JP2526565B2 - Solid-state imaging device - Google Patents

Description

The present invention relates to a solid-state imaging device having an electronic shutter mechanism.

[Outline of the Invention] The present invention is a solid-state imaging device having an electronic shutter mechanism, in which charges accumulated by exposure up to that time are swept out as unnecessary charges during a vertical blanking period, In the solid-state imaging device in which the charges accumulated in the subsequent exposure are read out as signal charges and the optical black signal in the vertical direction is read out within the vertical blanking period, a high-speed transfer means for reading signal charges is provided. Since the optical black signal is transferred and read at high speed, the effective image screen is not affected at all when the electronic shutter is operated, and the optical center of the output signal and the effective center of the image signal (vertical synchronization signal The exposure time can be extended and the sensitivity can be improved without shifting the center). is there.

[Prior Art] Conventionally, as a solid-state imaging device having an electronic shutter mechanism, there has been proposed a solid-state imaging device whose plane structure is schematically shown in FIG.

In FIG. 3, (1) shows a semiconductor substrate. In this solid-state imaging device, an interline transfer system is adopted, and light receiving (2) (2) ... 2), charge coupled device (CC
Vertical register section consisting of D) (3) (3) ... (3),
A horizontal register section (4) composed of the same charge coupled device (CCD) and a charge detection section (5) composed of a floating diffusion amplifier are provided, and light receiving sections (2) (2).
The signal charge accumulated in (2) is applied to the vertical register section (3).
(3) ... Transferred to the charge detection unit (5) via the horizontal register unit (4) and the charge detection unit (5) detects this signal charge and outputs it to the output terminal (6). It is designed so that a video signal can be obtained. In this case, a timing generator (which drives the transfer electrodes (not shown) of the vertical register sections (3), (3), ... (3) by receiving a predetermined synchronization signal from the synchronization signal generating circuit (7). 8)
Drive pulse signals φ _V1 , φ _V2 , φ _V3 generated in
And φ _V4 are supplied through terminals (9A ₁ ) (9A ₂ ) (9A ₃ ) and (9A ₄ ), and a timing generator (8) is provided to a transfer electrode (not shown) of the horizontal register section (4). The two-phase drive pulse signals φ _H1 and φ _H2 generated in ( ₁ ) are supplied via terminals (10A ₁ ) and (10A ₂ ). Further, the light receiving parts (2) (2) ... (2) consisting of photodiodes are arranged in a matrix in a matrix of 504 (V) x 540 (H), and the leftmost 30 bits of each horizontal line and the vertical direction. A light shielding layer is formed above each of the light receiving portions of the 12 horizontal lines at the lower end (light receiving portions shaded by solid lines in FIG. 3),
A so-called optical black signal is obtained from these light receiving portions. Incidentally, (11) and (12) are respectively the light receiving section (2).
Shows a read gate portion forming a passage for transferring a signal charge from the vertical register portion (3) to the vertical register portion (3) and a read gate portion forming a passage for transferring a signal charge from the horizontal register portion (4) to the charge detection portion (5), and ( 13) shows a charge sweeping area for sweeping unnecessary charges as described later.

Further, in this solid-state imaging device, the exposure time is set to one field period, and the light receiving sections (2) and (2) are set during the one field period.
(1) All charges accumulated in (2) are used as signal charges
In addition to reading out for each field period, an electronic shutter mechanism is provided so that the exposure time can be set within the vertical blanking period. In this case, in the vertical blanking period as shown in FIG. 4A, as shown in FIG. 4C, the unnecessary charge read pulse P ₁ is transferred from the timing generator (8) to the read gate section (11). It is supplied, and the light receiving parts (2) (2)
The electric charge accumulated in (2) is the vertical register section (3) (3)
It is read in (3). Then, as shown in FIG. 4E, the timing generator (8) changes to the vertical register sections (3), (3), ... (3).
(3) The vertical register sections (3), (3), ... so that the charges read out to (3) can be transferred at high speed to the charge sweeping areas (13), (13), ... (13). four-phase drive pulses (3) capable of driving example _{600KHz φ V1 ', φ V2'} , ( described only in FIG. 4 E φ _V1 ') φ _V3' and phi _V4 'is supplied, unnecessary charge read The charges read to the vertical register sections (3) (3) (3) by the pulse P ₁ are swept out to the charge sweep regions (13) (13) (13) as unnecessary charges. After that, as shown in FIG. 4D, when the required time in the vertical blanking period elapses, the signal charge read pulse P ₂ is supplied from the timing generator (8) to the read gate unit (11), and the required time The electric charges accumulated in the light receiving portions (2) (2) ... (2) during this period are read out to the vertical register portions (3) (3). Then, as shown in FIG. 4E, from the timing generator (8) to the vertical register sections (3) (3).
(3) can drive the vertical register sections (3) (3) ... (3) so that the read signal charges can be transferred to the horizontal register section (4) within one field period, for example, 1
4.75KHz 4-phase drive pulses φ _V1 , φ _V2 , φ _V3 and φ _V4 are supplied, and the light receiving sections (2) (2) ... (2) to the vertical register sections (3) (3) ... (3) The signal charges read out to are transferred to the horizontal register section (4). Thereafter, this signal charge is transferred from the horizontal register section (4) to the charge detection section (5) and detected by the charge detection section (5). In this way, in this solid-state imaging device, a video signal based on the charges obtained during the exposure time set within the vertical blanking period can be obtained.

In addition, in this solid-state imaging device, each light receiving unit (2)
(2) The charges accumulated in (2) are read out by interlacing, and in this case, as shown in FIG. 4F, the vertical optical black signals S _B1 , S _B2 of 6 horizontal lines. S _B6 and the effective video signals S ₀₁ , S ₀₂ and S ₀₃ of the three horizontal lines following it are read out within the blanking period.
Incidentally, FIG. 4B shows a horizontal synchronizing signal.

[Problems to be solved by the invention]

In the conventional solid-state imaging device斯Ru in this manner, the optical black signal S _B1 of 6 horizontal line, S _B2 ‥‥‥ S _B6 and subsequent 3
The effective video signals S ₀₁ , S ₀₂ , S _{03 of the} horizontal line are read during the vertical blanking period. In this case, the vertical register units (3) (3) (3) ... To 15.75KHz 4-phase drive pulse φ _V1 , φ _V2 , φ _V3
And φ _V4 supply, the light receiving section (2) (2) (2)
Since the signal charges read out from are driven so as to be transferred to the horizontal register section (4) within one field period, in such a solid-state imaging device, the unnecessary charge read pulse P ₁ and the signal charge read pulse P ₂ Even if the time interval between, and exposure time is maximized, it cannot exceed 1 / 1,800 seconds. Such a solid-state image pickup device is suitable for application to an electronic still camera that necessarily requires a vertical optical black signal, but is 1/1800 in a video camera that does not necessarily require a vertical optical black signal. The exposure time of seconds cannot be said to be a sufficient exposure time, and there is a problem in that the sensitivity required for practical use cannot be obtained, and measures against it have been demanded.

In this case, if the supply of the signal charge read pulse P ₂ is delayed to increase the exposure time as shown in FIG. 4G, in such a conventional solid-state imaging device, FIG.
As shown in Fig. 3, not only the vertical optical black signal protrudes during the effective video period, but also the optical center of the output signal and the effective center (center for the vertical synchronizing signal) as the video signal are deviated. .

The present invention has been made in view of the above problems, and an object thereof is to provide a solid-state imaging device capable of increasing the exposure time and improving the sensitivity without such inconvenience.

[Means for solving problems]

A solid-state imaging device according to the present invention is, for example, shown in FIGS.
As shown in the figure, in the vertical blanking period, the charges accumulated in the previous exposures are swept out as unnecessary charges, and the charges accumulated in the subsequent exposures in the vertical blanking period are read out as signal charges and A solid-state image pickup device which reads out a vertical optical black signal within a vertical blanking period, and which is provided with a high-speed transfer means for reading out a signal charge so that the vertical optical black signal is transferred and read at a high speed. Is.

[Action]

In the present invention, since the high-speed transfer means for reading the signal charge is provided so that the optical black signal in the vertical direction can be transferred and read at high speed, the read time of the optical black signal in the vertical direction can be read. The vertical optical black signal is not extended in the effective image period, and the optical center of the output signal and the effective center of the image signal are not displaced, thereby increasing the exposure time and increasing the sensitivity. It is possible to improve.

〔Example〕

An embodiment of the solid-state image pickup device of the present invention will be described below with reference to FIGS. 1 and 2. This Figure 1 and 2
In the figure, parts corresponding to those in FIGS. 3 and 4 are designated by the same reference numerals, and detailed description thereof will be omitted.

In this example as well, a timing generator (14) for driving by receiving a supply of a predetermined synchronization signal from the synchronization signal generation circuit (7) is provided, but the timing generator (14) of this example has a read gate section (11). ), And charges accumulated in the light receiving portions (2) (2) ... (2) as unnecessary charges or signal charges are added to the vertical register portions (3) (3).
(3) Unnecessary charge read pulse P ₁ for reading (3)
And the signal charge read pulse P ₂ and the vertical register section (3) (3) ... (3) so that the charge can be transferred to the horizontal register section (4) side at a normal speed. 3) (3) ... 15.75KHz for driving (3)
4 phase drive pulses φ _V1 , φ _V2 , φ _V3 and φ _V4 and the vertical register sections (3) (3) (3) so that the charges can be transferred at high speed to the charge sweep area (13) side. ) 600K for driving
Hz 4-phase drive pulse φ _V1 ′, φ _V2 ′, φ _V3 ′ and φ _V4 ′
And a 120 KHz four-phase drive pulse φ _V1 ″, φ for driving the vertical register sections (3) (3) (3) so that charges can be transferred to the horizontal register section (4) side at high speed. _V2 ″, φ
_V3 ″ and φ _V4 ″ and a 9.5 MHz two-phase drive for driving the horizontal register unit (4) so that the charges can be transferred to the horizontal register unit (4) and transferred to the charge detection unit (5). Pulse φ
_It is configured to generate _H1 and φ _H2 . Others are similar to those of the conventional example shown in FIG.

Then, in the solid-state imaging device of this example, the timing generator (14) is operated as follows.

First, this solid-state imaging device is set in a normal mode, that is, the exposure time is set to one field period, and all the charges accumulated in the light receiving portions (2), (2) ... If you try to read as
As shown in FIG. C, the signal charge read pulse P ₂ is supplied to the read gate section (11) at a required time point within the vertical blanking period, and is accumulated in the light receiving sections (2) (2) ... (2). The electric charges are read out to the vertical register sections (3) (3) ... (3). Then, as shown in FIG. 2D, four-phase drive pulses φ _V1 , φ _V2 , φ _V3 and φ _V4 of 15.75 KHz are applied to the vertical register section (3).
(3) --- (3) and a 2-phase drive pulse (not shown) of 9.5 MHz are supplied to the horizontal register section (4), and the light receiving sections (2), (2) ... (2) vertically Register part (3)
(3) The charges read out to (3) are transferred to the vertical register sections (3) (3) (3) and the horizontal register section (4).
To the charge detection unit (5) via. By doing so, as shown in FIG. _2E , the output signal S _B1 ,
S _B2・ ・ ・ S ₀₁ , S ₀₂・ ・ ・ S ₀₂₄₆ can be obtained. In this case, the signal charge read pulse P ₂ is the optical black signals S _B1 , S _B2, ..., S _{B6 of 6} horizontal lines and the effective video signals S ₀₁ , S _{02 of} 3 horizontal lines subsequent thereto in the vertical blanking period. , S ₀₃ and so on are supplied at the timing of reading.

Also, this solid-state image pickup device is set in the electronic shutter mode, that is, the exposure time is set within the vertical blanking period, and the electric charges accumulated in the light receiving portions (2) (2). When the charge is read out, the unnecessary charge read pulse P ₁ is supplied to the read gate section (11) at the vertical blanking period as shown in FIG. Charges accumulated in the parts (2), (2), ... (2) are transferred to the vertical register parts (3), (3) ,.
(3) Read out. Then, as shown in FIG. 2H,
Four-phase drive pulse φ _V1 ′ of 600 KHz for transferring charges to the charge sweep regions (13) (13) (13) at high speed with respect to the vertical register sections (3) (3) (3) , Φ _V2 ′,
Supply φ _V3 ′ and φ _V4 ′ to read unnecessary charge pulse
The charges read by P ₁ are swept to the charge sweep regions (13), (13), ... (13) within 7 horizontal periods as unnecessary charges. Next, as shown in FIG. 2G, the signal charge read pulse P ₂ is supplied to the read gate section (11) after the required time in this vertical blanking period elapses, and during this required time, that is, the exposure time. Light receiving part (2) (2)
The electric charge accumulated in (2) is applied to the vertical register section (3) (3)
(3) Read it. Then, as shown in FIG. 2H, a 4-phase drive pulse φ _V1 ″ of 120 KHz (15.75 KHz × 8),
φ _V2 ″, φ _V3 ″ and φ _V4 ″ are vertical registers (3)
(3) ... Supplying (3) and a 2-phase drive pulse (not shown) of 9.5 MHz to the horizontal register section (4).
In this case, this 120KHz 4-phase drive pulse φ _V1 ″,
φ _V2 ″, φ _V3 ″, and φ _V4 ″ are supplied only for one horizontal period, after which the normal four-phase drive pulse φ _{V1 of} 15.75 KHz,
Supply φ _V2 , φ _V3 and φ _V4 . By doing so, as shown in FIG. 2I, the vertical optical black signals S _B1 , S _B2, ..., S _{B6 of 6} horizontal lines and the effective video signals S ₀₁ , S _{02 of} 2 horizontal lines subsequent thereto. Will be compressed into one horizontal line and output. In this case, this timing generator (14) and vertical register section (3) (3) (3)
And constitute a high-speed transfer means for reading signal charges. Therefore, in this example, the signal charge read pulse P ₂ is
Vertical optical black signals of 6 horizontal lines S _B1 , S _B2 ‥‥‥ S _B6
And two horizontal lines S ₀₁ subsequent, S 8 effective video signal S ₀₃ and a vertical blanking horizontal line 1 of the horizontal line signal signal is formed by compression of the one horizontal line followed by the effective video signal of ₀₂ It is supplied at the timing of being read within the period. In this way, as shown in FIG. 2I,
In the effective video period, the effective video signal can be output at the same timing as in the conventional example of FIG. still,
2A and 2B show a vertical synchronizing signal and a horizontal synchronizing signal, respectively.

As described above, in the solid-state imaging device of this example, the exposure time is defined as one field period, and the charge accumulated in the light receiving portions (2), (2) ... In addition to being able to read every time, the exposure time is set within the vertical blanking period, and the charges accumulated in the light receiving portions (2), (2), ... (2) during this exposure time are read as signal charges. You can also

In this case, in the solid-state imaging device of the present example, the signal to be read in the original vertical blanking period, i.e., following the vertical optical black signal S _B1, S _B2 ‥‥‥ S _B6 and its 6 horizontal line 3 Of the effective video signals S ₀₁ , S ₀₂ , S ₀₃ of the horizontal line, 6 vertical optical black signals of the horizontal line S _B1 , S _B2
Effective video signal of _B6 and two horizontal lines subsequent S _01, S ₀₂
And are compressed and read as one horizontal line, so that the vertical optical black signals S _B1 , S _B2, ..., S _B6 and the effective video signals S ₀₁ , S ₀₂ of the following three horizontal lines are obtained. , S ₀₃
It is possible to shorten the time for reading out by 7 horizontal periods as compared with the conventional example of FIG.

Therefore, in the solid-state imaging device of this example, the vertical optical black signal is not squeezed out, and the optical center of the output signal and the effective center of the video signal are not displaced, and the exposure time is extended. Yes, for example about 1/1000
It can be set to seconds, and the sensitivity can be improved.

Further, according to the solid-state imaging device of the present example, a solid-state imaging device having a light receiving unit for obtaining a vertical optical black signal, that is,
There is an advantage that the solid-state image sensor generally developed for application to an electronic still camera can be applied to a video camera that does not necessarily require a vertical optical black signal.

It should be noted that 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.

〔The invention's effect〕

According to the present invention, since the vertical optical black signal is transferred and read at high speed, the read time of the vertical optical black signal can be shortened and the vertical optical black signal can be effectively used. It does not protrude in the video period, does not affect the video screen at all, and does not shift the optical center of the output signal and the effective center as the video signal.
There is an advantage that the exposure time can be extended and the sensitivity can be improved.

Further, according to the present invention, there is an advantage that the solid-state image pickup device having the light receiving portion for obtaining the vertical optical black signal can be applied to the video camera which does not necessarily require the vertical optical black signal.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing a planar structure of an embodiment of the solid-state image pickup device of the present invention, FIG. 2 is a diagram used for explaining the example of FIG. 1, and FIG. 3 is a plane view of a conventional solid-state image pickup device. FIG. 4 is a diagram schematically showing the structure, and FIG. 4 is a diagram used for explaining the example of FIG. (1) is a semiconductor substrate, (2) is a light receiving part, (3) is a vertical register part, (4) is a horizontal register part, (5) is a charge detection part, (6) is an output terminal, and (7) is synchronous. Signal generation circuit,
(11) is a read gate section, (13) is a charge sweep area,
(14) is a timing generator.

Claims (1)

(57) [Claims] 1. The vertical blanking period sweeps out the charges accumulated by the previous exposures as unnecessary charges, reads the charges accumulated by the subsequent exposures during the blanking period as signal charges, and at the same time the vertical blanking period. In a solid-state image pickup device that reads out a vertical optical black signal within a ranking period, a high-speed transfer means for signal charge reading is provided, and the vertical optical black signal is transferred at a high speed and read out. Solid-state imaging device.