JPH1144532A - Range finder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a highly accurate range finder which has been downsized and simplified by placing an A/D conversion means and an arithmetic control means on a first semiconductor chip and a photoelectric conversion element and an amplification element on a second semiconductor chip, respectively. SOLUTION: Light from an infrared light emission diode IRED 3 is projected via a projection lens 1 to a subject. Reflection signal light from the subject by a light receiving lens 2 is incident to a semiconductor light position detection element PSD 4, and two output signals therefrom are amplified by amplifiers 6a, 6b. Since PSD 4 as a photoelectric conversion element and the amplifiers 6a, 6b as amplifying elements are constructed on a semiconductor chip 4a, noise is not likely to appear, thereby improving detection accuracy. In addition, a one-chip microcomputer 10 incorporates an A/D-converter 9 and a CPU 11 of an arithmetic control means. Two signals from the amplifiers 6a, 6b are input to the one-chip microcomputer 10 to be converted into digital values by the A/D 9. Then they are input to the CPU 11 and subjected to predetermined calculation, and then resulted distance information is output from the CPU 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distance measuring apparatus, and more particularly, to projecting a distance measuring signal light from an apparatus to an object to be measured, and receiving the reflected signal light to thereby obtain a distance to the object. Related to the technology for measuring.

[0002]

2. Description of the Related Art A distance measuring apparatus is conventionally known. In particular, it is used for focusing of a camera, etc., and is a small, inexpensive, and accurate distance measuring apparatus for providing a small and inexpensive camera. The idea has been made for a long time. The applicant also
JP-A-5-173059 proposes to provide a distance measuring device with a simple configuration by effectively using a port of a one-chip microcomputer. Also, Japanese Patent Application Laid-Open No.
In Japanese Patent Application Laid-Open No. 8211, the output of the light receiving means is processed by a circuit having a simple configuration to reduce the cost.

[0003]

However, in the above-mentioned Japanese Patent Application Laid-Open No. Hei 5-173059, an integrating capacitor is required for performing distance measurement, so that the apparatus becomes large. Further, the above-mentioned Japanese Patent Application Laid-Open No. 4-1582
In Japanese Patent Application Laid-Open No. 11-115, a switch is provided for switching the output of the light receiving sensor, so that there is a disadvantage that the distance measurement accuracy is reduced due to the generation of switching noise.

The distance measuring apparatus of the present invention has been made in view of such a problem, and an object thereof is to achieve a distance measuring apparatus which is more compact and simplified while ensuring higher accuracy. It is to provide a device.

[0005]

In order to achieve the above object, a distance measuring apparatus according to a first aspect of the present invention comprises: a light projecting means for projecting a light beam on a distance measuring object; A photoelectric conversion element that receives reflected light from the object to be measured and converts the reflected light into an electric signal corresponding to the light receiving position; an amplification element that amplifies the electric signal; and a signal output from the amplification element at a predetermined timing. A / D conversion means for performing A / D conversion a plurality of times with:
In a distance measuring apparatus having arithmetic control means for calculating a distance signal to the object to be measured using the results of the plurality of A / D conversions, the A / D converting means and the arithmetic control means are formed and arranged. A first semiconductor chip, and a second semiconductor chip on which the photoelectric conversion element and the amplification element are formed and arranged.

A distance measuring apparatus according to a second aspect of the present invention provides a light projecting means for projecting a light beam in a continuous pulse manner on an object to be measured, and a reflected light of the light beam from the object to be measured. Receiving light,
A photoelectric conversion element that converts the electric signal into an electric signal corresponding to the light receiving position, and an A / D that performs A / D conversion of the electric signal output from the photoelectric conversion element a plurality of times at a timing of a predetermined operation cycle time.
In a distance measuring apparatus having conversion means, and arithmetic control means for calculating a distance signal to the object to be measured using the results of the plurality of A / D conversions, the driving frequency of the light projecting means is set to A It should be less than half the reciprocal of the operation cycle time in the / D conversion means.

A distance measuring apparatus according to a third aspect of the present invention provides a light projecting means for projecting a light beam in a continuous pulse to an object to be measured, and a reflected light of the light beam from the object to be measured. Receiving light,
A light receiving means for converting the electric signal into two electric signals corresponding to the light receiving position, amplifying and outputting the electric signal, a gain control means for changing and controlling an amplification factor of the electric signal by the light receiving means, and an amplified output from the gain control means A / D conversion means for A / D converting the electric signal obtained, and changing the gain by switching the gain by the gain control means during a single distance measurement, and controlling the A / D conversion according to the gain control means. Calculation control means for calculating a distance signal to the object to be measured using an output value of the conversion means.

[0008]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1A is a diagram showing the configuration of the first embodiment of the present invention. In FIG. 1A, light of an infrared light emitting diode (IRED) 3 as a light projecting means is projected through a light projecting lens 1 to a subject (not shown) as distance measuring light. The reflected signal light from the subject received by the light receiving lens 2 is transmitted to a semiconductor optical position detecting element (PS
D) 4), and the two output signals are inputted to the amplifiers 6a and 6a.
b. Each signal amplified by the amplifiers 6a and 6b is a one-chip microcomputer (OCM).
10 and its size is determined.

As shown in FIG. 1A, in this embodiment, a PSD 4 as a photoelectric conversion element and amplifiers 6a and 6b as amplification elements are formed on the same semiconductor chip 4a. As a result, the two output signals from the PSD 4 are immediately amplified, so that noise is less likely to occur and the detection accuracy is improved.

The one-chip microcomputer 10 includes a multiplexer (hereinafter referred to as MPX) 7, a sample-and-hold circuit (hereinafter referred to as S / H) 8, and A / D conversion means (hereinafter referred to as A / D) 9. And CPU 1 as arithmetic control means
1 is built in. MPX7 has amplifiers 6a and 6b
And sequentially input to the S / H8. The signals sequentially sampled and held by the S / H 8 are sequentially converted to digital values by the A / D 9.

The two output signals of the PSD 4 which have been converted into digital values by such a process are input to the CPU 11 as operation control means and subjected to a predetermined operation, and as a result, distance information is output from the CPU 11. . This C
The PU 11 controls the light emission of the IRED 3 by the driver 12.
, And also has a function as a sequence controller, such as controlling the MPX7 and S / H8 and controlling the power of the amplifiers 6a and 6b.

FIG. 1B shows a state in which the signal light emitted from the IRED 3 is reflected by the subject 5 and enters the PSD 4. The distance between the principal points of the light emitting and receiving lenses 1 and 2 is called a base line length (S), and if the PSD 4 is placed at the position of the focal length f of the light receiving lens 2, the object 5 at the distance L
The light reflected from the light enters the PSD 4 at a position x in the figure.
PSD4 includes a photoelectric conversion function, by the action of the current division in the surface resistance portion, based on the entire length t and the signal light incident position x, 2 two weak current signals i _a, and outputs the i _b. These current signals i _a, i _b is

[0013]

(Equation 1) Is established. Therefore, i _a, a signal proportional to i _b, the V _1, V ₂

[0014]

(Equation 2) That relationship can be derived. Here, since the total length t is known, the signal light incident position x is obtained. According to the principle of triangulation, the relationship between the base line length S, the focal length f, the signal light incident position x, and the distance L is as follows.

[0015]

(Equation 3) Therefore, the CPU 11 can obtain the distance L of the subject 5 from the output of the PSD 4 by the calculations of the equations (3) and (4). The output current i _a of the PSD 4, i _b amplifiers 6a, V ₁ the result of converting the voltage in 6b, V ₂
Then, the outputs V ₁ and V ₂ of the amplifiers 6a and 6b obtained when the IRED 3 emits pulses continuously have the form as shown in FIG.

FIG. 3 shows an amplifier 6a connected to the PSD 4,
FIG. 6b is a diagram showing a detailed circuit configuration of FIG. 6b. In FIG.
Amplifier 6 to which one current output signal from SD4 is input
a includes a resistor 29a, a capacitor 30a, and an amplifier 31a, and the amplifier 6b to which the other current output signal from the PSD 4 is input includes a resistor 29b, a capacitor 30b, and an amplifier 31b. With these configurations, the amplifier 6
a and 6b function as filters with a current / voltage conversion function. Photocurrents other than AC signals are supplied to the capacitors 30a and 30b.
Therefore, only the AC signal by the pulse projection is amplified by the amplifiers 31a and 31b.

By the way, if the amplifiers 6a and 6b are always in a power-on state, the battery runs out immediately when a battery or the like is used as the power supply. Control. The amplifiers 6a, 6
In order to perform the amplifying operation properly, a time is required immediately after the power is turned on until the potentials at both ends of the capacitors 30a and 30b stabilize to a predetermined value. As shown in FIG. It is preferable to perform A / D conversion.

FIG. 4 is a flowchart for explaining the operation of the first embodiment. Step S1 is IR
This is a step of starting continuous pulse oscillation of the ED 3, and Step S 2 is a time measuring step for waiting until the above-mentioned stabilization time has elapsed.

In the configuration of FIG. 1A, since the S / H 8 has only one system, the input of the MPX 7 is sequentially switched, and the amplified voltage signals V ₁ and V ₂ of the PSD 4 shown in FIG. A / D after sample hold in
Convert.

In step S5, the above equation (3)
The calculation described in (4) is performed to calculate the distance L of the subject 5. FIG. 5 shows MPX7, S / H8, A shown in FIG.
It is a figure showing the internal configuration of / D9.

In FIG. 5, the MPX 7 has a configuration in which a plurality of switches SW _{1 to} SW _n (21) are sequentially switched by the output of the decoder 20, and the output of each switch is input to the S / H 8. S / H8 is switch 2
The voltage input through the capacitor 2 is connected to the charge holding capacitor C2.
3 and output as buffer means 24
Therefore, after the switch 22 is turned off, the same voltage can be output to the next-stage comparator 25 while the stored charge is held.

The comparator 25 compares the two voltages. One input receives the output of the buffer means 24, and the other input receives the comparison voltage V _comp . The comparison voltage V _comp is switched by the successive approximation register 26 connected to the CPU 11 by the switching operation.
8 is obtained by changing the resistance value of the resistance array 27 by switching, and is a voltage obtained by dividing V _ref1 by resistance.

The CPU 11 operates in the successive approximation register 2 described above.
6 are sequentially switched, and this switched state and
According to the timing at which the comparator 25 is inverted, CP
U11 can digitally determine the output of S / H8.

According to the first embodiment, since the light receiving element and the amplifier are formed on the same semiconductor chip, the weak signal based on the weak reflected signal light is immediately amplified. As a result, mixing of noise can be suppressed, and high accuracy of distance measurement can be achieved. In addition, since a multiplexer, a sample-and-hold circuit, and an A / D conversion circuit are built in a one-chip microcomputer and are effectively used, a distance measuring device having a simple configuration and low cost can be provided.

Hereinafter, a second embodiment of the present invention will be described.
FIG. 6A is a diagram showing the configuration of the second embodiment of the present invention. In this embodiment, a one-chip microcomputer having a high-speed A / D conversion function is used to output the resistance array 27 during one pulse emission interval A of the IRED 3 as shown in FIG. By changing the comparison voltage V _comp of
The A / D conversion operation ends. To do this,
The driving frequency of the IRED 3 may be set to be equal to or less than half the reciprocal of the operation cycle time in the A / D 9.

According to such a configuration, even if the voltage is not stored in the sample and hold operation as in the first embodiment,
Since the peak value of the output voltage can be A / D converted, S / H8
Is unnecessary. In particular, as shown in FIG. 6B, as the waveform during pulse emission increases, the measurement error can be minimized by increasing the comparison voltage V _comp .

That is, in the second embodiment, A / D conversion is performed while changing the direction of change of the comparison voltage V _comp of the A / D 9 according to the direction of change of the amplified signal waveform. Accurate A / D conversion is possible even without S / H8. Therefore, the S / H 8 can be deleted, and the configuration can be further simplified.

Since the PSD 4 and the amplifiers 6a and 6b have the same configuration as in the first embodiment, an effect of being resistant to noise can be obtained as in the first embodiment. in this case,
Capacitor 30 as a filter for amplifiers 6a and 6b
A and 30b need to be designed to support pulsed light emission at a frequency of twice or less the A / D conversion time.

Hereinafter, a third embodiment of the present invention will be described.
FIG. 7 is a diagram for explaining the third embodiment of the present invention. The outputs V ₁ and V _{2 of the} amplifiers 31a and 31b shown in FIG.
_Varies with reference to _Vref2 applied to the + input terminals of the amplifiers 31a and 31b. Therefore, until the previous embodiments, as shown in FIG. 8, enter the size of the peak V _11, V ₂₁ output V _1, V ₂ of the waveform, the exact subtracts the V _ref2 uniformly Was getting the value.

However, in this method, as shown in FIG. 7, since only half of the changing waveforms of V ₁ and V ₂ are used, the amount of information is reduced by half. Therefore, in the third embodiment, the difference between the waveform changes when the IRED light emission is turned ON / OFF is used, that is, the MAX value and the MIN value of the waveforms of V ₁ and V ₂ are sampled and held, and the difference is used as a result of the difference. An arithmetic operation is performed to obtain a distance measurement value.

The output V _1, V ₂ varies as shown in FIG. 7, but in the configuration shown in FIG. 5, SW ₁ of MPX7 to S
W _n sequentially switched to, of V _1, V ₂ of the waveform MAX, MIN
When the S / H 8 is operated at the timing of (1), the output of the buffer 24 of the S / H 8 changes as shown by B in FIG. 7, so that this output is stable (the output is V ₁₁ , V ₁₂ ,
A / D 9 may be operated at V ₂₁ and V ₂₂ ).

FIG. 9 is a flowchart showing the operation of the third embodiment. First, in step S11, the IRE
D oscillation is started. Next, the MA of the waveforms of V ₁ and V ₂
After sample-holding the X value (V ₁₁ ) and the MIN value (V ₁₂ ), A / D conversion is performed while the output is stable (steps S12 and S13). Next, V ₁₁ and V ₁₂ at step S14
And V ₁ to seek the difference between. Similarly, after the next MAX value (V ₂₁ ) and MIN value (V ₂₂ ) of the waveforms of V ₁ and V ₂ are sampled and held, A / D conversion is performed while the output is stable (steps S15 and S16). ). Next, step S17
And V ₂ and obtains the difference between V ₂₁ and V ₂₂ in. Finally, V
_1, V ₂ in the equation described above on the basis of (3), determine the distance L ₁ of the object 5 by performing calculation in (4) (step S1
8).

When a large photocurrent flows under high luminance, so-called shot noise or the like is generated in a pulse shape, and the output waveform of the amplifier may fluctuate as shown in FIG. However, in the third embodiment, as described above,
Since distance measurement is performed using the difference in waveform change at the time of light emission ON / OFF, momentary pulse noise 40 is applied and V
Even if there is only a variation of V _OFF from the level of _ref2 , the magnitude of the signal can be correctly determined.

According to the above-described third embodiment, distance measurement can be accurately performed even in a high luminance environment or an environment where noises are likely to ride. Further, even if there is no noise, since the amplitude of the signal is obtained from the difference between the MAX value and the MIN value of the signal that fluctuates in an AC manner,
The amount of information is larger than in the first and second embodiments, and accurate distance measurement is possible.

Hereinafter, a fourth embodiment of the present invention will be described.
FIG. 12 is a diagram showing the configuration of the fourth embodiment of the present invention.
As shown in FIG. 12, when amplifying the output of PSD4,
The gain control is applied.

That is, the output of the PSD 4 is connected to the amplifier 6a,
After amplification at 6b, amplifiers 40a and 40a capable of switching the values of feedback resistors 41a and 41b by the output of decoder 42.
If the signal from the amplifiers 6a and 6b is further amplified by b, the amplification factor of the output signal of the PSD 4 can be variably controlled while switching the decoder 42 under the control of the CPU 11.

FIG. 11 shows how the signal changes at this time. This is because after the continuous pulse emission by IRED3,
This shows the change in the signal when the gain is changed from 1 to 2 in the middle, and the output of V ₁ from V ₁₁ to V ₁₂ is
Changes from the _second output V ₂₁ to V _22, shows how to become each twice as large.

[0038] In this case, the relationship and of V ₁₁ and V _12, V ₂₁ and V
The relationship of V ₂₂ of ₂₁ is as follows. V ₁₂ = 2 × V ₁₁ (5) V ₂₂ = 2 × V ₂₁ (6) Here, assuming that the relationship between V ₁₁ and V ₂₁ is V ₂₁ = 0.6 V ₁₁ (7), V <a relation _{V 11 ... (8), V} 22 = 2 × V 21 = 1.2V 11> 21 relationship V ₁₁ ... (9) is satisfied. However, when V ₂₁ = 0.4V ₁₁ (10), the equation (8) holds, but the equation (9) does not hold.

That is, the CPU 11 stores the four outputs V ₁₁ , V ₁₂ , V ₂₁ , and V ₂₂ obtained while switching the gain as shown in FIG. 11, and compares them with each other. As shown, four types of magnitude relationships can be compared.

That is, light emission of the IRED is started in step S20, and V ₁₁ and V ₂₁ are sequentially performed in steps S21 and S22.
(This process is the same as that described in the above embodiment), and the gain is set to 2 in step S23.
In steps S24 and S25, V ₁₂ , V
₂₂ is A / D converted. Remember these data,
Subsequently, at step S26, S27, S28, it will compare the sequence size, when V ₁₁ before the amplification is larger than V ₂₂ after amplification in step S28 is, V ₁₁ is V ₂₁
Means a bigger thing than This is shown in FIG.
In the case of the arrangement as shown in FIG. 1A, it means that the signal light is incident on the extreme end of the PSD 4. Therefore, from the principle of the triangulation described with reference to FIG. It is very close. Therefore, in this case, the process branches to step S33, and the device outputs an output corresponding to the “close” distance. Also,
When V ₁₁ is lower than V ₂₂ at step S28 performs the output corresponding to the distance "near the middle".

[0041] Conversely, if it is larger V ₂₁ before amplification from V ₁₂ after amplification in step S27, PSD 4
Means that the signal light has entered the opposite end of the
This indicates that the subject is at a long distance. Therefore, in this case, the process branches to step S30, and an output corresponding to the “far” distance is performed. Further, V ₁₂ at step S27 is V
_If it is larger than _21, an output corresponding to the "middle and far" distance is performed.

As described above, in the fourth embodiment, the gain control means is provided, and four-stage distance determination can be performed only by determining the magnitude relationship between the signal outputs before and after the gain switching. Therefore, the CPU 11 does not need any computing power, and can perform high-speed processing.

The distance between "far" (step S30) and "close" (step S33) in FIG. 13 changes depending on the variation of the arrangement position of the PSD 4. Therefore, the degree of the variation is grasped at the time of manufacturing the device. By inputting the result into a writable memory (E ² PROM) 43, the level of “far” or “near” finally determined can be switched, so that more accurate distance measurement can be performed. Can be performed.

Further, by using the gain control function of the fourth embodiment, it is possible to determine a farther distance. If the subject is at a very long distance, the reflected signal light does not return, the value is zero, and the data does not change whether amplified or not. Fig. 1
The processing shown in FIG. That is, step S2
After the determination in step 7 is YES, first, V ₂₁ is input (step S41), and then the gain V ₂₂ is amplified by switching the gain.
Is input (steps S42 and S43). Then comparing the V ₂₁ and V ₂₂ input (step S44), it determines that if there is a difference in a long distance (step S46), if there is no difference, the object distance is infinity (Step S45).

The distance measuring device for making such a determination can be applied to, for example, taking a picture of a landscape with a camera.
Therefore, it is possible to determine whether the subject is very far or not according to the output change before and after the gain control switching.

As described above, in the fourth embodiment, the signal before and after the determination is determined by A / D converting the signal based on the output of the PSD 4 while switching the gain of the signal amplification. Therefore, it is possible to provide a device excellent in distance measurement performance at a long distance that the light projection type distance measurement device is not good at. Especially AF
When applied to a camera, a camera capable of taking a beautiful landscape photograph can be provided.

Note that the A / D conversion and C as described in the first to third embodiments are performed while performing gain control.
Distance measurement by PU calculation may be performed. In this case, as shown in the step of FIG. 15, the value of the gain control is first set to an intermediate value (V ₀ ), light emission is started (step S 51), and A / D conversion of V ₁ is performed (step S 51).
52), comparing data V ₁ and V ₀ obtained (step S53). When the obtained data V ₁ is smaller than V _{0, the} gain is increased (step S 55), and when the obtained data V ₁ is larger than V _{0, the} gain is reduced (step S 54). .

In the above-described third embodiment, the signal amount is determined from the values of MAX and MIN of the fluctuating amplifier output signal. However, even during gain control, as shown in FIG. If you set the gain accordingly, more reliable gain setting,
And distance measurement.

Note that this gain control part is
It may be formed on the same chip as the SD4, or may be formed on the same chip by the same process as the one-chip microcomputer 10. The specific embodiments described above include inventions having the following configurations. (Supplementary Note 1) Light projecting means for projecting light for distance measurement to the object to be measured, and receiving a reflected signal light of the light for distance measurement reflected from the object to be measured, according to the light receiving position. Light-receiving means for amplifying and outputting the two electric signals, and an A / D for A / D-converting the output signal of the light-receiving means a plurality of times at a predetermined timing.
In a distance measuring apparatus having a conversion means and a calculation control means for performing a distance calculation using the results of the plurality of A / D conversions, the A / D conversion means and the calculation control means are provided on the same semiconductor chip. A ranging device characterized by being formed. (Supplementary Note 2) In Supplementary Note 1, the arithmetic control unit may perform A / A multiple times in each state of the on / off operation of the light emitting unit.
A distance measuring device for performing a / D conversion operation and calculating the distance signal based on an output value of an A / D conversion result obtained at each timing of an ON state and an OFF state. (Supplementary note 3) In Supplementary note 2, the light receiving means has gain control means for controlling the amplification factor of the electric signal by the arithmetic control means, and the arithmetic control means has an A / A signal obtained at each of the timings. A distance measuring device, wherein said gain control means is controlled according to a difference between D conversion results. (Supplementary note 4) In Supplementary note 1, further comprising gain control means for controlling the amplification factor of the electric signal by the arithmetic control means, and performing the A / D conversion operation on one of the two electric signals. Thereafter, the gain control means is controlled, and the A / D conversion operation is performed on the other of the two electric signals to compare the amplification factor with the A / D conversion value of the two signals. A distance measuring device for determining a distance to the object. (Supplementary Note 5) In the supplementary note 1, the light receiving means has a light receiving sensor for receiving the projection light and an amplifying element for amplifying an electric signal, and these are formed on the same semiconductor chip. Distance measuring device. (Supplementary Note 6) Light projecting means for projecting a light beam to the object to be measured, and receiving reflected light of the light beam from the object to be measured.
Light receiving means for converting the electric signal into two electric signals corresponding to the light receiving position and amplifying and outputting the electric signal; A / D converting means for A / D converting the electric signal amplified and output from the light receiving means;
The light beam of the light projecting means is controlled to be projected on the object to be measured with continuous pulses at predetermined time intervals, and further output from the light receiving means according to the reflected light from the object to be measured by the light projecting means. An arithmetic control means for performing an A / D conversion operation on the electric signal of the pulse waveform at a predetermined timing, and calculating a distance signal to the object to be measured using an output value of a plurality of A / D conversion results. A distance measuring device, comprising: (Supplementary note 7) In Supplementary note 6, the A / D conversion means and the arithmetic control means are formed on one semiconductor chip. (Supplementary Note 8) In Supplementary Note 6, the semiconductor chip is a one-chip microcomputer. (Supplementary note 9) In Supplementary notes 6 and 7, the light-receiving means includes the photoelectric conversion element and the amplification element, and both elements are formed on one semiconductor chip. (Supplementary note 10) In Supplementary note 6, the light emitting means is turned on / off so as to emit a light beam to the object to be measured at predetermined time intervals.
An OFF operation is performed, and the arithmetic control unit causes the A / D conversion operation to be performed a plurality of times based on each ON / OFF operation state of the light projecting unit, and the A obtained at each timing of the ON / OFF state. The distance signal is calculated based on the output value of the / D conversion result. (Supplementary Note 11) In the supplementary note 6, the predetermined timing for performing the A / D conversion operation on the electric signal having the pulse waveform is as follows:
It is determined based on the maximum value and the minimum value of the pulse waveform. (Supplementary Note 12) Light projecting means for projecting a light beam to the object to be measured, and light reflected from the object to be measured of the light beam is received and converted into two electric signals corresponding to the light receiving position. Receiving means for amplifying and outputting the electric signal, gain control means for changing and controlling the amplification factor of the electric signal by the light receiving means, and A / D converting means for A / D converting the electric signal amplified and output from the light receiving means. Controlling the light flux of the light projecting means to the object to be measured with continuous pulses at predetermined time intervals, and further output from the light receiving means in accordance with the reflected light from the object to be measured by the light projecting means. Control means for performing an A / D conversion operation on an electric signal having a pulse waveform at a predetermined timing, and calculating a distance signal to the object to be measured using output values of a plurality of A / D conversion results And having Distance measuring apparatus according to claim. (Supplementary note 13) In Supplementary note 12, the arithmetic control means controls the gain control means according to the difference between the A / D conversion results obtained at the timing. (Supplementary note 14) In Supplementary note 12, a first output value obtained by performing the A / D conversion operation on one of the two electric signals with a first gain by the gain control means; A second output value obtained by performing the above-mentioned A / D conversion operation with the second gain by the gain control means and the other electric signal of the two electric signals are converted into the first output value by the gain control means. A third output value obtained by performing the A / D conversion operation with a gain, and a fourth output value obtained by performing the A / D conversion operation with the second gain by the gain control means; The distance to the object is determined by comparing the first to fourth output values of the A / D conversion values for the two signals. (Supplementary Note 15) In Supplementary Note 12, a first output value obtained by performing the A / D conversion operation at a first gain by the gain control means for one of the two electric signals, and the gain control Means for performing the above-mentioned A / D conversion operation with the second gain by the means, and comparing the first and second output values of the A / D conversion value, and according to the amount of change thereof. The distance to the object is determined. (Supplementary Note 16) In the supplementary note 15, as a result of comparing the first and second output values of the A / D converted value, if the change amount is smaller than a predetermined value, it is determined that the distance to the object is infinite. (Supplementary Note 17) A light projecting unit that emits a light beam in a continuous pulse to the object to be measured, and two light sources that receive reflected light of the light beam from the object to be measured and correspond to the light receiving position. Light receiving means for converting into a signal, amplifying and outputting the signal, gain control means for changing and controlling the amplification factor of the electric signal by the light receiving means, and A / D conversion of the electric signal amplified and output from the gain control means A / D conversion means that performs switching control of the gain control means during a single distance measurement, and uses the change control results of a plurality of different gain control means and the output value of the A / D conversion means to perform the switching. A distance control device for calculating a distance signal to the object to be measured.

[0050]

According to the present invention, a distance measuring apparatus can be provided with a simple configuration. Further, since the configuration is simple, the cost of parts and assembly can be reduced, and the size can be reduced. For example, an autofocus camera or the like can be provided at low cost.

[Brief description of the drawings]

FIG. 1A is a diagram illustrating a configuration of a first embodiment of the present invention, and FIG. 1B is a diagram illustrating a state in which signal light emitted from an IRED is reflected by a subject and enters a PSD. It is.

FIG. 2 is a diagram illustrating an output of an amplifier obtained when an IRED emits pulses continuously.

FIG. 3 is a diagram showing a detailed circuit configuration of an amplifier connected to a PSD.

FIG. 4 is a flowchart for explaining the operation of the first embodiment of the present invention.

FIG. 5 is a diagram showing an internal configuration of a multiplexer, a sample hold circuit, and A / D conversion means shown in FIG.

FIG. 6A is a diagram showing a configuration of a second embodiment of the present invention, and FIG. 6B is a diagram for explaining the operation of FIG.

FIG. 7 is a diagram for explaining a third embodiment of the present invention.

FIG. 8 is a diagram for explaining a distance measuring method according to first and second embodiments of the present invention in comparison with a third embodiment.

FIG. 9 is a flowchart showing the operation of the third embodiment of the present invention.

FIG. 10 is a diagram for explaining an effect of the third embodiment of the present invention.

FIG. 11 is a diagram illustrating a state of a signal change when a fourth embodiment of the present invention is performed.

FIG. 12 is a diagram showing a configuration of a fourth embodiment of the present invention.

FIG. 13 is a flowchart illustrating a method for measuring a distance to an object using the method according to the fourth embodiment of the present invention.

FIG. 14 is a diagram for explaining an improved example of the measurement method shown in FIG.

FIG. 15 is a diagram for explaining a gain setting method when performing distance measurement according to the first to third embodiments while performing gain control according to the fourth embodiment;

FIG. 16 is a diagram for explaining an embodiment in which the method of the fourth embodiment of the present invention is applied to the third embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Projection lens, 2 ... Light receiving lens, 3 ... Infrared light emitting diode (IRED), 4 ... Semiconductor light position detection element (PSD), 4a ... Semiconductor chip, 5 ... Subject, 6a, 6b ... Amplifier, 7 ... Multiplexer (MPX), 8: sample and hold circuit (S / H), 9: A / D conversion means (A / D), 10: one-chip microcomputer, 11: CPU, 12: driver.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI G03B 13/36 G03B 3/00 A

Claims (3)

[Claims] A light projecting means for projecting a light beam onto the object to be measured, and a photoelectric device for receiving reflected light of the light beam from the object to be measured and converting the reflected light into an electric signal corresponding to the light receiving position. A converting element, an amplifying element for amplifying the electric signal, and a signal output from the amplifying element being subjected to A multiple times at a predetermined timing.
A distance measuring device comprising: A / D conversion means for performing A / D conversion; and arithmetic control means for calculating a distance signal to the object to be measured using the results of the plurality of A / D conversions. A first semiconductor chip on which the conversion means and the arithmetic control means are formed and arranged; and a second semiconductor chip on which the photoelectric conversion element and the amplification element are formed and arranged.
A distance measuring device, comprising: a semiconductor chip according to claim 1. 2. A light projecting means for projecting a light beam in a continuous pulse manner on an object to be measured, and receiving an reflected light of the light beam from the object to be measured, and an electric signal corresponding to the light receiving position. A plurality of times at a timing of a predetermined operation cycle time with an electric signal output from the photoelectric conversion element.
A distance measuring device comprising: A / D converting means for performing A / D conversion; and arithmetic control means for calculating a distance signal to the object to be measured using the results of the plurality of A / D conversions. Wherein the driving frequency of the A / D converter is not more than half the reciprocal of the operation cycle time of the A / D conversion means. 3. A light projecting means for projecting a light beam on the object to be measured in a continuous pulse manner, and receiving two reflected lights of the light beam from the object to be measured and two light sources corresponding to the light receiving positions. Light receiving means for converting the electric signal into an amplified signal and outputting the amplified signal; gain control means for changing and controlling the amplification factor of the electric signal by the light receiving means; and A / D conversion of the electric signal amplified and output from the gain control means. A / D conversion means for converting, and, during one distance measurement, the gain is switched by the gain control means to perform change control, and an output value of the A / D conversion means according to the gain control means is used. A distance control device for calculating a distance signal to the object to be measured.