIGS. 9C and 9D).

  The sinusoidal oscillation signal Bs is sent to the frequency conversion circuit 30, where frequency reduction processing is performed to obtain a sinusoidal oscillation signal Cs (see FIG. 9 (e)). As a result, the frequency f3 of the sinusoidal oscillation signal Cs is set to a frequency that can be processed by a general electronic circuit, for example, several hundred kHz, and at this time, the phase state is maintained even if the frequency changes. Specifically, the phase angle of the sinusoidal oscillation signal Bs is taken over by the phase angle of the sinusoidal oscillation signal Cs. Then, the timing of the pulse train of the pulse signal Bp with respect to the pulse train of the pulse signal Ap advances and retreats, and when the phase of the sinusoidal oscillation signal Bs advances and retreats by the same amount and the phase angle increases or decreases, the sinusoidal oscillation signal Cs The phase angle also increases and decreases.

On the other hand, the reference signal Ds is also given a sinusoidal waveform having the same frequency f3 as the sinusoidal oscillation signal Cs by the reference signal generating circuit 40 (see FIG. 9F), but the phase state is different. That is, the phase of the reference signal Ds does not change in conjunction with the phase of the pulse signal Bp or the sine wave oscillation signal Bs as in the case of the sine wave oscillation signal Cs, but the timing of the pulse train of the pulse signal Ap or the reference The signal generation circuit 40 is fixed with respect to a unique reference timing.
The reference signal Ds and the sinusoidal oscillation signal Cs are input to the phase difference detection circuit 50, where the phase difference E between them is detected (see FIGS. 9E and 9F). This phase difference E is obtained by extending the time difference G on the time axis, and even an electronic circuit having a general processing speed can be accurately measured with sufficiently high resolution.

  Further detailed description will be given with specific numerical examples. For example, in the pulse signal Ap, when a pulse having a period of 1.5 μs, that is, a frequency of 666.66 kHz and a width of 10 ns is repeated, the pulsed light is also transmitted from the light emitting unit 12 to the light receiving unit 13 with the same period and frequency. If the propagation distance of light in the light transmitting / receiving unit 10 at that time is 1.5 mm and the propagation delay time Δt of the pulsed light there is 5 ps, further delay in the light emitting unit 12 and the light receiving unit 13 and delay in the signal wiring Since the light propagation time Δt is equal to the time difference G between the pulse signal Ap and the pulse signal Bp if it is ignored for simplicity because it is constant, the amount of change in the phase angle of the sinusoidal oscillation signal Bs due to the light propagation time Δt, that is, the phase difference Δθx. When the frequency f1 is 2 GHz, for example, the corresponding period T1 is 500 ps, so that Δθx = 360 × (Δt / T1) = 3.6 ° is substituted into a predetermined calculation formula.

  If the frequency conversion from the sinusoidal oscillation signal Bs to the sinusoidal oscillation signal Cs is performed while the phase state is maintained and the frequency f3 is reduced to 333.33 KHz, for example, the corresponding time difference ΔTx is Δt × f2 / It is extended to f3 = 30 ns. This time difference ΔTx is obtained by converting the phase difference E into a time unit when the reference signal Ds is synchronized with the pulse signal Ap. Then, if necessary, the light propagation time Δt is calculated by the formula [Δt = ΔTx × f3 / f2] or [Δt = Δθx / (f1 × 360)], if necessary, according to the output form required by the application purpose. Further, the light propagation distance Δr is calculated by the equation [Δr = c × Δt], where c is the speed of light. Therefore, in this numerical example, since the propagation time of the pulsed light of 5 ps is measured as 30 ns, it is equivalent to the measurement with the time axis expanded to 6000 times (= f2 / f3), and as a result, about 100 MHz. Even if a general and simple electronic circuit having a response speed is employed, the propagation time and propagation distance of light can be calculated in the order of ps or mm.

FIG. 10 is a block configuration diagram of a conventional pulsed light propagation time measurement device that can obtain position information in three-dimensional coordinates.
This pulse light propagation time measuring device is different from that described above in that a multiplexer 63 (between the light receiving unit 13 and the phase-locked loop circuit 20 is provided between the light receiving unit 13 and the phase locked loop circuit 20. MUX, a signal selection circuit), and a microprocessor 60 is added as a switching control means and position information calculation means for obtaining position information in three-dimensional coordinates.

The multiplexer 63 employs one having four inputs and one output, and selects one of the four inputs as a pulse signal Bp according to the switching control signal and sends it out to the phase lock loop circuit 20. . Further, the pulse signal Ap, the pulse signal Bp passing through the optical path R1, the pulse signal Bp passing through the optical path R2, and the pulse signal Bp passing through the optical path R3 are sent to the input as they are.
In order to perform the switching control, a switching control routine 62 is introduced into the microprocessor 60, and the selection target of the multiplexer 63 is cyclically switched among the four inputs according to the processing. The switching cycle is set to about several ms, for example.

  A displacement calculation routine 61 (position information calculation means) is also installed in the microprocessor 60, and the switching control routine 62 calculates a relative displacement or the like as the position information F. Specifically, the phase difference E is input from the phase difference detection circuit 50, and the phase difference E1 corresponding to the pulse signal Bp passing through the optical path R1 and the optical path R2 are input to the phase difference E according to the switching timing of the switching control routine 62. The phase difference E2 corresponding to the passed pulse signal Bp and the phase difference E3 corresponding to the pulse signal Bp passed through the optical path R3 are classified. Then, desired position information and the like are calculated based on the plurality of phase differences E1, E2, and E3. In this case, three optical paths R1, R2, and R3 are established by the three sets of light receiving units 13, and the phase difference E is obtained for each, so that known information such as the relative position between the light emitting unit 12 and each light receiving unit 13 is obtained. Can also be used to obtain position information in three-dimensional coordinates.

  Further, some circuits and the like will be described in detail. For example, the oscillation circuit 11 includes a small-sized oscillator 11a that oscillates at high speed and a frequency divider 11b that generates a pulse signal Ap from the oscillation signal. The oscillation signal of the oscillator 11a is used as a clock CLK for the microprocessor 60 and the counter circuit of the phase difference detection circuit 50 as it is or after appropriate waveform shaping and frequency division. The light emitting unit 12 employs a pulsed laser transmitter incorporating a semiconductor laser or a light emitting diode that emits infrared rays, and the light receiving unit 13 employs a photodiode or a phototransistor that performs photoelectric conversion.

  Further, the frequency conversion circuit 30 receives a balanced mixer 30a that inputs a sine wave oscillation signal As of frequency f4 and a sine wave oscillation signal Bs of frequency f2, and a signal component of frequency f3 from the output signal, that is, a sine wave oscillation signal Cs. A band-pass filter 30b or a low-pass filter is provided. As a result, the frequency f3 becomes the difference between the frequency f2 and the frequency f4, and the variation in the phase angle of the sinusoidal oscillation signal Bs is inherited by the sinusoidal oscillation signal Cs, and the same variation is also exhibited in the phase angle. To do.

  Although the reference signal generating circuit 40 is known to be not synchronized with the pulse signal Ap, a circuit that generates a reference signal Ds synchronized with the pulse signal Ap is employed here, and the pulse signal Ap of the frequency f1 is used. And a phase lock loop circuit 41 that generates a sine wave oscillation signal As having a frequency f2, and a frequency division that generates a reference signal Dp having a frequency f3 by performing binarization and frequency division from the sine wave oscillation signal As. Circuit 42. Similar to the phase-locked loop circuit 20, the phase-locked loop circuit 41 fixes the phase of the sinusoidal oscillation signal As at the timing of the pulse train in the pulse signal Ap, and at that time, also multiplies the frequency, and the magnification is also It is the same.

  The phase difference detection circuit 50 includes, for example, a binarization comparator 50a and a digital time difference calculation circuit 50b. The comparator 50a inputs the sine wave oscillation signal Cs and a predetermined threshold voltage and outputs a binary pulse signal Cp. The time difference calculation circuit 50b counts at the pulse leading edge of the reference signal Dp. Is cleared and a counter circuit that holds the count value at the trailing edge of the pulse signal Cp and counts the number of pulses of the clock CLK during that period is sufficient. The count value is repeatedly sent to the microprocessor 60 as the phase difference E.

  In this case, every time the input selection switching by the multiplexer 63 is completed, the three phase differences E related to the optical paths R1, R2, and R3 are calculated and delivered to the displacement calculation routine 61. For example, the light emitting unit 12 is movable. When three sets of light receiving units 13 are arranged at the vertices of a triangle in the fixed unit, the three-dimensional coordinates of the movable unit are obtained from a plurality of measured propagation distances (R1, R2, R3). Application as a three-dimensional pointing device is also possible. In addition, since only a plurality of light receiving sections 13 are provided, the apparatus is small and inexpensive.

  In this case, not only the pulse signal Bp passing through the optical paths R1 to R3 but also the pulse signal Ap not passing through the optical paths R1 to R3 are selectively sent to the phase-locked loop circuit 20 and the frequency conversion circuit 30 via the multiplexer 63. Therefore, it is possible to dynamically perform correction and compensation processing as needed by holding the measured phase difference E and referring to it when calculating the phase difference E when the pulse signal Bp is selected. it can.

  Further, for example, if the frequency f3 is 333.33 kHz, the phase difference E is obtained every 3 μs. Therefore, when the multiplexer 63 is switched every 3 ms, the phase difference E can be measured 1000 times during that time. The S / N (signal / noise) can be further improved by statistical processing. Therefore, although it depends on the S / N of the original pulsed optical signal, the propagation time or propagation distance can be measured with very high accuracy on the order of ps and mm.

  By the way, although it is not a pulse light propagation time measuring device, the method of detecting a hand shake optically is known (for example, refer to patent documents 2). The gist of this technology is that light is emitted from a plurality of light emitting elements to a hand shaking area, and reflected light from the hand by the emitted light is received by a plurality of light receiving elements provided corresponding to each light emitting element, The movement direction and movement speed of the hand movement are detected based on the difference in the amount of light received by the plurality of light receiving elements and the change over time of the sum.

JP 2001-349788 A JP 10-148640 A, Patent 3240941

However, in such a hand movement detection technique, the movement direction and movement speed of the hand can be detected, but it is not considered to know the three-dimensional position of the hand or fingertip. Moreover, detection becomes difficult when the moving speed of the hand is slow.
Therefore, the pulse light propagation time measurement technique described above is also applied to hand gesture detection, and the reflection position in the three-dimensional space by the hand or finger is obtained by measuring the propagation delay time from the light emitting part to the light receiving part. It is considered that the three-dimensional position of the hand or fingertip can be detected regardless of the behavior state regardless of whether the fingertip is stationary or moving.

However, when the hand to be measured is greatly shaken, the light receiving level also changes greatly. Therefore, when applying the above-described conventional pulsed light propagation time measuring device, in order to ensure sufficient measurement accuracy even under usage conditions in which the light reception level changes greatly, the influence of light reception level fluctuations is eliminated / suppressed. Therefore, it is required to further improve the measurement accuracy.
After examining the pulse light propagation time measurement device for the relationship between the light reception level and the propagation time, there is room for improvement in relation to the phase-locked loop circuit interposed in order to achieve both pulse transmission and phase difference detection. It turned out to be.
Therefore, based on such knowledge, it is a technical problem to realize a pulsed light propagation time measuring device that can accurately measure the pulsed light propagation time even if the measurement target moves violently.

  The pulsed light propagation time measuring device of the present invention (Solution 1) was devised to solve such a problem. In the phase-locked loop circuit 20, the phase of the sinusoidal oscillation signal Bs is changed to the pulse signal Bp. When matching, conventionally, only the rise timing of the pulse has been adopted. However, since the pulse width and rise / fall timing fluctuate in accordance with the change in the light reception level, the light reception level fluctuation is the phase of the sinusoidal oscillation signal Bs. As a result, it has been found that the measurement accuracy is undesirably affected, so that the following configuration is adopted in order to eliminate or suppress the influence.

  That is, a light emitting unit that emits pulsed light at a predetermined period, a light receiving unit that generates a pulse signal based on the presence or absence of light reception, and a phase-locked loop circuit that generates a first sine wave oscillation signal having a high frequency based on the pulse signal A frequency conversion circuit that performs signal processing to maintain a phase state and generates a second sine wave oscillation signal having a low frequency from the first sine wave oscillation signal, and a reference signal having the same frequency as the second sine wave oscillation signal In the pulsed light propagation time measuring device, comprising: a reference signal generating circuit for generating a phase difference; and a phase difference detecting means for detecting a phase difference between the reference signal and the second sinusoidal oscillation signal. A plurality of sets of frequency conversion circuits and the phase difference detection means are provided, one of which responds to the rise of the pulse signal, and the other set Are those responsive to the falling of the pulse signal, wherein the average value calculating means for taking an average phase difference of the both sets are provided.

  Further, the pulsed light propagation time measuring device of the present invention is (the solution means 2), the pulsed light propagation time measuring device of the solution means 1, wherein the light emission power variable circuit for changing the light quantity of the light emitting unit, and the pulse signal. A pulse width measuring circuit for measuring the width of the light emission, and a pulse width control means for performing power control of the light emission power variable circuit so as to alleviate a sudden change in the pulse width measured by the pulse width measuring circuit. And

  Further, the pulsed light propagation time measuring device of the present invention (solving means 3) is the pulsed light propagation time measuring device of the solving means 2, wherein the first propagation time is based on the phase difference averaged by the average value calculating means. And the second propagation based on the control amount of power control (from the pulse width control means to the light emission power variable circuit) and the pulse width (of the pulse signal measured by the pulse width measurement circuit). The time is calculated, and when the difference between the two times is large, the second propagation time is adopted, and when not so, the first propagation time is adopted.

In such a pulsed light propagation time measuring apparatus of the present invention (Solution 1), the phase lock loop circuit, the frequency conversion circuit, and the phase difference detection means are doubled so that the phase difference based on the rising edge of the pulse signal is obtained. And a phase difference based on the falling edge of the pulse signal, and an average of the phase differences is obtained, thereby obtaining a phase difference corresponding to the timing at the center of the pulse.
Even if the light reception level changes greatly and the pulse width and rise / fall timing fluctuate, the center of the pulse hardly changes, and the influence of the light reception level is so small that it can be ignored.
Therefore, according to the present invention, it is possible to realize a pulsed light propagation time measuring apparatus that can accurately measure the pulsed light propagation time even when the measurement target moves violently and the received light level changes.

  Further, in the pulsed light propagation time measuring device of the present invention (Solution means 2), the emission power control for mitigating the sudden change in the pulse width is performed, so that the measurement object is further close or far away. Even if a large distance is moved, the light reception level does not change greatly, and the pulse signal is stable. Therefore, the pulse light propagation time measurement based on the pulse transmission and the phase difference detection is accurately performed. Then, the stabilization of the light reception level and the pulse width and the improvement for obtaining the phase difference corresponding to the central timing of the pulse described above further improve the measurement accuracy.

In addition, in this case, since the phase difference detection avoids the influence of the pulse width variation as described above, the pulse width measurement circuit does not have to be high, and the pulse width measurement circuit has a simple configuration. You can do it with something. For the same reason, the control of the pulse width does not require strictness or high responsiveness.
Therefore, according to the present invention, it is possible to easily realize a pulsed light propagation time measuring apparatus that can accurately measure the pulsed light propagation time with less change in the received light level even when the measurement object moves violently.

Furthermore, in the pulsed light propagation time measuring device of the present invention (Solution means 3), in addition to the propagation time measurement based on the phase difference, the propagation time measurement based on the pulse width or the like is also performed, depending on the degree of the difference between the two. Thus, it is possible to measure a wider range by determining whether or not the propagation time measurement based on the phase difference is appropriately performed and adopting an appropriate one. In addition, since the propagation time measurement based on the added pulse width and the like can be performed with the aid of the control amount and the pulse width measurement value used in the light emission power control described above, it can be implemented with a simple circuit or the like.
Therefore, according to the present invention, the pulse light propagation time is accurately measured when the propagation time measurement based on the phase difference can be performed, and the pulse width can be measured even when the measurement target cannot move and the propagation time measurement based on the phase difference cannot be performed. It is possible to easily realize a pulsed light propagation time measuring device that can measure the pulsed light propagation time by propagation time measurement based on the above.

About such a pulsed light propagation time measuring apparatus of the present invention, a specific form for carrying out this will be described by the following embodiments and Examples 1 to 5.
The basic embodiment shown in FIG. 1 embodies the above-described solving means 1 to 3 (claims 1 to 3 as originally filed).
Moreover, Example 1 shown in FIGS. 2 to 3, Example 2 shown in FIG. 4, Example 3 shown in FIGS. 5 to 6, Example 4 shown in FIG. 7, Example shown in FIG. Reference numeral 5 denotes an application example to an apparatus for measuring and inputting a three-dimensional position (applied pulse light propagation time measuring application apparatus of claim 4 at the beginning of the application).
In addition, since the same reference numerals are given to the same constituent elements as those in the past in the illustration thereof, and what is described in the background art section is also common to the following embodiments, it is redundant. The description of this will be omitted, and the following description will focus on differences from the prior art.

[Basic embodiment]
A specific configuration of a basic embodiment of the pulsed light propagation time measuring apparatus of the present invention will be described with reference to the drawings. 1A is a block diagram, and FIG. 1B is a signal waveform example.
The pulse light propagation time measuring device of FIG. 1A is different from that of FIG. 9A described above in that the set of the phase lock loop circuit 20, the frequency conversion circuit 30, and the phase difference detection circuit 50 is different. Another point is that a similar circuit 21 + 31 + 51 is provided, and an average value calculation circuit 52, a pulse width control routine 71, a pulse width measurement circuit 72, and a light emission power variable circuit 73 are added.

  Another set of additional circuits 21 + 31 + 51 is a combination of the phase-locked loop circuit 21, the frequency conversion circuit 31, and the phase difference detection circuit 51. The phase-locked loop circuit 20 responds to the rising edge of the pulse signal Bp, that is, the phase is locked to the leading edge of the pulse, whereas the phase-locked loop circuit 21 responds to the falling edge of the pulse signal Bp, that is, the pulse. The difference is that the phase is locked to the trailing edge, but the rest of the configuration is the same. The frequency conversion circuit 31 has the same configuration as the frequency conversion circuit 30, and the input is a sinusoidal oscillation signal Bs output from the phase-locked loop circuit 21. The phase difference detection circuit 51 has the same configuration as the phase difference detection circuit 50, and the input is a sine wave oscillation signal Cs output from the frequency conversion circuit 31.

The average value calculating circuit 52 (average value calculating means) inputs a phase difference from both the phase difference detection circuits 50 and 51, calculates an average value thereof, and outputs this as a phase difference E. For example, two inputs This is easily realized by combining a wiring (1 bit shift function) ignoring the least significant bit on the output side using an output circuit of one output.
For example, a digital potentiometer is employed as the light emission power variable circuit 73, and the light emission power variable circuit 73 varies the light amount of the light emitting unit 12 by increasing or decreasing the energization amount of the light emitting unit 12 according to the control command of the pulse width control routine 71. It is like that.

The pulse width measurement circuit 72 may be a simple circuit similar to the time difference calculation circuit 50b described above as long as the pulse width of the pulse signal Bp can be measured. For example, the count value is cleared at the leading edge of the pulse signal Bp and the pulse signal Bp A counter circuit that holds the count value at the trailing edge of the pulse and counts the number of pulses of the clock CLK during that period is sufficient. The count value is repeatedly sent to the pulse width control means 71.
The pulse width control routine 71 (pulse width control means) is a control method such as PID control or PI control, which is embodied by a program of the microprocessor 60, for example, and performs a sudden change in the pulse width measured by the pulse width measurement circuit 72. A control command for relaxing is calculated and sent to the light emission power variable circuit 73. Since there is no problem even if the pulse width of the pulse signal Bp changes to some extent, it is easy to adopt low gain follow-up control that targets a constant value or control that returns gently only when it deviates from a certain range. Stable operation even with simple methods.

  Although not shown in the figure, for example, when a physical quantity equivalent to the light propagation time for application purposes such as the position information F in FIG. 10 described above is calculated by the program processing of the microprocessor 60 or the like, the pulse light propagation time that is the basis of the calculation is calculated. As described above, two of the first and second propagation times are obtained. That is, the first propagation time is calculated as described above based on the phase difference E averaged by the average value calculation circuit 52, and the control command value (control amount) from the pulse width control routine 71 to the light emission power variable circuit 73 is calculated. The second propagation time is calculated based on the pulse width of the pulse signal Bp measured by the pulse width measuring circuit 72.

The second propagation time is calculated, for example, by multiplying the time of the pulse width of the pulse signal Bp and the light emission amount according to the energization amount according to the control amount.
Further, one of the two propagation times is adopted for calculating the position information F or the like. That is, when the difference or ratio between the first and second propagation times exceeds a preset threshold value, the difference between the two propagation times is large, and it is highly likely that there is a malfunction in the calculation based on the phase difference. Therefore, the second propagation time is adopted, and if not, the first propagation time is adopted.

  About the pulse light propagation time measuring apparatus of this embodiment, the use aspect and operation | movement are demonstrated. FIG. 1B shows the waveform Bp− of the pulse signal Bp when the received light waveform of the pulsed light when the received light amount is different and the received light waveform of the pulsed light when the received light amount is large are binarized by the threshold Bp-S. 2 is a signal waveform example relating to 1 and a waveform Bp-2 of the pulse signal Bp when the received light waveform of the pulsed light when the received light amount is small is binarized by the threshold value Bp-S.

  In this case, the calculation of the phase difference by the light transmission / reception unit 10, the phase lock loop circuit 20, the frequency conversion circuit 30, the reference signal generation circuit 40, and the phase difference detection circuit 50 is the same as already described for the conventional circuit of FIG. To be done. In addition, the calculation of the phase difference by the light transmission / reception unit 10, the phase lock loop circuit 21, the frequency conversion circuit 31, the reference signal generation circuit 40, and the phase difference detection circuit 51 is performed in substantially the same manner. The difference is that the phase-locked loop circuit 20 responds to the rising edge of the pulse signal Bp while the phase-locked loop circuit 21 responds to the falling edge of the pulse signal Bp. Then, the two phase differences calculated by the phase difference detection circuits 50 and 51 are averaged by the average value calculation circuit 52 and combined into one phase difference E.

  Here, if the amount of light received by the light receiving unit 13 is large, in the waveform Bp-1 of the pulse signal Bp obtained by binarizing the pulsed light with the threshold value Bp-S, the pulse leading edge T1a (rising edge) moves forward and the pulse trailing edge T1b (falling) recedes backward and the pulse width (T1b-T1a) increases. On the other hand, when the amount of light received by the light receiving unit 13 is small, in the waveform Bp-2 of the pulse signal Bp obtained by binarizing the pulsed light with the threshold value Bp-S, the pulse leading edge T2a (rising edge) moves backward and after the pulse The edge T2b (falling) advances forward and the pulse width (T2b-T2a) becomes narrower. However, the pulse centers T1c and T2c are hardly changed.

Then, the phase difference calculated by the phase difference detection circuit 50 corresponds to the pulse leading edges T1a and T2a, and the phase difference calculated by the phase difference detection circuit 51 corresponds to the pulse trailing edges T1b and T2b. Since the phase difference E integrated by the average value calculation circuit 52 corresponds to the pulse centers T1c and T2c, the influence of the change in the received light level on the calculation of the phase difference is so small that it can be ignored.
Therefore, according to this embodiment, even if the measurement object moves violently and the received light level changes, the phase difference E and thus the pulse light propagation time can be accurately measured.

  Further, in this pulsed light propagation time measuring device, when the light receiving level increases or decreases and the pulse width of the pulse signal Bp expands or contracts, the pulse width is measured by the pulse width measuring circuit 72, and based on the pulse width. Automatic control for changing the energization amount of the light emitting unit 12 in the returning direction is performed by the pulse width control routine 71 and the light emission power variable circuit 73. For this reason, if the measurement target approaches and the light reception level starts to increase, the light emission power is reduced to avoid an excessive increase in the light reception level, and if the measurement target moves away and the light reception level starts to decrease, the light emission power is increased and the light reception level is excessively decreased. Therefore, the pulse light propagation time based on the phase difference E can be measured over a wide range from near to far.

Measurement of the pulse light propagation time based on such a phase difference is appropriately performed as long as the pulse appears in the pulse signal Bp and the phase-locked loop circuits 20 and 21 are phase-locked (phase-fixed tracking). An accurate measurement result (phase difference E, first propagation time) is obtained.
On the other hand, when the measurement target is too close or moves violently and the phase lock loop circuits 20 and 21 fail to phase lock, the measurement result (second propagation time) of the pulsed light propagation time based on the pulse width or the like is adopted. Is done.

  That is, in this pulsed light propagation time measuring device, in parallel with the calculation of the first propagation time (phase difference E), the control command value of the pulse width control routine 71 and the measured pulse width of the pulse width measuring circuit 72 Based on the above, the second propagation time is calculated. When the phase-locked loop circuits 20 and 21 are unlocked, the first propagation time greatly deviates from the second propagation time, so the adoption of the first propagation time is refrained, and instead the second propagation time. Is adopted. Therefore, even when the measurement object moves violently and the propagation time measurement based on the phase difference cannot be performed, the pulse light propagation time can be measured by the propagation time measurement based on the pulse width or the like.

  About the Example 1 of the pulse light propagation time measuring apparatus of this invention, the specific structure is demonstrated referring drawings. FIG. 3 is a block diagram of a pulsed light propagation time measuring apparatus capable of measuring a three-dimensional position. FIG. 2A is a perspective view of a mounting position of the light transmitting / receiving unit 81, and FIG. (C) is a pattern diagram of three-dimensional position measurement, (d) is a detailed diagram of a light emission power variable circuit.

  The pulse light propagation time measuring device of FIG. 3 is different from that of FIG. 10 described above, as in the above-described embodiment, the phase lock loop circuit 21, the frequency conversion circuit 31, the phase difference detection circuit 51, and the phase difference detection. A circuit 51, an average value calculation circuit 52, a pulse width control routine 71, a pulse width measurement circuit 72, and a light emission power variable circuit 73 are added, and the number of light receiving units 13 is increased from three to two (13U). , 13D, 13R, 13L, 13C). There are also four light emitting units 12 (see FIG. 2), all of which are arranged in the vicinity of the central light receiving unit 13C (see FIGS. 2A and 2B), and are based on the light emission power variable circuit 73. Since the variable control of the light emission power is also performed together (see FIG. 2D), it can be regarded as one in terms of function.

The gist of the modification is as follows. First (see FIG. 3), PLL circuits 20 and 21 phase-locked at the rising edge and falling edge of the received light signal Bp are provided in parallel, and the subsequent phase difference detection circuits 50 and 51 are respectively provided. The phase difference E corresponding to the center of the pulse can be easily measured with high accuracy simply by averaging the two phase differences detected in the above.
Second, the light receiving unit 13 is provided at the center (13C) and the top, bottom, left and right (13U, 13D, 13L, 13R) (see FIGS. 2A and 2B), and the three light receiving units required for three-dimensional measurement. The propagation time is calculated for 13 combinations 4 patterns (13U, 13L, 13R), (13D, 13L, 13R), (13U, 13D, 13L), (13U, 13D, 13R) (see FIG. 2C). In this, a combination that does not include the light receiving unit 13 having a large influence of background reflection can be selected. If the influence of reflection from something other than a measurement target such as a fingertip, such as a palm or an arm, is strong, the propagation distance shifts to the larger side, so that the selection can be made based on the degree of deviation.

Third, the current flowing to the light emitting unit 12 is controlled using the pulse width of the pulse signal Bp of the light receiving pulse or the distance information from the reflection part P to the center light receiving unit 13C so that the light receiving waveform is not saturated. It is.
Fourth, even when the phase-locked loop circuits 20 and 21 do not phase-lock with respect to the pulse of the pulse signal Bp output by the two adjacent light receiving units 13 on the top, bottom, left and right, three-dimensional position measurement is performed with the remaining three light receiving units. It is to be able to do.
Fifth, a pulse width measuring circuit 72 for measuring the pulse width of the pulse signal Bp from each light receiving unit 13 is provided, and the pulse width and a control command value from the pulse width control routine 71 to the light emission power variable circuit 73 are provided. Even when the phase-locked loop circuits 20 and 21 are not phase-locked with respect to the pulse signals Bp from all the light receiving units 13 by obtaining the second propagation time based on the presence / absence or the like of the hand as a reflector. It is to be able to obtain the outline information of the movement.

  The pulse light propagation time measuring device is incorporated as a hand mouse in the notebook computer 80 (see FIG. 2A), and the touch pad in which the light transmitting / receiving unit 81 is used as a pointing device of the notebook computer 80. It is made by adding a light sensor to the. The light receiving unit 13C and the light emitting unit 12 are disposed in the center of the light transmitting / receiving unit 81 (see FIG. 2B), and the light receiving units 13U, 13D, 13L, and 13R are distributed on the four sides of the light transmitting / receiving unit 81, respectively. Has been. Then, by placing or moving the fingertip, for example, at a position about 20 mm to 70 mm away from the light transmitting / receiving unit 81, three-dimensional pointing using a finger can be performed.

Further, the frequency conversion circuit 31 will be described in detail. The frequency conversion circuit 31 includes a mixer 31a having the same configuration as the mixer 30a, and a bandpass filter 31b having the same configuration as the bandpass filter 30b.
The phase difference detection circuit 51 will be described in detail. The phase difference detection circuit 51 includes a comparator 51a having the same configuration as the comparator 50a and a time difference calculation circuit 51b having the same configuration as the time difference calculation circuit 50b.

  The use mode and operation of the pulsed light propagation time measuring apparatus according to the first embodiment will be described with reference to the drawings. FIG. 2A is a perspective view where the fingertip is operating, and FIG. 2C is a pattern diagram of three-dimensional position measurement.

  In this example, pulsed light is continuously emitted at equal intervals from the light emitting units 12 provided on the top, bottom, left, and right in the vicinity of the light receiving unit 13C at the center of a substantially square (about 70 mm × 70 mm) light transmitting / receiving unit 81. Reflected light from the hand and the light receiving unit 13C at the center of the light transmitting / receiving unit 81 and the light receiving units 13U, 13D, 13L, and 13R attached to the four sides on the top, bottom, left, and right are converted into electrical signals at the respective points. At this time, the pulse signal Bp is set in accordance with the magnitude relationship compared with the fixed level (binarization threshold). One of the pulse signals Bp output from each light receiving unit 13 is selected in turn by a multiplexer 63 (signal selection circuit, MUX), and the selected pulse signal Bp is input to the phase lock loop circuits 20 and 21. .

  In the phase-locked loop circuit 20, the phase of the sinusoidal oscillation signal Bs at the frequency f2 is fixed at the rising timing of the pulse train in the pulse signal Bp at the frequency f1, and in the phase-locked loop circuit 21, the falling timing of the pulse train in the pulse signal Bp at the frequency f1. The phase of the sinusoidal oscillation signal Bs having the frequency f2 is fixed. The sinusoidal oscillation signal Bs having the frequency f2 output from the phase-locked loop circuit 20 is converted into the sinusoidal oscillation signal Cs having the low frequency f3 by the frequency conversion circuit 30 while retaining the phase information of the pulse rising. On the other hand, the sinusoidal oscillation signal Bs having the frequency f2 output from the phase-locked loop circuit 21 is converted into the sinusoidal oscillation signal Cs having the low frequency f3 by the frequency conversion circuit 31 while retaining the phase information of the pulse falling. .

The frequency-converted sinusoidal oscillation signal Cs is input to the phase difference detection circuit 50 when the pulse rising phase information is held, and the time difference and the phase difference from the reference signal Dp of the frequency f3 are measured. The one holding the phase information is input to the phase difference detection circuit 51, and the time difference from the reference signal Dp of the frequency f3 and the phase difference are measured. Then, these two phase differences are input to the average value calculation circuit 52 and integrated into one phase difference E.
As described above, although the pulse width (T1b-T1a) and (T2b-T2a) of the waveform of the pulse signal Bp varies greatly depending on the light reception level (see FIG. 1B), the center of the pulse {T1c = (T1b Since -T1a) / 2, T2c = (T2b-T2a) / 2} is not affected by the magnitude of the received light level, the accuracy of measurement of the propagation delay time is improved by associating it with the center of the pulse.

In this example, the rising edge (T1a) of the pulse and the falling edge (T1b) of the pulse are converted into the phase of the pulse signal Bp having a high frequency (for example, f1 = 360 MHz).
If the maximum distance from the light emitting unit 12 to the hand or finger is 200 mm, the maximum propagation distance until it is reflected by the hand or finger and returns to the light receiving unit 13 is about 400 mm. When f1 = 360 MHz, the wavelength is λ = Since the phase difference is 833 mm, the phase difference is 360 degrees at the propagation distance of 833 mm, and the phase difference is 173 degrees at the propagation distance of 400 mm. Therefore, the phase change due to the propagation delay at the center of the received light pulse is within 180 degrees. Therefore, under the above conditions, the phase corresponding to the pulse center may be simply calculated as the average (θia + θib) / 2 of the rising phase (θia) and the falling phase (θib).

If the phase corresponding to the center of the light transmission pulse is θo, the phase difference (θix) of the light reception pulse center due to propagation delay is θix = {(θia−θo) + (θib−θo)} / 2.
Converted to propagation delay time Tx (unit: pS), Tx = 2778 · (θid / 360)
When converted to the propagation distance Lx (unit: mm), Lx = 833 · (θid / 360).
Light emitted from the light emitting unit 12 in the vicinity of the light receiving unit 13C (see FIG. 2A) is reflected at the point P of the hand or finger and propagates until returning to the light receiving units 13C, 13U, 13D, 13L, and 13R. Assuming that the delay times are Tcc, Tuc, Tdc, Tlc, and Trc, the propagation delay times Tcp, Tup, Tdp, Tlp, and Trp from the light receiving portions 13C, 13U, 13D, 13L, and 13R to the reflection site P are
Tcp = Tcc / 2, Tup = Tuc−Tcc / 2, Tdp = Tdc−Tcc / 2,
Tlp = Tlc−Tcc / 2, Trp = Trc−Tcc / 2.

  If these propagation times are converted into distances, the distances from the upper, lower, left, and right light receiving portions 13U, 13D, 13L, and 13R to the reflection part P can be known, so that the three-dimensional coordinates of the P point can be obtained using the Pythagorean theorem. . In order to know the three-dimensional coordinates, it is sufficient to know the distances from the three light receiving portions. Therefore, the background reflection (the fingertip is used as the measurement reflection point) among the four light receiving portions 13U, 13D, 13L, and 13R on the top, bottom, left, and right. In this case, the coordinates of the reflection point are measured by three light receiving units excluding a sensor (for example, the light receiving unit 13D when the palm is in the lower part) which is greatly influenced by the palm or the like.

  In addition, when using a light-receiving unit that is greatly affected by background reflection (see FIG. 2C), an error that delays the fall of the pulse and increases the propagation delay time occurs. Each position (P1, P2, P3) of the reflection part P measured by four types of combinations (13U, 13L, 13R), (13D, 13L, 13R), (13U, 13D, 13L), (13U, 13D, 13R) , P4) and the distances between the light receiving parts 13U, 13D, 13L, and 13R are compared with the distance between the light receiving part and the reflection part P that are not included in the measurement combination, and the measurement distance difference is When it becomes larger than a certain value (Lk), the measurement value of the combination including the light receiving unit is not adopted.

  For example, the reflection part position P1 measured with the combination (13U, 13L, 13R) and the distance Lp1d to the light receiving part 13D, and the reflection part P2 and the light receiving part 13D measured with the combination (13D, 13L, 13R) including the light receiving part 13D. If the distance Lp2d is compared and Lp2d> Lp1d + Lk, the light receiving unit 13D determines that the influence of the background reflection is large, and the measured values P2, P3, and P4 in the combination including the light receiving unit 13D are adopted. By not doing so, the influence of background reflection can be reduced.

In addition, even when the phase lock is easily released by the pulse signal Bp from any one of the upper, lower, left, and right light receiving portions, the position of the reflection site P can be measured only by removing the light receiving portion from the measurement combination.
Furthermore, if the central light receiving unit 13C is the target of measurement combination, new combinations (13C, 13U, 13R), (13C, 13U, 13L), (13C, 13D, 13L), (13C, 13D, 13R) are also possible. Therefore, even when the phase lock is easily released by the pulse signals Bp from the two adjacent light receiving parts among the light receiving parts 13U, 13D, 13L, and 13R, the reflection part can be obtained by simply removing the light receiving part from the measurement combination. Since the position of P can be measured, stable measurement can be performed.

The problem when the pulse center is the measurement target is that when the light reception level is too high, the light reception waveform is saturated and a trailing phenomenon occurs, and an error also occurs at the pulse center.
In order to avoid this problem, the current flowing through the light emitting unit 12 such as a light emitting diode is controlled by the light receiving pulse width Pwc or the measurement distance Lcp between the light emitting unit 13C and the reflecting portion P so that the light receiving level becomes an optimum value. Thus, accurate measurement is possible without being saturated even at a short distance. Since the power of the light transmission pulse can be lowered to an appropriate level necessary for measurement, the background reflection can also be reduced.

  The case where the hand mouse capable of three-dimensional pointing is used will be described in more detail (see FIG. 2A). The periphery (for example, up, down, left, and right) of the center light receiving unit 13C of the square light transmitting / receiving unit 81 (about 70 mm × 70 mm). Infrared pulses having a pulse width of 75 nS are emitted toward a fingertip operated in the air at a repetition frequency of 1.333 MHz from a light transmitting section (for example, an infrared LED) provided in the vicinity of these four locations. The reflected pulse light from the fingertip is converted into an electric signal by the center of the light transmitting / receiving unit 81 and the light receiving portions 13C, 13U, 13D, 13L, and 13R on the upper, lower, left, and right sides, and compared with the binarized fixed level by the comparator. Become. The pulse signal Bp from each of the light receiving units 13C, 13U, 13D, 13L, and 13R is selected by the multiplexer 63, and the pulse signal Bp from one light receiving unit is selected. The signal is input to the lock loop circuit 21 and converted into a sinusoidal oscillation signal Bs having a high frequency f2, for example, 360 MHz + 0.333 MHz. The reference synchronization phase-locked loop circuit 41 receives a pulse signal Ap having a frequency f1, which is the source of the light transmission pulse, as a reference signal, which is converted into a sinusoidal oscillation signal As of f4 = 360 MHz.

  The beat-down signal (f2-f4) of the sinusoidal oscillation signal Bs having the frequency f2 and the sinusoidal oscillation signal As having the frequency f4 that has passed through the balanced mixer 30a and the bandpass filter 30b is a sinusoidal oscillation having a low frequency f3 = 333 kHz. The beat-down signal (f2-f4) of the sinusoidal oscillation signal Bs having the frequency f2 and the sinusoidal oscillation signal As having the frequency f4 that has been converted into the signal Cs and passed through the balanced mixer 31a and the bandpass filter 31b is also a low frequency f3. = Sine wave oscillation signal Cs of 333 KHz, but the phase difference information is inherited as it is in any case. Therefore, the sinusoidal oscillation signal Cs is binarized by the comparators 50a and 51a, and the pulse signal Cp having the frequency f3 converted into a digital signal is input to the time difference calculation circuits 50b and 51b. Θix = {(θia−θo) + (θib−θo)} / 2 corresponding to the phase difference is obtained.

Further, the pulse width of the pulse signal Bp from each light receiving unit 13 is measured by the pulse width measuring circuit 72, and is used for determination when a reflector such as a finger or hand is not present in front of the light transmitting / receiving unit 81. In order to describe this in detail, the pulse widths corresponding to the light receiving units 13C, 13U, 13D, 13L, and 13R measured by the pulse width measuring circuit 72 are PWc, Pwu, PWd, PWl, and PWr.
Since the pulse width is almost proportional to the size of the light receiving level, the value obtained by adding the pulse widths at each light receiving unit ΣPW = PWc + Pwu + PWd + PWl + PWr Become. The value obtained by adding the pulse width to the range that can be phase-locked with the reflected light pulse (for example, 100 mm) has a measurement range that is roughly double (for example, 200 mm). Can be used as data.

Specific examples of determination criteria for this determination method are shown below.
Determines that there is no finger or hand in front of the pad: ΣPW <k1
A finger or hand is present in front of the pad, but it is determined that tertiary measurement is not possible: k1 <ΣPW <k2
Judge that finger and hand positions can be measured in third order: k3 <ΣPW
Judge that the position of the finger or hand is too close to the light receiver: k4 <Pwi (one of PWc, Pwu, PWd, PWl, PWr)
Judge finger / hand on left side: Pw1-Pwr> K5
Determines that a finger or hand is on the right side: Pwr-Pwl> K5
Judge that the finger or hand is on the upper side: Pwu-Pwd> K5
Judge that the finger or hand is on the lower side: Pwd-Pwu> K5

It is also possible to know in which direction the finger or hand is moving by using the following change amount for each measurement cycle Ts (for example, 16 mS).
Judge that the finger or hand is moving to the left: Δ (Pw1−Pwr)> K6
Judge that the finger or hand is moving to the right: Δ (Pwr−Pwl)> K6
It is determined that the finger or hand is moving up: Δ (Pwu−Pwd)> K6
It is determined that the finger or hand is moving down: Δ (Pwd−Pwu)> K6
Determines that finger or hand is approaching the pad: ΔΣPW> K7
Even when the position of the finger or hand is in a position where three-dimensional measurement cannot be performed, the function as a hand mouse can be supplemented by using the above determination result.

  Next, a detailed procedure will be described in detail. First, in a situation where a finger or hand is not present in front of the pad, a normal light reception pulse signal cannot be input to the phase lock circuit, and the phase lock circuit becomes unstable. If it is determined that the tertiary measurement is not possible, the multiplexer 63 selects the same pulse signal Ap as the light transmission pulse so that the center of the light transmission pulse is measured. If it is determined by the determination based on the pulse width information that tertiary measurement is possible, the multiplexer 63 first selects the pulse signal Bp from the central light receiving unit 13C, and the rising phase θia, falling phase θib, and reference phase θo of the pulse are selected. The center phase difference of the received light pulses θix = {(θia−θo) + (θib−θo)} / 2 is repeatedly measured 1024 times, and the average value thereof is calculated.

  Since the frequency difference between the phase-locked loop circuit 41 and the phase-locked loop circuit 20 is set to 333.3 kHz, the phase information (θa, θb) of the phase-locked frequency f1 (360.333 MHz) of the rising and falling of the received light pulse is set. ) Is converted into phase information of frequency f1-f2 = 333.3 KHz. Since the period of 333.3 KHz is 3 μS, the time required for one phase measurement is also 3 μS. The time required to measure the phase 1024 times is 1024 × 3 μS = 3072 μS. Next, the multiplexer 63 selects the pulse signal Bp from the upper light receiving unit 13U. After waiting for a time (for example, 96 μS) until the phase lock circuits 20 and 21 are stabilized, the phase of the pulse center is repeatedly measured 1024 times to obtain an average value.

  Subsequently, the multiplexer 63 selects the phase θcx, θux of the light receiving pulse center in the order of the pulse signal Bp from the lower light receiving unit 13D, the pulse signal Bp from the left light receiving unit 13L, and the pulse signal Bp from the right light receiving unit 13R. , θdx, θlx, θrx are measured. The measurement time from the five light receiving units is (3072 μS + 96 μS) × 5 = 15840 μS. Since data capable of determining three-dimensional coordinates is provided every about 16 mS, 62 position data can be obtained in one second. This is considered to be a sufficient measurement speed to obtain trajectory data in the three-dimensional space of the fingertip or hand.

Since the phase data uses the average value of 1024 measurements, even if the phase jitter is about ± 15 degrees, the fluctuation of the average value of 1024 measurements is reduced to 1 / √1024 = 1/32. The fluctuation of the phase measurement value can be suppressed to about ± 0.5 degrees. ± 0.5 degrees corresponds to ± 1.16 mm when converted to propagation distance.
Since phase measurement accuracy of about ± 0.5 degrees is possible at short distances, three-dimensional position measurement is possible with about ± 2 mm.

The pulse light propagation time measuring device of the present invention shown in the front view in FIG. 4 is different from that of the first embodiment described above in that the installation location of the light transmitting / receiving unit 84 introduced instead of the light transmitting / receiving unit 81 is different. Is a point.
While the above-described first embodiment is for a notebook computer and the optical sensor is arranged horizontally, the pulsed light propagation time measuring device of the second embodiment (see FIG. 4) is for a desktop computer and is below the display 82. The light transmission / reception unit 84 is installed in parallel with the display 82, and the arrangement of the light receiving / receiving units 13 on the upper / lower / left / right sides of the light transmission / reception unit 84 is also adjusted to the aspect ratio of the screen of the display 82.

In the first embodiment described above, the operation is performed with the fingertip facing downward. In the second embodiment, the fingertip may be operated horizontally above the keyboard 83 and preferably in a direction perpendicular to the screen of the display 82.
A specific measurement procedure corresponding to the operation is the same as that of the first embodiment described above.

  A specific configuration of a third embodiment of the pulsed light propagation time measuring apparatus according to the present invention will be described with reference to the drawings. FIG. 5 is a front view showing the installation state of the light transmission / reception unit of the pulsed light propagation time measuring device capable of measuring a three-dimensional position, and FIG. 6 is a block configuration diagram of the pulsed light propagation time measuring device.

The pulse light propagation time measuring apparatus of the third embodiment is also mainly used for a desktop computer, but unlike the first and second embodiments, the split unit 85 in which the light emitting unit 12 and the light receiving unit 13 are integrated is displayed. The upper and lower left and right 12U + 13U, 12D + 13D, 12L + 13L, and 12R + 13R are provided, and the central light transmitting / receiving unit is omitted.
A palm is used as the reflector and the measurement accuracy is inferior, but the measurable distance extends to about 1 to 2 m.

In this case, a specific measurement procedure is as follows. The light emitting unit 12 is selected one by one from the upper, lower, left, and right divided units 85 by the light emitting unit selection power control circuit 74, and the light emitting unit 12 is operated in the same manner as in the first embodiment. The propagation time to the light receiving unit 13 is measured. For example, the propagation time Tup from the light emitting unit 12U provided on the display 82 to the reflection part of the hand is Tup = the propagation time of the pulse center from the light transmission of the light emitting unit 12U to the light reception of the light receiving unit 13U is Tup = It can be calculated as Tupu / 2.
Similarly, the propagation times Tdp, Tlp, Trp from the light emitting parts 12D, 12L, 12R to the reflection part of the hand are Tdp = Tdpd / 2, Tlp = Tlpl / 2, Trp = Trpr / 2.

Then, if these are converted into distances, the three-dimensional coordinates of the reflection part can be obtained in the same manner as in the above-described embodiment.
Since the number of the light receiving units 13 is four in this example as compared to the five in the first embodiment, the measurement time is (3072 μS + 96 μS) × 4 = 12672 μS. In this case, since data for determining a three-dimensional coordinate is prepared every 12.7 mS, 78 position data can be obtained in one second.

  In such a pulsed light propagation time measurement device, the three-dimensional position of the fingertip and the reflection part of the hand can be measured more accurately than the propagation time of the light pulse, so that slight movement of the fingertip in the air is possible. As a result, the mouse and touchpad functions can be added, and one-dimensional information is added as new information. For example, it is possible to change the cursor size, rotate the direction of the arrow, or change the color. . Also, since it is not necessary to hold and move the mouse, even if a handicapped person cannot move the mouse using his arm, the cursor can be operated by moving the fingertip slightly, so mouse operation is impossible Even those who are can operate the computer. Further, when the method as in the third embodiment is used, it is possible to perform a cursor operation and an operation instruction of a device in which functions of a television and a personal computer are integrated only by a hand movement.

The pulse light propagation time measuring device according to the present invention, which shows the installed state of the light transmitting / receiving unit and the side view of the divided unit in FIG. 7, is a mouse that can operate the tongue tip as described above.
By attaching optical systems such as condensing lenses 87a and 87b to the light emitting unit 12 and the light receiving unit 13 and limiting the light irradiation region and the light receiving region, it is difficult to be affected by background reflected light from outside the operation region, The operation area is effectively irradiated with light, and the reflected light from the operation area can be effectively condensed on the light receiving unit. For this reason, for example, even a handicapped person can perform the same operation as the mouse operation by the operation of the tongue.

When operating with the tip of the tongue, unlike the fingertip operation, teeth and lips are close to the periphery of the tongue (see FIG. 7 (a)), so that the influence of background reflected light from these periphery is eliminated. Is required.
A condensing lens 87a is attached to the light emitting unit 12 so that the irradiated light only hits the tongue in the oral cavity, and a condensing lens 87b is also attached to the light receiving unit 13 to view the background reflected light from the teeth and lips. The reflected light from the tongue in the oral cavity can be effectively received.

  The splitting unit 87 equipped with one light emitting unit 12 and one light receiving unit 13 will be described in further detail (see FIG. 7B), and an optical system using condensing lenses 87a and 87b is added to the light emitting unit 12 and the light receiving unit 13. In order to limit the light irradiation area to the area from A1 to T1 to A2 to T2 and limit the light receiving area from B1 to R1 to B2 to R2, the light axes A0 to T0 of the light emitting section 12 and the light of the light receiving section 13 are used. By setting the axes B0 to R0 so as to intersect with each other and using the sensitive area 88 defined by them as the detection area of the tongue, the influence of background reflected light from outside the detection area such as teeth and lips is eliminated. .

In this example (see FIG. 7A), the ear-transmitting frame 86 is connected to the light transmitting / receiving unit 86 so that the light transmitting / receiving unit 86 is positioned at a position about 60 mm away from the mouth, and the condensing lenses 87a, 87b. A dividing unit 87 to which an optical system such as the above is added is attached at the center of the light transmitting / receiving unit 86 and at four positions with a radius of 30 mm therefrom. The light transmitting / receiving unit 86 is fixed to the head via the ear hook frame so that the light emitting unit 12 and the light receiving unit 13 of each divided unit 87 are always in a fixed direction with respect to the mouth.
In this case, since the movement of the tongue tip is detected without contact, it is sufficiently hygienic.

Further, as a modification, the detection of teeth and lips is not completely excluded, and a portion that is convenient for the detection can be adopted to make it easier to use. For example, the cursor operation and pointing operation can be performed with the tip of the tongue, the click operation can be performed by opening and closing the lips, and the double click can be performed by opening and closing the teeth. Can be realized.
Furthermore, since not only the vertical and horizontal movements of the tongue but also the longitudinal movement of the tongue can be detected, it is possible to add new information to the mouse function.

The pulsed light propagation time measuring apparatus of the present invention whose front view is shown in FIG. 8 is one in which the divided units 87 of Example 4 described above are dispersedly installed on the four sides of the display 82. Note that the sensitive region 88 by the dividing unit 87 is extended farther than in the fourth embodiment.
In this case, by limiting the operation region by hand to the sensitive region 88, the distance between the division unit 87 equipped with the light emitting unit 12 and the light receiving unit 13 and the operation region is increased.
For this reason, the operation area in the vertical and horizontal directions is reduced, but the operable distance can be increased.

[Others]
In the above embodiment, the average value calculation is performed by the average value calculation circuit 52. However, the average value calculation may be performed by a program of the microprocessor 60 or the like.

  The pulse light propagation time measuring device of the present invention can be applied to any device having a three-dimensional position measuring unit in addition to a straightforward application device such as a distance meter, a displacement meter, a speedometer, a position measuring device, and a pointing device. Can do. For example, a mouse as a computer input device, a remote control device for a digital television receiver, a remote control device for a projector, a remote control device for a factory automation device, and a touch pad detection range of a portable information terminal that is extended to three dimensions. By incorporating the pulsed light propagation time measurement device of the present invention into a three-dimensional position measurement unit such as a unit or an operation unit of a virtual experience game machine, performance improvement and cost reduction of these application devices can be achieved at the same time.

(A) is a block diagram and (b) is an example of a signal waveform for the basic pulse light propagation time measuring apparatus of the present invention. In Example 1 of the present invention, (a) is a perspective view of a light transmitting / receiving unit mounting destination of a pulsed light propagation time measuring device capable of measuring a three-dimensional position, (b) is a plan view of the light transmitting / receiving unit, and (c) is A pattern diagram of three-dimensional position measurement, (d) is a detailed diagram of the light emission power variable circuit. It is a block block diagram of the pulse light propagation time measuring device. It is a front view which shows the transmission / reception unit installation state of the pulsed light propagation time measuring device which can measure a three-dimensional position about Example 2 of this invention. It is a front view which shows the transmission / reception unit installation state of the pulsed light propagation time measuring device which can measure a three-dimensional position about Example 3 of this invention. It is a block block diagram of the pulse light propagation time measuring device. (A) is a perspective view which shows the light transmission / reception unit installation state of the pulse light propagation time measuring apparatus which can measure a three-dimensional position about Example 4 of this invention, (b) is a side view of the division | segmentation unit of a light transmission / reception unit. . It is a front view which shows the transmission / reception unit installation state of the pulsed light propagation time measuring device which can measure a three-dimensional position about Example 5 of this invention. (A) is a block configuration diagram, and (b) to (f) are signal waveform examples of a conventional basic pulsed light propagation time measuring device. It is a block block diagram of the conventional pulse light propagation time measuring apparatus which can measure a three-dimensional position.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Light transmitter / receiver, 11 ... Oscillator circuit, 11a ... Oscillator, 11b ... Frequency divider,
12 ... Light emitting part (pulse light transmission), 13 ... Light receiving part (photoelectric conversion),
20 ... Phase-locked loop circuit (PLL), 21 ... Phase-locked loop circuit (PLL),
30 ... Frequency conversion circuit, 30a ... Mixer, 30b ... Band pass filter (BPF),
31 ... Frequency conversion circuit, 31a ... Mixer, 31b ... Band pass filter (BPF),
40 ... reference signal generation circuit, 41 ... phase locked loop circuit (PLL), 42 ... frequency divider,
50 ... Phase difference detection circuit, 50a ... Comparator (binarization), 50b ... Time difference calculation circuit,
51 ... Phase difference detection circuit, 52 ... Average value calculation circuit,
60 ... microprocessor, 61 ... displacement calculation routine,
62 ... switching control routine, 63 ... multiplexer (MUX),
71 ... Pulse width control routine, 72 ... Pulse width measurement circuit,
73: Light emission power variable circuit, 74: Light emission section selection power control circuit,
80 ... notebook computer, 81 ... light transmission / reception unit, 82 ... display,
83 ... Keyboard, 84 ... Transmission / reception unit, 85 ... Split unit,
86: Transmitting / receiving unit, 87: Dividing unit, 88 ... Sensitive area

Claims (4)

  A light emitting unit that emits pulsed light at a predetermined period; a light receiving unit that generates a pulse signal based on the presence or absence of light reception; a phase-locked loop circuit that generates a first sinusoidal oscillation signal having a high frequency based on the pulse signal; A frequency conversion circuit for generating a second sine wave oscillation signal having a low frequency from the first sine wave oscillation signal by performing signal processing for maintaining a phase state, and generating a reference signal having the same frequency as the second sine wave oscillation signal In the pulsed light propagation time measuring device comprising: a reference signal generating circuit for detecting a phase difference; and a phase difference detecting means for detecting a phase difference between the reference signal and the second sinusoidal oscillation signal. A plurality of sets of circuits and the phase difference detecting means are provided, one set of which responds to the rising edge of the pulse signal, and the other set includes the pulse. Are those responsive to the falling edge of the signal, the pulse light propagation time measuring apparatus characterized by averaging means for taking an average phase difference of the both sets are provided.   A light emission power variable circuit that varies the amount of light of the light emitting unit, a pulse width measurement circuit that measures the width of the pulse signal, and a light emission power variable circuit that alleviates a sudden change in the pulse width measured by the pulse width measurement circuit. The pulse light propagation time measuring device according to claim 1, further comprising pulse width control means for performing power control.   The first propagation time is calculated based on the phase difference averaged by the average value calculating means, and the second propagation time is calculated based on the control amount of the power control and the pulse width, and the degree of divergence between the two times 3. The pulse light propagation time measuring device according to claim 2, wherein the second propagation time is adopted when the time is larger, and otherwise the first propagation time is adopted.   Mouse as a computer input device, remote controller for digital television receiver, remote control for projector, remote control device for factory automation equipment, input unit that extends touch pad detection range of portable information terminal in three dimensions, A pulse light propagation time measurement application device such as an operation unit of a virtual experience game machine, wherein the pulse light propagation time measurement device according to any one of claims 1 to 3 is incorporated in a three-dimensional position measurement unit. Application device for measuring pulsed light propagation time.

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