JPS59183320A - Light projection amount controller - Google Patents

Abstract

PURPOSE:To detect distance by a light projection amount according to the condition of an object by controlling the light projection amount detecting charge amount stored in a charge storage section for storing a charge of a photoelectric conversion section during the projection and in a charge storage section for storing a charge of a conversion section during the fixed period in the non-projection. CONSTITUTION:With the emission of light from a light emitting element, reflected lights from an object form an image on a photoelectric conversion element. The conversion element is provided with photoelectric conversion sections AS and BS and the sum of reflected lights and ambient lights by projection is stored into charge storage sections AL and BL while ambient lights during a fixed period in the non-projection time are stored into charge storage sections AD and BD. Charges of the charge storage sections AL and AD and BL and BD are read out and the sum and difference of difference portions therebetween are detected as output VA+B and output VA-B respectively. The output VA+B is compared with a reference voltage by a resistance and a comparison output causes the duty from an oscillator to vary, for example, by 50, 25 or 12.5% to drive a light emitting element. The output VA-B drives by focusing through a control circuit. Thus, the control of the light projection can be done according to the condition of the object.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a light projection amount control device, and in particular, it projects light onto a subject, receives reflected light from the subject with a light receiver, and uses a signal from the light receiver to control the light intensity of the subject. The present invention relates to a light projection amount control device that is effective when detecting a distance to a distance.

Conventionally, a distance detection method is known in which distance is detected by projecting light of a certain value onto the subject and detecting the reflected light with a detector, but when the subject is close, the amount of reflected light is too large and when the subject is far away. In contrast, the amount of reflected light is small and the SI is quite good.
N could not be obtained and the detectable object distance was also short.

Furthermore, since a fixed amount of light is emitted, the power consumption of the light source is also large.

The present invention provides a control device for light projection that can efficiently utilize the power consumption of a light source, increase the detectable object distance, and achieve a highly accurate distance detection system. purpose.

The main features of the light projection amount control device for achieving the object of the present invention are a light source for projecting light onto a subject, and at least one photovoltaic device for receiving reflected light from the subject, whose charge amount changes depending on the amount of incident light. a photoelectric conversion means having a conversion section; a first charge storage section that accumulates charges generated in the photoelectric conversion section while the light source is projecting light onto the photoelectric conversion section; Two charge storage sections, a second charge storage section that accumulates charges generated in the photoelectric conversion section for a certain period of time, are respectively disposed, and the second charge storage section stores charges generated in the photoelectric conversion section for a certain period of time. The present invention further includes a control means for detecting at least one of the charges accumulated in the second charge storage section with a detector and controlling the amount of light emitted from the light source based on the detection result. be. Note that the light source may be provided outside the light projection amount control device.

In order to better achieve the object of the present invention, the first
．． When the difference in the amount of charge accumulated in the second charge storage section reaches a certain value, the amount of light emitted from the light source is reduced.

Further, the control means is performed by means for changing the duty.

When the light projection amount control device is used in a distance detection system, it is preferable to configure the photoelectric conversion means with two photoelectric conversion sections and utilize the amount of charge obtained from each photoelectric conversion section.

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

FIGS. 1(a), 1(b), and 1(C) are conceptual diagrams of storage type photoelectric conversion means used in the light projection amount control device according to the present invention. FIG. 1(a) shows that when light is emitted from a light source, two photoelectric conversion units A1.
This is conceptually shown as the amount of charge A, B generated on B+ and the amount of charge Ao, Bob generated by ambient light when light emission is stopped, and the sum of each amount of charge A, + AD, ■3+
B.

or each photoelectric conversion unit A1. 1st from B1. The charges AO and Bo accumulated in the second charge storage sections A2 and B2, respectively, and generated in the photoelectric conversion sections A+ and B+ when no light is emitted, are the charges AO and Bo stored in the second charge storage sections A2 and B2, respectively. Fourth
The charges are stored in charge storage units A3 and B5, respectively. The difference between these accumulated charges is taken by a differential circuit, and as shown in Fig. 1(b), the amount of charge Ai of the reflected light component due to the projection of light is
.

Only B is detected, and as a result, as shown in Fig. 1(C), the charge i
When A and B are A=H, for example, the lens system of the distance detection system is determined to be in focus, and when A)B is determined to be a front focus state, and when A<H, it is determined to be a rear bin state.

Also, if the value of charge iA+B is kept constant at this time, the slope of A-B near the in-focus position becomes almost constant,
This is preferable because focusing accuracy can be maintained constant.

FIG. 2 is an explanatory diagram of one embodiment of the storage type photoelectric conversion means used in the present invention, and As and BS are the first . The 20th source power converter, AL, BL is the 1st power converter, which accumulates the sum of the reflected light from the projected light and the ambient light when the light is projected. The second charge accumulating parts AD and BD accumulate ambient light when no light is emitted. a fourth charge storage section;
ICGI and ICG2 are integral clear gates for clearing the charges generated from the photoelectric conversion sections As and BS when the control pulse φICG is at a high level, and SH1 and SH2 are charge transfer gates that clear the photoelectric conversion when the control pulse φSH1 is at a high level. Charges generated from the conversion sections As and BS are transferred to the charge storage section A.
When the control pulse φSH2 is at a high level, the charge generated from the photoelectric conversion unit AJB8 is stored in the charge storage unit A, BL.
D, accumulates in BD. T01 to TG4 are charge transfer gates, and when φTG is at a high level, the charges accumulated in the charge storage section are transferred to the charge voltage conversion sections BC1 to BC4 for signal readout. (Signal of human AO of al, B- for BC2) - Signal of 13o, BC3
The AO signal is output to BC4, the Bo signal is output to BC4, and (A-1-Ao)-(Ao
)=A1 via differential amplifier circuit 2 (B+Bo
) - (Bo) = B, A via differential amplifier circuit DA3
-B signal VA-a is output. Also, the charges accumulated in AL and BL and AD and BD (Jinshijin o ) + (B + B
o) and AO+BO are floating goo)FGl
, Fe2, and the differential amplifier circuit D
(A0Ao)+(B+Bo)-(A
The g number vA+B of D+Bo)=λ+B is output. When the output of VA+8 reaches the reference value, the signal is read out.

After signal reading is detected, φRS is set to high level to reset unnecessary signals.

FIG. 6 is an explanatory diagram of an embodiment of an electric circuit that drives the photoelectric conversion element shown in FIG. 2 and realizes the present invention, and FIGS. 4, 5, and 6 show the main parts of FIG. This is a timing chart, and the light emission duty is 50 inches, 25%, and 12.5-
This is a diagram at the time of . When the power switch SW is turned on at time to, the power E1 is applied to each part, the oscillator O8C starts oscillating, and outputs a constant power RBQ. Simultaneously, the output of the AND gate ANO is inverted to a high level for a short time determined by the capacitor C20 and the resistor R20 in synchronization with the rising pulse of the VCO8C, so the one-shot circuit ON1 generates a one-shot pulse, and OR3° OR4, O
During the time t O-t 217), unnecessary charges in the accumulation dimming electric conversion element are cleared via R5. Time t
1, the R8T flip 70gRF1 is reset in synchronization with the rising pulse of O20. In addition, the D flip-flop DF1 is initialized in synchronization with the rising pulse of O20 for a short time determined by the capacitor C40 and the resistor R40, and the one-shot circuit ON3 generates a one-shot pulse in response to the rising edge of the AND output. The D flip-flop DF2 is initialized in synchronization with the rising edge of the pulse.

The signal of the oscillator O8C is frequency-divided by the D flip-flop DF1, and the signal from the oscillator O8C is divided by the D flip-flop DF1. Inverter IN5
- Various control outputs are generated through the INS when the light projection duty is 25 inches as shown in FIG. The Q output signal of the D flip-flop is frequency-divided by the D flip-flop DF2, and the Q output signal is divided by the D flip-flop DF2. Inverter IN6~IN7
As shown in FIG. 6, various control outputs are generated when the light projection duty is 12.5%.

As shown in FIG. 4, the output pulse of the oscillator O8C is used as is for each control output when the sleep duty is 50%. These various control information are provided by ANDGATE AN! 1
2~AN41. Orgate. When the output of OR52 (selected through a selection circuit consisting of 62 to 0FL54) is at a high level, Trl is turned on, so the light emitting element LD emits light with the current regulated by the resistor RIK, and the light emitting lens LN
The reflected light is projected onto the subject OB via I, and the reflected light is sent to the receiving lens L.
It is connected to the photoelectric conversion element via N2. When a reflected light image forms at the center of the A sensor and the B sensor, the photoelectric conversion unit A1
．． The configuration is such that the outputs of B1 are equal, which is the in-focus position. When the output of one-shot ONl is reversed to low level at time t2, when the output of 0R32 is high level, the reflected light signal at the time of light emission is the charge storage section AL, and when the output of BLKOR3, 3 is high level, at the time of light emission. Signals of the corresponding non-light emitting period are alternately accumulated in the charge accumulation sections AD and BD.

AND gate ANA via inverters IN4 to IN7
A Nr 8-1l-J--This is an unnecessary period for the accumulation of information, and a high-level signal is applied to φICG via 0R34, so that the charge generated in the charge conversion section of the storage type photoelectric conversion element is not accumulated. Drive to clear.

Also, between time 10 and 110, D flip frog DF3~
DF4 is initialized and R8T flip knobs fLp3 to RF4 are reset. When the photoelectric conversion element starts accumulating charge at time t2, V^1B
The signal is the reference voltage V determined by the resistors 66 to R34.
Since it is F3, VF4 or lower, it is andgoo) AN29
．． AN, the way 50 comes out is at a low level, and gate AN3
Since the number 1 will be at a high level, the AND gate AN40 ~
Output of O20 and inverter INS via AN41,
That is, light emission and light reception are controlled by duty 50.

Resistors R30 to R62, capacitor C30,) transistor Tr51. The output of the timer circuit consisting of the comparator cp5 is inverted to high level at time tA. When Sv^1B is compared with the reference voltages VF3 and VF4 and is detected to be greater than c
The output of p7 becomes high level, and the Q output of DF4 is inverted to high level in synchronization with the rise of cp5. NextFCO8C
RF4 is set in synchronization with the rising edge of ADEAN30.
The output of AN61 is inverted to high level, and the output of AN61 is inverted to low level.
Light emission and light reception are controlled after time tA with the outputs of 4 to AN6, that is, a duty of 25%.

Also, when VA+B is greater than VF3, Cp6, cp7
Since the Q outputs of DF3 and DF4 are inverted to high level in synchronization with the rise of Q and OR5, in which the outputs of both are high, RF3 and RF4 are set in synchronization with the rise of O20, and the output of AN29 becomes high. Level, AN! Since the output of 11 is inverted to low level, AND gates AN32 to AN5
5 to the outputs of AN7 to AN9, that is, the duty 12
．． At 5%, light emission and light reception after time tA are controlled.

When VA+B is smaller than VF4, comparator Cp
Since both 6゜cp7 outputs are at low level, D F 3 ,
DF4゜RF5. There is no change in the state of R11i'4, and light emission and light reception control is performed with a duty of 50% even after time t^.

At time t3, when the signal of VA+8 exceeds the reference voltage determined by resistors R2 and R3, the output of the comparator cpl is inverted to the high level side, so at time t4, the RAT flip-flop RF1 is switched in synchronization with the rising edge of the pulse generated from 0R35.
is set, one-shot ON2 generates a one-shot pulse for one cycle of the pulse generated from 0R65, and φ
The fcG is set to a high level to complete the storage of image information in the storage-protected photoelectric conversion element. At the same time, AND gate AN1. φTG is set to high level through OR gate OR5 to read accumulated information, and sample and hold circuit 8HDK is set at time t.
The information of V^-B is sampled and held between 4 and t5.

AND GO between time t5 and t6) AN2. Inverter IN2, φR5 is raised via OR5
Therefore, unnecessary charges stored in the charge-voltage converter are reset, and storage of new image information is started from time t6.

At time gts, RFl is reset by the output of λN2, and at the rise of φR9, RF3 and RF4 are reset, and DF3. 5 is configured such that DF4 is initial set.

Image information is detected during time t k t 10 in the same way as between times tO and t6, and new image information is sampled and held between times t8 and t9.

5HDK sample held information is sent to control circuit CKT
It is used to drive the photographing lens to the in-focus position via the .

As described above, by using the present invention, it is possible to emit light with the minimum amount of energy necessary depending on the condition of the subject, which not only saves power but also provides good distance measurement information for horses in a short time. There is a remarkable feature that allows you to obtain

In this embodiment, two photoelectric conversion units A1. The case where distance detection is performed using the signals from the two charging conversion units At and B1 using B1 has been shown, but it is possible to use one photoelectric conversion unit and, for example, calculate the maximum value of the output signal from one photoelectric conversion unit. It goes without saying that the light projection amount control device of the present invention can also be applied to the case where the distance to an object is detected by detection.

In addition, in the present invention, the source of light emitted from the light source is infrared light,
It may be any visible light. Furthermore, the modulation of the light emitted from the light source may be performed not only electrically but also mechanically.

[Brief explanation of the drawing]

FIGS. 1(a), (b), and (C) are explanatory diagrams of an accumulation type photoelectric conversion means used in the light projection amount control device according to the present invention, and FIG. 2 is an example of the photoelectric conversion means used in the present invention. FIG. 3 is an explanatory diagram of an embodiment of an electric circuit for driving the photoelectric conversion means used in the present invention. 4. Fifth. FIG. 6 is an explanatory diagram of a timing chart of the main part of FIG. In the figure, A+, Bi are photoelectric conversion parts, A2. A3. B2. B
3 is a charge storage section, and A, B, AD, and 13o are charge amounts. Patent applicant: Canon Co., Ltd. Procedural amendment (voluntary) August 19, 1980 Commissioner of the Japan Patent Office Kazuo Wakasugi 1 Display of the case 1981 Patent application No. 57202 2 Name of the invention Light emitting amount control device 3 Make an amendment Relationship with the patent applicant case Address: 3-30-2 Shimono I, Ota-ku, Tokyo Name (too) Canon Co., Ltd. Representative Ryu Nagaku Sanbu 4 Agent Address Address: 3-3 Shimomaruko, Ota-ku, Tokyo 30-25 Target of amendment (1) Specification (2) Drawing 6, Contents of amendment (1) (a) From the first line to the second line of page 4 of the specification, ``The light source... ...You may leave it there.'' is deleted. (b) [Correct the charge amount A1J to "charge amount A" on page 5, line 6 of the specification. (c) rREQJ on page 7, line 16 of the specification [RF3
Q is Vc J, and [0R5J on the 18th line is corrected as [OR5, 0R6J. ) “D flip-flop” on page 8, line 14 of the specification
is corrected with [D flip-flop DF1j. (E) Delete "using two photoelectric conversion units A1. and B1" from line 14 to line 15 on page 16 of the specification. ρ) Figure 3 of the drawings shall be amended as shown in the attached sheet.

Claims (1)

[Scope of Claims] (1) A photoelectric conversion means having a light source for projecting light onto a subject, and at least one photoelectric conversion unit for receiving reflected light from the subject, the amount of charge changing depending on the amount of incident light. , a first charge storage section that accumulates charges generated in the photoelectric conversion section while the light source emits light to the photoelectric conversion section; and a first charge storage section that accumulates charges generated in the photoelectric conversion section while the light source emits light to the photoelectric conversion section; a second charge accumulation section for accumulating charges generated in the first charge accumulation section; It is characterized by comprising a control means for detecting at least one of the charges accumulated in the second charge storage section with a detector, and controlling the amount of light emitted from the light source based on the detection result. Light emission control device. (2) Above 1. Light projection amount control according to claim 1, characterized in that the amount of light emitted from the light source is reduced when the difference in the amount of charge accumulated in the second charge storage section reaches a certain value. Device. (6) The light projection amount control device according to claim 1, wherein the control means includes means for changing a duty. (4) The above-mentioned Genden Conversion Means Company consists of two photoelectric conversion sections,
The light projection amount control device according to claim 1, wherein the control means controls the light projection amount from the light source by using the amount of charge obtained from each of the two photoelectric conversion units. .