JP3527911B2 - Optical sensor monitor circuit - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical sensor monitor circuit which is used in an autofocus device such as a camera and monitors an optical sensor having a plurality of charge storage type photoelectric conversion elements.

[0002]

2. Description of the Related Art Conventionally, as a sensor of an autofocus device such as a camera or a photometric device, an array or area array of photosensor circuits having charge storage type photoelectric conversion elements is used. The subject image is formed on the lens through the lens. In these photosensor circuits, photocharges are integrated for a certain period of time to obtain image data. In order to determine the integration time, data corresponding to the data of the photosensor circuit having the largest amount of received light in each photosensor circuit, that is, the largest output, is monitored and output. Generally, such a monitor output is called a peak output. FIG. 9 shows a conventional optical sensor monitor circuit. This circuit photodiode ₁ 1 to 1 _n, the operational amplifier 2 ₁ to 2 _n and the integral capacitor 3 ₁ integrating circuit consisting to 3 _n to detect the optical switch 4 ₁ to 4 _n to reset the integration circuit, the operational amplifier 2 ₁ - Transistor 5 ₁ with the output of 2 _n input to its gate and its drain connected to GND
~ 5 _n , the constant current source 6 for the circuit for monitoring the above-mentioned peak
It consists of The circuit for monitoring this peak is equivalent to a circuit in which the outputs of the operational amplifiers 2 ₁ to 2 _n are input to the source follower circuit composed of the transistors 5 _{1 to} 5 _n , and the respective outputs are connected.

Next, the operation of the conventional circuit will be described. motion
Switch 4 as the beginning of₁~ 4_nTurn on. Then each
Op-amp 2 of optical sensor circuit₁~ 2_nOutput is V_REFTona
Also, monitor output M_OUTIs (V_REF+ Pch transition
Star V_thValue) is close to the value. Then switch
Four₁~ 4_nWhen all of them are turned to 0FF, the photodiode 1
₁~ 1_nThe photocharges generated in the₁~ 3_nTo
Integrated operational amplifier 2 ₁~ 2_nOutput of each
Todiode 1₁~ 1_nDescends according to the amount of light received
It Then, monitor output M_OUTIs operational amplifier 2₁~ 2_nof
Follows the maximum value of the output (in this case, the output that is the lowest)
And then descend.

[0004]

By the way, since the conventional one-point distance measurement has been the mainstream for cameras, the sensor data (integrated data of each pixel) used for distance measurement is data of the entire sensor area. Therefore, the whole sensor area was suitable for the sensor area to be monitored. However, recently, multi-point distance measurement has become common in cameras, and the number of pixels that make up the sensor has increased more than in the past.
Depending on the direction of distance measurement, sensor data of a part of the sensor area is used instead of using the entire area of the sensor. Therefore, if the entire sensor area is monitored as in the conventional case, if there is a peak in an area that is not used for distance measurement, if the integration time is set based on the peak monitor output, There is a problem that the dynamic range of the area desired to be used for distance measurement cannot be sufficiently obtained.

[0005]

Means for Solving the Problems] To solve the above problems, according to claim 1 invention, the generated electric charge according to the amount of light received from a plurality of photoelectric conversion elements arranged in an array or area shape each converted into a voltage by each <br/> charge-voltage converter circuit connected to each photoelectric conversion element, a conversion voltage of this P-type transistor or N-type transistor
As well as input to the gate of consisting source follower circuit, a constant current source of each source follower circuit is connected
Output terminal is a common monitor output line via the second switch
Connected via the second switch and the monitor output line
The maximum output value of the output voltage of each charge-voltage conversion circuit.
It is characterized by nitting .

[0006] According to a second aspect of the invention, by the charge-voltage converter circuit connected to generate electric charge in response to the received light amount from a plurality of photoelectric conversion elements arranged in an array or area shape for each photoelectric conversion element each converted into a voltage, P-type Trang constant current source to convert this voltage <br/> the source is connected
Source follower consisting of transistor or N-type transistor
As well as input to the gates of the circuit, the common block monitor the output terminals of all of the source follower circuit and a corresponding plurality of source follower circuits are classified for each block and a photoelectric conversion element and the constant current circuit into a plurality of blocks
Connected to each other with a
Connect to the common monitor output line through the switch of
Block monitor line, second switch and monitor output
Output of each charge-voltage conversion circuit for each block via line
It is characterized in that the maximum output value of the voltage is monitored .

[0007] According to a third aspect, by the charge-voltage converter circuit connected to generate electric charge in response to the received light amount from a plurality of photoelectric conversion elements arranged in an array or area shape for each photoelectric conversion element each converted into a voltage, P-type conversion voltage of this <br/> transistor or N-type transistor
Input to the gate of the source follower circuit.
The output terminal of the source follower circuit
Connected to the common monitor output line via each second switch
And connect this monitor output line to a constant current source,
Change the charge voltage via the switch and the monitor output line.
The maximum output value of the output voltage of the switching circuit is monitored .

[0008] The invention of claim 4, wherein, due the charge-voltage converter circuit connected to generate electric charge in response to the received light amount from a plurality of photoelectric conversion elements arranged in an array or area shape for each photoelectric conversion element each converted into a voltage, P-type conversion voltage of this <br/> transistor or N-type transistor
Input to the gate of the source follower circuit.
The output terminal of the source follower circuit
Connected to a common constant current source line via each second switch
In addition, this constant current source line is connected via the third switch.
A second switch and the constant current source connected to a current source
The maximum output voltage of each charge-voltage conversion circuit
It is characterized by monitoring the force value .

[0009] According to a fifth aspect, by the charge-voltage converter circuit connected to generate electric charge in response to the received light amount from a plurality of photoelectric conversion elements arranged in an array or area shape for each photoelectric conversion element each converted into a voltage, P-type conversion voltage of this <br/> transistor or N-type transistor
Input to the gate of the source follower circuit.
And all source follower circuits and corresponding
The photoelectric conversion element is divided into multiple blocks and each block is
And block the output terminals of multiple source follower circuits.
Connect these block common lines to each other by connecting
Connect to a single constant current source via two switches
Through the second switch and the block common line.
Monitor the maximum output value of the output voltage of the charge-voltage conversion circuit
Characterized in that it.

[0010] According to a sixth aspect of the invention, by the charge-voltage converter circuit connected to generate electric charge in response to the received light amount from a plurality of photoelectric conversion elements arranged in an array or area shape for each photoelectric conversion element each converted into a voltage, P-type conversion voltage of this <br/> transistor or N-type transistor
Input to the gate of the source follower circuit.
And all source follower circuits and corresponding
The photoelectric conversion element is divided into multiple blocks and each block is
And block the output terminals of multiple source follower circuits.
Connect these block common lines to each other by connecting
When connected to the constant current source line via the 2 switches respectively
Both of these constant current source lines are connected via the third switch.
Of the constant current source line and the second switch.
The maximum output voltage of each charge-voltage conversion circuit
It is characterized by monitoring the force value .

[0011] The invention of claim 7, wherein, in have your <br/> the photosensor monitoring circuit according to claim 2 or claim 5 or claim 6 wherein, the photoelectric conversion elements of each block in the same number respectively
And wherein a call.

[0012] The invention according to claim 8, in have your <br/> the photosensor monitoring circuit according to claim 2 or claim 5 or claim 6, wherein, the photoelectric conversion element sections forming blocks in the center
The number of photoelectric conversion elements is greater than the number of photoelectric conversion elements of the blocks formed at the ends .

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a first aspect of the invention according to claim 1.
3 is a circuit diagram showing an embodiment of FIG. This photosensor monitor circuit includes photodiodes 1 ₁ to 1 _n , which are a plurality of photoelectric conversion elements arranged in an array or area, operational amplifiers 2 ₁ to 2 _n , which are a charge-voltage conversion circuit, and an integration capacitance. An integrator circuit 3 _{1 to} 3 _n, a first switch 4 ₁ to 4 _n for resetting the integrator circuit, a source follower circuit, and a p-type transistor 5 ₁ having a drain connected to GND.
˜5 _n , the constant current source 6 _{1 to} 6 _{n of} the source follower circuit, and the second switch 7 ₁ connected to the output of the source follower circuit.
˜7 _n , a common monitor output line 9 connected to the other ends of the second switches 7 _{1 to} 7 _n , and the outputs of the source follower circuits are connected to each other by the monitor output line 9.
It becomes the peak monitor output M _OUT .

Next, the operation of the circuit shown in FIG. 1 will be described. motion
First, as the initial stage of the second switch 7₁~ 7_nOf, distance measurement
Turn on the second switch of the optical sensor circuit used for
It Next, the first switch 4₁~ 4_nTurn on. Do
And op amp 2 of each optical sensor circuit₁~ 2_nOutput is V_REF
And monitor output M_OUTIs V_REFTo Pch tiger
Register V_thThe value is close to the potential added. So
After the first switch 4 ₁~ 4_nTo turn off all at once
And photodiode 1₁~ 1_nThe photocharge generated in
Integral capacity 3₁~ 3_nIs integrated into the operational amplifier 2₁~ 2_nof
Each output is its photodiode 1₁~ 1_nReceived light
It descends according to the amount of light. Then, monitor output M_OUTIs
Operational amplifier 2₁~ 2_nTo the second switch in the output of
Therefore, the one selected, that is, the second switch
The maximum value of the output of the operational amplifier of
Also descends following the output that is rising. By this
Specify an arbitrary area and monitor the peaks in it.
It becomes possible. In addition, the monitored peak value
Based on the dynamic of the area you actually want to use for ranging
It is possible to set the range to a sufficient one.

FIG. 2 is a circuit diagram showing a second embodiment according to the invention described in claim 2. In this embodiment, the connection of the monitor output unit in the embodiment of FIG. 1 is changed, the same parts as those in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted. Only different parts will be described. In the first embodiment shown in FIG. 1, the second switches for peak selection are all connected to each optical sensor circuit, but the sensor area actually used for distance measurement is about 3 to 7 elements. In many cases, it is sufficient to select an appropriate number of photosensor circuits as one block, even if the pixel output cannot be specified for monitoring the peak output in many cases.

Therefore, in this embodiment, as shown in FIG. 2, m (n) photosensor circuits are set as one block.
> Divided into blocks of m), each block the output of each source follower circuit block monitor line 10 ₁ -
After being connected to 10 _m, it is connected to the common monitor output line 9 through the second block selection switches 7 _{1 to} 7 _m . In this embodiment, since the sensor area to be monitored can be selected in block units, the number of second switches for selecting the sensor area is reduced, and the scale of the circuit for controlling the second switch is reduced. It will be small.

FIG. 3 is a circuit diagram showing a third embodiment according to the invention described in claim 3. In the first embodiment shown in FIG. 1, the source follower circuit is connected to each photosensor circuit, but in this embodiment, this source follower circuit is used as a peak monitoring circuit, and the input transistor of the source follower circuit is used. Only one is connected to each optical sensor circuit. That is, this circuit includes photodiodes 1 ₁ to 1 _n for detecting light, an integrating circuit composed of operational amplifiers 2 ₁ to 2 _n and integrating capacitors 3 _{1 to} 3 _n, and first switches 4 ₁ to 4 _n for resetting the integrating circuit. , P-type transistors 5 _{1 to} 5 _n and p-type transistor 5 in which the outputs of operational amplifiers 2 _{1 to} 2 _n are input to the gates and the drains are connected to GND
The second switch 7 ₁ to _7-n which are connected to a source of ₁ to 5 _n,
The constant current source 6 is commonly connected to the other ends of the second switches 7 _{1 to} 7 _n . In this embodiment, a constant current source is not provided for each photosensor circuit, so that the degree of freedom in layout is improved when the photosensor circuit is designed by an LSI or the like.

FIG. 4 is a circuit diagram showing a fourth embodiment according to the invention described in claim 4. The circuit of this embodiment is
Photodiodes 1 ₁ to 1 _n for detecting light, operational amplifier 2
_{1 to} 2 _n and integration capacitors 3 _{1 to} 3 _n , an integrator circuit, first switches 4 ₁ to 4 _n for resetting the integrator circuit, and an operational amplifier 2
Outputs of _{1 to} 2 _n are input to the gate and drain is connected to GND. P-type transistor 5 ₁ to
5 _n , a constant current source commonly connected to the other ends of the second switches 7 _{1 to} 7 _n and the second switches 7 _{1 to} 7 _n connected to the sources of the p-type transistors 5 _{1 to} 5 _n Line 11, a third switch 8 ₁ to 8 _k connected in parallel to the constant current source line 11, a third switch
The constant current sources 6 _{1 to} 6 _k are respectively connected to the other ends of the switches 8 ₁ to 8 _k .

[0019] This is because the third embodiment shown in FIG. 3 is a one across the constant current source, followability to the peak of the operational amplifier 2 ₁ to 2 _n the number of the light sensor circuit selected for monitoring output The present invention is intended to improve a slight difference from the embodiment of FIG. That is, in this embodiment, k = n is set, and the second switches 7 _{1 to} 7 _n and the third switch
If in conjunction with the switch 8 ₁ to 8 _k are ON, the circuit becomes a circuit equivalent to the embodiment of FIG. 1, the operational amplifier 2 ₁ -
The followability to the 2 _n peak can be made similar to that of the circuit of the embodiment of FIG. However, since the peak follow-up property is slightly different depending on the subject image formed on the sensor, k = n is not always necessary.

FIG. 5 is a circuit diagram showing a fifth embodiment according to the invention of claim 5. In this embodiment, the connection of the monitor output unit in the embodiment of FIG. 1 is changed, the same parts as those in FIG.
The different parts will be described. The circuit of this embodiment is
Similar to the embodiment of FIG. 2, a plurality of photosensor circuits are divided into m blocks (n> m) as one block, and the source side of the p-type transistors 5 _{1 to} 5 _n is block common line 12 for each block. After being connected to each other by _{1 to} 12 _m , the block common lines 12 _{1 to} 12 _m and the whole common constant current source 6 are connected via the second block selecting switches 7 _{1 to} 7 _m. . In this embodiment, since the sensor area to be monitored can be selected in block units, the number of second switches for selecting the sensor area is reduced, and the scale of the circuit for controlling the second switch is reduced. It will be small.

FIG. 6 is a circuit diagram showing a sixth embodiment according to the invention of claim 6. In this embodiment, a plurality of constant current sources are connected to the embodiment of FIG. 5, parts common to those of FIG. 5 are designated by the same reference numerals, description thereof will be omitted, and different parts will be described. In the figure, the right end side of the second switches 7 _{1 to} 7 _m for block selection is connected to the constant current source line 13 common to the whole, and the constant current source line 13
Is connected to the constant current sources 6 _{1 to} 6 _k via the third switches 8 ₁ to 8 _k . This circuit, similar to the embodiment of FIG. 4, it is possible to improve the followability to the peak of the operational amplifier 2 ₁ to 2 _n.

FIG. 7 is a diagram showing a seventh embodiment according to the invention of claim 7. In FIG. This seventh embodiment is shown in FIG.
Second embodiment, FIG. 5 fifth embodiment, and FIG. 6 sixth embodiment.
The above embodiment is applied to an optical sensor circuit array of a phase difference detection method used in a general camera, and a method of dividing the optical sensor circuit when performing monitor detection in block units will be described. In the figure, an example of block division of each sensor in the left sensor array and the right sensor array is shown. The number of sensors forming both arrays is n, and the number of divided blocks m is 5. If the block is divided evenly, the number of sensors in the block is n /
It becomes 5. In this embodiment, since the number of optical sensor circuits in each block is the same, when used for multi-point distance measurement,
All the viewing angles of the sensor with respect to the subject are equalized, and the advantage of maximizing flexibility is obtained.

FIG. 8 is a diagram showing an eighth embodiment according to the invention of claim 8. This eighth embodiment is shown in FIG.
9 illustrates another method of block division according to the seventh embodiment of FIG. This embodiment is applied when the entire viewing angle is not used for distance measurement, and is applied when it is desired to finely control the viewing angle. That is, as shown in the drawing, the number of photosensor circuits in the block 3 at the center of the array is set to 6 times the number of photosensor circuits in the blocks 1, 2, 4, 5 at the end of the array, and the blocks are divided. did. This division makes it possible to deal with the light amount drop characteristic of the imaging lens, etc., as compared with the case of even division as shown in FIG.
Therefore, there is an advantage that the performance and usability are improved.

In the seventh and eighth embodiments, the number of blocks m is set to 5, but other division numbers can be similarly applied. Further, these embodiments can be similarly applied to an optical sensor circuit configured in an area shape. In each of the embodiments shown in FIGS. 1 to 6, a P-type transistor having a drain connected to GND is used as the source follower circuit, but a source follower circuit using an N-type transistor having a drain connected to V _DD is used. Can also be configured.

From the above, according to each of the above-described embodiments, it becomes possible to designate an arbitrary area and monitor the peaks therein, and to set the dynamic range of the area actually used optimally. be able to. As a result, when the present invention is used for distance measurement, by selecting a monitor area suitable for the sensor area to be used for distance measurement,
It becomes possible to control the more optimal integration time of the sensor area to be used for distance measurement.

[0026]

As described above, according to the inventions of claim 1, claim 3 and claim 4, whether or not each photoelectric conversion element is used is set by the second switch and actually used. It is possible to monitor only the photoelectric conversion element that operates.

According to the inventions of claim 2, claim 5, and claim 6, each photoelectric conversion element is divided into blocks, and whether or not each photoelectric conversion element is used is determined by the second switch in block units. By setting by, it is possible to monitor only the block including the photoelectric conversion element actually used.

According to the seventh aspect of the invention, by making the number of photoelectric conversion elements of the block uniform, when the present invention is used for multi-point distance measurement, the total viewing angle of the sensor with respect to the subject becomes uniform, and the flexibility is improved. The advantage of maximum efficiency is obtained.

According to the invention of claim 8, the number of photoelectric conversion elements of the block formed in the central portion is larger than that of the end blocks, so that the setting corresponding to the detection characteristic based on the arrangement position of the elements can be performed. Becomes

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a first embodiment according to the invention of claim 1.

FIG. 2 is a circuit diagram showing a second embodiment according to the invention described in claim 2.

FIG. 3 is a circuit diagram showing a third embodiment according to the invention of claim 3.

FIG. 4 is a circuit diagram showing a fourth embodiment according to the invention of claim 4.

FIG. 5 is a circuit diagram showing a fifth embodiment according to the invention of claim 5.

FIG. 6 is a circuit diagram showing a sixth embodiment according to the invention of claim 6;

FIG. 7 is a diagram showing a seventh embodiment according to the invention of claim 7;

FIG. 8 is a diagram showing an eighth embodiment according to the invention of claim 8;

FIG. 9 is a circuit diagram showing a conventional example.

[Explanation of symbols]

1 ₁ to 1 _n photodiode 2 ₁ to 2 _n operational amplifier 3 _{1 to} 3 _n integration capacitance 4 ₁ to 4 _n first switch 5 _{1 to} 5 _n p-type transistor 6, 6 _{1 to} 6 _k , 6 _n constant current source 7 _{1 to} 7 _m , 7 _n Second switch 8 ₁ to 8 _k Third switch 9 Common monitor output line 10 ₁ to 10 _m Block monitor line 11 Constant current source line 12 _{1 to} 12 _m Block common line 13 All Common constant current source line

Continuation of the front page (56) Reference JP-A-63-169879 (JP, A) JP-A-8-15603 (JP, A) JP-A-6-235658 (JP, A) JP-A-5-215602 (JP , A) JP-A-4-175619 (JP, A) JP-A-4-33479 (JP, A) JP-A-3-32154 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB) Name) G01J 1/02 G01J 1/42-1/46 G01B 11/00-11/30 102 G01C 3/00-3/36 G01R 19/10 G02B 7/28-7/38 G03B 3/00 G03B 7 / 081-7/099 G06G 7/14 H01L 27/14 H01L 31/10 H04N 5/222-5/257 H04N 5/30-5/335 G03B

Claims (8)

(57) [Claims] 1. A photoelectric conversion device generates electric charges generated from a plurality of photoelectric conversion elements arranged in an array or an area according to the amount of received light.
Each converted into a voltage by each charge-voltage converting circuit connected to each transducer, P-type transient transformation this voltage
Source follower circuit consisting of a star or N-type transistor
As well as input to the gate of the road, the source follower
Connect the output terminal to which the constant current source of the lower circuit is connected to the second switch.
Switch to the common monitor output line and connect the second switch.
Each charge-voltage conversion circuit via the switch and the monitor output line.
An optical sensor monitor circuit characterized by monitoring the maximum output value of the output voltage of . 2. A photoelectrically generated charges according to the amount of light received from a plurality of photoelectric conversion elements arranged in an array or area shape
Each converted into a voltage by each charge-voltage converting circuit connected to each transducer, P-type transistor a constant current source to convert this voltage to the source is connected or N-type transient
Input to the gate of the source follower circuit , which is composed of all the transistors, and all the source follower circuits, the corresponding photoelectric conversion elements and the constant current circuit are divided into multiple blocks, and the output of multiple source follower circuits in each block is divided.
Input terminals together with a common block monitor line,
These block monitor lines are commonly connected via the second switch.
Connect to the monitor output line and connect the block monitor line to the second
Each block via switch and monitor output line
The maximum output value of the output voltage of each charge-voltage conversion circuit is
An optical sensor monitor circuit, which is characterized in that 3. A plurality of photoelectric conversion elements arranged in an array or area form photoelectric charges generated according to the amount of received light.
Each converted into a voltage by each charge-voltage converting circuit connected to each transducer, P-type transient transformation this voltage
Source follower circuit consisting of a star or N-type transistor
Input to each gate of the road
Each output terminal of the follower circuit is connected to the second switch.
Connected to a common monitor output line, and this monitor output
Connect the wire to the constant current source, a second switch and before Symbol monitor
The maximum output voltage of each charge-voltage conversion circuit is output via the output line.
An optical sensor monitor circuit characterized by monitoring a large output value . 4. The photoelectrically generated charges according to the amount of light received from a plurality of photoelectric conversion elements arranged in an array or area shape
Each converted into a voltage by each charge-voltage converting circuit connected to each transducer, P-type transient transformation this voltage
Source follower circuit consisting of a star or N-type transistor
Input to each gate of the road
Each output terminal of the follower circuit is connected to the second switch.
Connected to a common constant current source line, and this constant current source line
It is connected to a constant current source through a third switch,
Each charge-voltage conversion circuit is connected via the switch and the constant current source line.
An optical sensor monitor circuit characterized by monitoring the maximum output value of the output voltage of the path . 5. photoelectrically generated charges according to the amount of light received from a plurality of photoelectric conversion elements arranged in an array or area shape
Each converted into a voltage by each charge-voltage converting circuit connected to each transducer, P-type transient transformation this voltage
Source follower circuit consisting of a star or N-type transistor
Enter each of the road gates and
Multiple follower circuits and corresponding photoelectric conversion elements
Multiple source followers for each block.
Connect the output terminals of the circuit to each other by a block common line,
Connect these block common lines to a single line via the second switch.
Connected to the constant current source of each of the second switch and the
Output voltage of each charge-voltage converter via block common line
Of these , an optical sensor monitor circuit that monitors the maximum output value . 6. converted from a plurality of photoelectric conversion elements arranged in an array or area shape to each voltage by each charge-voltage converting circuit that the generated charges according to the amount of received light are connected to each photoelectric conversion element, P-type transient the conversion voltage of this
Source follower circuit consisting of a star or N-type transistor
Enter each of the road gates and
Multiple follower circuits and corresponding photoelectric conversion elements
Multiple source followers for each block.
Connect the output terminals of the circuit to each other by a block common line ,
These block common lines are connected to the constant voltage via the second switch.
Connect to each source line and connect this constant current source line.
Connecting a plurality of constant current sources via a third switch,
Charge-voltage conversion via constant current source line and second switch
An optical sensor monitor circuit characterized by monitoring the maximum output value of the output voltage of the circuit. 7. The method of claim 2 or the optical sensor monitoring circuit according to claim 5 or claim 6 wherein the optical sensor monitoring circuit, wherein the kite to the photoelectric conversion elements of each block in the same number respectively. 8. The optical sensor monitor circuit according to claim 2, 5 or 6, wherein the optical sensor monitor circuit is sectioned in the center.
The number of photoelectric conversion elements in the block, which is divided at the end
An optical sensor monitor circuit characterized in that the number is larger than the number of photoelectric conversion elements of the block .