JP2696676B2 - Image sensor output device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] BACKGROUND OF THE INVENTION The present invention relates to a camera for photographing.
Image sensor used as a focus detection device, etc.
It relates to an output device of a server. [0002] 2. Description of the Related Art A recent car having an autofocus function has been developed.
The camera makes the subject light incident on the image sensor,
Focus detection is now performed from video signals (imaging signals).
ing. A CCD element is used as an image sensor.
In most cases, the light received by an image sensor is used.
The subject image is focused on the reference area and reference area
The reference area image to the reference area image.
The so-called phase difference detection method that detects the focal point by
Also, when the subject is in focus, the subject formed on the image sensor
Iwayu that uses the maximum image contrast
Contrast detection method is adopted. FIG. 12 shows an image sensor shown as a conventional example.
FIG. 3 shows a block diagram of a server. The image sensor is public
A known CCD element with a reference area and a reference area
Sensor array 11, reset gate 12, shift gate
13 and a CCD shift register 14.
The image sensor is located close to the monitor
FIG. 14 shows the monitor voltage Vm from the sensor 15 for use.
Thus, the charge accumulation time is determined. That is, the monitor voltage Vm is shown in FIG.
As described above, the reset pulse φr is generated together with the sensor array 11.
The monitor voltage Vm is input and output from the amplifier 16.
Until a predetermined set voltage Vt is reached, the sensor
The array 11 stores charge; [0006] The amount of charge thus accumulated is determined by a shift pulse.
Moved to CCD shift register 14 by φs input
Later, transfer pulse φ₁, Φ_TwoAccording to this shift register
The video signal is sent out sequentially from the
The signal voltage Vos is output. [0007] The video signal voltage Vos is
And outputs the difference voltage as A /
Digitally converted by D converter and sent to signal processing circuit
The distance measurement calculation is performed. [0008] SUMMARY OF THE INVENTION As described above,
The monitoring sensor 15 is on the sensor array 11
Monitor the average luminance distribution in the reference area of
Therefore, an image with a high contrast ratio is projected on the sensor array 11.
When shaded, or when strong light is
At the same time, the charge amount curve A shown in FIG.
As shown, some pixels are saturated and accurate video signal
The voltage Vos cannot be obtained, and an error appears in the calculation result of the distance measurement.
You. In order to avoid this saturation, monitor voltage Vm
May be set at a low level.
However, in this case, the subject having a low contrast ratio
In the case of detection, the amount of charge
As the S / N ratio of Vos deteriorates, the saturation region
It is necessary to limit the amount of charge stored at a level with a margin.
And does not effectively use the capabilities of the image sensor,
It is not preferable to use at a low N ratio. In the case of the above-mentioned conventional example, the monitor cell
Sensor 15 is the same subject or object as the image sensor.
Because it does not receive light from the photo frame, depending on the subject,
In some cases, control of the accumulated charge amount cannot be performed. On the other hand, the object projected onto the sensor array 11
If the contrast ratio of the object image is small, the video signal
The signal change component of the voltage Vos− (Vmax−Vmin) is
Difference voltage between video signal voltage Vos and compensation voltage Vcs−
(Vos−Vcs) is much smaller than the average voltage.
Therefore, a high-resolution A / D converter is required. Also, as can be seen from FIG.
The monitor voltage Vm corresponding to the reset pulse φr
Time until the voltage reaches a certain set voltage Vt after power is applied
Is the charge accumulation time of the image sensor.
The average voltage of the described difference voltage− (Vos−Vcs) is constant.
And amplify such voltage to A / D converter
Will be entered. The brightness of the subject is low and the monitor voltage V
m does not reach the set voltage Vt within the specified time.
In this case, the above-described difference is determined according to the level of the monitor voltage Vm.
The voltage − (Vos−Vcs) was amplified. In such a case, the difference voltage-(Vo
s-Vcs), the amplification degree is in accordance with the average voltage.
A / D conversion is effective for subjects with small dark differences.
I can't do that. Further, in the conventional image sensor, the average
When performing focus detection on a dark subject,
Long charge accumulation time is required even when there is a contrast ratio
There was a problem to say. Therefore, the present invention solves the above-mentioned problems.
The solution is to use as few components as possible
Of image sensor for the purpose of simplifying
The aim is to propose a force device. [0017] SUMMARY OF THE INVENTION The present invention is directed to the above objects.
To achieveAs a first invention,The incident light is
Image under the output condition according to the monitor signal
The output device of the image sensor that outputs the signal
And one sensor means such as a CCD element,
The strongest partial light and the weakest light incident on the sensor means
Detects partial light and generates a maximum light detection signal and a minimum light detection signal.
Monitoring means for outputting the difference signal of
Image sensor output characterized by
Suggest a device.As the second inventionThe incident light
Monitor and monitor the image under output conditions according to the monitor signal.
Image sensor output device
And one sensor means such as a CCD element,
The strongest partial light and the weakest light incident on the sensor means
Detecting means for detecting the partial light; and output from the detecting means.
Input the maximum light detection signal and the minimum light detection signal
Differential amplification that outputs the difference signal of the detection signal as a monitor signal
Means and said differential amplifier according to said monitor signal
Set the degree of gain of the means, the maximum light detection signal of the detection means
And the minimum light detection signal, and charges the sensor means.
Output condition setting means for stopping accumulation and sensor means
After the charge accumulation of the
Switching means for switching to an image signal output operation.
The sensor removed from the sensor means by switching the replacement means
Signal and the minimum light detection signal output by the detection means.
The signal is input to the above-described differential amplifier, and this differential amplifier is
The difference signal between these input signals is output as an image signal.
Image sensor output device
Suggest. [0018] The output device of the first invention isIf the monitor means
The strongest part and the weakest part of the light incident on the
Detects light and detects the difference between the maximum light detection signal and the minimum light detection signal.
Signal as a monitor signal. [0019]The output device of the second invention isAs above
Image according to the monitor signal output from the monitor
The signal output conditions are set, and then the sensor
Load accumulation is stopped, and the image is
A signal is output. [0020] BRIEF DESCRIPTION OF THE DRAWINGS FIG.
explain. FIG. 1 shows an image for detecting the focus of a camera according to the present invention.
Block showing an example implemented as a sensor output device
In the figure, 21 is a sensor array, 22 is a reset gate,
23 is a shift gate, 24 is a CCD shift register.
These are the same as in the conventional example constituting the image sensor.
Things. The image sensor is a drive control circuit 25.
Reset pulse φr, shift pulse φ
s, transfer pulse φ₁, Φ_TwoTo operate and the video signal V
Outputting os has already been described.
You. The image sensor includes a sensor array.
21 of the pixels where the strongest light is incident
A maximum light detection circuit 26 for electrically detecting the amount of accumulated charge;
Electrically detect the amount of charge stored in the pixel where the weakest light enters
A minimum light detection circuit 27 is provided. That is, FIG.
(A), (b), FIG. 6 (a), (b), FIG. 7 (a),
As shown in (b), the maximum value and the minimum value of the accumulated charge amount appear.
Therefore, the maximum value and the minimum value are determined by the detection circuit 2 described above.
6, 27. FIG. 2 shows a specific example of the detection circuits 26 and 27.
FIG. In this embodiment, the sensor-array
N-channel with gate connected to each photoelectric element 21
MOS FETs 28a, 28b, 28c ...
.. the amount of charge stored in the photoelectric element
The Vmin signal corresponding to the minimum light taken out as a follower
Output, and similarly connected P-channel MOS
Type FETs 29a, 29b, 29c ...
It is configured to output a Vmax signal corresponding to the maximum light.
You. Detected by the maximum light detection circuit 26
The Vmax signal is sampled /
Vmax signal sent to the
Signal and the held Vmax signal are supplied to the selector circuit 32.
And input to the differential amplifier circuit 33. Detected by the minimum light detection circuit 27
Vmin signal is sent to another sample via the amplifier 34.
/ Hold circuit 35, where the sampled V
differential amplification of the min signal and the held Vmin signal
Input to the circuit 33. Sample / hold circuits 31, 3
5 is a sample / hold sent from the drive control circuit 25
Input signal φsh to change from sample state to hold state
Switch to. The selector circuit 32 described above operates as a selector.
Analog switch that operates by inputting the
And the selector signal Sel becomes a High voltage.
The Vmax signal changes to a low voltage, thereby canceling the Vmax signal.
From the CCD shift register 24 sent via the
Are selected and input to the differential amplifier circuit 33.
Force. On the other hand, the Vmax signal of the maximum light detection circuit 26
Is sent to the comparison circuit 37 and is compared with a predetermined comparison voltage Vt.
Are compared. This comparison voltage Vt is stored in the sensor array 21.
Input the Vmax signal when the accumulated charge approaches saturation
Thus, the comparison circuit 37 is inverted. That is, the light enters the sensor array 21.
The subject light is bright, and the partial light saturates the charge accumulation
, The comparison circuit 37 outputs Vma corresponding to the partial light.
It is inverted by the x signal. For example, if the Vmax signal is a sensor
The ratio when the saturation level of the array 21 is about 80%
The comparison circuit 37 is inverted. The inverted output of the comparison circuit 37 is a shift pulse system.
Input to the control circuit 38. This shift pulse control circuit 38
Are switched by inputting a shift selection signal Ss.
When s is at the low level, the inverted output of the comparison circuit 37
Can be input, and this signal Ss becomes High level.
In this case, the input of the inverted output is blocked and shift signals
Enter the number Es. Then, according to the input of the inverted output,
The shift control is performed according to the input of the shift signal Es.
The control signal Sc is sent to the drive control circuit 25. The shift signal Es is differentiated by the monitor operation.
The amplification degree of the amplification circuit 33 is set according to the contrast of the subject.
Is set, and sent from the microcomputer described later.
The shift signal is supplied to the shift pulse control circuit 38.
While inputting Es and outputting shift control signal Sc,
The input of the inverted output from the comparison circuit 37 is blocked. this
The shift control signal Sc sent to the drive control circuit 25 in the state
Is shaped into an appropriate pulse and the shift pulse φs is
It is sent to the footgate 23. The differential amplification circuit depends on the brightness of the object.
Before the amplification of the road 33 is set, that is, the monitor operation
The inverted output from the comparison circuit 37 is
When input to the path 38, the drive control circuit 2
5 is shifted by the input of the shift control signal Sc in the same manner as described above.
Pulse φs to the shift gate 23, and
The shift monitor circuit 39 confirms that the control signal Sc has been sent.
Monitor. The shift monitor circuit 39 outputs the shift control signal S
c and the sensor array 21 starts the next charge accumulation.
Do not monitor the contrast of the subject until
Make. The output device of the above image sensor is shown in FIG.
Microcomputer 60 as in block 50 of 3
Various signals are exchanged between the two. Microcomputer
The signal input from the data 60
In addition to the selection signal Ss and the shift signal Es, the start signal S
t, the amplification degree selection signal Asel, and the transfer control signal φcnt
is there. The start signal St is used to store the electric charge of the sensor array 21.
This signal instructs the start of the product. The amplification selection signal Asel is supplied to the differential amplifier 3
3 is a signal for setting the degree of amplification. Transfer control signal φcn
t is a control signal for driving the CCD shift register 24 at high speed.
No. Normally, the output signal Vo of the differential amplifier circuit 33 is output.
Is the speed at which A / D conversion can be performed.
Is taken out, but the video signal Vos is not
When necessary, this shift register 24 is driven at a high speed,
Unnecessary charges are discharged. Signal to be output to microcomputer 60
The output signal Vo of the differential amplifier circuit 33 and the A / D
There is an imaging signal Sad. The output signal Vo is monitored
Output signal -Am according to the contrast of the subject to be output at the time of composition
(Vmax-Vmin) and the video from the image sensor
Output signal -As (Vos
-Vmin). The A / D timing signal Sad is a CCD system.
A included in the shift register 24 and the microcomputer 60
A signal for measuring the timing of the / D converter, and the differential amplifier circuit 3
3. The output signal Vo of 3 is stable and A / D conversion is possible.
Is transmitted. Next, the output device of the above-described image sensor will be described.
Refer to the time chart shown in FIG.
It will be explained while referring to the figures. (1) Setting of amplification degree by monitor When the start signal St is input as a High voltage
The drive control circuit 25 resets the voltage as a low voltage.
Signal φr is output to open the charge storage in the sensor array 21.
Start. The drive control circuit 25 shares with the start signal St.
The shift selection signal Ss is input as a low voltage
, The sample / hold signal φsh and the select signal
Sel both output as High voltage. The sample / hold signal φsh is a sample
/ Hold circuits 31, 35 are both held in sample mode
And the select signal Sel selects the Vmax signal.
The selection circuit 32 is switched as described above. Also, the shift pulse control circuit 38
The selection signal Ss is input and the inverted output from the comparison circuit 37 is output.
Move on to inputting. Note that the differential amplifier circuit 33 has
Is set to a predetermined amplification degree Am in consideration of the circuit configuration of
Supply the amplification degree selection signal Asel. In the above state, the electric charge of the sensor array 21 is stored.
The product advances, and Vm detected by the maximum light detection circuit 26
ax signal and Vm detected by the minimum light detection circuit 27
The in signal is supplied to the sample / hold circuits 31 and 35, respectively.
And is input to the differential amplifier circuit 33. did
Therefore, from the differential amplifier circuit 33,       Vm = −Am (Vmax−Vmin) (1) Is output. The output signal Vo = Vm is A / D converted.
Data processing by the microcomputer 60.
The output signal Vo = Vm is supplied to the computer 60.
Therefore, a predetermined level has been reached within a predetermined time.
At this time, the amplification degree selected by the microcomputer 60
5 (c), 6 (c) and 7 (c).
Is sent as the monitor signal Vo = Vm shown in FIG.
The amplification Am of the circuit 33 is projected on the sensor array 21.
A constant amplification degree according to the contrast of the subject image
In addition, the amplification As is set. This amplification degree As is:       As = (Vf / Vm) · Am K (2) Set so that Note that Vf is the signal of the A / D converter.
It is a scale. K is a constant, and the monitor
And output the video signal Vos described below.
In consideration of the difference in the characteristics of the sensor array 21 when
This is a defined safety factor, and it is preferable to set it to about 0.8.
New 5 (b), 6 (b) and 7 (b).
Calculation of the output signal Vo = Vm with a small amount of accumulated charge
If the processing value does not reach the predetermined level within the specified time,
By the lapse of the specified time, the amplification degree selection signal Asel becomes
5 (d), FIG. 6 (d), and FIG. 7 (d).
The monitor signal Vo is sent as Vo = Vm and the output signal Vo =
The amplification As is set as the amplification according to the value of Vm.
It is. In this case, the level of the output signal Vo = Vm is
Judgment and A / D conversion as shown in FIG. 5 (b) and FIG. 7 (b)
If the output signal Vo is not sufficient,
Is switched to make it suitable for A / D conversion.
You. The amplification degree selection signal Asel is supplied as a 3-bit signal.
Assuming that, the amplification degree As is set as shown in Table 1 below.
Can be specified. [0046] [Table 1] (2) Output operation of video signal Vos As described above, the output signal Vo = V of the differential amplifier circuit 33
When m reaches a predetermined level, the amplification circuit 33
At the same time, the shift selection signal Ss is set to Lo.
The voltage changes from the w voltage to the High voltage, and the shift pulse control circuit
The path 38 shifts to the state of inputting the shift signal Es, and thereafter,
Thereafter, until the monitor operation is performed again, the operation of the comparison circuit 37 is stopped.
Prohibits the input of transfer output. The shift signal Es is such that the shift selection signal Ss is H
From the microcomputer 60 after the voltage becomes high
This is a positive pulse signal to be sent, and
The shift system output from the shift pulse control circuit 38
The control signal Sc is sent to the drive control circuit 25, and as described above.
Thus, the shift pulse φs is supplied, and the sensor array 2
The one accumulated charge is transferred to the CCD shift register 24. Also, the shift pulse φs is applied to the shift gate 2
3, the reset pulse φr is changed from the low voltage
High voltage, and charge accumulation of the sensor array 21
Abort. That is, the differential amplifier circuit 33, the shift pulse
A control circuit 38, a microcomputer 60
The accumulation of the sensor array 21 by the operation of the first circuit means
Charge is taken out. As described above, the shift signal Es is output to the output device.
When supplied, that is, when the output signal Vo = Vm
The charge accumulation in the sensor array 21 is stopped
The charge accumulation time becomes-(Vmax-Vmin)
Therefore, it is determined, and the higher the contrast ratio, the shorter the time
If the contrast ratio is not high, it will take a long time
You. On the other hand, whether the shift selection signal Ss is a low voltage
Change to High voltage, the select signal Sel
The high voltage changes to the low voltage, and the selector circuit 3
2 passes the Vmax signal,
os, and the sample / e
The negative signal φsh also changes from High voltage to Low voltage.
And the sample / hold circuits 31, 35 are in the hold state.
Is held. The start signal St becomes H after a predetermined time has elapsed.
From the high voltage to the low voltage, the transfer
Loose φ₁, Φ_TwoIs input to the CCD shift register 24,
The data of the shift register 24 is sent serially sequentially.
And a video signal Vos is output. Thus, the video signal is supplied to the differential amplifier circuit 33.
The signal Vos and the held Vmin signal are input and
The output signal Vo is       Vs = −As (Vos−Vmin) (3) Is output as This output signal Vo = Vs
Φ₁, Φ_TwoA / D conversion sequentially output one pixel at a time in synchronization with
The pixel data sent to the device and subjected to A / D conversion is stored in the arithmetic operation unit.
Are sequentially stored. All pixel data necessary for the distance measurement calculation is stored and calculated.
Once stored in the section, the monitor amplification Am is set again and
Move on to the monitor operation described. In FIG. 4, Ti is
The charge accumulation time, Ts, from the CCD shift register 24
The charge signal extraction time, To indicates the operation processing time, and T
i_TwoIs the second charge accumulation time. As can be seen from the above equations (2) and (3),
The video signal V at the amplification As according to the maximum contrast of the object
Since the difference between the os and the Vmin signal is amplified,
When the value is small, the amplification As is large, and when the contrast is large,
In this case, the amplification As is reduced, and as a result, the brightness difference is small.
The output signal Vs is A / D-converted with extremely high accuracy even in the case of
Will be replaced. For example, a full-scale 4V A / D converter
If (Vmax−Vmin) is 100
When mV, the amplification degree As = 40, (Vmax-Vmi
n) is 500 mV, the amplification degree As = 8 and-(V
os-Vmin) signal. The video signal Vos is as shown in FIG.
Appears, but the video signal Vos is amplified as it is.
Without a true signal as a-(Vos-Vmin) signal
Since only the change component is amplified, signal changes can be captured with high accuracy.
I can get it. For example, if the subject light of 100: 90 is set to 100
90 to 100 signals are obtained even if A / D conversion is performed with a resolution of
, But increase the-(Vos-Vmin) signal by 10 times
A / D conversion to obtain 0-100 signals
Using an A / D converter with 10 times the resolution
It is as effective as it is. Note that FIG.
This shows a case where the dark difference is large.
Results in a smaller contrast. (3) Monitoring operation of sensor array saturation The sensor array 21 is charged while monitoring the contrast of the subject.
The comparison circuit 37 detects whether the saturation level of the accumulation is approached.
Put out. (See Fig. 8) As described above, the comparison circuit 37 controls the brightness of the subject when the subject light is bright.
Vmax when the sensor array 21 approaches the saturation level.
Input the signal and invert it.
Send to Road 38. At this time, the shift selection signal Ss becomes low and
The shift pulse control circuit 38 outputs the inverted output
And sends the shift control signal Sc to the drive control circuit 25.
You. Therefore, the above state is applied to the shift monitor circuit 39.
Therefore, while being monitored, the CCD shift register 24
The stored charge is transferred. At this point, however, the differential amplifier 33
The output signal Vo = Vm = -Am (Vmax-Vmin)
The shift selection signal Ss has not reached the predetermined level and is low.
Since the voltage is w, the sample / hold circuit 3
1 and 35 are in the sample state, and the selector circuit 32 is in the Vmax
The signal is selected. Therefore, in this case, the amplification degree selection signal
The signal Asel is set again, and the output signal Vm of the above equation (1) is set.
Reaches a predetermined level. From this, shift
The selection signal Ss changes from the Low voltage to the High voltage,
Sample / hold circuits 31, 35 are in hold mode,
The selector circuit 32 is in the selection mode of the video signal Vos.
The differential amplifier circuit 33 outputs the signal according to the above equation (3).
The signal Vo = Vs is output. In the case of the above operation, the sensor array 21
Charge accumulation time of the comparison circuit 37, the shift pulse control circuit
38 and the like. (4) Forced execution operation In the case of darkness, the brightness monitor
The output signal Vo = Vm does not reach the predetermined level,
The circuit 37 is not inverted. At this time,
When the first specified time measured by the computer 60 has elapsed
At this point, based on the level determination result of Vo = Vm,
Then, the shift selection signal Ss is set to a High voltage to
By inputting the signal Es as valid, the CCD shift
The stored charges are transferred to the register 24. For example, as shown in FIG.
Vm is 1/4 or more of the predetermined level, and
Therefore, when distance measurement calculation and contrast judgment are possible,
Or, a contrast based on the data taken last time
The level of Vo = Vm by the current monitor based on the judgment result
However, when it is determined that the distance measurement can be calculated, the sensor
The moving speed of the subject image on the ray 21 is high (lens movement
It is judged that it is meaningless to extend the charge storage time any longer
When the shift signal Es (High) is forcibly
give. In the above-mentioned first specified time, the accumulated charge becomes CC
If the condition is not transferred to the D shift register 24,
Extend the charge accumulation time to 2 specified time, and
Unconditionally give shift signal Es (High)
A shift pulse is generated and stored in the sensor array 21.
The transferred charge is transferred to the CCD shift register 24.
You. Therefore, when the above operation is performed,
, The charge storage time of the sensor array 21 is the first or
It is determined by the second specified time. FIG. 10 is a flowchart of the output circuit shown in FIG.
- As shown, step ST_TwoAt
The amplification degree Am is set, and the charge accumulation of the sensor array 21 is reduced.
To start, then step ST_ThreeNow the output signal Vm
(Specifically, the processing value of the microcomputer 60)
It is determined whether or not the predetermined level has been reached.
When reached, step ST₆Proceed to and set the amplification As
And then step ST₇And-(Vos-Vmin) signal
The signal is A / D converted after amplification. Whether or not to perform distance measurement again after the distance measurement calculation is performed
Is a step ST_TenBut the distance is measured again
The Vmax signal has reached the comparison voltage Vt
Step ST₁₁And reaches the comparison voltage Vt.
If it is the initial step ST₁Return to high speed
Operation is performed, and then the operation according to the above loop is performed.
When the reference voltage Vt has not been reached, step ST
_ThreeAnd the process proceeds from the level determination step of the output signal Vm.
Will be. Step ST_ThreeAt the output signal Vm
Has not reached the constant level, and the Vmax signal is equal to the comparison voltage Vt.
Reaches the amplification level according to the monitoring of charge storage saturation.
Am is reset and step ST₆To
If the output signal Vm does not reach the predetermined level even after the time elapses
In the same manner, the amplification degree Am is reset again and the step ST_FiveOr
Step ST₆And then-(Vos-Vmi
n) Amplification of the signal and A / D conversion of the output signal Vs are performed.
You. Next, the charge accumulation of the sensor array 21 is started.
Time chart showing an example of execution at various times
Is shown in FIG. In this figure, the phase Ph₁Is V
Example executed as a result of the max signal reaching the comparison voltage Vt
And Ti₁Is the charge storage time, Ts₁Is a CCD shift register
Signal extraction time of the star 24, To₁Is the data processing
The processing time is shown. In this case, the amplification degree Am is
Am₁Is reset to Phase Ph_TwoIs the signal extraction time Ts₁But
An example in which charge accumulation is started immediately after completion
_Two, Ts_Two, To_TwoIs the charge accumulation time and signal extraction
Time and calculation processing time are shown. Phase Ph_ThreeIs the signal extraction time Ts_Two
In this example, charge accumulation starts immediately after
In this case, the calculation processing time To_TwoThe Vmax signal is
Since the pressure Vt has been reached, high-speed discharge of charges occurs during the time Te.
After that, the phase Ph_FourCharge storage time
Ti_FourIs started. Phase Ph_FourThen, the output signal at the time of shift
Vo = Vm, the amplification degree of Vos−Vmin−As
_TwoIs selected. Phase Ph_FiveThen, the charge accumulation time T
i_FourAfter the end of the charge accumulation time Ti_FiveIn the example where
Calculation processing time To_FourDuring accumulation time Ti_FiveIs completed and immediately
Issue time Ts_FiveIs in. Phase Ph₆Is the charge accumulation time Ti₆But
It becomes longer than the fixed time, and the shift signal Es is forcibly given.
This is an example of execution. An image sensor using a CCD element has been described.
Although described with the example of a server, the present invention is not limited to this.
Image sensor using a MOS sensor, for example
-Can be similarly implemented. [0077] As described above, the output device of the present inventionIs
Using the same sensor means for the monitor signal and the image signal
The output is configured to improve monitor accuracy.
In addition to installing a sensor for monitoring,
Since there is no need, the number of parts is reduced and the configuration is simplified.
It becomes a suitable practical image sensor output device. This output device isThe sensor means
Even when high contrast light enters, the detection
The difference signal between the maximum and minimum light detection signals
Monitor signal according to the state.
The output condition of the image signal is determined by the monitor signal of
Can be. Further,This output device outputs the sensor output signal.
The difference signal between the signal and the minimum light detection signal
The signal is amplified and output to the sensor means.
Image signal consisting of only the light signal component
You.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram embodying the present invention as an output device of an image sensor for focus detection of a camera. FIG. 2 is a circuit diagram showing a specific example of a maximum light detection circuit and a minimum light detection circuit provided in the output device. FIG. 3 is a block diagram showing a signal transmission / reception state between the output device and a microcomputer. FIG. 4 is a time chart showing the operation of the output device. FIG. 5 is an explanatory diagram showing charge accumulation and monitor signals at low luminance. FIG. 6 is an explanatory diagram showing charge accumulation and monitor signals at medium luminance. FIG. 7 is an explanatory diagram showing charge accumulation and monitor signals at high luminance. FIG. 8 is a diagram showing a charge accumulation state of a sensor array provided in the image sensor. FIG. 9 is a diagram showing a video signal extracted from a CCD shift register provided in the image sensor. FIG. 10 is a flowchart of the output device. FIG. 11 is a time chart showing an example in which the charge accumulation start point of the sensor array is changed in various ways. FIG. 12 is a block diagram of an image sensor shown as a conventional example. FIG. 13 is an operation waveform diagram of the conventional image sensor. FIG. 14 is an explanatory diagram showing monitor voltages of the conventional image sensor. FIG. 15 is a diagram showing the amount of charge accumulated in a sensor array provided in the conventional image sensor. [Description of Signs] 21 Sensor array 24 CCD shift register 25 Drive control circuit 26 Maximum light detection circuit 27 Minimum light detection circuit 31, 35 Sample / hold circuit 32 Selector circuit 33 Differential amplifier circuit 37 Comparison circuit 38 Shift pulse Control circuit 39 Shift monitor circuit

   ────────────────────────────────────────────────── ─── Continuation of front page    (56) References JP-A-58-119279 (JP, A)                 JP-A-59-124159 (JP, A)                 JP-A-60-58780 (JP, A)                 JP-A-60-153274 (JP, A)                 JP-A-62-113468 (JP, A)                 JP-A-63-196181 (JP, A)

Claims (1)

(57) [Claims] In an output device of an image sensor for monitoring an incident light in advance and outputting an image signal under an output condition according to the monitor signal, one sensor means such as a CCD element and the strongest light incident on the sensor means are provided. An output device for an image sensor, comprising: monitor means for detecting a partial light and a weakest partial light and outputting a difference signal between a maximum light detection signal and a minimum light detection signal as a monitor signal. 2. In an output device of an image sensor for monitoring an incident light in advance and outputting an image signal under an output condition according to the monitor signal, one sensor means such as a CCD element and the strongest light incident on the sensor means are provided. Detecting means for detecting the partial light and the weakest partial light;
A differential amplifier for inputting a maximum light detection signal and a minimum light detection signal output by the detector and outputting a difference signal between the detection signals as a monitor signal; and a differential amplifier for the differential amplifier according to the monitor signal. Means for setting the amplification degree, holding the maximum light detection signal and the minimum light detection signal of the detection means, and setting output conditions for stopping the charge accumulation of the sensor means, and a monitor signal after the charge accumulation of the sensor means is stopped. Switching means for switching from the output operation to the image signal output operation, and the sensor signal extracted from the sensor means by the switching of the switching means and the minimum light detection signal output by the detection means are input to the differential amplification means. Wherein the differential amplifying means outputs a difference signal between these input signals as an image signal. Location.