JP2565247B2 - Exposure time control method for solid-state imaging device and video camera - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid-state image pickup device having an electronic shutter mechanism suitable for use in, for example, a video camera and an electronic still camera, and an exposure time control method for the video camera.

[0002]

2. Description of the Related Art Conventionally, in a solid-state image pickup device, exposure control is performed by electric means in this solid-state image pickup device,
When this is used in, for example, a video camera, there has been a demand for eliminating the need for a mechanical shutter device that is generally used in the past, and for making the video camera smaller, lighter and less expensive. Here, a solid-state image pickup device capable of selecting two types of exposure time, long and short, has already been proposed.

This solid-state image pickup device has one exposure time of 1
1/30 seconds of the same time as the frame period, and the other exposure time is about 1/200 of the same time as the vertical blanking period.
It is set to 0 seconds. That is, when 1/30 seconds is selected as the exposure time, this solid-state imaging device reads out the signal charge accumulated in the light receiving unit during one frame period as a video signal as it is, and the exposure time is 1/200.
When 0 second is selected, all the signal charges accumulated before the vertical blanking period are read out to the vertical register, transferred at high speed and swept out, and newly accumulated during the vertical blanking period. Only the signal charges can be read out as a video signal.

[0004]

However, in such a conventional solid-state image pickup device, only two kinds of exposure times can be selected, and therefore, even if it is used in, for example, a video camera, There is an inconvenience that the mechanical shutter device used in the video camera cannot be eliminated.

Further, in such a conventional solid-state image pickup device,
When sweeping out the signal charges accumulated before the vertical blanking period, it is necessary to perform high-speed transfer in the vertical register, which causes a disadvantage that extra power is consumed.

In view of the above, the present invention provides a solid-state image pickup device in which the exposure time can be variably controlled to a desired time by electrical control and the power consumption for this purpose can be reduced. An object is to provide an exposure time control method for a video camera.

[0007]

A solid-state image pickup device according to the present invention includes a first conductive type semiconductor substrate 1 and a first conductive type semiconductor substrate 1 as shown in FIGS. The first conductivity type of the solid-state image pickup device having the second conductivity type region 2 formed on the surface and the signal charge storage region 3 formed on the surface of the second conductivity type region 2. Semiconductor substrate 1
In the solid-state imaging device in which the sweep-out voltage is supplied to the signal charge storage region 3 so that the signal charge accumulated in the signal charge storage region 3 can be swept out to the semiconductor substrate 1 of the first conductivity type. The sweep-out voltage supplied to the semiconductor substrate 1 is pulsed, and the exposure time is controlled by changing the time at which the pulsed sweep-out voltage is supplied.

The method of controlling the exposure time of the video camera according to the present invention is the semiconductor substrate 1 of the first conductivity type, and the region 2 of the second conductivity type formed on the semiconductor substrate 1 of the first conductivity type.
And the signal charge storage region 3 formed on the surface of the region 2 of the second conductivity type.
The exposure time of the video camera, in which the sweep voltage is supplied to the semiconductor substrate 1 of the conductivity type and the signal charges accumulated in the signal charge storage region 3 can be swept to the semiconductor substrate 1 of the first conductivity type. In the control method, the exposure time is controlled by supplying a pulsed sweeping voltage to the semiconductor substrate 1 of the first conductivity type immediately before the start of exposure.

[0009]

According to the present invention, the pulse-shaped predetermined voltage V _H is supplied to the semiconductor substrate 1 of the first conductivity type so that the signal charges accumulated in the signal charge accumulation region 3 are of the first conductivity type. Therefore, the pulse signal P ₁ having the predetermined voltage V _H at any time point during one frame period or one field period can be swept out to the semiconductor substrate 1 of the first conductivity type. To the first conductivity type semiconductor substrate 1 by sweeping out the signal charges accumulated from the time when the signal charges were first read to the time when the pulse signal P ₁ was supplied. The signal charge accumulated until the next read time can be read as a video signal. Therefore, according to the present invention, it is possible to change the exposure time by changing the time when the pulse signal P ₁ is supplied to the first conductivity type semiconductor substrate 1 to obtain a desired exposure time.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A solid-state image pickup device according to the present invention and an exposure time control method for a video camera according to an embodiment of the present invention will be described below with reference to FIGS. Let me give you an example.

In FIG. 1, reference numeral 1 denotes an N-type silicon substrate. In this example, the N-type silicon substrate 1 is used as a base on the N-type silicon substrate 1 to receive a light-receiving portion 4, a vertical register portion 5, and a horizontal register. A section (not shown) and an output section (not shown) are provided, and the so-called interline transfer system C is used.
It is configured as a CD type image pickup device.

In this case, the P type region 2 is formed on the surface side of the N type silicon substrate 1 by, for example, an epitaxial growth method, and the N ⁻ type region 6 is further formed on the surface side of the P type region 2. Then, the light receiving portion 4 is provided with the N ⁻ type region 6
Forming a shallow P ^{+ +} type region 7 on the surface region of
^It is configured by forming the N ⁺ type region 3 forming the signal charge storage region below the ⁺⁺ type region 7. In this case, a P ⁺ -type region 8 forming a channel stopper is formed adjacent to the P ⁺ -type region 7 and the N ⁺ -type region 3, and an insulating layer made of SiO ₂ is formed on the P ⁺ -type region 7. 9 is formed.

Further, the vertical register portion 5 forms an N ⁺ type region 11 forming a signal charge transfer region adjacent to a P type region 10 forming a read gate region, and the N ⁺ type region 11 is formed.
Insulating layer 9 made of SiO ₂ and Si on ⁺ type region 11
_The transfer electrode 13 made of polysilicon is formed through the insulating layer 12 made of ₃ N ₄ .

In this case, one end of the transfer electrode 13 also serves as the read gate electrode 13A. Further, a P-type region 14 for preventing smear is formed below the N ⁺ -type region 11 which constitutes the signal charge transfer region, and a light-shielding aluminum layer 15 is provided above the transfer electrode 13 via the insulating layer 9. Set up.

In FIG. 1, two transfer electrodes 13 and 1 are provided.
Although only 3 is shown, in this example, a predetermined number of transfer electrodes are arranged so that the vertical register section 5 can be driven by a four-phase driving method as is well known in the art. Although not shown, the horizontal register section and the output section are configured as well known in the art.

Further, in this example, the DC power supplies 16 and 1
Each of the negative electrode terminals of 7 and the P-type region 2 are commonly connected and grounded, and the positive electrode terminals of the DC power sources 16 and 17 are connected to one and the other fixed contacts 18A and 18B of the switch circuit 18, respectively. The movable contact 18C of the switch circuit 18 is connected to the N-type silicon substrate 1.

In this case, the output voltage V of the DC power supply 16
_When this voltage V _L is supplied to the N-type silicon substrate 1, the potential of the P-type region 2 becomes slightly lower than the potential of the P ^{+ +} -type region 7 on the surface, as shown by the solid line X in FIG. A voltage capable of accumulating signal charges in the signal charge accumulating region 3 and effectively suppressing blooming, for example, 10 V, and an output voltage V of the DC power supply 17
_{When the} voltage V _H is supplied to the N-type silicon substrate 1, the potential of the P-type region 2 becomes lower than the potential of the signal charge storage region 3 as indicated by the broken line Y in FIG.
The signal charge accumulated in the signal charge accumulation region 3 is set to a voltage capable of being swept out to the N-type silicon substrate 1, for example, 30V.

Further, the switch circuit 18 enables switching control by a control signal supplied through a control signal input terminal 19.

In the solid-state image pickup device of this example having the above-described structure, the output voltage 10V of the DC power supply 16 is applied to the N-type silicon substrate 1, and the read pulse as shown in FIG. 3A is applied to the read gate electrode 13A. When P ₂ is supplied, the signal charge stored in the signal charge storage region 3 is read out to the vertical register unit 5.

Therefore, in this example, the read pulse P ₂ is supplied to the read gate electrode 13A within the vertical blanking period in one field cycle.

Then, after the read pulse P ₂ is supplied to the read gate electrode 13A again, the switch circuit 18 is controlled at any time within one field period to apply a voltage to the N-type silicon substrate 1 as shown in FIG. 3B. supplying pulse or sweep pulses P ₁ of 30 V, after the supply of the previous read pulse P _2, signal charges accumulated in the signal charge accumulating region 3 for a period t ₂ until the supply of the sweep-out pulse P ₁ is N It is swept onto the mold silicon substrate 1. For this reason,
When the next read pulse P ₂ is supplied to the read gate electrode 13A, the signal charge is accumulated during the period t ₁ after the previous sweep pulse P ₁ is supplied until the read pulse P ₂ is supplied. The signal charges accumulated in the area 3 are read out to the vertical register section 5.

As described above, in the solid-state image pickup device of this embodiment,
Sweep since time t ₁ until the read pulse P ₂ which follows from the pulse P ₁ in the sweep pulse P ₁ is the exposure time, sweep pulses P ₁ desired by varying the time supplied to the N-type silicon substrate 1 The exposure time can be.

Therefore, according to the solid-state image pickup device of this embodiment, when the solid-state image pickup device is used in, for example, a video camera, a mechanical shutter device is not required, and the size, weight and cost of the video camera can be reduced. Have a profit

Further, in the solid-state image pickup device of this embodiment, it is not necessary to operate the vertical register section 5 at high speed in order to sweep out the signal charges as in the conventional solid-state image pickup device, and the N-type silicon substrate 1 is pulsed with a voltage of 30 V Since it is sufficient to supply only the electric power, there is an advantage that the electric power required for performing the exposure control can be significantly reduced.

Further, according to the present example, the pulse P ₁ as the sweep voltage is supplied to the N-type silicon substrate 1 in a pulse form immediately before the start of exposure, so that the sweep pulse P ₁ is
There is an advantage that the period applied to the type silicon substrate 1 is shortened to reduce the potential fluctuation of the P-type region 2 to obtain an accurate exposure time and a uniform exposure time in the entire imaging region.

The present invention is not limited to the above-described embodiments, and it goes without saying that various other configurations can be adopted without departing from the gist of the present invention.

[0027]

According to the present invention, there is an advantage that the exposure time can be changed to a desired exposure time, and when this is used for a video camera, for example, a mechanical shutter device is unnecessary. In addition, there is an advantage that the size, weight and cost of the video camera can be reduced.

Further, according to the present invention, when such electrical exposure control is performed, it is sufficient to supply a pulsed predetermined voltage to the semiconductor substrate of the first conductivity type, and the power consumption can be greatly reduced. There are also benefits.

Further, according to the present invention, since the sweep voltage is supplied to the first conductivity type semiconductor substrate in a pulse form immediately before the start of exposure, the sweep voltage is applied to the first conductivity type semiconductor substrate. Since the exposure period is short, the potential variation in the second conductivity type region is small, and there is an advantage that an accurate exposure time can be obtained and a uniform exposure time can be obtained in the entire imaging region.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a main part of an embodiment of a solid-state imaging device of the present invention.

FIG. 2 is a diagram showing a potential in a thickness direction including a signal charge storage region in the example of FIG.

FIG. 3 is a diagram which serves to explain the example of FIG.

[Explanation of symbols]

1 N-type silicon substrate 2 P-type region 3 Signal charge storage region 4 Light receiving part 5 Vertical register part 6 N ^- type region 7 P ⁺⁺ type region 11 Signal charge transfer region 16, 17 DC power supply 18 Switch circuit

Continuation of the front page (72) Inventor Kazuya Yonemoto 6-735 Kitashinagawa, Shinagawa-ku, Tokyo Within Sony Corporation (56) Reference JP 58-125961 (JP, A) JP 58 -71772 (JP, A)

Claims (2)

(57) [Claims] 1. A semiconductor substrate of a first conductivity type, a region of a second conductivity type formed on the semiconductor substrate of a first conductivity type, and a surface side of the region of the second conductivity type. A sweep voltage is supplied to the semiconductor substrate of the first conductivity type of the solid-state imaging device having the formed signal charge storage region, and the signal charge stored in the signal charge storage region is supplied to the first conductivity type semiconductor substrate. In a CCD solid-state image pickup device capable of being swept onto a semiconductor substrate of a conductive type, the sweep voltage supplied to the semiconductor substrate of the first conductivity type is pulsed, and the time of supplying the pulsed sweep voltage is variable. A solid-state image pickup device characterized in that the exposure time is controlled by doing so. 2. A first conductivity type semiconductor substrate, a second conductivity type region formed on the first conductivity type semiconductor substrate, and a surface side of the second conductivity type region. A sweep voltage is supplied to the semiconductor substrate of the first conductivity type of the CCD solid-state imaging device having the formed signal charge storage region, and the signal charge stored in the signal charge storage region is supplied to the first conductive type semiconductor substrate. In a method for controlling an exposure time of a video camera, which is adapted to sweep to a conductive type semiconductor substrate, exposure is performed by supplying a pulsed sweep voltage to the first conductive type semiconductor substrate at a timing immediately before the start of exposure. An exposure time control method for a video camera, characterized in that the time is controlled.