JPH02117277A - Image pickup device - Google Patents

Abstract

PURPOSE:To prevent moire from being generated even when a liquid crystal element is used by synchronizing both driving sources so that one of a first frequency and a second frequency can be interger-number fold of the other frequency. CONSTITUTION:A drive circuit 15 for a liquid crystal lens 13 is connected through a line 28 to a synchronizing circuit 27 and synchronized with a drive circuit 23 for a solid-state image pickup element 22, a preamplifier 24, a signal processing circuit 25 and a drive circuit 8 for a motor 6. For example, when a signal reading frequency f1 of the element 22 and a rotating number f2 of a rotary filter 5 is respectively 90Hz and 30Hz, a driving frequency VL of a lens 13 is integer-number fold of the f1 or f2 or an integer number 1. Accordingly, the fine fluctuation of a focal distance for the lens 13 and the signal reading of the element 22 or the change of R, G and B for the filter 5 are not interrupted. Then, the moire is not generated.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to an imaging device such as a videoscope.

[Conventional technology]

Recently, in imaging devices such as videoscopes, it has been proposed to eliminate mechanically driven parts by using liquid crystal elements such as liquid crystal lenses (variable focus lenses) and liquid crystal apertures.

An example of this is the clock shown in FIG. 2, which is a frame-sequential color imaging device.

1 is a light source lamp; 2 is a condenser lens that once converts the light from the light source lamp 1 into a parallel beam and then condenses it again; 3 is a condenser lens that converts the light condensed by the condenser lens 2 into a videoscope tip BS;
4 is the tip end BS of the light guide fiber bundle.
an illumination lens that is disposed on the end face of the light guide fiber bundle 3 and illuminates an object (not shown) with the light emitted from the light guide fiber bundle 3;
5 is a rotary filter having three filter parts of R, G, and B which are sequentially inserted into the parallel light beam part of the condenser lens 2 by rotation; 6 is a motor that rotates the rotary filter 5 via a transmission system 7; This is a drive circuit that drives the mokro at a predetermined frequency so that the rotary filter 5 rotates at a predetermined speed, and these constitute an illumination system that sequentially irradiates R, G, and B light onto the object surface. .

Reference numeral 11 denotes a concave lens which also serves as a cover glass, which is disposed on the end face of the videoscope tip BS, 12 is an aperture diaphragm which is disposed behind it, and 13 is a liquid crystal lens which is further disposed behind it. It constitutes the objective lens 14. Reference numeral 15 denotes a drive circuit that applies an alternating current voltage of a predetermined frequency to the liquid crystal lens 13 to drive it.

Here, the liquid crystal lens 13 consists of a liquid crystal cell 16 and a polarizing plate 17 arranged in front of the liquid crystal cell 16, as shown in FIG. 2 Transparent plate made of acrylic etc. 18. ], and 8, respectively, by covering the transparent electrodes 19 and oriented [920], and inserting the nematic liquid crystal 21 into the convex lens-shaped gap formed by the opposing surfaces. ing.

When the switch SW is OFF and no voltage is applied, the molecular arrangement of the θ crystal 21 is a homogeneous arrangement in which the direction in which the long axes of the molecules are arranged (rubbing direction) coincides with the vibration direction of the polarizing plate 17. It has become. Therefore, the refractive index of the liquid crystal 21 is high relative to the incident light transmitted through the polarizing plate 17, and the focal length of the liquid crystal lens 13 becomes short. Furthermore, when the switch SW is ON and a voltage of a certain value or more is applied, the molecular arrangement of the liquid crystal 21 becomes a bomeotropic arrangement, that is, an arrangement in which the long sleeve direction of the molecules is orthogonal to the vibration direction of the polarizing plate 17, so that each incident light 6 is On the other hand, the refractive index of the liquid crystal 21 becomes lower, and the focal length of the liquid crystal lens 13 becomes longer.

22 is a solid-state image sensor on which the image formed by the objective lens 14 is formed; 23 is a drive circuit that drives the solid-state image sensor 22 at a predetermined frequency to output video signals (R, G, B signals); and 24 is the same body. A preamplifier that amplifies the video signal from the image sensor 22; 25 is a signal processing circuit that processes the video signal from the preamplifier 24 and converts it into a combined video signal;
26 is a television monitor that displays a color image by inputting the composite video signal from the processing circuit a, 27 is a drive circuit 8.23.Preamplifier 24.Signal processing port 1 path 2
5 and synchronizes the operations of these circuits, and together with the objective lens 22, these constitute an imaging/observation system.

[Problem to be solved by the invention]

However, in the case of the above-mentioned conventional example, when the liquid crystal lens 13 is driven with alternating current, the point distance of the liquid crystal lens I3 varies minutely at that frequency, unless the frequency is particularly high.
Furthermore, although the signal readout of the solid-state image sensor 22 and the rotation of the rotary filter 5 are performed at a predetermined frequency, the driving of the liquid crystal lens 13 and other optical elements such as the solid-state image sensor 221 and the rotary filter 5 is They were not synchronized at all.As a result, minute fluctuations in the focal length of the liquid crystal lens 13, signal readout of the solid-state image sensor 22, changes in R and CB of the rotary filter 5, etc. interfere with each other, causing moiré (stripes in the TV image). There was a problem in that a phenomenon in which the flow of water occurred.

SUMMARY OF THE INVENTION An object of the present invention is to overcome the above-mentioned problems and provide an imaging device that does not cause moiré even when a liquid crystal element is used.

Means and Effects for Solving Problem C] The imaging device according to the present invention includes a liquid crystal element driven by a drive source having a predetermined first frequency, and a liquid crystal element driven by a drive source having a predetermined second frequency. In an imaging device equipped with an optical element, the two layer motion sources are synchronized so that one of the first frequency and the second frequency is an integral multiple of the other, thereby preventing the occurrence of moiré. This is how it was done.

〔Example〕

Hereinafter, the present invention will be described in detail based on the illustrated embodiment, with the same reference numerals assigned to the same members as in the above-mentioned conventional example.

FIG. 1 shows one embodiment, which shows a liquid crystal lens 13.
The drive circuit 15 for
7 is connected to a drive circuit 23 for the solid-state image sensor 22.
．． Preamplifier 24. Signal processing circuit 25. Same as drive circuit 8 for motor 6! It is now possible to call 111. For example, the driving frequency ν of the liquid crystal lens 13 is
Signal readout frequency (field frequency) of solid-state image sensor 22 Number of rotations (frame frequency) of one-rotation filter 5
When fz is 90 Hz and 30 Hz, respectively, it is as follows.

1'L (H2)..., 5. 10.
15. 22゜5. 30. 45. 60. 9
0 120, 150, 180,210.240,
270 In other words, ν becomes an integral multiple or fraction of 1 or f7.

Therefore, according to this embodiment, since the driving of the liquid crystal lens 1:3 and the solid-state image sensor 222, the rotary rotary filter 5, and other optical elements are synchronized, minute fluctuations in the focal length of the liquid crystal lens 13 and the solid-state image sensor 222 are synchronized. 22 and changes in R, G, B of the rotary filter 5, etc. do not slow down, and no moiré occurs.

Even if L is not an integral multiple or a fraction of f2, there is a range of ν that can be used practically.

One is when ν is sufficiently higher than f, , f, that is, when there are many liquid crystal lens driving waveforms in one field and one frame. Specifically, νt>2f+ or ν>2f2. This occurs with ν and [, ν.

The only condition is that the beat of is greater than rl. The same applies to f2.

On the other hand, if ν5 is lower than rI and r2, temporally ν1
- will be sampled ↑ by f or f2, so
The beat frequency is.

fl　−ν.

Nu is f2-ν.

However, in order for this to not be offended by the human eye as ') v1 and L7, it is necessary that 1) -v, 〉10 or f2-ν, 〉10.

[Effects of the Invention] As described above, the imaging device according to the present invention has the practically important advantage that moiré does not occur even when a liquid crystal diode is used.

[Brief explanation of the drawing]

Fig. 1 is a block circuit diagram of an embodiment of an imaging device according to the present invention, Fig. 2 is a block circuit diagram of a conventional example, and Fig. 3 is a -F
FIG. 2 is a schematic cross-sectional view of a conventional liquid crystal lens. 1...Light source lamp, 2...Condensing lens, 3...
・Light guide fiber bundle, 4...Lighting lens,
5... Rotation filter, 6... Morph, 7...
Transmission system, 3.15.23...drive circuit, 11.
...Concave lens, 12...Aperture diaphragm, 13...Liquid crystal display:/Z, 14...Objective lens, 16...Liquid crystal cell, 17...Polarizing plate, 18...・Transparent plate, 19
...Transparent electrode, 20 ...Alignment film, 2I...
Machiic liquid crystal, 22...solid-state image sensor, 24...
...Preamplifier, 25...Signal processing circuit, 26.
...TV monitor, 27...Synchronization circuit, 28...
··line.

Claims (1)

[Claims] In an imaging device including a liquid crystal element driven by a drive source having a predetermined first frequency and an optical element driven by a drive source having a predetermined second frequency, An imaging device characterized in that both of the driving sources are synchronized so that one of the frequencies of the driving sources is an integral multiple of the other.