JPS60101967A - Differential type sensor device - Google Patents

Abstract

PURPOSE:To improve an S/N, and to enhance the capacitance of distance measurement by obtaining focus adjusting informations by using a storage type photoelectric conversion element and through arithmetic operation in a differential type sensor device. CONSTITUTION:When an LED emits light and a photoelectric spot PS is image- formed on photoelectric conversion sections SA1, SA2, SB1, SB2, an image is converted by the photoelectric conversion section in a zone A and a zone B in a photoelectric manner, and charges in the sum of beam projection and peripheral beams are stored in charge storage sections TA1, TA2, TB1, TB2, and transferred to charge transfer sections CA1, CB2. When the LED is put out, only the informations of peripheral beams are transmitted over the conversion sections SA1-SB2, and stored in the storage sections TA1-TB2. Optical informations generated in a beam projection section and optical informations generated in a non-beam projection section are transferred and stored simultaneously into circulation type storage sections M1-M4 in succession. These stored informations are read and arithmetically operated through floating gate means FG1, FG2, and the difference of intrinsic beam-projection signals each generated in the zone A and the zone B is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a differential sensor device, and more particularly, to a differential sensor device, which projects light onto a subject, receives reflected light from the subject by a light receiving means, and uses a signal from the light receiving means to transmit light to the subject. The present invention relates to a differential sensor device that is effective when used for distance detection.

Conventionally, non-storage photoelectric conversion elements such as silicon photodiodes have been used as photoelectric conversion elements for distance detection, but since the output signals generated by these photoelectric conversion elements are very small, circuit noise is generated during amplification. The shadow area was large, making it difficult to obtain a good signal-to-noise ratio, and the detection distance that could be measured was also short.

The purpose of the present invention is to provide a differential sensor device that has good signal readout characteristics and can obtain signals with a high S/N ratio. The obtained difference ftj+ is intended to serve as a sensor device.

The main features of the differential sensor device for achieving the purpose of the present invention are a light source for projecting light onto the subject and at least two photoelectric conversion units 8A1 for receiving reflected light from the subject.
, SB1, and two charge storage sections TA1 that accumulate charges generated in the two photoelectric conversion sections SA1 and SB1, respectively.

charge accumulating means having TBl, two charges QALI I QADI stored in the charge accumulating section TA1 when the light source emits light and when the light source does not emit light; , the two charges QBLI and BDI stored in the load storage 4TB1, the total of four charges L1
゜A charge transfer means CAB for sequentially transferring QADI I QBLI I QBDI, and 4 charges transferred from the charge transfer means CAB to a predetermined charge storage section 1. The four charge storage sections MI r M21 ``31 '4, which are configured in a circular manner, including the charge storage section M for sequentially storing the charge via the charge storage section M, and the four charge storage sections MI + 4 r MS r ]V. charge circulation means for accumulating charges in the four charge storage sections "IwJ+MSr" while cyclically and sequentially transferring them in correspondence with periods of light emission and non-light emission of the light source; M4
and a readout means for generating a signal corresponding to the charge stored in the memory.

Although the charge circulation means is not necessarily required, it is preferable for efficiently transferring and storing charges to the charge storage section.

In order to better achieve the object of the present invention, floating gate means may be provided in the reading means, and the floating gate means may be controlled so that the photoelectric conversion unit SAI
A light emitting signal sl corresponding to the difference in the amount of charge generated when the light source emits light and when it does not emit light, When the light emission signal corresponding to the difference in the amount of charge generated when the light source emits light and when it does not emit light in the conversion unit SB1 is 82, a signal of the difference and sum of the light emission signal S1 and the light emission signal S2. It is to calculate.

In order to achieve the object of the present invention, it is further preferable to provide a detection means for detecting whether the sum of the light projection signal S1 and the light projection signal S2 has reached a certain value by means of a floating gate means, A signal representing the difference between the light projection signal s1 and the light projection signal 82 is output based on the signal of the detection means.

Next, embodiments of the present invention will be described using the respective figures.

Figure @1 is a 1072 diagram of distance detection in which light is projected onto a subject and the distance to the subject is detected using reflected light from the subject. A light source LB such as a laser or a light emitting diode modulates and emits light from the pulse φTlIC via the buffer BP, and the light is projected onto the object OB by the projection lens LN1. The reflected light from the object is visualized by the light receiving lens LN2 as a projected spot image ps on the photoelectric conversion element SD, which is a part of the photoelectric conversion means.

The distance to the subject is detected by detecting the position of the projected light spot image on the photoelectric conversion element SD.

In addition to the spot image from the projected light, light information from the subject is superimposed on the photoelectric conversion element SD. Efficiently removing this light information from the subject (information about ambient light) is essential for distance detection. This is important to improve accuracy.

In the present invention, this ambient light information is efficiently removed.

FIGS. 2(aL(1)) and (Q) are schematic explanatory diagrams of the accumulation type light sea conversion means used in the differential type sensor device according to the present invention.

Figure 2 (a) shows the charges tA and B generated in the photoelectric converter AI+131 by the reflected light from the subject when the light is emitted from the light source, and the charge t AOt BO generated by the ambient light when the light emission is stopped. This is a conceptual representation of the sum of each charge amount A+Ao, B+B.

is from each photoelectric conversion unit AI + Bl to charge storage unit A,
.

B! When the light is not emitted, the photoelectric conversion parts A1゜B,
The charge Δ generated on , Bo are accumulated in the charge storage parts A, , B, respectively. By taking the difference between these accumulated charges in a differential circuit, only the charges fRA and B of the reflected light component due to the projection of light are detected, as shown in Fig. 1(b), and as a result, Fig. 1(C) When the electric charges A and B are A=B, for example, the lens system of the distance detection system determines that the in-focus point is yellow, and when A>B, it is determined that it is in the front bin state, and the simple extraction bin state is A × B. do.

Also, if the value of the charge tA+B is kept constant at this time, the slope of A-B near the in-focus position will become almost constant.
Focusing accuracy can be maintained at a constant level.

3iJ is an explanatory diagram of an embodiment of the differential type sensor device of the present invention. SA1. EI81 is a photoelectric conversion means consisting of a first and a 20th photoelectric conversion section, and SA2°SB2 is two lights 1f provided auxiliary to improve the distance detection ability.
Two or more of these photoelectric conversion units may be provided in the variable W8 section. The function of Konera's photoelectric conversion unit is photoelectric conversion unit SA1.8.
It is the same as 1N.

TAI and TBl are photoelectric conversion units εA1. The first SB1 stores photoelectric conversion information generated in SB1. SA2. SB2 auxiliary photoelectric conversion unit SA2. When SB2 is provided, this is a charge storage section provided correspondingly.

By arranging four photoelectric conversion units in the horizontal direction as in this embodiment, even if the projected light spot head PS shifts significantly, it is easy to form an image on a part of any of the photoelectric conversion units. As a result, even if the out-of-focus state becomes thicker, the projected spot image ps
This is preferable because the position of the object can be detected accurately, and the distance detection ability can be improved.

If there are four photoelectric conversion units, for example, two photoelectric conversion units S
The charges generated from Ai and SA2 may be considered as one in the subsequent processing.

In addition, the projected spot image PS is composed of two photoelectric conversion units SAI and B.
Detecting that the output charge far is within the range of Bl,
I know of two other photoelectric conversion units SA2. It is preferable that the S/N ratio can be increased by correcting the operation of SB2.

(CG is an integral clear gate for clearing the charge generated from 1.SA2; 8B1.SB2 to the photoelectric conversion unit S when the pulse φIOG is at a high level, and a charge transfer gate for SH1; Accumulation section TA1
, TA2; TBj, the charge accumulated in Ta2 is transferred to the charge transfer unit OA having a CCD analog shift register.
I is a charge transfer gate that transfers to GBL. The charges transferred to charge transfer units OA4 and OBl are sequentially transferred to Ml, M2 . . . via other charge transfer units GA and GB. M5°M4 charge storage section and G1, G2. G5. The charge of G4 is transferred to and accumulated in a storage means having a charge circulation means for temporarily storing the charge and circulating the charge to the rear charge storage section,
Ru.

FGl and Fe2 are 70-Tig gate means and φF'
When G is at the embryonic level, it is reset to the reference voltage, VFG.

The output of the floating gate is field effect transistors FTi to FT3, resistors R1 and R2, capacitor C1,
A reference voltage vR1F is applied to the non-inverting input terminal, and the output signal is outputted via an output circuit consisting of an operational amplifier OP1 in which an FT3 is installed, and necessary information is synchronized with the sample pulse φH. Sample hold circuit S/H
The sample is held and output.

OM1 and TOM2 are charge transfer section GA and charge storage section M.
This is the 3rd clear gate.

Also 01~()4. Nox φ applied to M1 to M4
G1~φG4. The configuration is such that cyclic transfer of accumulated charges is controlled by φM1 to φM4.

FIG. 4 is a timing chart of the main parts of FIG. 3 and a timing chart of output.

Time t. When φIOG is inverted to low level at K, photoelectric conversion units SA1, SA7! ;The charges generated in SB4.8B2 are transferred to the charge storage parts TA4, TA2; TBl, Ta
sMR is performed at 2.

During Ll when φT'R is at a high level, the light emitting diode 1. emits light, and a light spot P is projected onto the photoelectric conversion unit.
S is imaged and photoelectrically converted by the first (entering zone) and second (B zone) photoelectric conversion parts, and the charge QkL is the sum of the projected light and ambient light.
1. QBLI is charge storage part TAi, TA2; TBI
, Ta2 and when φSH1 becomes high level, the charge transfer unit OA4. Transferred to OBi.

At time t, the light emitting diode LE turns off when φwork R becomes a low level, and the optical information Q generated on the photoelectric conversion section
BD1 is transferred to a circulating charge storage section M1 via charge transfer fi CBi, GB, and GA. Charge storage section 114, M'5. M2. Optical information stored in Ml QAL1, Q, BLl, QADl, QBD
When I is transferred to the charge storage parts M1, M4, M3, and M2, the light information Q, AL2 generated in the photoelectric conversion part of the A zone during the light projection period L2 at time t becomes the light information Q, AL2, which is divided into groups 1 and GA. Since the charge is stored in the charge storage section M1 through the charge storage section M1
The sum of optical information QAL1 and QAL2 is stored in . Similarly, optical information %Q, BLI and Q, BT, sum of 2, optical information Q, AD1 and QA [sum of 2, optical information # QBDI and Q, B
The sum of D2, . . ., is sequentially accumulated cyclically.

These accumulated information are stored in floating gate means FG1.
It is read out via FG2 as follows.

For example, when a reset/curse occurs as in φF(1) and φT(1)()2. Charge Q of G1, ALI and QBLl
A voltage corresponding to the difference between the sum voltage vAL++vBLI and the reference voltage vRF is stored in the capacitor C1, and the output vouT
(1) is fixed to Vvtv. Next, time t, ~t10
When G1゜G2 charges are transferred and rearranged, V
. uT(1)ld VRF + VAp+ +VBL+
□Next, ff1l from time tto to t4 is G2. G1
Since the charge Q, BL1 and QAI)1 enters, VOut(1
) is VouT(1)=Vny+vAy, ++Vnz+
-VBIII-VADI=VRP+VQ, ALI-vQ
AIN Similarly, between time t4 and ttt, VOIIT(1) = vR1'+vAI++ -VAD
I+VBL l+VAD I='VRF+VAL
I+VBL 1 time tII~ dose line VouT(1)=VuytoWAL++VnII+-WA
D +-VBD I='Any) (Vxr, +-'VA
DI ) + (V[1I-VBD I ), that is, the reference voltage v
It is possible to obtain a signal that is the sum of the true light projection signal generated in the A zone and the true light projection signal generated in the B zone with reference to 1. Furthermore, when the sum of the true light emitting signals reaches a certain level, pulses are generated such as φFG(2)φ(T) and φTOM, and when 410M is at a high level, the pulses are transferred to the GA via the 0M1 gate. By configuring the device to clear the information that has been transmitted, it is possible to detect the true light emitting signal as if it were returned.

Between time tto and t□, Vour(1) = VRF+VBLI+VAD + between time t□ and t□, VouT(1)=VRF+VBII I+VAD +
-VAD I -VBD I"" VRF+VBLI
-VBDI During time ttt "" tts, Vout(1)=Vny+Vnr, +-VBDI+V
ADI+VBD1=VR7+VBLI+VAD+ Time 118 ``”' t! 4 is from time ttt to t
Since φTOM is at a high level during ts, the optical information Q in the L section
, LA2 is cleared, so VouT(1)=Vny+VBIl++VAD+-VA
LI-VBDI= VRy+CVBL+-VBDI)
-(VALI-VADI) That is, it is possible to obtain a signal representing the difference between the true light projection signal occurring in the A zone and the true light projection signal occurring in the B zone, with reference to the reference voltage VRF.

Information on the difference between the true light projection signals is sampled and held in the sample and hold circuit S/H by the sample and hold pulse φH, and held until the next generation of difference information.

Automatic focus adjustment can be performed by driving the photographing lens so that the difference between this true light emission signal (G4) becomes zero.The difference signal between the true light emission signal is sampled and held by S/H. After that, it is necessary to set the clear gate TOM2 to a high level and clear the unnecessary charges by circulating the cyclic charge storage section once.

Then time t. In the same way, you can return the system to a clear state and repeatedly obtain focus adjustment information.

As described above, when the present invention is used, focus adjustment information can be obtained by calculating within the differential sensor device without using any other arithmetic processing circuit, so the influence of noise is small (S/N does not increase as above). There are significant features that can significantly improve the measured Vn'Q force.

In addition, photoelectric conversion units SA1 and SB1; SA2 and EIB2
The optical information generated by ;,...,... is transferred to an analog register for charge transfer independently [:! By providing charge transfer gates SHE, SR1, .
If the signal difference between the true light emitting signal of the zone and the true light emitting signal of the B zone is large, focus detection is performed based on the light information from the entire photoelectric conversion unit, and the true light emitting signal of the A and B zones is detected. If the difference between the light emitting signals is smaller than a certain value, the configuration is configured so that focus detection is performed based on light information from only the central photoelectric converter BA1.881, thereby eliminating the influence of unnecessary ambient light. (remarkably reduced focus detection, very good focus detection information, etc.)
By selecting the photoelectric conversion unit according to the above, unnecessary optical information can be cut and focus detection accuracy can be improved.

[Brief explanation of drawings]

Fig. 1 is a block diagram when the differential type sensor device of the present invention is applied to distance detection. Fig. 2 (a) and (1) L(0) are the functions of the differential type sensor device according to the present invention. An explanatory diagram schematically showing. Fig. 3 is an explanatory diagram showing the signal processing process of the differential sensor device of the present invention, and Fig. 4 is a timing chart diagram of the main parts of Fig. 2g3. In the figure, LK is the light 7 thickness, LNl is the light emitting lens, LN2 is the light receiving lens, SD is the photoelectric conversion means, OB is the object, A,
, B1. SAi, GA2. SB1 and SB2 are photoelectric conversion parts, A, B, A, , B, charge amount, T
Al, TA2. TBl, TB2, M, , M2
゜Totl, , M, , G1. G2, G3. G4 charge storage section, SH1 charge transfer gate, OAl, OB
1, GA, and GB are charge transfer units. Figure 2 (2nd elementary school) ” 苧IC6 5HI ° City

Claims (1)

[Claims] (Li) A light source for projecting light toward the subject and at least two photoelectric conversion units SA1 for receiving reflected light from the subject.
, a photoelectric conversion means having SBI, the two photoelectric conversion sections SA1, and two charge storage sections TA1. a charge storage means having TBi;
When the light source emits light and when the light source does not emit light, the charge accumulating portion T
Two charges QALI stored in A1. QADI and two 'charges "BLI" stored in the charge storage section TB1 when the light source emits light and when the light source does not emit light, respectively.
Total 4 charges of BDI QALII QADI I Q
BL, IQBD, tl - a charge transfer means CAD for sequentially transferring; and a charge accumulation section for sequentially accumulating the four charges transferred from the charge transfer means CAB through a predetermined charge accumulation section M. The four charge storage units M1 + Mt + MR + M4 and the four charge storage units M, , M, , M3 .
A charge circulation means for cyclically and sequentially transferring and accumulating charges in the four charge storage units M1 + Ml! in correspondence with periods of light emission and non-light emission of the light source; ＋M! l
A differential sensor device characterized by comprising + reading means for generating a signal according to the charge accumulated in M4. (2) The reading means has a floating gate means, and controls the floating gate means to compensate for the difference in the amount of charge generated when the light source of the photoelectric conversion unit SAI emits light and when the light source does not emit light. The light emission signal S1 and the light emission signal corresponding to the light emission signal S2 are 81 and the light emission signal corresponding to the difference in the amount of electric charge generated in the photoelectric converter 8B1 when the light source emits light and when the light source is not emitting light, respectively. Claim 17'11, characterized in that the difference and sum signals from the optical signal S2 are calculated.
The differential type sensor device according to item 1. (3) The floating gate means outputs a signal representing the difference between the light projection signal S1 and the light projection signal S2 based on the signal of the light projection record detection means. The differential type sensor device described.