JPH10126682A - Image detection system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide signal charges with sufficient contrast and to realize accurate automatic focusing by switching addition/non-addition in a vertical direction and a horizontal direction on the signal charges obtained in area sensors. SOLUTION: The charges of the plural pixels are added during the transfer of the charges. Thus, a range to be read becomes large but the number of the pixels to be read does not change. When the preceding detection result is not reliable (#40), whether the preceding integration is under low luminance or not is judged (#45). When the integration is under low luminance, the reading of this time is executed in addition mode (#55). When preceding integration is not under low luminance and this reading mode is an addition mode, the reading this time is executed in the non-addition mode (#60) and the reading this time is executed in the addition mode when the preceding reading mode is the non-addition mode. Thus, data by this integration is read at the optimum read mode based on the preceding detection result and brightness.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image detection system having an area sensor used for auto focus and image blur detection.

[0002]

2. Description of the Related Art Conventionally, in an image sensor, obtained signal charges are sometimes added. For example, in interlacing of an area sensor in a video camera, signal charges for two pixels in the vertical direction are added when signal charges are transferred by a vertical transfer clock in order to obtain a smooth image. Then, the signal charges after addition are averaged and displayed as signal charges for one pixel.

[0003]

In the image blur detection, it is necessary to repeatedly perform integration and data dump while the shutter is open. Therefore, it is necessary to read out the signal charges in the image blur detection area in a short time. is there. Therefore, when an area sensor is used, the size of the image blur detection area is limited to read out in a short time.

However, when the brightness of the subject is low, a signal charge having a sufficient contrast cannot be obtained only from a limited area, so that a correct comparison cannot be performed and an accurate image shake is not obtained. The problem arises that the quantity cannot be detected. This problem can be solved by widening the image blur detection area. However, simply increasing the readout area increases the time required to read out signal charges and reduces the number of times image blur detection can be performed. Cannot be detected following the image blur.

Accordingly, in the present invention, in a system for detecting an image blur using an area sensor, when the luminance of a subject is low, the readout area is widened by adding the signal charges by applying the above-mentioned conventional example. Consider that the reading time does not change. However, in the interlace of the conventional area sensor, addition is performed in only one direction, and there is no function of selecting addition or non-addition of data. Therefore, according to the brightness of the subject,
Cannot select non-addition. Further, since the addition direction cannot be selected, addition cannot be performed in a direction corresponding to a subject having any luminance distribution.

According to the present invention, there is provided an image detection system capable of obtaining a signal charge having a sufficient contrast from any subject having different contrast, frequency, control sequence, etc., and enabling accurate autofocusing. The purpose is to do.

[0007]

In order to achieve the above object, according to the present invention, in an image detection system having an area sensor, signal charges obtained by the area sensor are added and non-added in a vertical direction and a horizontal direction, respectively. To switch. Therefore, when the subject has low luminance, addition of signal charges can be performed, and further, the direction of addition can be selected according to the luminance distribution of the subject.

Further, according to the present invention, the signal charges in the vertical or horizontal direction are added during the transfer of the signal charges obtained by the area sensor. That is, when reading out the electric charge of a certain pixel, the electric charge of the surrounding pixels is added and then read out, so that the electric charge obtained from each read out pixel is larger than the electric charge obtained from one pixel. However, since the addition is performed during the transfer of the signal charge, no special time is required, and the time required for reading out one pixel is the same as that during non-addition.

[0009]

FIG. 1 shows two area sensors 1, 2;
And a device configuration diagram of a camera image detection system having a control circuit 8 for controlling the same. The outputs of the area sensors 1 and 2 are used for auto focus (AF) and image blur detection as described later. The area sensors 1 and 2 and monitors 3 and 4 to be described later are composed of photoelectric conversion elements.

This device comprises a horizontal transfer register 21
area sensors 1 and 2 having a and 21b, L-shaped monitors 3 and 4 along each two sides of the area sensors 1 and 2, an AGC circuit 7, a control circuit 8, a gain variable amplifier 10, and an S / H (sample hold) circuit 22,
Clamp circuit 11, output selection circuit 9, temperature detection circuit 1
2. It is composed of each main element of the microcomputer μC, and has each output buffer and each output switch.

That is, the output buffers 2 of the monitors 3 and 4
6, 27, output switches 5, 6, horizontal transfer register 21
a, 21b output buffers 24, 25 and output switch 3
0 and 31 are provided. In this device, the control circuit 8 is an area sensor drive unit, the variable gain amplifier 10, the S / H circuit 22, the clamp circuit 11, and the output selection circuit 9 are an area sensor output processing circuit unit. Here, the monitors 3 and 4 monitor the accumulated charges of the corresponding area sensors 1 and 2, respectively. The horizontal transfer registers 21a and 21b temporarily hold the charges of the area sensors 1 and 2 and serially output the charges.

The clamp circuit 11 operates at the timing when the charge of the black reference pixel (OB) is output from the area sensors 1 and 2, and clamps the voltage corresponding to the dark current to a predetermined voltage. The output selection circuit 9 is common to all outputs, and the control circuit 8 selects and outputs the outputs of the area sensors 1 and 2, the outputs of the monitors 3 and 4, and the output of the temperature detection circuit 12.

This device has a microcomputer μ
Each component except C is formed as a one-chip IC (integrated circuit) provided on one substrate. Hereinafter, the device formed on this chip is
Devices not formed on this chip are assumed to be formed outside. Monitor signals output from the monitors 3 and 4 are selectively supplied to an AGC circuit 7 and an output selection circuit 9 via output buffers 26 and 27 and output switches 5 and 6.

The switches 5 and 6 are formed of MOS transistors, respectively, and are turned on when switching signals A and B generated from the control circuit 8 are applied to their gate electrodes at a low level. The monitor signal supplied to the AGC circuit 7 and the output selection circuit 9 is selected depending on which switch is turned on. That is, one of the monitor signals of the monitors 3 and 4 can be selected by the switching signal A or B. The selection of the monitor signal will be described later.

The area sensors 1 and 2 and the monitors 3 and 4 simultaneously start integration. When the integration starts, the AGC circuit 7 monitors the input monitor signal to reach a predetermined voltage, and when the monitor signal reaches the predetermined voltage, transmits the information to the control circuit 8. Upon receiving the information, the control circuit 8 terminates the integration of the area sensors 1 and 2 and notifies the external microcomputer μC that the integration has been completed (hereinafter, this integration completion is referred to as “natural termination”). AG
The C circuit 7 can be composed of, for example, a comparator using the predetermined voltage as a reference voltage and using the monitor signal as a comparison voltage.

If the monitor signal does not reach the predetermined voltage even after the lapse of the predetermined time, that is, if the information that the predetermined voltage has been reached is not transmitted from the control circuit 8 to the external microcomputer μC after the lapse of the predetermined time, The microcomputer μC instructs the control circuit 8 to forcibly terminate the integration of the area sensors 1 and 2, and the forcible termination is performed.

In either case of natural termination or forced termination of the integration, when the integration is completed, the monitor signal supplied from the output selection circuit 9 to the external microcomputer μC via the Vout terminal 46 is output at the timing of the completion of the integration. A / D conversion is performed by an A / D converter 32 built in the microcomputer μC, and an amplification factor applied to the output of the area sensor is determined according to the digital value. This amplification factor
The variable gain amplifier 10 is transmitted to the control circuit 8 and
The amplification factor is set for. Here, when the integration ends naturally, the amplification factor becomes 1. In the case of natural termination, the amplification factor may be set to 1 without A / D conversion of the monitor signal to determine the amplification factor.

On the other hand, after the integration is completed, the outputs of the area sensors 1 and 2 are transferred to the horizontal transfer registers 21a and 21b.
The signal is input to the variable gain amplifier 10 via the output buffers 24 and 25 and the switches 30 and 31, and is amplified at the amplification factor set previously. The switches 30 and 31 have the same configuration as the switches 5 and 6, and the control circuit 8 generates the switching signals X and Y to select the output of the area sensor 1 or 2 which is given to the variable gain amplifier 10.

At this time, in this embodiment, the control circuit 8 alternately selects the outputs of the two area sensors 1 and 2. The details will be described with reference to the timing chart of FIG. Here, the output from the area sensor 1 is referred to as a sensor output α, and the output from the area sensor 2 is referred to as a sensor output β. From the area sensors 1 and 2, respectively (a) and (b)
As shown in (1), data is output in synchronization with the same transfer clock (not shown) generated from the control circuit 8.

The control circuit 8 controls the switches 30 and 31 to conduct the sensor outputs α and β by switching signals X and Y which are switched at twice the frequency of the transfer clock as shown in (c) and (d). Switch. The switches 30 and 31 are turned on when the switching signals X and Y are at a high level, and turned off when the switching signals X and Y are at a low level. Therefore, the output of the area sensors 1 and 2 is alternately output for each high level of the switching signals X and Y, that is, alternately.
Is input to

The sensor outputs α and β amplified by the variable gain amplifier 10 are sampled and held by the S / H circuit 22. (E) shows the sampling pulse generated for that. The sample-held signal is supplied to the clamp circuit 11.

Here, the voltage corresponding to the dark current is clamped to a predetermined voltage at the timing when the electric charge of the black reference pixel is output. The sensor outputs α and β are output from the output selection circuit 9 and V
The signal is input to an A / D converter 32 built in the microcomputer μC via an out terminal 46. (F) shows the waveform of the signal (output of the S / H circuit 22) given to the A / D converter 32 at that time. (G)
The signal after A / D conversion is simply shown.

In this process, once sampling and holding using the sampling pulse is performed, the switching signals X,
Switch 3 for alternately outputting Y at low level and conducting
This is to remove the influence of switching noise generated by switching between 0 and 31. In this way, by using the above method, it is possible to take in data from the two area sensors 1 and 2 output at the same timing and perform A / D conversion while driving the area sensors 1 and 2 with the same clock.

In this embodiment, the area sensor 1 shown in FIG.
Numeral 2 is used as a dual-purpose sensor for an image blur detection sensor and an autofocus sensor. When used as an autofocus sensor, the outputs of the area sensors 1 and 2 are processed by the methods shown in FIGS. 2A to 2G. Change the timing for A / D conversion. Here, only differences (changes) in the case of image blur detection will be described.

That is, in the case of image blur detection, only one of the area sensors 1 and 2 is required. For example, when image blur detection is performed using the output of the area sensor 1, the sensor output The A / D converter 32 is operated only at the timing when α is given to the A / D converter 32, and the A / D converter 32 is deactivated at the timing when the sensor output β is given. Conversely, when image blur detection is performed using the output of the area sensor 2, the sensor output β becomes A /
A / D only at the timing given to the D converter 32
The converter 32 is operated, and when the sensor output α is given, the A / D converter 32 is deactivated.

Instead of this method, a sampling pulse is generated by the logic circuit shown in FIG. 3 by switching between auto focus and image blur detection, and A
A / D conversion may be performed with a / D conversion start signal. In other words, sample and hold only necessary data,
A / D conversion is performed on the sampled and held data. This logic circuit, as shown in FIG.
Input terminals 33, 34, 35, 36, a NAND circuit 38,
39, AND circuits 37 and 40, an OR circuit 41, and an output terminal 42.

From the input terminal 33, the sampling pulse α
However, a sampling pulse β is input from the input terminal 36. Here, the sampling pulse α and the sampling pulse β will be described. As shown in FIG. 4H, sensor outputs α and β are alternately supplied to the S / H circuit 22 by switching signals X and Y generated by the control circuit 8.

The sampling pulse α is a pulse generated at the timing when the sensor output α is given to the S / H circuit 22, as shown in FIG. Similarly, the sampling pulse β is a pulse generated at the timing when the sensor output β is given as shown in FIG.
These sampling pulses are provided from the control circuit 8.

From the input terminal 35, a signal is provided which specifies whether the sensor output to be sampled and held is one or both of the two sensor outputs α and β.
When only one sensor output α or β is used as in the case of image blur detection, that is, when the sampling pulse α or β is output from the output terminal 42 alone, a high level is input.

When both sensor outputs α and β are used as in the case of autofocusing, that is, when two sampling pulses α and β are output from the output terminal 42, a low level is input. On the other hand, from the input terminal 34,
In the image blur detection, a high level is input when the sampling pulse α is independently output from the output terminal 42, and a low level is input when the sampling pulse β is output alone from the output terminal 42.

For example, when a low level is input to the input terminal 35, the sampling pulse output from the output terminal 42 is the sampling pulse α as shown in FIG. And the sampling pulse β are combined. As a result, the sampling pulse becomes similar to the sampling pulse shown in FIG.
Both the sensor outputs α and β are sampled and held by the S / H circuit 22.

When a high level is input to the input terminal 35 and a high level is input to the input terminal 34, the sampling pulse output from the output terminal 42 becomes a single sampling pulse α as shown in (ヲ). And
Only the sensor output α is sampled and held by the S / H circuit 22.

Next, FIGS. 5 and 6 show the details of the positional relationship between the monitors 3 and 4 and the area sensors 1 and 2. FIG. In FIG. 5, the monitors 3 and 4 are connected to the horizontal transfer registers 21a and 21b and the black reference pixel 1 around the area sensors 1 and 2.
They are arranged in an L-shape, avoiding the portions where 4 and 15 are present.

The reason why the portions where the horizontal transfer registers 21a and 21b and the black reference pixels 14 and 15 exist are avoided.
This is because the effective pixels are separated from the effective pixels 2 and the positions viewed by the monitors 3 and 4 are greatly shifted from the positions actually viewed by the area sensors 1 and 2. In addition, monitors 3, 4
Is arranged so as to surround the entire area sensors 1 and 2 instead of the L-shape, the chip area increases and the cost increases.

In FIG. 6, the monitors 3 and 4 are connected to the horizontal transfer registers 21a and 21b in the area around the area sensors 1 and 2.
It is arranged in a U-shape, avoiding only the part with the mark. The reason why the black reference pixels 14 and 15 are not avoided is that the area occupied by the black reference pixels 14 and 15 is smaller than the area occupied by the horizontal transfer registers 21a and 21b. The deviation from the part being viewed is not large and is within an acceptable range.
This is because it is considered that a problem in the case where there is a high-luminance portion in the vicinity of 4 or 15 can be avoided. In FIG. 6, the purpose is to prevent the overflow when a high-luminance image is formed in the vicinity of the black reference pixels 14 and 15 by monitoring it more reliably than the cost. And

FIG. 7 shows a device configuration diagram of a camera image detection system having two area sensors 1 and 2 which is different from FIG. The area sensors 1 and 2 in FIG. 7 are also used as dual-purpose sensors for autofocus and image blur detection as in FIG. In FIG. 7, the monitors 3 and 4 of FIG.
b and 4a, 4b, and the outputs of the respective monitors 3a, 3b, 4a, 4b are output from an output buffer 26.
a, 26b and 27a, 27b and switches 5a, 5b and 6
The signals are supplied to the AGC circuit 7 and the output selection circuit 9 via a and 6b. At this time, AGC is performed by switching signals A1, A2, B1, and B2 output from control circuit 8.
The monitor signal supplied to the circuit 7 and the output selection circuit 9 is selected.

Further, in the device shown in FIG.
Is configured to have a plurality of predetermined voltages that serve as criteria for determining whether integration should be terminated naturally or forcibly, and the predetermined voltage is switched by a control signal C generated by the control circuit 8. For example, the control circuit 8 sets the switching signals A1 and A2 to a low level to simultaneously turn on the switches 5a and 5b, thereby setting the monitors 3a and
In the mode where the monitor signal of 3b is used simultaneously, A
The predetermined voltage of the GC circuit 7 is switched to a higher voltage by the control signal C.

On the other hand, in a mode in which only one of the switches 5a and 5b is turned on to use only one of the monitors 3a and 3b, the predetermined voltage of the AGC circuit 7 is lowered by the control signal C. Switch to voltage. When the switches 6a and 6b are controlled to use the monitor signals of the monitors 4a and 4b, the predetermined voltage of the AGC circuit 7 is switched. Other configurations are the same as those in FIG.

When the image detection system shown in FIGS. 1 and 7 is applied to image blur detection, the data of one of the two area sensors 1 and 2 is used as described above. Since only one is required, the integral control is performed using the monitor signal of the monitor corresponding to the area sensor to be used. When the image detection systems of FIGS. 1 and 7 are applied to auto focus, data of two area sensors 1 and 2 are required.

The selection of the monitor used for the integration control at this time will be described with reference to the flowchart of FIG. First, in step # 5, it is determined whether or not the current integration is the first integration.
10 and the first monitor (monitor 3 in FIG. 1, FIG. 7
In this case, integration control is performed using the monitor signal of the monitor 3a).

If the current integration is not the first integration, the process proceeds to step # 15, where it is checked whether there is a saturated pixel area in the effective area of the area sensors 1 and 2 in the previous integration result, If there is a pixel area, the monitor signal of the monitor in the vicinity is used (step # 2).
0). For example, in the image detection system of FIG. 7, it is assumed that the integration control was performed last time using the monitor signal of the monitor 3a.

When a saturated portion is detected near the monitor 3b in the area sensor 1 in the previous integration result, integration control is performed using the monitor signal of the monitor 3b in the current integration. Alternatively, area sensor 1
When a saturated portion is not detected in the area sensor 2 and a saturated portion is detected near the monitor 4b in the area sensor 2, integration control is performed using the monitor signal of the monitor 4b in this integration. On the other hand, if a saturated portion is not detected in the effective area of the area sensors 1 and 2 in step # 15, the integral control is directly performed using the monitor signal of the monitor used last time (step # 25).

FIGS. 9 and 10 are schematic diagrams of an optical system when the image detection system shown in FIGS. 1 and 7 is applied to image blur detection and autofocus. FIG. 9 is a schematic diagram of an optical system for detecting an external light phase difference type focus used in a lens shutter type camera or the like. The subject light in the detection sensitivity range 16 in the object scene is transmitted to a pair of separator lenses 17.
The optical path is divided and projected onto a pair of area sensors 1 and 2 composed of CCDs. The distance is measured based on the two divided images to perform autofocus.

FIG. 10 is a schematic view of an optical system used for a single-lens reflex camera or the like for detecting the focus of a TTL phase difference method. Film equivalent surface 1 on which the photographic light of the subject forms an image
The light re-imaged by the condenser lens 20 located behind the light path 9 is split into an optical path by a pair of separator lenses 17 and projected onto a pair of area sensors 1 and 2 composed of a CCD. . Find the defocus on the film surface based on the two divided images,
Perform auto focus. When performing image blur detection,
In either case, the determination is performed using an image projected on one of the two area sensors 1 or 2.

Next, an embodiment in which the area sensors 1 and 2 shown in FIGS. 1 and 7 are applied to image blur detection will be described. In the case of image blur detection, only data of a part of one area sensor 1 or 2 is required. Then, the integration and data dump must be repeated many times during the short time when the shutter is open. Therefore, in the present embodiment, only the required portion of the accumulated charge is read out by a data ratio capable of A / D conversion by the A / D converter 32 built in the microcomputer μC, and the accumulated charge of the other unnecessary portion is read out at high speed. We take the method of sweeping away.

An example of the simple control method will be described with reference to a timing chart of FIG. 11 and a more detailed configuration diagram of the area sensor of FIG. This timing chart represents one integration and data dump, and in practice, the operations on this timing chart are repeatedly performed to detect image blur. Here, external signals CMP, HST, MD1,
MD2, MD3, IST, RST, and CBG are provided from an external microcomputer μC.

When MD1 and CBG are at low level, the integration can be started, so that IST is output at high level. In synchronization with the transition of the IST to the high level, the control circuit 8 outputs the ADT at the high level, and unnecessary charges accumulated in the pixels are discharged.
During this time, three timing pulses P1 and P3 are supplied from the microcomputer μC to the control circuit as MD3.
2, P3 are sequentially generated, and MD2 is used as a data signal.
Various modes of the image detection system of FIGS. 1 and 7 are set. Here, the system of FIG. 1 will be described as a representative.

First, the contents to be set are selection of the area sensors 1 and 2, selection of the H / L gain (sensitivity), and selection of addition / non-addition of pixel data described later. After these selections are made, the IST is output at a low level, so that the control circuit 8 starts integration of the two area sensors 1 and 2 and the respective monitors 3 and 4. When the integration is started, Vout is supplied from the Vout terminal 46 via the output selection circuit 9.
The area sensor 1 or 2 previously selected as the out signal
Is output from the monitor 3 or 4 corresponding to.

At the same time, the monitor signal is supplied from the switch 5 or 6 to the AGC circuit 7. AGC
When the monitor signal reaches a predetermined voltage within a predetermined time, the circuit 7 transmits this information to the control circuit 8, and the control circuit 8 terminates integration of the area sensors 1 and 2 (natural termination). At the same time, the control circuit 8 outputs ADT at a low level to output the external microcomputer μ.
Inform C that integration has been completed. Control circuit 8
After the integration is completed, a shift pulse is generated internally, and charges accumulated in each pixel 29 of the area sensors 1 and 2 are transferred through the shift gate 13 to the vertical transfer register 1.
8

However, if the monitor signal of the monitor 3 or 4 does not reach the predetermined voltage of the AGC circuit 7 even after the lapse of the predetermined time, that is, even after the lapse of the predetermined time, the ADT is low from the control circuit 8 to the external microcomputer μC. If not output, the external microcomputer μC
The integration is forcibly terminated by outputting BG at a high level. Accordingly, ADT is output at a low level.

At the end of the integration, the Vout terminal 46
The monitor signal of the monitor 3 or 4 output from the A / D converter 32 is A / D converted. And that A
The gain of the variable gain amplifier 10 with respect to the sensor outputs α and β is determined according to the result of the / D conversion. The monitor signal continues to be output from the Vout terminal 46 until the output selection circuit 9 selects the output from the temperature detection circuit 12.

After the integration is completed, if there is an unnecessary horizontal line in the selected area sensor 1 or 2 first, the microcomputer μC outputs HST at a high level.
Then, a vertical transfer clock Vcp is generated internally from the control circuit 8, and the charge is vertically transferred.

At this time, the internal pixel transfer clock (vertical transfer clock Vcp, horizontal transfer clock Hcp) is sent from the control circuit 8 in accordance with the high level transition of HST.
Is output at high speed. That is, the vertical transfer clock Vcp also becomes faster, and unnecessary charges on unnecessary horizontal lines are vertically transferred and discharged at high speed. As in the case of the Cout output in this case, the fact that a number of pulses are continuously output is represented by a rectangle in which both the high level and the low level are connected by a straight line on the timing chart.

While unnecessary horizontal lines are being vertically transferred, the control circuit 8 internally outputs RCG at a high level to keep the register clear gate 23 open. Therefore, the unnecessary charges of the unnecessary pixels are discarded by being discharged to the OD 28. The counter 43 of the microcomputer μC counts unnecessary horizontal lines. When the counting is completed, the microcomputer μC outputs CMP at a high level, the control circuit 8 stops vertical transfer, and further closes the register clear gate 23.

Next, in order to set the previously determined amplification factor in the variable gain amplifier 10, the microcomputer μC first generates a timing pulse P4 based on the MD3 signal. Accordingly, the microcomputer μC is operated by the IST
And MD2 are input to the control circuit 8 as data signals, and the control circuit 8 sets the gain information set by the IST and MD2 in the variable gain amplifier 10.
In this case, the contents of IST and MD2 are amplification factors to be set.

After that, the microcomputer μC operates the MD
1 at a high level, the area sensor 1,
2 is the read mode. When the microcomputer μC generates an RST pulse, the area sensors 1 and 2 start reading.

With the generation of the RST pulse, the control circuit 8 generates one vertical transfer clock Vcp to vertically transfer the charge of each horizontal line by one line, and the microcomputer μC resets the built-in counter 43. I do. Further, the control circuit 8 supplies the horizontal transfer clock Hcp to the horizontal transfer register 21 to transfer the charges in the horizontal transfer register 21 horizontally. At this time, the outputs from the two area sensors 1 and 2 are alternately input to the variable gain amplifier 10 as described with reference to FIG. That is, the charges of the corresponding pixels of the area sensors 1 and 2 are sequentially and alternately input.

The sensor outputs α and β are output from the S / H circuit 2
2, the CBG is output at a low level from the microcomputer μC at the timing when the charge of the black reference pixel is output, and the clamp circuit 11 operates accordingly. , The voltage corresponding to the dark current is clamped to a predetermined voltage.

After the charge of the black reference pixel is clamped, the sensor outputs α and β are given to the output selection circuit 9. Then, when selected by the output selection circuit 9, the Vout terminal 46
, And the output at that time is one of the periods during which the data of one pixel is output from each of the area sensors 1 and 2.
The sensor output α and the sensor output β are alternately present in every period of / 2 (see FIG. 2F).

In the case of image blur detection, as described above, only one sensor output α or β is required,
In the D converter 32, the sensor output α or β is converted by the A / D converter 3
The A / D conversion is performed at the timing of input to the second input terminal. The A / D converted sensor output data is used for image blur detection.

The method of detecting image blur will be described later with reference to FIG. Further, in the above embodiment, the outputs of the two area sensors 1 and 2 are alternately taken out. However, only the output of one of the area sensors 1 or 2 may be selected at the sample and hold stage. Has only one sensor output α or β in the A / D converter 32
Will be entered. To sample and hold only one output, a high level may be input to the input terminal 35 in the above-described logic circuit of FIG.

Returning to FIG. 11, after the above-mentioned clamping is completed,
The microcomputer μC sets CBG to high level. And if there is an unnecessary pixel immediately after the black reference pixel,
The microcomputer μC is a counter 43 shown in FIG.
The microcomputer μC sets the HST to a high level in order to set the number of unnecessary pixels at a high speed and to sweep out the charges of the unnecessary pixels at high speed.

Accordingly, the control circuit 8 similarly generates the horizontal transfer clock Hcp at high speed, and the charges of the unnecessary pixels are horizontally transferred at high speed and discharged. And Cou
The Cout clock is output from the t terminal at a high speed. The charges of the unnecessary pixels are finally discarded because they are not selected by the output selection circuit 9 (thus, are not led out to the Vout terminal 46).

Counter 4 of microcomputer μC
3 counts the Cout clock for the unnecessary pixels, and after the counting is completed, the microcomputer μC sets the CMP to low level. After the low-level transition of the CMP, the microcomputer μC changes HST to low level,
Set ST to high level. The control circuit 8 controls the HS
The horizontal transfer clock Hcp is generated at a low speed with the low-level transition of T, and Vout is generated with the high-level transition of IST.
The terminal 46 outputs an effective pixel signal (effective signal).

Counter 4 of microcomputer μC
When 3 finishes counting the number of effective pixels, the microcomputer μC outputs CMP at a high level. Here, in the case where unnecessary pixels still remain on this horizontal line, the microcomputer μC sets the number of unnecessary pixels in the counter 43 and sets HST to a high level.
Inside, the charges of the unnecessary pixels are horizontally transferred at high speed, discharged, and discarded. Further, immediately after the transition of the HST to the high level, the microcomputer μC changes the IST to the low level, while the control circuit 8 outputs the reference voltage (REF) from the Vout terminal 46 instead of the unnecessary pixel output.

After counting the number of remaining unnecessary pixels,
The microcomputer μC outputs CMP at the low level, and the control circuit 8 ends the horizontal transfer. Then, in order to read the next horizontal line, the microcomputer μC generates an RST pulse. Accordingly, the control circuit 8 generates one vertical transfer clock Vcp, vertically transfers the charge of each horizontal line by one line, and repeats the above-described horizontal line read operation. The CCDs of the area sensors 1 and 2 of the present embodiment employ an interline transfer (IT) system, but may employ a frame interline transfer (FIT) system or a frame transfer (FT) system.

Further, in this embodiment, when various modes of the image detection system are set, addition or non-addition of pixel data is selected. Before describing the selection of addition / non-addition of pixel data, the significance of the addition will be described. First, in the case of image blur detection as described above, integration and data dump must be repeated many times in a short period of time. Gets worse. Therefore, in order to make the pixel area that can be read as large as possible and to reduce the number of pixels to be read as much as possible, a method of adding the charge of the adjacent pixel to the charge of the read pixel is introduced.

More specifically, when the detected area is small for a low-frequency subject, a sufficient contrast cannot be obtained, so that a correct comparison cannot be performed and a correct image shake amount cannot be detected. In order to solve this problem, it is necessary to read out a wider area. However, if a wide area is simply read out, one reading time becomes longer, so that sufficient image blur detection and image blur correction cannot be performed.

Although it is only necessary to read out pixels at a high speed as much as the readout area is widened, that is, as much as the number of readout pixels is increased, this is not so much due to the limitation of the data ratio that can be A / D converted by the A / D converter. Cannot read at high speed. Therefore, in the present embodiment, by adding the charges of a plurality of pixels during the transfer of charges, the readout range is widened, but the number of readout pixels is kept unchanged. In addition, there is also an advantage that a sufficient charge can be obtained in a short integration time even under low luminance because the charges of a plurality of pixels are added.

Details of the driving method at this time will be described with reference to the timing charts of FIGS. 13 and 14 and the configuration diagram of the area sensor of FIG. FIG. 13A is a timing chart of the vertical non-addition mode. Here, one pulse of the vertical transfer clock Vcp is input, the charge of each horizontal line is vertically transferred by one line, and each time the charge of one horizontal line is transferred to the horizontal transfer register 21, the pixel of one horizontal line is transferred. A horizontal transfer clock Hcp for several minutes is continuously input to transfer charges horizontally.

On the other hand, in the vertical N-pixel addition mode (N = 2 in this embodiment) in FIG. 13B, N pulses of the vertical transfer clock Vcp are input, and the horizontal transfer register 21 has N horizontal lines. The horizontal transfer clock Hcp is input after the charges of N pixels vertically and vertically adjacent in the horizontal transfer register 21 are added in the horizontal transfer register 21.

FIG. 14A is a timing chart of the horizontal non-addition mode. Here, a sampling pulse is input every time one pulse of the horizontal transfer clock Hcp is input, and sample-and-hold is performed for each charge of one pixel. On the other hand, in the horizontal N pixel addition mode (N = 2 in this embodiment) in FIG. 14B, the horizontal transfer clock Hc
Although p is input at N times the frequency of FIG. 14A, the frequency of the sampling pulse is not changed.

Therefore, in the S / H circuit 22, the sample and hold is performed each time the charge of N pixels is input, so that the charge of N pixels in the horizontal direction is added. Therefore, A /
Although the transfer clock of the data input to the D converter 32 does not change, the charge for N pixels in the horizontal direction is added and input. Selection between addition and non-addition will be described with reference to the flowchart in FIG. First, in step # 35, it is determined whether or not this integration is the first integration. As a result, if it is the first integration, it is not known whether or not the data is reliable. To read.

If the current integration is not the first integration, the operation proceeds to step # 40. If the previous detection result is reliable, the operation proceeds to step # 65 to continue the previous reading mode and perform integration. If the last detection was unreliable,
Proceeding to step # 45, it is determined whether or not the previous integration was performed under low luminance.
Proceeding to step # 55, the current reading is performed in the addition mode.

If the previous integration was not performed under low luminance, the process proceeds to step # 50, and if the previous reading mode is the addition mode, the current reading is performed in the non-addition mode (step # 60). If the previous reading mode is the non-addition mode, the current reading is performed in the addition mode (step # 55). By performing such control, it is possible to read out the data obtained by the current integration in the optimum reading mode based on the previous detection result and brightness. Further, in the addition mode, the mode of addition only in the vertical direction, addition only in the horizontal direction, and addition in both directions are switched according to the contrast, frequency, control sequence, and the like of the subject.

Next, a case where the area sensors 1 and 2 of the present embodiment are applied to auto focus will be described. When the area sensors 1 and 2 are applied to autofocus, data of a specific partial area of the two area sensors 1 and 2 is read out of data obtained by one integration. That is, it is used in the line sensor mode.

The size of one pixel of a normal area sensor is
This is only about a fraction of the pixel size of the line sensor used for autofocus, and the sensitivity of a low-luminance subject is insufficient. For this reason, in the present embodiment, the accumulated charges for several pixels of the area sensors 1 and 2 are added to the charges for N pixels in the vertical direction according to the timing chart of FIG. Try to ensure sensitivity.

The driving method at this time will be described with reference to the configuration diagram of FIG. 12 and the timing chart of FIG. First, a timing chart in the case of the normal area sensor mode is shown in FIG. As an integration start operation, a shift pulse is input to open the shift gate 13, and the electric charges accumulated in each pixel 29 before integration are discharged to the vertical transfer register 18. Thus, integration is started.

Next, the register clear gate 23 provided to the horizontal transfer register 21 is opened by setting RCG to high level. In this way, the charges transferred to the horizontal transfer register 21 can be discharged to the OD 28. Then, in order to vertically transfer the charges of all the horizontal lines, a vertical transfer clock Vcp is input, and the charges initially accumulated in each pixel 29 are discharged to the OD 28 (integration clear time). After that, the RCG is set to low level and the register clear gate 23 is closed.

When it is detected that sufficient integration has been performed using the monitors 3 and 4, the integration is naturally terminated (of course, the integration is forcibly terminated). Thereafter, by inputting a shift pulse and opening the shift gate 13, charges of each pixel 29 are transferred to the vertical transfer register 18. Then, after the electric charge of the horizontal pixel column for one line is transferred to the horizontal transfer register 21 by inputting one pulse of the vertical transfer clock Vcp,
The horizontal transfer clock Hcp is continuously input to drive and read the horizontal transfer register 21. Hereinafter, by repeating this operation, the charges of all the pixels 29 are read.

For the normal area sensor mode,
FIG. 16B shows a timing chart when the area sensors 1 and 2 are switched to the line sensor mode for autofocus. The operation up to the integration end operation is the same as in the normal area sensor mode. Then, when the vertical transfer is performed by inputting the vertical transfer clock Vcp, the unnecessary charges of the horizontal pixel row not used as the line sensor
CG is set to the high level to open the register clear gate 23, and the horizontal transfer register 21 is discharged to the OD.

For a horizontal pixel column used as a line sensor, RCG is set to a low level and the register clear gate 23 is closed using the vertical addition mode shown in FIG. The vertical transfer clocks Vcp for the number of pixels required for the operation are input, so that the charges of the pixels are combined (added) in the horizontal transfer register 21.
I do. Then, the horizontal transfer clock Hcp is input and the horizontal transfer register 21 is driven to read out as a line sensor. By driving in this manner, the area sensors 1 and 2 can be used as line sensors.

In autofocusing, it is necessary to use the two area sensors 1 and 2 in the line sensor mode, and to read data obtained from the two area sensors 1 and 2 by one integration. As for the driving method at that time, as described above with reference to the timing chart of FIG.
The signal is supplied to the D converter 32 to perform A / D conversion.

When the area sensors 1 and 2 of FIGS. 1 and 7 are used as an autofocus sensor in the line sensor mode, in this embodiment, the area sensors 1 and 2 are used as much as possible so as not to overflow the portion used as the line sensor. The site is located near the monitors 3 and 4. Further, the area sensors 1 and 2 are also used for image blur detection.

Here, since both the part used for autofocus and the part used for image blur detection (selected from the entire area sensor) are important in relation to the optical axis center of the optical system, the area sensors 1, 2 In FIGS. 17A to 17D, the portion used for the line sensor and the center of the optical axis of the optical system in FIG.
And will be described. Here, the system of FIG. 7 will be described as a representative.

In the first example shown in FIG. 17A, the monitor 3b
4b, an auto-focus area 44 is set in a portion close to the auto-focus area 4b.
The center of the area sensors 1 and 2 is set not the center of the area sensor 4. Such an arrangement is inconvenient because the center of the auto-focus area 44 is not at the center of the screen. However, if the detection area of the area sensors 1 and 2 is not too large with respect to the entire screen, the auto-focus area 44 The deviation from the screen is not so large and is acceptable. In addition, when image blur is detected, the probability of capturing the main subject increases.

In the second example of FIG. 17B, the monitor 3b
An autofocus area 44 is set in a portion near 4b, and the optical axis center 45 of the optical system is set at the center of the autofocus area 44. Such an arrangement has an autofocus area 44 at the center of the screen, and is similar to a normal autofocus sensor. on the other hand,
Although the image blur detection area deviates from the center of the screen and the probability of capturing the main subject decreases, the possibility of capturing a background still object is high and effective. At this time, the image blur detection area is empty,
Or it is necessary to set it not to be only on the ground.

In the third example of FIG. 17C, the pixel arrangement is the same as that of FIG. 17B, but the horizontal transfer registers 21a and 21
This is an example in which the position of b is changed according to the chip layout of the ICs of the area sensors 1 and 2. When the horizontal transfer registers 21a and 21b are arranged in this manner, the same reading method as in FIG. This can be achieved by performing vertical transfer for each line, adding pixel charges during horizontal reading, and selectively storing necessary data during A / D conversion.

In the fourth example of FIG. 17D, the center of the optical axis 45 of the optical system is the center of the area sensors 1 and 2, and the center of the autofocus area 44 and the center of the image blur detection area are arranged at the center 45 of the optical axis. Have been. With this arrangement,
Although the auto focus area 44 or the image blur detection area in FIGS. 17A and 17B does not deviate from the optical axis center 45, the auto focus area 44 does not move.
And the monitor are separated from each other, making it difficult to effectively perform integral control using the monitor signal.

Therefore, in the present embodiment, the first integration performs the integration control using the monitor voltage (monitor signal) of a certain monitor. However, in the second and subsequent integrations, the integration time of the previous monitor and the current time of the monitor used last time are used. The integration is controlled based on the monitor voltage of. A specific example of the control method at this time will be described with reference to FIG. First, in the first integration,
The area sensors 1 and 2 integrate until the monitor voltage reaches the predetermined voltage V1 of the AGC circuit 7, and terminate naturally (the integration time at this time is t1).

For example, at this time, it is assumed that accurate integration control is not performed by the monitor output, and it is determined that the integration amount in the area sensors 1 and 2 is excessive. Since the change rate of the integration amount of the area sensor is considered to be constant, the optimum integration time t3 can be obtained from the time t1 and the excess integration amount.

As in the case of the area sensor, the rate of change of the monitor voltage is considered to be constant, so that the relationship between time and monitor voltage is as shown by a straight line in FIG. From this straight line, the monitor voltage at time t3 in the first integration, that is, the optimum monitor voltage V3 at the end of integration can be found. In the second integration, the integration is performed until time t, which is the time required for the monitor voltage to reach V3. It can be seen from FIG. 18 that the time t can be obtained using the following equation (Equation (1)).

T = t3 × (2 × t2 / t1) (1)

Here, t2 is a time required for the monitor voltage to reach a voltage V2 which is 1/2 of the predetermined voltage V1 in the second integration. The time t2 is monitored using the AGC circuit 7. That is, a predetermined voltage V1 and a voltage V2 which is half of the predetermined voltage are set in the AGC circuit 7, and the monitor voltage is
2 is monitored. Then, the microcomputer μC obtains t from Expression (1), and forcibly terminates the integration at time t. In the third and subsequent integrations, integration control is performed in the same manner as in the second time, with the previous integration time as t1.

FIG. 19 shows an integration control method in which the method of FIG. 18 is performed in a circuit. The process up to the setting of the predetermined voltage V1 in the AGC circuit 7 and the integration to obtain the optimum monitor voltage V3 is the same as in the case of FIG. And here, this V
In the next integration, the microcomputer μC monitors the monitor voltage in the next integration, and controls the integration by forcibly terminating the monitor voltage at V3.

Further, the AGC circuit 7 is configured to input the monitor natural end voltage V3 from an external D / A converter to the AGC circuit 7 and to use the optimum monitor voltage V3 from the outside as a predetermined voltage for natural end of integration. If it is set to 7, the integration after the second time can also be controlled using the natural end function.

Next, the selection of the auto focus area will be described with reference to a simple flowchart shown in FIG. First, in order to prevent the area used for autofocus from becoming saturated, it is checked in step # 70 whether the areas near the monitors 3 and 4 can be used. In this method, the contrast of an area to be used for autofocus is obtained, and it is determined whether there is sufficient contrast for performing autofocus. If it is determined that there is sufficient contrast, the process proceeds to step # 75, and this area is used.

If it is determined that there is no contrast, the flow advances to step # 80 to move the detection area to the next area, and the flow advances to step # 85 to check the contrast. If it is determined that there is contrast in this area, the process proceeds to step # 90, and this area is used. If it is determined that the area is not yet sufficient in contrast, the process returns to step # 80, further moves the area, proceeds to step # 85, and repeats the contrast calculation to search for an area having sufficient contrast.
Go to step 90 to determine the auto focus area.

In the second and subsequent autofocus operations, the detection is continuously performed in the previous detection area. If the area becomes low contrast (a state without reliability) in this area, the detection area is moved to the vicinity of the detection area and is continuously performed. Like that. Next, one method of selecting an image blur detection area and performing image blur detection will be described with reference to a simple flowchart of FIG. 21 and a diagram illustrating an image blur detection sequence of FIG. The lattice-shaped part in FIG. 22 shows the light receiving part of the sensor.

First, after the end of autofocusing, the flow proceeds to step # 100 to judge whether panning has occurred. If there is no panning, it is considered that the main subject exists in the autofocused area. An area (several pixels) having a sufficient contrast is searched for in the area, and if an area having a contrast is found, the process proceeds to step # 115 and the area is changed to the state shown in FIG.
As shown in (a), it is a reference portion for calculating the image blur amount. FIG.
2 (a) shows the reference portion 100 in this case. At this time,
The reference unit 100 specifies where in the area sensor 1 or 2 it is located.

In order to perform image blur detection, the integration and data dump are repeated after the shutter is opened. When reading the data obtained by the next integration,
As shown in FIG. 22 (b), the area to be read is an area slightly larger than the reference section 100 determined earlier as the reference section 1.
Read as 10. The reference section is provided here to reduce the probability that the moved reference section is mistakenly recognized as another contrast area by limiting the area where the reference section can exist, and to read only the reference section. Just put it out,
This is because reading can be performed faster than reading the whole.

Then, an area 120 having the highest correlation with the reference section 100 is detected in the reference section 110, and the area sensor 1 is detected.
Alternatively, the position within 2 is specified, the amount of movement from the reference portion is calculated, and this is used as the amount of image shake, and image shake correction is performed based on this. Further integration is performed, and this time, as shown in FIG. 22C, the region 120 having the highest correlation with the reference portion first is obtained.
This area is read as a reference section 111 with a slightly wider area centered on. Then, the area 121 having the highest correlation with the area 120 is detected in the reference unit 111, the position in the area sensor 1 or 2 is specified, the movement amount from the area 120 is calculated, and the movement amount is calculated. The image blur correction is performed based on this.

Further integration is carried out, and as shown in FIG.
2, the area 122 having the highest correlation with the area 121 is detected in the reference portion, the position in the area sensor 1 or 2 is specified, and the movement amount from the area 121 is calculated.
This is used as an image blur amount, and based on this, image blur correction is further performed. The same operation is repeated until the shutter is closed to perform image blur correction.

Returning to FIG. 21, if it is determined in step # 100 that panning has occurred, it is considered that the main subject does not exist in the area where autofocusing has been performed. , A region having a contrast is searched, and if a region having a contrast is found, the process proceeds to step # 115, and the region is used as a reference portion for performing image blur detection, and image blur detection is performed as described above.

Here, if there is panning,
Since it is considered that the main subject is deviated from this area, an area having a contrast is searched for excluding the area where the autofocus is performed. Of course, a region having a contrast may be sequentially searched without removing this region.

As in the panning determination method, the sensor output can be obtained from the correlation between the light distribution patterns at predetermined time intervals, as in the case of the camera shake detection. The temporal shift amount of the light distribution pattern at a predetermined time interval of the sensor output used for camera shake detection is obtained, and if the temporal shift amount is equal to or more than a predetermined amount, it is determined that the shift is not due to camera shake but due to panning, The panning amount can be detected based on the shift amount.

As another method, an automatic focus detection operation can be used. In the automatic focus detection operation, if the defocus amount detected by the focus detection operation is equal to or less than a predetermined value, it is determined that the object is a still object. If the amount of defocus is equal to or more than a predetermined value, it is determined that panning has been performed. Then, the camera enters the AF lock mode in which the automatic focus detection operation is stopped. In addition, the detected defocus amount is equal to the above 2
If the distance is between the two predetermined values, it is determined that the subject is a moving subject and the apparatus enters the continuous AF mode. It is also possible to determine panning based on this operation.

[0108]

According to the present invention, in image blur detection in which the area of the readout area is limited, when the subject has low luminance, the signal charges of the pixels to be read out are added to each other in the same time as in the case of non-addition. A wider area can be read. That is, since signal charges having sufficient contrast can be repeatedly detected in a short time from a subject having any luminance, accurate image blur detection can be performed.

In addition to the image blur detection, when the area sensor is used as a line sensor for auto-focusing, signal charges having sufficient contrast may not be obtained with charges of pixels for one horizontal line. is there. Therefore,
By adding and reading out the charges of several horizontal line pixels, it is possible to read out signal charges with sufficient contrast for any subject, and to perform accurate autofocus Becomes

Further, addition and non-addition of signal charges can be selected in each of the vertical direction and the horizontal direction. Therefore, in the image blur detection, it is possible to obtain an appropriate signal charge from any subject having different contrast, frequency, control sequence, and the like, and it is possible to accurately perform the image blur detection.

If the charges are added in the analog circuit section which processes the transferred charges during or after the transfer, it is not necessary to perform the transfer at a high speed, and the readout range is irrespective of the limitation of the processing capability of the subsequent processing circuit. Can be widened.

[Brief description of the drawings]

FIG. 1 is a device configuration diagram of an image detection system having two area sensors and a control circuit for controlling the area sensors.

FIG. 2 is a timing chart related to an output from the area sensor of FIG. 1;

FIG. 3 shows a logic circuit for adjusting a sampling pulse.

FIG. 4 is a diagram showing a specific example of a sampling pulse generated from the logic circuit of FIG. 4;

FIG. 5 is a diagram showing details of an arrangement relationship between a monitor and an area sensor.

FIG. 6 is a diagram showing another example of the details of the arrangement relationship between the monitor and the area sensor.

FIG. 7 is an example of a device configuration diagram of an image detection system having two area sensors and a control circuit for controlling the area sensors, which is different from FIG.

FIG. 8 is a flowchart for selecting a monitor in the case of auto focus.

FIG. 9 is a schematic diagram of an optical system to which the image detection systems of FIGS. 1 and 7 are applied.

FIG. 10 is a schematic diagram of another optical system to which the image detection systems of FIGS. 1 and 7 are applied.

FIG. 11 is a timing chart of a control method of image blur detection.

FIG. 12 is a detailed configuration diagram of an area sensor.

FIGS. 13A and 13B are timing charts of (a) non-addition in the vertical direction and (b) addition of charges for two pixels in the vertical direction.

FIGS. 14A and 14B are timing charts of (a) non-addition in the horizontal direction and (b) addition of charges for two pixels in the horizontal direction.

FIG. 15 is a flowchart of selection of addition / non-addition.

FIG. 16 is a timing chart of (a) a normal area sensor mode and (b) a line sensor mode in the case of auto focus.

17A is a diagram illustrating an autofocus area and an optical axis center in the area sensor according to the first example, FIG. 17B, a second example, FIG. 17C, a third example, and FIG.

FIG. 18 is a diagram showing a relationship between an integration time and a monitor voltage when the integration of the area sensor is controlled by time.

FIG. 19 is a diagram showing the relationship between the integration time and the monitor voltage when the integration of the area sensor is controlled by the monitor voltage.

FIG. 20 is a flowchart for selecting an auto focus area.

FIG. 21 is a flowchart of selection of an image blur detection area.

FIG. 22 is a diagram showing an example of a sequence obtained by the (a) first (b), second (c), third (d), and fourth integration at the time of image blur detection.

[Explanation of symbols]

 1, 2 area sensor 3, 4 monitor 3a, 3b monitor 4a, 4b monitor 5, 6 monitor output switch 7 AGC circuit 8 control circuit 9 output selection circuit 10 gain variable amplifier 11 clamp circuit μC microcomputer 14, 15 black reference pixel Reference Signs List 18 vertical transfer register 21 horizontal transfer register 21a, 21b horizontal transfer register 22 S / H circuit 23 register clear gate 30, 31 area sensor output switch 32 A / D converter 46 Vout terminal

Claims (5)

[Claims] 1. An image detection system having an area sensor, wherein signal charges obtained by the area sensor are switched between addition and non-addition in a vertical direction and a horizontal direction, respectively. 2. The image detection system according to claim 1, wherein the addition of the signal charges in the vertical or horizontal direction is performed during the transfer of the signal charges obtained by the area sensor. 3. The image detection system according to claim 1, wherein the addition of the signal charges in the vertical direction is performed in a horizontal transfer register. 4. The image detection system according to claim 1, wherein the addition of the signal charges in the horizontal direction is performed in an analog circuit. 5. A plurality of photoelectric conversion means arranged to generate electric charge according to the amount of received light, charge reading means for reading out the electric charge generated by the photoelectric conversion means, and a signal for reading the electric charge by the charge reading means. And a mode for reading out the charges of the photoelectric conversion units one by one, and a mode for adding and reading out the charges from the plurality of photoelectric conversion units. An image detection system, comprising: control means for controlling.