JP2548705B2 - Imaging device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an imaging device having a photometric function, and more particularly to an imaging device intended to form photometric information in a short time and enable high-speed photography.

[Prior Art] As an image pickup device having a photometric function, a device using a nondestructive readable image pickup device as shown below has been proposed.

FIG. 5 (A) is a schematic block diagram of an image pickup apparatus for adjusting the output gain by the AGC circuit, and FIG. 5 (B) is
It is a flowchart which shows the schematic operation flow.

In both figures, first, the brightness is detected by the AE sensor 508 (# 501), and the image sensor 510 is detected by the exposure control means 509.
The amount of light incident on is determined (# 502). Imaging is performed with this exposure (# 503), then the image signal for one field is read out nondestructively from the image sensor 510 (# 504), and integrated by the integrating circuit 512 via the AGC circuit 511 set to the initial value. Photometric information is formed (# 505). The arithmetic circuit 513 determines the AGC control amount based on this photometric information (# 506), and the image signal is read out again according to the determined gain (# 50).
7).

With such a configuration, even with the image pickup device 510 having a wide dynamic range, signal processing can always be performed at an appropriate operating point, and an image signal with good S / N and less distortion can be obtained.

[Problems to be Solved by the Invention] However, the above-described conventional image pickup apparatus performs the read operation of the image signal for one field when forming the photometric information, similarly to the rereading for obtaining the image signal. Is going. For this reason, even if the reading operation during photometry is performed faster than during rereading, there is a limit to the speedup.

[Means for Solving the Problems] An image pickup apparatus according to the present invention is an image pickup apparatus in which a plurality of sensor signals are temporarily stored in nondestructive readable storage means and then read out. And an image signal read-out unit for reading each sensor in time series, and an arithmetic unit that calculates photometric information based on an addition output of the addition unit, and an output unit of the arithmetic unit. Signal processing means for processing the output of the image signal reading means.

[Operation] In order to calculate the readout photometric information by collectively adding a plurality of sensor signals (for example, signals of one horizontal line) in this way, it is not necessary to perform readout operation and arithmetic processing for each pixel as in the conventional case, and The time required is shortened, and high-speed shooting is possible as a whole. In addition, the same sensor signals are collectively added and read out, and then time-series image signals are subjected to signal processing, which enables highly accurate signal processing.

Embodiments Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a schematic circuit diagram of an image pickup element in an embodiment of an image pickup apparatus according to the present invention.

In this embodiment, the nondestructive read-out sensor 101 is mx
Each of the sensors 101 is arranged in an area of n, and each sensor 101 includes a base storage type phototransistor and a capacitor for controlling the base potential. By controlling the base potential via a capacitor, the sensor 101 accumulates carriers excited by incident light in the base region, reads the accumulated voltage as a sensor signal, and removes accumulated carriers.

The capacitor 101 of the sensor 101 has a horizontal line HL ₁ for each row.
~ HLn, read or refresh pulse φr
_{1 to} φrn is applied.

The emitter electrodes of the sensor 101 have vertical lines VL ₁ to
The storage capacitors C _{1 to} Cn, which are connected to VLn and have the same capacitance, are connected to each vertical line. Further, each vertical line is connected to the output line 102 through the transistors Qa _{1 to} Qan.
The output line 102 is connected to the amplifier 103. Pulses φh _{1 to} φhn are applied to the respective gate electrodes of the transistors Qa _{1 to} Qan from a scanning circuit (not shown),
Select the sensor signal.

Further, each vertical line is grounded via the transistors Qb _{1 to} Qbn and connected to the common line 104 via the transistors Qc _{1 to} Qcn, and the common line 104 is connected to the amplifier 10 by the amplifier 10.
Connected to 5. The gate electrode of the transistor Qb ₁ ~Qbn is applied to the pulse φvc your common, transistor Qc ₁
A pulse φt is commonly applied to the gate electrodes of Qcn.

The output line 102 is grounded through the transistor Qr ₁ and the common line 104 is grounded through the transistor Qr ₂ , and a pulse φhc is commonly applied to each gate electrode.

Next, the operation of the image sensor having such a configuration will be described.

FIG. 2 is a timing chart for explaining the operation of the image pickup device.

It is assumed that carriers corresponding to the amount of incident light are accumulated in the base of each sensor 101.

Photometry is performed in this state. First, by applying the pulse φr ₁ to each capacitor electrode of the sensor 101 in the first row,
Each sensor signal is read out from the emitter electrode to each vertical line and stored in the capacitors C _{1 to} Cn.

Then, the pulses φt cause the transistors Qc _{1 to} Qcn to
The ON state is set, and the capacitors C _{1 to} Cn are connected to each other via the common line 104. This makes the common line 10
At 4, the average value (= added value / n) of the sensor signals stored in each capacitor appears. This average value is amplifier 10
It is output to the integrator circuit, which will be described later, as a substantial addition value Sae through 5.

Then, with the pulses φhc and φvc, the transistor
Qr ₂ and Qb _{1 to} Qbn are turned on, and carriers remaining in the common line 104 and the capacitors C _{1 to} Cn are removed.

Similarly, the added values Sae of the second row to the nth row are output by the pulses φr _{2 to} φrn, and photometric information is formed by integration processing and arithmetic processing as described later. After the output gain is determined by this photometric information, each sensor
The sensor signal accumulated in 101 without being destroyed is read again.

First, the sensor signal of the first row is read by the pulse φr ₁ and stored in the capacitors C _{1 to} Cn. Subsequently, the transistor Qa ₁ is turned on by the pulse φh ₁ , the sensor signal accumulated in the capacitor C ₁ appears on the output line 102, and is output as the output signal Sout through the amplifier 103. Then, the pulse φhc turns on the transistor Qr _1.
And the output line 102 is reset.

Similarly, the pulses φh _{2 to} φhn are used to
The sensor signals accumulated in C _{2 to} Cn are sequentially taken out to the output line and serially output through the amplifier 103.

When the sensor signal of the first row is read in this manner, the sensor signal of the third row is similarly output by the pulse φr ₃ . Thereafter, the sensor signals of the odd lines are sequentially output to read the odd fields, and then the even fields are read in the same manner.

In the present embodiment, photometry was performed by non-destructive reading, but a destructive reading sensor can be used in exactly the same manner. However, re-imaging is required after forming the photometric information.

FIG. 3 is a schematic block diagram showing the overall configuration of this embodiment.

In the figure, the image sensor 1 is as shown in FIG. The output signal Sout of the image sensor 1 is output gain adjusted by the AGC circuit 2, and is output as a standard television signal such as an NTSC signal by the signal processing circuit 12.

Further, the added value Sae for each row of the image sensor 1 is calculated by the integration circuit 5
To the arithmetic circuit 6 as the photometric information. The arithmetic circuit 6 determines the AGC control amount based on the photometric information and outputs it to the AGC circuit 2.

Each pulse for driving the image pickup device 1 is given from the driver circuit 3, and the driver circuit 3 operates by the clock pulse from the clock circuit 4.

Further, a light receiving element 7 for photometry (hereinafter referred to as AE sensor 7) is provided separately from the image pickup element 1, and a photometric circuit 8 calculates subject brightness based on the sensor output, and a system controller 9 (hereinafter (Abbreviated as Syscon 9)).

The syscon 9 starts its operation by the trigger switch 10, and controls the clock circuit 4, the exposure control means 11, etc. based on the inputs from the photometry circuit 8 and the arithmetic circuit 6. The exposure control unit 11 is composed of a diaphragm, a shutter, and the like, and adjusts the amount of light incident on the image sensor 1.

Next, the operation of this embodiment having such a configuration will be described.

FIG. 4 is a flowchart showing a schematic operation of this embodiment.

First, when the trigger switch 10 is turned on (# 400), the photometric circuit 8 calculates the subject brightness based on the output from the AE sensor 7 (# 401) and outputs it to the syscon 9. The syscon 9 controls the exposure control means 11 based on the output of the photometric circuit 8 to control the amount of light incident on the image sensor 1 (# 402). And
An image signal is stored in each sensor 101 of the image sensor 1 (# 40
3).

When the image pickup is finished, the syscon 9 controls the exposure control means 11 to shield the image pickup device 1 from the light, and as described above, the added value for each row.
Sae is read out and integration processing is performed by the integration circuit 5 (# 40
Four). In this way, the added value S obtained by adding the sensor signals row by row
Since ae is input, the read operation and the integration process are significantly speeded up as compared with the conventional method of scanning and reading each sensor. The photometric information from the integrating circuit 5 is input, the arithmetic circuit 6 determines the AGC control amount (# 405) and outputs it to the AGC circuit 2 to set the gain of the output signal Sout.

Then, the sensor signals are sequentially read from the image sensor 1 (# 406), amplified by the AGC circuit 2 with an appropriate gain, and output to the signal processing circuit 12.

In the above embodiment, the AGC circuit 2 is determined by the photometric information.
However, the present invention is not limited to this, and the syscon 9 may control the exposure control means 11 to redetermine the exposure based on the photometric information, and the image pickup device 1 may perform reimaging. However, in this case, the image sensor 1 does not need to be nondestructively readable.

 Further, the following imaging method may be used.

First, the exposure control means 11 is opened and the image pickup device 21 picks up an image.

Then, the added value Sae of each row is read nondestructively at a preset clock speed f, and the integration circuit 5 performs integration processing to form photometric information v ₁ .

Then, in the arithmetic circuit 6, the photometric information v ₁ is set to the set value v ₂
And v ₃ (where v ₂ <v ₃ ). If v ₁ <v ₂ , the syscon 9 controls the clock circuit 4 to add the value Sae.
The clock speed f at the time of reading is increased to increase the added value Sae. If v ₁ > v ₃ , the clock speed f is increased to Sa
lower e.

When v ₂ ≤v ₁ ≤v ₃ by this operation, the syscon 9 controls the exposure control means 11 based on the photometric information v ₁ and the clock speed f at that time to determine the exposure. Then, re-imaging is performed by the image sensor 1, and the output signal Sout is output to the signal processing circuit.
Output to 12. In this case, the AGC circuit 2 is not necessary because the exposure is proper.

In any of the above-mentioned image pickup methods, by reading the added value Sae for each row of the image pickup device 1, the signal reading for photometry can be speeded up, and the integration process can be simplified to speed up the photometric information. Can be calculated by

[Effects of the Invention] As described in detail above, the image pickup apparatus according to the present invention has a plurality of sensor signals (for example, signals of one horizontal line).
In order to calculate read-out photometric information by adding all together, read-out operation and calculation processing for each pixel are not required unlike the conventional case, and the time required for photometry is shortened. As a result, high-speed shooting is possible as a whole, and since dark current is reduced, photometric accuracy and signal processing accuracy are improved.

[Brief description of drawings]

FIG. 1 is a schematic circuit diagram of an image pickup device in an embodiment of an image pickup device according to the present invention, FIG. 2 is a timing chart for explaining the operation of the image pickup device, and FIG. FIG. 4 is a schematic block diagram showing the overall configuration, FIG. 4 is a flowchart showing a schematic operation of the present embodiment, and FIG. 5 (A) is a schematic block diagram of an image pickup apparatus for adjusting an output gain by an AGC circuit. FIG. 5 (B) is a flow chart showing its schematic operation flow. 1 ... Imaging device, 2 ... AGC circuit, 5 ... Integration circuit, 6 ... Arithmetic circuit, 7 ... AE sensor, 8 ... Photometric circuit, 9 ... System controller, 10 ... Trigger switch, 101 ... Sensor, 102 ... Output line 103, 105 …… Amplifier 104 …… Common line Sout …… Output signal Sae …… Addition value

Claims (1)

(57) [Claims] 1. An image pickup apparatus, wherein a plurality of sensor signals are temporarily stored in non-destructive readable storage means and then read out. In an image pickup apparatus, an addition means for collectively adding the sensor signals stored in the storage means and a time for each sensor. An image signal read-out means for reading out serially; a calculation means for calculating photometric information based on the addition output of the addition means; and a signal for signal-processing the output of the image signal read-out means according to the output of the calculation means. An image pickup apparatus comprising: a processing unit;