JPH02266674A - Solid-state image pickup device - Google Patents

Abstract

PURPOSE:To prevent mis-development with simple constitution by interposing a liquid crystal shutter between a solid-state image pickup element and an optical system forming an object image onto the solid-state image pickup element and shutting the light from the solid-state image pickup element during the video readout period. CONSTITUTION:A liquid crystal (LCD) shutter 2 is provided onto an optical axis of an optical system 1 and an electronic camera 3 provided with a solid- state image pickup element (CCD) 3a forming an object image with the optical system 1 is provided to the back side of the LCD shutter 2. Then the LCD shutter 2 is driven and opened synchronizing with a exposure period of the CCD 3a to form the object image onto the CCD 3a and the electric charge is stored into the CCD 3a, the drive of the LCD shutter 2 is stopped synchronizing with the charge transfer period to shut the light of the CCD 3a. Since no mechanical drive system is used in this way, smear is prevented with simple constitution.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Application of the Invention) The present invention relates to a solid-state imaging device that prevents the smear phenomenon.

(Prior art and problems to be solved by the invention) Solid-state imaging devices using a charge transfer device have been put into practical use using a frame transfer method or an interline transfer method, and are used in consumer equipment as they are small, lightweight, and have low power consumption. .

In such a conventional charge transfer imaging device, light that is incident at an angle with respect to the main surface of the photoelectric conversion section is reflected on the surface of the semiconductor substrate and multiple reflections within the insulating layer and the electrode layer. If unnecessary charges are generated in other areas, and this occurs during the period when signal charges are being transferred, a dark output occurs, causing a faint trailing phenomenon called smear phenomenon in the vertical direction of the screen.

In order to prevent this, conventionally a mechanical shutter has been interposed in the imaging optical path to prevent exposure during the image readout section.

However, this mechanical shutter requires advanced technology for synchronization with the solid-state image pickup device, requires mechanically movable parts, and has drawbacks such as increasing the size of the device.

(Means for Solving the Problems) In view of the above-mentioned circumstances, one aspect of the present invention is to provide a liquid crystal shutter between a solid-state image sensor and an optical system that forms a subject image on the solid-state image sensor, and to read out images. During this period, the solid-state image sensor is shielded from light.

(Example) Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a diagram showing an embodiment of the apparatus of the present invention, FIG. 2 is a flow chart of the apparatus of the present invention, and FIG. 3 is a time chart of the apparatus of the present invention.

In FIG. 1, a liquid crystal (hereinafter referred to as LC) is placed on the optical axis of the optical system 1.
A shutter 2 (referred to as D) is provided, and behind the shutter 2 (LCI), an electronic camera 3 is provided with a solid-state image pickup device (hereinafter referred to as COD) 3a for forming an image of a subject using an optical system 1.

These LCD shutter 2 and electronic camera 3 are driven by a control circuit 4.

The control circuit 4 includes a first delay circuit 4a, a trigger circuit 4b, a second delay circuit 4c, an LCD trigger circuit 4d, and an LCD drive circuit 4e. When the imaging command signal 5 enters the first delay circuit 4a, After a certain delay time, the trigger circuit 4b
At the same time, a signal is sent to the second delay circuit 4C, and after a certain delay time, the LCD drive circuit 4e is driven by the LCD trigger circuit 4d, and the LC
The D shutter 2 is opened. Then, after a certain delay time, the second delay circuit 4C sends out an LCD shutter OFF signal to close the LCD shutter.

The operation of the present invention configured as described above will be explained in detail with reference to FIGS. 2 and 3.

When the imaging command signal 5 enters the first delay circuit 4a in FIG. 1, a trigger signal is sent to the CCD of the electronic camera 3 (11) after a certain delay time (10).

When the COD is turned on by the trigger signal, the CCD
As shown in FIG. 3, the charge on the COD is cleared (Tl-72) by the control circuit in the electronic camera 3 (not shown).
,, COD charge accumulation is started, COD charge accumulation is finished (T9) L, and transferred to the outside as a video output signal (T9-T
IO).

On the other hand, the second delay circuit 4C sends out a trigger signal (LCD) as shown in FIG. 3 to the LCD drive circuit 4e via the trigger circuit 4d. The LCD drive circuit 4e opens and closes the LCD shutter 2 according to a curve of <T4-T5-T7-T8 as shown in FIG.

CCD) The charge on the COD is cleared (1) by the trigger signal.
2), COD charge accumulation is started (13), and in synchronization with this, after a delay time (14), the LCD shutter 2 is triggered (15).

LCD shutter 2 is opened (16), and after an appropriate delay time (17), the LCD shutter trigger is set to 0ff (18).
Then, the LCD shutter 2 is closed (19), and in synchronization with this, the charge accumulation of COD is completed (20) L, CO
The process moves to D charge transfer (21), and video output is sent out (22).

In FIG. 3, the LCD is opened and closed within the COD accumulation period, but it goes without saying that it may be opened and closed beyond this period as long as the smear phenomenon does not occur.

(Effects) As described above in detail, according to the first aspect of the invention, since no mechanical drive system is used, smear can be prevented with a simple configuration.

[Brief explanation of drawings]

The wSf diagram is an embodiment of the apparatus of the present invention, FIG. 2 is a flow chart of the apparatus of the present invention, and FIG. 3 is a time chart of the apparatus of the present invention. l: Optical system, 2: LCD shutter, 311: Electronic camera, 3aφ: Solid-state image sensor, 4: Control circuit

Claims (1)

[Claims] A liquid crystal shutter is interposed in an optical path of an optical system that forms a subject image on a solid-state image sensor provided in an electronic camera, and the liquid crystal shutter is driven and opened in synchronization with an exposure period of the solid-state image sensor. forming a subject image on the solid-state image sensor, accumulating a charge in the solid-state image sensor, and stopping driving of the liquid crystal shutter in synchronization with a transfer period of the charge, thereby shielding the solid-state image sensor from light. A solid-state imaging device featuring: