JPH0771239B2 - Imaging device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup device such as a video camera having an optical / electrical conversion unit.

2. Description of the Related Art In recent years, solid-state image pickup devices have been used in image pickup apparatuses such as video cameras. The solid-state image sensor has various advantages such as small size and light weight, uniform spatial resolution on the screen, and low afterimage.
However, while further improvement in resolution is desired for EDTV, HDTV, etc., increasing the number of pixels of a solid-state image sensor has become an issue in terms of IC processing accuracy and yield. Therefore, a method has been proposed in which the incident light of the solid-state image sensor is vibrated for each field, and the resolution is equivalently doubled. Hereinafter, description will be given with reference to the drawings. FIG. 4 is a block diagram showing the configuration of the conventional image pickup device 20. In FIG. 4, 2 is an imaging lens, 21 is an optical low-pass filter (LPF), 22 is a photoelectric conversion means, 23 is an output end, and 24 is an optical LPF drive means. The incident light that has passed through the imaging lens 2 passes through the optical LPF 21, is subjected to light-electric conversion by the photoelectric conversion means 22, and is output to the output end 23. The optical LPF driving unit 24 drives the optical LPF 21, and changes the tilt angle with respect to the photoelectric conversion unit 22 for each field. This state is shown in FIGS. 3 (a) and 3 (b). As a result, the pixel interval of the photoelectric conversion means 22 is set to a
Then, the optical path exiting the optical LPF 21 can be shifted by a / 2 on the photoelectric conversion means 22, and equivalently, the resolution can be doubled.

However, in the above configuration, since the open loop control is performed, the optical path shift amount may not be a / 2 completely due to temperature characteristics, element variation, and the like. For example, as shown in FIG. 5A, it is assumed that the photosensors of the photoelectric conversion means are arranged at pixel intervals a. . In FIG. 5 (a), when the first field state is set, the second field is shifted by c as shown in FIG. 5 (b). When the pixel arrangements of the first field and the second field are combined, the result is as shown in FIG. 5 (c). However, since c ≠ a / 2, moire does not disappear, and sufficient resolution improvement cannot be achieved. There was a problem.

Means for Solving the Problems In order to solve the above problems, an imaging device according to the present invention is
An imaging lens, an optical low-pass filter whose vibration width is switched for each field, a photoelectric conversion unit, an area memory that stores a signal of a predetermined area of an image, a high-pass filter, a detection unit, an optical low-pass filter amplitude control unit, The optical low-pass filter drive means and the photoelectric conversion means drive device, the incident light that has passed through the imaging lens,
After passing through the optical low-pass filter, is input to the photoelectric conversion means, as an electrical signal, the output end, and
Output to the area memory, and in the area memory,
The signals for each field are aligned, the output signal of the area memory, after extracting a high-frequency component by the high-pass filter, is detected by the detection means, is input to the optical low-pass filter amplitude control means, The optical low-pass filter amplitude control means outputs a control signal according to the output level of the detection means to the optical low-pass filter driving means, and a clock output from the photoelectric conversion means driving device causes the photoelectric conversion means to operate. The read operation is controlled and output from the photoelectric conversion means driving device,
Another control pulse is input to the optical low-pass filter driving means, the optical low-pass filter driving means is configured to drive the optical low-pass filter, so that the output of the detection means is maximum, The vibration width of the optical low-pass filter is configured to be closed-loop controlled.

Action With the above-described configuration, the image pickup apparatus of the present invention can accurately obtain twice the resolution as compared with the conventional example.

Embodiment Hereinafter, an image pickup apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the image pickup apparatus of the present invention. In FIG. 1, the incident light that has passed through the imaging lens 1 is input to the photoelectric conversion means 12 via the optical LPF 11. In the photoelectric conversion means 12,
Receives light and electricity, area memory 13, and output terminal 19
Is output to. The area memory 13 is a memory that stores a video signal of a predetermined area on the screen, for example, an area for obtaining autofocus information. The area may be set on the entire screen. In the area memory 13, the signals of a plurality of fields are aligned with the signal of one frame. For example, FIG. 2A shows a signal train of the first field,
Assuming that FIG. 2B is the signal train of the second field, the aligned signal train has a layout in which pixels are interpolated in the horizontal direction as shown in FIG. A high pass filter (HPF) 14 is applied to the output signal of the area memory 13. For example, HPF is applied in the H → H ′ direction of FIG. 2 (c). The HPF output is detected by the detection means 15, and then the optical LPF amplitude control means 16
Then, the output of the optical LPF amplitude control means 16 is input to the optical LPF driving means to control the oscillation width of the optical LPF 11 to cause periodic oscillation. Further, the read timing of the photoelectric conversion means 12 is determined by the output clock of the photoelectric conversion means driving device 17, another control pulse is input to the optical LPF driving means 18, and the oscillation cycle of the optical LPF 11 is determined. At this time, a closed loop is configured so as to control the vibration width of the optical LPF 11 so that the output of the detection means 15 becomes maximum. As a result, assuming that the distance between the photosensors is a and the pixel position in the first field is set at the position shown in FIG. 2 (a), as shown in FIG. 2 (b), The pixel position in the second field is exactly
Since it shifts by a / 2, the resolution can be sufficiently improved. In this embodiment, the optical LPF11 is
Although the example of inclining in the horizontal direction has been shown, it is also possible to incline in the vertical direction and perform pixel interpolation in the vertical direction. At this time, HPF14
A vertical filter including an H memory (H: 1 horizontal scanning period) memory is preferable. Further, as the photosensor row of the photoelectric conversion means, an example in which vertically arranged rows are formed as shown in FIG. 2 is used. You may. Further, the optical LPF drive unit 18 may directly drive the photoelectric conversion unit 12 to shift the spatial position, and the optical LPF 11 may be fixed. Also, the same effect can be obtained by vibrating an optical element other than the above. The photoelectric conversion means 12 may be any solid-state image sensor. Further, an AD converter may be provided after the photoelectric conversion means 12, and the following configuration may be a digital circuit. Further, although the present invention has been described as a two-field sequence, a sequence of three or more fields may be used.

EFFECTS OF THE INVENTION As described above, according to the imaging means of the present invention, the effect of improving the resolution due to the optical LPF vibration can be stably and completely realized regardless of the temperature change and the element variation.

[Brief description of drawings]

FIG. 1 is a block diagram of an image pickup apparatus according to an embodiment of the present invention, FIG. 2 is a schematic diagram showing an effect of pixel interpolation by optical LPF vibration, and FIG. 3 is an optical path shift caused by optical LPF vibration. FIG. 4 is a block diagram of an image pickup apparatus in a conventional example, and FIG. 5 is a schematic diagram showing a state of pixel interpolation in a conventional example. 1 ... Imaging lens, 11 ... Optical low-pass filter, 12 ...
... photoelectric conversion means, 13 ... area memory, 14 ... high-pass filter, 15 ... detection means, 16 ... optical low-pass filter amplitude control means, 17 ... photoelectric conversion means drive device, 18 ...
Optical low-pass filter driving means, 10 ... Imaging device.

Claims (1)

[Claims] 1. An imaging lens, an optical low-pass filter whose vibration width is switched for each field, a photoelectric conversion means, an area memory for storing a signal of a predetermined area of an image, a high-pass filter, a detection means, and an optical low-pass filter. It is composed of an amplitude control means, an optical low-pass filter driving means, and a photoelectric conversion means driving device, and the incident light having passed through the imaging lens is input to the photoelectric conversion means after passing through the optical low-pass filter, and an electric signal. As the output terminal and the output to the area memory, the signals for each field are aligned in the area memory, and after the high-pass filter is extracted from the output signal of the area memory by the high-pass filter, The optical low-pass filter is detected by the detecting means and input to the optical low-pass filter amplitude control means. The filter amplitude control means outputs a control signal according to the output level of the detection means to the optical low-pass filter drive means, and a read operation of the photoelectric conversion means is performed by a clock output from the photoelectric conversion means drive device. Another control pulse that is controlled and output from the photoelectric conversion unit driving device is input to the optical low-pass filter driving unit, and is configured to drive the optical low-pass filter by the optical low-pass filter driving unit. The imaging apparatus is characterized in that the oscillation width of the optical low-pass filter is closed-loop controlled so that the output of the detection means becomes maximum.