JPH08233571A - Range finder - Google Patents

Abstract

PURPOSE: To simplify control of pulse which decides timing of charge transfer from a sensor array to a linear CCD connected to a ring CCD integrating signal change, in a distance measuring device wherein an object is illuminated for triangulation. CONSTITUTION: Signal charge generated in each sensor block S1 -S5 is transferred at turn-off of floodlinghting to the second accumulation part 14, and at tarn-on of floodlinghting, transferred to the first accumulation part 15. These accumulation parts 14 and 15 adjust timing so that the charges obtained by each sensor block S1 -S5 both at turn-off of floodlighting and turn-on of floodlinghting are transferred, parallel and at the same time, to each CCD stage 3A-12A of a linear CCD 17.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distance measuring device for measuring a distance to a measuring object, and is suitable for application to, for example, an AF mechanism of a camera.

[0002]

2. Description of the Related Art Conventionally, a distance measuring device shown in FIG. 5 is well known as a distance measuring device for projecting a spot on a measuring object whose distance is desired to be measured and receiving reflected light thereof for triangulation. That is, from the light emitting diode (IRED) 41 to the projection lens 4
The light is projected onto the measuring object 45 via the spot light 3, and the reflected light is transmitted through the light receiving lens 44 to the position detecting element (PSD) 42.
To receive light. Since the PSD 42 outputs signals A and B corresponding to the light receiving position from both terminals, the signals A and B
The light receiving position of the PSD 42 can be detected and the distance to the measurement target 45 can be known from the light receiving position.

FIG. 6 shows a signal processing circuit of this range finder.

The outputs A and B of the PSD 42 are AMP, respectively.
The current-voltage conversion is performed by 1 _A and 1 _B , and the direct current component is removed by the capacitors C _A and C _B. As a result, the blinking signal corresponding to the on / off of the IRED41 becomes A.
It is input to MP2 _A and 2 _B , where it is inverted and amplified. A
The flashing signal amplified by MP2 _A , 2 _B is selectively switched to AMP3 _A , 3 _B in synchronization with the flashing operation through an analog switch controlled by the S / H signal.
Is input to Then, the integration in the capacitor is started by the control of the analog switch by the INT signal. By synchronously integrating with the S / H signal in this way,
A weak signal from the PSD 42 generated by the reflected light from the measurement target is detected, ΣA and ΣB are obtained, and distance measurement is possible.

However, the conventional distance measuring devices shown in FIGS. 5 and 6 have the following problems. That is, S /
Considering the N ratio, AMP1 _A , 1 _B for weak signals
Since the noise generated from the resistance of the PSD 42 and the resistance of the PSD 42 each time the synchronous integration, in order to increase the signal component, the distance measuring block including the light projecting lens 43, the light receiving lens 44, etc. is increased, and the power of the IRED 41 is increased. Therefore, it is difficult to reduce the size of the distance measuring device.

In order to widen the measurement distance range, P
Although it is necessary to lengthen the SD42, if the PSD42 is lengthened, the rate of change of the obtained A and B signals with respect to the distance is reduced, and there is also a problem that the accuracy of position detection is reduced.

FIG. 7 shows a device using a sensor array instead of the PSD proposed in USP 4,521,106.

A sensor block S ₁ having an integration function,
A CCD 62, which is a charge transfer means, is provided in parallel with the sensor array 61 composed of S ₂ , S ₃ , ....
The CCD 62 is configured with the number of stages twice as many as the number of sensor blocks so as to transfer charges corresponding to ON and OFF of the light projecting means for each sensor block, and CK ₁ , C
It is driven by a two-phase clock of K ₂ . The charges transferred by the CCD 62 are transferred to the output stage (FDG: Floating Diffusion).
It is converted into a voltage signal by the Gate) 64 and taken out. Further, the CCD 62 is reset via the MOS gate 63 controlled by the RS signal. SH is a shift gate.

FIG. 8 shows the operation timing of the device shown in FIG.

The signal IRED is generated by the light projecting means (IRED).
Shows the on / off timing and emits light at a high level
Turns on. The signal SH corresponds to each sensor block S₁,
S₂, S₃, To transfer charge from CCD to CCD 62
The gate signal that drives the shift gate SH of
Each sensor block outputs 1 pulse of SH by minging
S ₁, S₂, S₃,… Each sensor is emptied at the same time
-Block S₁, S₂, S ₃, ..., when light emission is off
The accumulation of external light begins. On the other hand, although not shown, R
First of CCD 62 via MOS gate 63 by S signal
Periodization is performed.

At the timing of B, the first CCD 62
Clocking CK₁, CK ₂Stop, and then S
One pulse of H is output and each sensor block S₁, S₂,
S₃, ... from the accumulated charge from the clock CK of the CCD 62₁so
Transfer every other portion to the driven part. And at a predetermined time
After a lapse of time, CK₁, CK₂Pulse by pulse, CC
The charge in D62 is advanced by one step.

On the other hand, from B to C, the light is turned on,
External light and signal light (reflected light) are applied to each sensor block S ₁ , S
₂ , S ₃ , ... Are accumulated. Then, one pulse of SH is output at the timing of C, and each sensor block S ₁ ,
The accumulated charge is transferred from S ₂ , S ₃ , ... To the clock C of the CCD 62.
Every other part is transferred to the part driven by K ₁ .

In this manner, the charges transferred by the CCD 62 are sequentially read by the output stage (FDG) 64, and the amount of charges accumulated in each sensor block S ₁ , S ₂ , S ₃ , ... Can be detected. it can. When such a multi-division sensor is used, the resolution for detecting the light receiving position is improved as compared with the case where PSD is used.

However, in the device described with reference to FIGS. 7 and 8, the amount of charge output from the CCD 62 is the amount of charge for one cycle of light projection, and since there is no function of synchronous integration, that charge is not present. The amount was small and the S / N ratio was not good. That is, this device had almost no effect in improving the distance measuring ability other than the resolution.

Next, FIG. 9 shows a distance measuring device proposed in Japanese Patent Publication No. 5-22843. This device has a synchronous integration function on the device in addition to the devices described with reference to FIGS. 7 and 8, and sequentially integrates the sensor output by a circular ring composed of a CCD. Further, it has a so-called skim (SKIM) function for excluding, from the CCD, a direct current signal component equivalent to a pair of on and off light projections.

In the figure, the sensor array 81 is composed of N sensor blocks.
The electric charge stored in the CCD is sent to the 2N-stage linear CCD 83, which is a charge transfer unit, through the N shift gates 82. These sensor array 81 and shift gate 8
2 and the linear CCD 83 are substantially the same as the sensor array 61, the shift gate SH, and the CCD 62 described in FIG.

In the apparatus shown in FIG. 7, CC which is a linear CCD is used.
Electric charges were directly sent from the D62 to the output stage (FDG) 64, but in the apparatus of FIG. 9, the linear CCD 83 has a 2N-stage C
It is connected to a ring CCD 84 composed of a CD.
The ring CCD 84 has one cycle in synchronization with one cycle of on / off of light projection, the timing of the SH signal is controlled, and the signal charge transferred to each stage by the previous SH signal. Further, the signal charges transferred to each stage by the next SH signal are just added. By this operation,
The ring CCD 84 adds charges while transferring the charges.

The CLR section 85 is means for extracting and clearing charges from the ring CCD 84 and the linear CCD 83, and is for initializing the device. Note that this clearing operation is prohibited during charge addition by the ring CCD 84. Reference numeral 87 is a means for non-destructively converting the charge amount into a voltage and reading the voltage.

The SKIM unit 86 turns on the light emission when the charge amount of the light emission off stage, that is, the amount of the external light signal exceeds a predetermined value so that each stage of the ring CCD 84 is not saturated by the addition of charges. This is a means for eliminating a fixed amount of charges from the pair of CCD stages in which the light is turned off so that only the charges due to the signal light are integrated in the continuous addition operation.

By the above operation, the increase of the signal component with respect to the external light component can be achieved. However,
The device shown in FIG. 9 operates at substantially the same timing as the timing shown in FIG.
The transfer clocks of 83 and the ring CCD 84 are almost stopped from B to C in FIG. 8, and the time is wasted. Further, since the linear CCD 83 and the ring CCD 84 are stopped at the same timing, there is also a problem that the S / N ratio is significantly reduced due to the occurrence of dark current unevenness between the CCDs. Further, this device has a problem that the transfer clocks of the linear CCD 83 and the ring CCD 84 are relatively complicated.

[0021]

In order to overcome the drawbacks of the conventionally known distance measuring devices described above, a device as shown in FIG. 10 has been considered.

This device is the same as the device described in FIG. Transfer clock is complicated 2. Occurrence of uneven dark current 3. It eliminates the drawbacks such as the ineffective use of the period when the transfer clock is stopped, and also has an electronic shutter function (ICG) that controls the amount of signal charge from each sensor block.

The sensor array 91 is composed of a plurality of sensor blocks S ₁ , S ₂ , S ₃ , ..., And the signal charges generated in each sensor block S ₁ , S ₂ , S ₃ ,. Is integrated with. In this example, the sensor array 91 and the integrating unit 92 are shown separately, but these are substantially the same as the sensor array 61 and the sensor array 81 described with reference to FIGS. 7 and 9.

Clear unit 9 driven by the ICG signal
Reference numeral 3 denotes a so-called electronic shutter, which has a function of preventing a certain amount of electric charge from the integrating unit 92 to overflow and preventing the overflow of the integrating unit 92, and a function of extracting all electric charges of the integrating unit 92 and initializing the integrating unit 92. .

The signal charge integrated by each integrator 92 is S
The signal is transferred to the storage unit 94 at the timing of the T signal, and the storage unit 9
It is temporarily accumulated and held at 4. Then, the charges held in the storage section 94 are transferred to the linear CCD 96 by the shift gate 95 at the timing of the SH signal. The linear CCD 96 is the same as the linear CCD 83 described in FIG. 9, and is connected to a ring CCD (not shown).

FIG. 11 shows the operation timing of the apparatus of FIG.

The signal IRED indicates whether the light projecting means (IRED) is on or off, and the high level is in the on state. An ICG pulse is supplied in correspondence with the on / off timing of the light projecting means, and each integrating unit 92 is cleared (initialized). Then, in the period from the ICG pulse to the next ST pulse, each sensor block S ₁ , S ₂ ,
Only the signal charges generated in S ₃ , ... Are integrated in each integrator 92 and transferred to each accumulator 94. Note that the timing of the ICG pulse moves back and forth according to the brightness of the measurement target, and approaches the timing of the ST pulse as the brightness increases.

As described with reference to the apparatus of FIG. 9, in this apparatus as well, one cycle of turning on and off the light projecting means (IRED) is synchronized with one cycle of the ring CCD (not shown). And
The signal charge integrated while the IRED is off is transferred to each storage unit 94 by the ST pulse a. This is a signal charge due to external light, and is transferred to the linear CCD 96 in the portion driven by the clock CK ₁ by the SH pulse b. At the same time, each storage unit 94 becomes empty.

Next, the signal charge integrated while the IRED is on is transferred to each emptied storage section 94 by the ST pulse c. This is a signal charge due to outside light + signal light. Then, the charge is generated at the timing delayed by one clock from the SH pulse b by the clock CK _1.
By the H pulse d, it is transferred to the linear CCD 96 at an alternate position when the IRED is off.

In this way, the signal charges of IRED off and on which are alternately transferred by the linear CCD 96 are transferred to a ring CCD (not shown) and circulate around the ring, as in the case of the device of FIG. Will be added by.

According to this apparatus, since the clock for driving the linear CCD 96 which is the charge transfer means and the ring CCD (not shown) does not need a stop period, the transfer clock is simplified and the clock stop period is not wasted. . Since there is no clock stop period, ring C
The dark currents in the CD and the linear CCD are averaged to eliminate the dark current unevenness.

However, in the apparatus of FIG. 10, I
Since the transfer of the signal in which the RED is off and the signal in which the RED is on to the linear CCD 96 must be performed in synchronization with two consecutive clocks of the clock CK ₁ , it is relatively difficult to control the generation timing of the clock ST and the clock SH. .

Further, the apparatus of FIG. 10 has the following problems. That is, most of the dark current generated in the storage section 94 controlled by the ST pulse is transferred to the IRED off signal. Then, the imbalance of the dark current in the IRED on and off signals is added and amplified by the ring CCD. In the worst case, it is supposed that the off signal should be less than the on signal, but it may be reversed, and if it is reversed, the skim portion described in FIG. That becomes impossible.

This problem is not so serious if the measurement is performed by projecting light for only one period, but for example, considering a long distance low reflectance measurement object, the detection level of the reflected light is very small. Therefore, the addition processing by the ring CCD is indispensable, and the problem becomes serious.

Therefore, an object of the present invention is to relatively easily control the clock generation timing and to project light even when a storage section for temporarily holding charges is provided between the sensor array and the charge transfer means. It is an object of the present invention to provide a distance measuring device in which an imbalance of dark current in the storage portion does not occur between on and off.

[0036]

In order to solve the above-mentioned problems, the present invention provides a distance measuring device for projecting a spot on a measuring object whose distance is to be measured and receiving the reflected light to perform a trigonometric distance measurement. There, a light projecting means for projecting light onto the measurement target, a sensor array in which a plurality of sensors for receiving and photoelectrically converting the reflected light from the measurement target are arranged, and from each sensor of the sensor array In a distance measuring device comprising integrating means for integrating output charges and charge transfer means for transferring charges integrated by the integrating means, at least a part of which is coupled in a ring shape, each of the integrating means and the charge transfer It further comprises a pair of charge storage means arranged in parallel with the means and temporarily holding charges transferred from the integration means to the charge transfer means.

In one aspect of the present invention, the first charge accumulating means of the pair of charge accumulating means holds the charge obtained from the sensor array through the integrating means when the light projecting means projects light. Then, the second charge storage unit holds the charge obtained from the sensor array via the integrating unit when the light projecting unit is not projecting light.

In one aspect of the present invention, there is further provided a skim means for removing a fixed amount of electric charge from the electric charge transferred by the electric charge transfer means.

In one aspect of the present invention, N pairs of the charge storage means are provided for the sensor array of N sensors, and the charge transfer means receives charges from the N pairs of the charge storage means. And a second charge transfer unit in which the same number of transfer stages as the first charge transfer units are coupled in a ring shape.

In one aspect of the present invention, gate means for extracting charges from the integrating means is further provided.

[0041]

In the present invention, the electric charges sent from the sensor array through the integrating section are temporarily held before being transferred to the charge transfer means, and the transfer of the charges to the charge transfer means is delayed by a predetermined time. Since each pair of charge accumulating means is provided, one of the charge accumulating means holds the electric charge obtained when the light projecting means projects the light, and the other charge accumulating means holds the charge obtained when the light projecting means does not project the light. It is possible to control the timing of transferring the charge from each charge storage means to the charge transfer means, and as a result, the charge storage means can be turned on and off. It is possible to reduce the imbalance of the dark current in. Further, by providing the charge storage means, it is not necessary to stop the clock for driving the charge transfer means when transferring the charges to the charge transfer means.

By providing the skim means, it is possible to prevent the charge from being saturated in the charge transfer means.

Further, for N sensors, N pairs of charge storage means, at least 2N first charge transfer sections and at least 2N charge transfer sections having the same number of stages as the first charge transfer sections are provided, respectively. As a result, the first charge transfer section and the second charge transfer section can alternately transfer the light-emission OFF and ON signals, and the second charge transfer section charges the light for each cycle of light projection. Can be added, and the first charge transfer unit and the second charge transfer unit can be driven by the same clock having a simple configuration.

Further, by providing the gate means for extracting charges from the integrating means, overflow of the integrating means can be prevented.

[0045]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to FIGS.

FIG. 1 shows the configuration of the main part of a distance measuring device according to an embodiment of the present invention.

The sensor array 11 is a sensor block S
_{1 to} S ₅ , and the signal charges photoelectrically converted by the sensor blocks S _{1 to} S ₅ are integrated by the integrating unit 12. It should be noted that the sensor array 11 is not limited to the five pixels in this embodiment, and may be generally N pixels (N: natural number). Each integrator 12 is provided with a clear unit 13 driven by an ICG pulse.

In the present embodiment, as shown in the figure, the first accumulating sections 15 and the second accumulating sections 14 composed of CCDs are alternately arranged in parallel with the sensor array 11, and each integrating section 12 is provided with the same. Each pair of storage units 14 and 15 correspond to each other. Then, the charges integrated by each integrating unit 12 are pulse ST ₁ ,
In ST ₂ , the data is transferred to the pair of storage units 14 and 15 alternately.

The output terminals of the pair of accumulators 14 and 15 are SH
It is connected to the linear CCD 17, which is the first charge transfer section of the charge transfer means, via the shift section 16 driven by a pulse. Further, the linear CCD 17 is coupled to the ring CCD 18 which is the second charge transfer section of the charge transfer means. These linear CCD 17 and ring CCD 18
Is composed of a two-phase CCD driven by two-phase clocks CK ₁ and CK ₂ . Each stage is a 3-phase CC
It may be configured by a D, 4-phase CCD or the like. Also, linear C
The CD 17 has 12 stages shown by CCD1 _{A to} 12 _A , and the ring CCD 18 has 12 stages shown by CCD1 _{B to} 12 _B.
Each is composed of columns. When the sensor array 11 has N pixels, the linear CCD 17 and the ring CCD
All 18 are (2N + 2) stages.

Next, the operation of transferring charges from the sensor array 11 to the linear CCD 17 will be described with reference to FIGS.

The signal charges generated by photoelectric conversion in each of the sensor blocks S _{1 to} S ₅ of the sensor array 11 are transferred to each of the integrators 12 and integrated. Prior to that, as shown in FIG. At the same time, the ICG pulse clears the charge of each integrator 12 and initializes each integrator 12 (thick line arrow in FIG. 4).

The projection of a light emitting diode (IRED) not shown
While the light is on, each sensor block of the sensor array 11 is
Ku S₁~ S_FiveFrom each integrated section 12 and integrated by
The load is ST₁It is transferred to the first storage unit 15 by a pulse.
(Thin line arrow in FIG. 4). Next, turn off the IRED
Each sensor block S of the sensor array 11 during the period₁~
S_FiveThe electric charge sent from the above to each integrating unit 12 and integrated is S
T₂Transferred to the second storage unit 14 by a pulse (Fig.
4 wavy arrow). Therefore, each integration unit by ICG pulse
From 12 clear to pulse ST₁, ST₂Until transfer by
Period t₁, T ₂Is the integration time. That is, the integration unit 12
The clear section 13 provided in the
The voltage that controls the integration time in each integration unit 12 by
It also has a function as a child shutter. For example, ICG
The timing of the loose is adjusted according to the brightness of the measured object.
The ST pulse timing as the brightness increases.
The integration time can be shortened by approaching.

Electric charges and S due to the outside light + signal light when the light is turned on, which are transferred to the first accumulator 15 by the ST ₁ pulse
The charges due to only the external light when the projection is off and transferred to the second storage unit 14 by the T ₂ pulse are transferred to the CCDs 3 _{A to} 12 _A of the linear CCD 17 by the SH pulse, respectively. As a result, for example, the charge generated when the light is turned off in the sensor block S ₁ is transferred to the CCD 3 _A , and C
The charges generated when the light emission is turned on in the sensor block S ₁ are transferred to the CD 4 _A , the charges generated when the light emission is turned off in the sensor block S ₂ are transferred to the CCD 5 _A, and so on. CCD3 _A- 12
To _A, and the charge at the time of charge and projecting on at projected off is transferred alternately, the linear CCD by the clock CK _1, CK ₂
Transferred inside 17.

At this time, in this embodiment, the electric charge when the light is turned off and the electric charge when the light is turned on are transferred through the different accumulating portions 14 and 15, so that the device described in FIG. By comparison, it is possible to reduce the imbalance of dark current in the storage unit when the light is turned on and off. Further, the charges at the time when the light is turned off and at the time when the light is turned on are transferred to the linear CCD 17 in parallel and simultaneously while being delayed by the storage units 14 and 15 for a predetermined time respectively, so that the clock CK for driving the linear CCD 17 is generated.
_Since it is not necessary to provide a stop period for ₁ and CK ₂ and transfer to the linear CCD 17 may be performed in synchronization with one clock of the clock CK ₁ (two clocks are required in the device of FIG. 10), pulses ST ₁ and ST There is a large degree of freedom in designing the timing of ₂ . In addition, if the ST ₁ pulse and the ST ₂ pulse are generated according to the level of the IRED signal, even if the on / off of the light projection is reversed, the pair of charges generated in one sensor block in the linear CCD 17 is reversed. Can always be transferred in the order of off → on.

In FIG. 1, C of the linear CCD 17 is used.
CD1_ATwo_AIs linear CCD 17 and ring CCD 1
It is a CCD added in the layout combined with 8, but it is empty.
It can be used as a CCD for offset adjustment.
Specifically, in the ring CCD 18, the charge
Is 12_B→ 11_B→ 10_B→… → 2_B→ 1_B→ 12 _B
The second storage unit 14 or the first storage unit 15
SH pulse for transferring charge from the CCD to the linear CCD 17
Is synchronized with one cycle of the ring CCD 18.
It That is, as shown in FIG.
Clock CK for transferring loads₁(CK₂Is also the same. )
SH pulse is generated every 12 clocks. Meanwhile, floodlight
ON / OFF and pulse ST synchronized with it₁, ST₂
Are all synchronized with the SH pulse.
Each sensor block S is turned on and off₁~ S_Five
The signal charge generated in 1 orbits in the ring CCD 18.
It is added every time. At this time, the number of stages of the linear CCD 17
This linear CCD 17 is also redesigned by making 12 stages.
Clock CK same as the CCD 18₁, CK₂Drive with
Can be That is, a pair of the linear CCD 17
10 stages for receiving charges from the storage units 14 and 15 of
CCD3_A~ 12_ACCD 1_ATwo_AAdd 12 steps
By setting CCD1_ATwo_ABut linear CCD
For adjusting the offset between 17 and ring CCD 18.
To work.

The gate of CCD 9 _B of the ring CCD 18 is a floating gate and is connected to the output section 20. The output unit 20 converts the charge amount in the CCD 9 _B into a voltage and outputs it as an OS signal from the amplifier 101. Further, RD is a reset potential, and the pulse R
The floating gate of CCD 9 _B is reset via the MOS gate driven by S ₁ .

[0057] The CCDCLR terminals provided on the CCD 1 _B of the ring CCD 18, intended for clearing the charge of CCD 1 _B by CCDCLR pulse, during the initialization of the device, in this portion, the charge of the linear CCD17 and ring CCD 18 Clear (see Figure 3).

Next, the structure of the skim portion 19 provided in the ring CCD 18 will be described. CCD of ring CCD 18
5 _B and CCD 4 _B are respectively composed of skimming elements SK ₁ and SK ₂ . That is, the first skimming element SK ₁ is formed with a potential well that stores only a certain amount of electric charge, and when the amount of electric charge transferred from the CCD 6 _B in the previous stage exceeds the capacity of the well. , The overflowed electric charge flows into the element DC ₁ . And CCD
The charge from 6 _B is the first skimming element SK ₁ and the element DC
After being distributed to ₁ , the charges are transferred to the second skimming element SK ₂ and the element DC ₂ by the CK ₂ pulse, respectively. The second skim element SK ₂ has a potential well having a smaller capacity than that of the first skim element SK ₁ , and the overflowed electric charge flows into the element DC ₂ and is transferred from the element DC _1. It is designed to be added to the electric charge.

The amplifier 10 provided in the skim section 19
2 has the same configuration as the amplifier 101 of the output unit 20 described above.
The device DC₂To the output stage C of the skim section 19
SKOS signal by converting the amount of charge transferred to CD into voltage
Output as. Also, the CCD of the output stage of the skim section 19
The floating gate of the reset signal RS₂By R
Reset to D level. The output of the amplifier 102
By looking at the force SKOS, the skim element SK₁, S
K₂It is possible to determine whether the electric charge has overflowed with
If the load overflows, the SKCLR pulse causes the second
Element for skim SK₂To next CCD3_BTransferred to
Charge is cleared. Furthermore, the element DC ₂Overflow in
Charge is CCD2_BTransferred to the ring CCD 18
Orbit. On the other hand, the skimming element SK₁, SK₂And the charge is
If it does not overflow, a SKCLR pulse is generated.
No, the second skim element SK₂Charge on the ring CC
Orbit D18.

This skim operation will be described in more detail with reference to FIG.

Here, among the charges corresponding to the turning on and off of the light projection, the one corresponding to the turning off first circulates around the ring CCD 18, and first, when the SKOS output is observed at the off portion, S
It is determined whether to output the KCLR pulse. And
If there is a SKOS output in the off portion, a SKCLR pulse is issued and the second skimming element SK ₂ to CCD 3
Clear the charge transferred to _B. On the other hand, the electric charge corresponding to the turning on of the light is subjected to the same clearing process only when the electric charge is judged to be cleared at the previous off portion.
As a result, the same amount of charge is always cleared by the pair of off and on of light projection. That is, it is the portion corresponding to the outside light component that is removed from the transferred signal, and the portion of the signal light goes around the ring CCD 18 as it is and is integrated. Therefore, the signal light can be detected by finally obtaining the difference between the charge outputs of the off / on pairs. It should be noted that the above-described first skimming element SK ₁ from CCD 5 _B to CCD 2 _B constitutes the skim portion 19.

The RS ₁ pulse and the OS output shown in FIG. 3 respectively show two values, normal and difference, depending on the timing of outputting the RS ₁ pulse from the output section 20.
The case of outputting the absolute value of each CCD and the case of outputting the difference between the above-mentioned projection off / on pair are respectively shown. That is, in the former case, when there is no charge in the CCD 9 _B , which is the output stage, the absolute value of the transferred charge is sequentially output by issuing the RS ₁ pulse and resetting. On the other hand, in the latter case, when the CCD 9 _B has a charge when the light is turned off, the RS ₁ pulse is output to reset the charge, and when the charge when the light is turned on is transferred, the charge is turned off when the light is turned off. A difference signal from which the charge component is subtracted is output.

In the distance measuring apparatus according to the embodiment of the present invention described above, the ring CCD 18 is formed on the device,
By rotating the ring CCD 18, the charges can be added, and the S / N ratio can be improved. Further, since the skim portion 19 for removing the external light component from the ring CCD 18 is provided, it is possible to prevent the ring CCD 18 from being saturated due to the addition of charges,
The / N ratio can be further improved.

[0064]

According to the present invention, the electric charge sent from the sensor array through the integrating unit is temporarily held in the electric charge storage means before being transferred to the electric charge transfer means, and the electric charge to the electric charge transfer means is transferred to the electric charge transfer means. Even when the transfer timing is adjusted, it is possible to relatively easily control the clock that determines the timing of the charge transfer to the charge transfer unit, and the dark current in the charge storage unit when the light projection is turned on and off. Can be reduced.

Further, by providing the skim means, it is possible to prevent the charge from being saturated in the charge transfer means.

Further, N pairs of charge accumulating means, at least 2N first charge transfer sections and second charge transfer sections having the same number of stages as the first charge transfer sections are provided for each of the N sensors. As a result, the first charge transfer section and the second charge transfer section can alternately transfer the light-emission OFF and ON signals, and the second charge transfer section charges the light for each cycle of light projection. Can be added, and the first charge transfer unit and the second charge transfer unit can be driven by the same clock having a simple configuration.

Further, by providing the gate means for extracting charges from the integrating means, overflow of the integrating means can be prevented.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a main part of a distance measuring device according to an embodiment of the present invention.

FIG. 2 is a timing chart showing the operation timing of each part when the charge is transferred from each sensor block to the linear CCD in the device of FIG.

3 is a timing chart showing the operation timing of each part of the ring CCD of the apparatus of FIG.

FIG. 4 is a schematic diagram showing the operation of an integration unit and a storage unit of the apparatus of FIG.

FIG. 5 is a schematic diagram showing a measurement principle of a conventional distance measuring device.

6 is a circuit diagram showing a signal processing circuit of the device of FIG.

FIG. 7 is a schematic view showing a main part of another conventional distance measuring device.

8 is a timing chart showing the operation timing of the device of FIG.

FIG. 9 is a schematic view showing a main part of still another conventional distance measuring device.

FIG. 10 is a schematic view showing a main part of an apparatus obtained by improving the apparatus of FIG.

11 is a timing chart showing the operation timing of the device of FIG.

[Explanation of symbols]

11 sensor array 12 integrating part 13 clearing part 14 second accumulating part 15 first accumulating part 16 shift part 17 linear CCD 18 ring CCD 19 skim part 20 output part S _{1 to} S ₅ sensor block

Claims (5)

[Claims] 1. A distance measuring device for projecting a spot onto a measuring object whose distance is to be measured, and receiving reflected light thereof to perform a trigonometric distance measurement, and a light projecting means for projecting light onto the measuring object. A sensor array in which a plurality of sensors that receive reflected light from the measurement target and photoelectrically convert it are arranged, an integrating unit that integrates output charges from each sensor of the sensor array, and a charge integrated by the integrating unit. In the distance measuring device, wherein at least a part of the charge transfer means is connected in a ring shape, and the charge transfer means is arranged in parallel between each of the integration means and the charge transfer means. A distance measuring device further comprising a pair of charge storage means for temporarily holding charges transferred to the means. 2. A first charge accumulating means of the pair of charge accumulating means holds a charge obtained from the sensor array through the integrating means when the light projecting means projects light,
2. The distance measuring device according to claim 1, wherein the second charge storage unit holds the charge obtained from the sensor array via the integrating unit when the light projecting unit is not projecting light. 3. The distance measuring apparatus according to claim 1, further comprising a skim means for removing a fixed amount of electric charge from the electric charge transferred by the electric charge transfer means. 4. N pairs of said charge storage means are provided for said sensor array of N sensors, said charge transfer means being at least 2N stages for receiving charges from N pairs of said charge storage means. 7. The first charge transfer section having a transfer stage of the same number, and the second charge transfer section having the same number of transfer stages as the first charge transfer section coupled in a ring shape. The distance measuring device according to any one of 1 to 3. 5. A gate means for extracting charges from the integrating means is further provided.
The distance measuring device according to any one of 1.