JPS63169892A - Color image pickup device - Google Patents

Abstract

PURPOSE:To improve the image resolution as well as the S/N of color signals by tilting the lengthwise direction of each fine filter streak of a stripe filter in response to the deformation of an effective beam spot shape due to the self-sharpening effect. CONSTITUTION:The 1st-3rd filter fine streaks F1-F3 are arrayed regularly and the lengthwise directions of these streaks are tilted by an angle theta against the vertical scanning direction. Thus, a stripe filter 2 is obtained. The angle thetais previously set so that the variation of the modulation degree due to the self-sharpening effect is reduced in response to the gradient of an effective crescent beam spot shown by the oblique lines in the diagram. The light received from an object forms an image on the photoconductive surface of an image pickup tube 3 through the filter 2 to undergo the photoconductive conversion. The electric signal extracted out of a signal electrode of the tube 3 is supplied to a preamplifier 4 to be amplified up to a proper level and then supplied to a separating circuit 5.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a color imaging device, and in particular, it captures an image of an object through an optical color separation striped filter (stripe filter) having a predetermined configuration to reduce the influence of self-sharpening effect. The present invention relates to a color imaging device in which light from a 11-m picture tube is imaged on a photoconductive surface (or photocathode) of an m-picture tube, and a color television 5 signal is obtained from a signal taken out from the m picture tube.

2. Description of the Related Art The present applicant previously proposed in Japanese Patent Publication No. 59-35550 a ``color television signal generator'' using a stripe filter having a predetermined configuration. This one is additive color method 3
A first filter strip that transmits only light of one of the primary colors, and light of one of the primary colors and the other two primary colors that passes through the first filter strip. A second filter strip that transmits only mixed color light and a third filter strip that transmits white light are arranged in a fixed order, and the longitudinal direction of each filter strip is perpendicular to the horizontal scanning direction. The light from the subject is applied to the photoconductive surface (or photocathode) of the image pickup tube through a stripe filter that is regularly arranged as shown in FIG. When separating and generating predetermined two primary color signals from a fundamental wave component of a carrier wave having a spatial frequency value determined by the repetition period of the filter strips and a second harmonic component of this carrier wave, the second harmonic component is is configured so that only the phase component is used and its amplitude component is not used.

According to the color television signal generation device proposed by the present applicant, the effect of color shading caused by the different modulation degrees between the center and peripheral parts of the target surface of the image pickup tube is determined only by the fundamental wave component. The second
Compared to conventional devices that use amplitude components of harmonic components to separate colors, the influence of color shading can be reduced, and two predetermined primary color signals can be separated and generated using average detection. , it is possible to reduce color errors compared to equipment that uses envelope detection, and it is also almost unaffected by noise in the second harmonic band, making it possible to generate color television signals with good image quality. It has excellent features such as:

Problems to be Solved by the Invention However, according to the apparatus proposed by the present applicant, in the frequency spectrum shown in FIG. Since the predetermined two primary color signals are separated and generated using the harmonic band B, the band of the luminance signal is as shown by Y in the figure, the fundamental wave component A.
The band was limited by an optical low-pass filter with predetermined spectral characteristics so that the band did not overlap.

Therefore, in order to obtain higher resolution, it is necessary to make the length (pitch) of one cycle of the filter strips of the stripe filter finer and correspondingly widen the band of the preamplifier. However, the noise distribution of the preamplifier is
As shown in the figure, noise tends to increase nonlinearly as the frequency increases, so even if you try to increase the resolution by making the pitch of the stripe filter finer, the S/N of the second high frequency component will deteriorate. Therefore, there was a problem in that it was difficult to improve the resolution beyond a predetermined value.

Furthermore, as is well known, the imaging tube using slow beam landing has the disadvantage that the scanning electron beam is accompanied by a self-sharpening effect.

Self-sharpening effect refers to the fact that when reading out the charge pattern on a target surface using a low-speed scanning electron beam, the edge of the beam spot is absorbed more efficiently, so the beam spot effectively becomes crescent-shaped. Refers to the phenomenon of deformation (Television Science Society Journal VO1, 37, N1
15 (1983) (7)l), 401).

Here, the shape of the beam spot is circular when the electron beam is stationary, as shown in FIG. 6(A), for example.
During scanning with an electron beam, it deforms into a crescent shape, for example, as shown in FIG. 6(B).

This is a low-speed electron beam! When reading out the signal charge accumulated on the target surface of the l1m tube, the part that has already been scanned, that is, the part above the current beam spot in FIG. 6(B) and the part in the opposite direction to the vertical scanning direction. ) and the left side portion (the portion in the opposite direction to the horizontal scanning direction), no charge is accumulated, so even if you try to read the charge in the circular portion originally surrounded by a broken line, it will actually be surrounded by a solid line. This occurs because only a partial charge can be read out. In this case, the crescent-shaped beam spot has an inclination angle θ (0° and θ<90°) with respect to the vertical scanning direction.
) has a sloped shape.

Therefore, in the conventional color 81 device using a stripe filter configured such that the longitudinal direction of each filter strip is arranged orthogonal to the horizontal scanning direction, the degree of modulation of the read signal is There is also the problem that the effective beam spot shape is greatly influenced by the direction of inclination.

Therefore, the present invention provides a collar 81 device that solves the above problems by tilting the longitudinal direction of each filter strip of the stripe filter according to the deformation of the effective beam spot shape due to the self-sharpening effect. The purpose is to

Means for Solving the Problems The color removal device of the present invention arranges predetermined first to third filter strips in a fixed order and in the longitudinal direction of each filter strip with respect to the scanning line direction. The light from the object is passed through the stripe filter, which is arranged so that the filter strips are inclined, and the scanning line is configured to select the pitch of the first to third filter strips in the direction perpendicular to the scanning line. Using the vertical correlation of the decoy tube output signals of at least two horizontal scanning lines by the conductive surface (or photocathode), the luminance signal and the fundamental wave component signal within the luminance signal band are separately output.

Operation: The first filter strip transmits only the first primary color light of any one of the three additive primary colors;
The filter strips of the first primary color light and the second primary color light of any one of the other two primary colors other than the first primary color light.
The third filter strip transmits only white light mixed with the primary color light.

Here, based on the deformed shape of the beam spot that is effectively deformed into a crescent shape due to the self-sharpening effect,
The angle of inclination between the scanning direction and the longitudinal direction of the first to third filter strips is selected in such a way that the modified beam spot occupies a maximum area on the same filter strip.

As a result, the image pickup tube output signal is
A phase difference is given between the fundamental wave component signals in the output signals of the book scanning lines. This phase difference is determined by how the number of scanning lines is set with respect to the pitch of the stripe filter viewed in the direction perpendicular to the scanning lines.

Therefore, by utilizing the correlation between the HEI tube output signals of at least two horizontal scanning lines, the fundamental wave component and the luminance signal can be separated. Therefore, it becomes possible to set the band of the fundamental wave component within the luminance signal band, which was previously impossible.

Embodiment FIG. 1 shows a stripe filter structure of a first embodiment of the present invention. In FIG. 1, Fl is the first filter strip that transmits only the first primary color light of any one of the three additive primary colors, and F2 is the first filter strip that transmits Fl. F3 is a second filter strip that transmits only the mixed color light of the primary color light and the second primary color light of which one of the other two primary colors other than the primary color of the primary color light is transmitted; The third filter strip is transparent. Here, - by way of example, the first filter strip F is a filter strip that transmits only green light, and the second filter strip F is a filter strip that transmits only green light.
2 will be explained below assuming that it is a filter strip that transmits only cyan light.

As shown in FIG. 1, the first to third filter strips F1 to F3 are regularly arranged in a certain order, and arranged so that their longitudinal direction is inclined by an inclination angle θ with respect to the vertical scanning direction. Configures a stripe filter.

The inclination angle θ is predetermined based on the inclination of the effective crescent-shaped beam spot shown by the hatched area in FIG. 1 so that the change in modulation degree due to the self-sharpening effect is reduced.

In this embodiment, as an example, exactly two scanning lines are located with respect to the pitch (indicated by P in FIG. 1) of the first to third filter strips F1 to F3 in a direction perpendicular to the scanning lines. The angle of inclination θ, the width of each filter wire, etc. are selected so as to achieve this. As a result, the phase difference between the scanning lines of the fundamental wave component signal is 1
It becomes 80°.

Furthermore, the phase difference between the scanning lines of the second m-th frequency bottom signal is always twice that of the fundamental wave component signal, so it is 360#.

Next, the configuration of an embodiment of the present invention will be explained with reference to the block diagram shown in FIG. 2. In FIG. After that, the light passes through the stripe filter 2 and is imaged on the photoconductive surface of the ms tube 3, where it is photoelectrically converted. The stripe filter 2 is built into the m-unit 3 and has a structure as shown in FIG. The electrical signal taken out from the signal electrode of the image pickup tube 3 is supplied to a preamplifier 4, where it is amplified to an appropriate level and then supplied to a separation circuit 5, which forms the essential part of the present invention.

Now, assuming that the output signal of the preamplifier 4 is 81, Sl becomes as shown in the following equation.

±As1n(ωt+ψ) where, i(=, iB, iR are current signals due to green light, blue light, and red light, and fl is the horizontal scanning line of filter strips F+ to F3 of stripe filter 2. It is a spatial frequency determined by the repetition period of the direction.Also, the phases of the odd-numbered high-frequency component signal and the fundamental wave component signal are inverted in one horizontal scanning period (180
with a phase difference of °).

This output signal S! As can be seen from equation (1), the DC signal and luminance signal, which are the mixed signals of the three primary colors in the additive coloring method, the carrier wave of the above spatial frequency f+, the carrier wave of an integral multiple of this spatial frequency f1, etc. It consists of a modulated color signal that is width-modulated and phase-modulated by a mixed signal of two primary color lights (red and blue light) other than the green light transmitted through the filter strips F1.

FIG. 3(A) shows the frequency spectrum of this output signal S+. In the same figure (A), ■1 and Inn are nth and n+
The fundamental wave component of each first scanning period, ■η and IF n
++ indicates the sideband of the fundamental wave component signal in each of the n-th and n+1-th scanning periods. Also, llIn.

■η+1 is the carrier wave f of each scanning period of n-th and n+1-th
The second harmonic component signal of z (-2f+), ■η
,■Tsukuda indicates its sideband.

As can be seen from FIG. 3(A), in the 62 adjacent scanning lines, the fundamental wave component signals are in opposite phases to each other, and as will be described later, vertical correlation can be used, so the luminance signal is as shown by V. The characteristics of the optical low-pass filter 1 are set so as to have a wide band up to frequency f2. That is, conventionally, the band of the luminance signal occupied a lower range than the fundamental wave component signal A, as shown by Y in FIG. 4, but in this embodiment, the fundamental component signal is within the band V of the luminance signal. The bandwidth is twice as wide as before.

In FIG. 2, the above output signal S1 is outputted by the IHii delay circuit 6 for one horizontal scanning period (1H)! It is extended and supplied to the subtraction black 7 and the adder 8, respectively, while it is directly supplied to the subtraction PJ7 and the adder 8, respectively.

As mentioned above, the luminance signal and the second harmonic component signal are in phase in each horizontal scanning period, whereas the fundamental wave component signal has a phase inversion every horizontal scanning period. As shown by the solid line in Figure 3 (B), the luminance signal and the second
The harmonic components and their sidebands are removed, and a signal S2 consisting only of the fundamental signal component and its sidebands is extracted.

On the other hand, as shown by the solid line in FIG. 3(C), from the adder 8,
A signal S3 consisting of a luminance signal V, a second harmonic component signal (2) and its sideband (2) from which the fundamental wave component signal and its sideband have been removed is extracted.

The signal S2 is converted into a P-wave from the fundamental wave component signal S4 by a bandpass filter 9 having a required passband width indicated by a broken line 3 in FIG. 3(B). On the other hand, the signal S3 is supplied to the low-pass filter 11, where the second harmonic component signal S5 is converted into a P wave by the bandpass filter 10 having the required passband width indicated by the broken line (■) in FIG. 3(C). The luminance signal indicated by V in FIG. 3(C) is separated into P waves and outputted to the output terminal 21. Although not shown, the signal S3 is a DC signal of the first term on the right side of equation (1) converted into a P wave by a low-pass filter, and then supplied to a color separation matrix circuit (not shown). Here, 84.8s is expressed by the following equation.

84-A 5in (ωt+ψ) ■The above signal S5 is made into a signal with a constant amplitude by the amplitude limiter rA12, and then is supplied to the multiplication circuit 13, where it is multiplied by the signal S4, and further only the fundamental wave component signal is The signals are supplied to an adder 15 and a subtracter 16 through a band pass filter 14, respectively.

The output signal of the adder 15 is outputted to the output terminal 19 through the detection circuit 17. Further, the output signal of the subtracter 16 is outputted to the output terminal 20 through the detection circuit 18. Separation circuit 5
The circuit after the output side is disclosed in the color television signal generator proposed by the applicant, and the adder 1
5 and the subtracter 16, both of which have a single carrier wave and whose amplitude changes depending on the color are taken out, so the detection circuit 1
7 and 18, detection is performed not only by envelope detection and square law detection, but also by average value detection. Detection circuit 17.1
A blue signal and a red signal are obtained from the output detection signal of 8 by the matrix circuit. Further, a green signal is obtained by matrixing the normal three-color mixed signal and these primary color signals.

Note that the second harmonic component signal can also be separated and extracted using a bandpass filter without using the 1HM extension circuit 6.

Furthermore, since the inclination angle θ is determined based on the deformed shape of the beam spot, it is not limited to that shown in FIG. 1, and if the scanning direction of the electron beam is reversed, Of course, the direction of inclination of the filter strips is also opposite to that shown in FIG.

Effects of the Invention As described above, in the present invention, the longitudinal direction of each filter strip of the stripe filter is tilted in accordance with the deformation of the effective beam spot shape due to the self-sharpening effect, so that the signal read out from the image pickup tube is It is possible to correct the change in modulation degree due to the self-sharpening effect in Since the signals are separated from each other, if the same color multiplex frequency as the conventional one is used, the luminance signal band can be changed from the conventional two.
The bandwidth can be doubled, and the resolution can be greatly improved compared to the conventional device.Also, since the fundamental wave component signal frequency can be the same as the conventional device, there is no need to widen the band of the preamplifier. Since the second high-frequency component signal can often be obtained with a good S/N, it has the advantage that the S/N of the color signal can also be improved.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a stripe filter structure according to an embodiment of the present invention, FIG. 2 is a block system diagram of an embodiment of the present invention,
FIG. 3 is a frequency spectrum diagram for explaining the operation of the block system shown in FIG. FIG. 6, a diagram showing the distribution, is a diagram for explaining the self-sharpening effect. 1... Optical low-pass filter, 2... Strive filter, 3... Image pickup tube, 5... Separation circuit, Fl...
- First filter strip, F2... second filter strip, F3... third filter strip. Patent applicant: Victor Japan Co., Ltd. 4 Figure 71 72 Solution J (Figure 5 Figure 6 (B)) = Self-voiced ξ3d pH

Claims (1)

[Claims] a first filter strip that transmits only the first primary color light of any one of the three additive primary colors; Any one
a second filter strip that transmits only the mixed color light of the second primary color light of the two primary colors and the first primary color light, and a third filter strip that transmits the white light, in a certain order, and , each filter strip is arranged so that its longitudinal direction is inclined with respect to the scanning line direction, and the number of scanning lines is selected with respect to the pitch of the first to third filter strips in the direction perpendicular to the scanning line. Applying light from the subject to the photoconductive surface (or photocathode) of the image pickup tube through the configured stripe filter,
Among the luminance signal taken out from the image pickup tube and the harmonic component signal of the fundamental wave component signal having a spatial frequency determined by the repetition period of the first to third filter strips in the scanning line direction,
A color device that sets the fundamental wave component signal within a band of the luminance signal, and separates and outputs the fundamental wave component signal and the luminance signal by utilizing vertical correlation of image pickup tube output signals of at least two horizontal scanning lines. The imaging device is configured to maximize the area occupied by the beam spot in the same filter strip based on the deformed shape of the beam spot that is effectively deformed into a crescent shape due to a self-sharpening effect. , the inclination angle between the scanning direction and the longitudinal direction of the first to third filter strips is selected.