JPS6218886A - Color image pickup device - Google Patents

Abstract

PURPOSE:To increase an S/N, to obtain excellent color reproducibility, and to decrease the number of scanning lines by scanning an image pickup tube in the lengthwise direction of stripes of a color stripe filter and using only a basic wave component for color demodulation. CONSTITUTION:A scan is made in the lengthwise direction of stripes of the color stripe filter 1a to perform color multiplexing with a carrier of relative low frequency of a basic wave component of 15.75kHzX6=94.5kHz with respect to the period of one group of G, C, and W. Consequently, the S/N is higher than that of a conventional device and the image pickup tube reproduces the state of the stripes faithfully, so the color reproducibility is improved. Further, an optional specific color is picked up prior to image pickup operation to store the basic wave component of a color multiplex carrier in the storage device 12 of a color demodulating circuit 12 and the stored signal is used during the image pickup operation to detects the basic wave synchronously by a period detecting circuit 15, thereby performing color demodulation. Consequently, only one scanning light beam of the image pickup tube 21 is required for each filter stripe.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a color imaging device, for example, in a single tube color television camera, a color multiplexed signal is obtained from an image pickup tube provided with a color stripe filter and color demodulated. Regarding equipment.

2. Prior Art Regarding the conventional single-tube color television camera, for example, the present applicant has disclosed Japanese Patent Application No. 54-28450 (Japanese Patent Publication No. 59-35).
For example, G (green), C (cyan),
A color multiplexed signal is obtained by scanning in a direction perpendicular to the longitudinal direction of the stripe of a color stripe filter consisting of repetitions of W (W light).

The above conventional method performs scanning in a direction perpendicular to the longitudinal direction of the stripe, so color multiplexing is performed using a relatively high carrier wave of 4 M +-+ Z for each cycle of the G, C, and W color stripe filters. The noise is higher in the higher frequencies, and the modulation degree of the image pickup tube is lower in the higher frequencies.As a result, the signal-to-noise ratio is low, and the image pickup tube cannot faithfully reproduce the color stripe state. There was a problem that the color reproducibility deteriorated because the color was removed.

In addition, since this device scans in a direction perpendicular to the longitudinal direction of the stripes, a color-multiplexed signal is obtained in the scanning direction.As a result, the luminance signal band is limited by the color-multiplexed carrier wave, and the band is There was a problem in that it became narrow and good horizontal resolution could not be obtained.

Therefore, in order to solve the above-mentioned problems, the present applicant previously proposed in a special edition application dated June 24, 1985 that a high S/N ratio could be obtained by color multiplexing using a relatively low carrier wave. We proposed I!2, a color imaging device that can provide good color reproducibility, widen the luminance signal band, and obtain good horizontal resolution.

FIG. 5 is a block system diagram of an example of a first-order device, and FIG. 6 is a diagram showing the relationship between the filters 1 to 1 to live filters used in the device and scanning lines. As shown in FIG.
The structure is such that scanning is performed in the longitudinal direction of the stripes a, and the number of scanning lines a is set to the number that can be reproduced by the color stripe filter 1a, for example, six for one set of G, C, and W. There is.

This device is said to be compatible with the step energy method, and since it is only necessary to reproduce the fundamental wave component and the second harmonic component in the step energy method, the number of scanning lines can be determined based on the sampling theorem. If there are four or more, it can be reproduced.

In FIG. 5, the color stripe filter 1a shown in FIG.
The signal 17 from the image pickup tube 1 equipped with 17 is supplied via the preamplifier 2 to the AD converter 3 where it is -AD converted, and is stored in the field memory 4' as all the points shown in the sixth figure.
a12, ai3, ”', all, a,'
2.

a23. ...a31. It is sequentially inserted in the direction of aν, 0 feathers, etc. (Fig. 7 (A)). Field memory 4'
The information signals written in the directions are perpendicular to the writing direction, that is, the points a++, a2e, a3+, -, ad2. an, a:
a.

..., a, 3. a23. The signals are sequentially read out in the directions an, . . . and supplied to the DA converter 5, where they are DA-converted.

The D△-converted (q signal is as shown in Fig. 8,
This signal is similar to the color multiplexed signal obtained by the general step energy method. In this case, if the above sampling theorem conditions are fnffi, the signal will be the same as the signal color multiplexed by the step energy method, and even if the sampling phase and its frequency change, the fundamental wave component signal and the second harmonic component will be generated. The signal can be faithfully reproduced.

The signal taken out from the DA converter 5 is supplied to a color demodulation circuit 6 having the same configuration as a step energy type color demodulation circuit and is color demodulated, but since the signal is read out in the vertical direction in the memory 4', If this continues, the screen will be tilted 90 degrees. Therefore, the output signal of the color demodulation circuit 6 is AI)
After being AD converted by the converter 7, it is supplied to the field memory 8', and the points a11. a2+, a3+, -, ad2
．． az2. a32゜...l a13. a23. a33
．． . . . (Fig. 7 (B)), and when reading, the writing direction is perpendicular to the writing direction, that is, the points an, ad2.
．． ah3. °=, a21°az2. a23.・−,
a3+, a32. a33. They are read out sequentially in the - direction.

The signal read from the memory 8' is converted to DA by the DA converter 9.
It is converted and taken out from the output terminal 10.

In this way, in the proposed device, the color stripe filter 1
Since scanning is performed in the longitudinal direction of the stripe a, the fundamental wave component is 15.75 kHz x 5 = 94.5kf-(
This means that color multiplexing is performed using a carrier wave with relatively low z,
As a result, the signal-to-noise ratio is higher than that of conventional devices, and the image pickup tube can faithfully reproduce the state of the color stripe, resulting in good color reproducibility.

In addition, in the proposed device, since the stripes are scanned in the longitudinal direction, there is no color multiplexing in the horizontal direction, and as a result, the same M image resolution as black and white can be obtained, and the luminance signal band is a color multiplexed carrier wave. Therefore, the band can be widened and good horizontal resolution can be obtained.

<; J3, The number of sets of live filters 1a to the bus 1 in the above proposed device is 240 sets (corresponding to 1 field in the NTSC system), and the vertical W? The image resolution is 2 TV lines, and the overall vertical resolution is 480 TV lines, which is NTS.
It is determined by the number of scanning lines of the C method, and the vertical resolution is the same as that of conventional devices.

On the other hand, FIG.
A block system diagram of the device proposed in the patent application No. 1 (title of the invention ``Color Imaging Device'') is not shown.

The output signal of the image tube 11 equipped with a color stripe filter 11a having the configuration shown in FIG. + =: c+ (2/3)i
While the DC component n + (1/3>iR is extracted, it is supplied to the bandpass filter 14, and while the imaging r! Detected 82 =A sin (ωt+
φ) sin(ω is assumed to be 10〉. Signal S+
, 82 are supplied to the matrix circuit 16 for calculation, and a color video signal is taken out from the output terminal 10.

In this way, the output signal of the thermal imaging tube 11 includes a DC component and a modulated wave in which a single carrier wave is amplitude- and phase-shift-modulated by a plurality of pieces of color information. By performing synchronous detection using a reference signal having a predetermined phase shift with respect to the fundamental wave component, each predetermined color signal can be individually demodulated. Has a given phase! Requires quasi-signal.

Therefore, prior to the start of image transport, an object of a specific color is imaged, and at this time, the fundamental wave component of a single carrier wave in the output signal of the image pickup tube 11 is stored in the storage device 17 for at least 61 fields. The fundamental wave components of the stored carrier waves are read out during the image carrying operation, and the reference signal generation circuit 18 generates reference signals each having a predetermined phase. Demodulation can be performed.

The fundamental wave component extracted from the bandpass filter 14 is sent to the FM detection comparison circuit 1 along with the reference signal from the reference signal generation circuit 18.
A signal corresponding to the frequency difference between the two signals is taken out from there, and the period of the clock signal of the tarock signal generator provided in the storage device 17 is controlled so that the frequency difference between the two signals is eliminated. do. By doing so, the reference signal supplied from the reference signal generation circuit 18 to the synchronous detection circuit 15 has the same time axis fluctuation as the time axis fluctuation of the output signal of the bandpass filter 14, and the deflection circuit Even if the frequency and phase of the color multiplex carrier wave change due to time axis fluctuations in the output signal of the image pickup tube due to stability or other reasons, the correct color signal is always output from the synchronous detector 15, and the white balance changes.45 color shading etc. will not occur.

Note that the address signal generator of the storage device 17 is reset by the output pulse of the carrier start position detection circuit 20.
and correct lettering is performed.

Therefore, the present invention has a configuration that combines the device shown in FIG. 5 and the device shown in FIG. Another object of the present invention is to provide a color imaging device that can widen the luminance signal band, obtain good horizontal resolution, and reduce the number of scanning lines.

Means In FIG. 1, the color stripe filter 1a includes an optical color separation means whose stripe longitudinal direction is arranged parallel (substantially parallel) to the scanning direction of the image pickup tube 21, an AD converter 3, and a field memory 4.
, the DA converter 5 is a means for obtaining a color multiplexed signal in a direction perpendicular to the scanning direction of the image pickup tube 21, and the color demodulation circuit 12 is a means for obtaining a color multiplexed signal in a direction perpendicular to the scanning direction of the image pickup tube 21, and a color demodulation circuit 12 is a means for obtaining a fundamental wave component of a color multiplexed carrier wave obtained by capturing an arbitrary specific color in advance before imaging. These are embodiments of a means for storing the fundamental wave component for at least one field and demodulating the color by using the stored fundamental wave component as a reference wave during imaging operation.

The working color stripe filter 1a is arranged with the longitudinal direction of its stripes G, C, W parallel (substantially parallel) to the scanning direction of the Ia picture tube 1,
A ΔD converter 3, a field memory 4, and a DA converter 5 obtain a color multiplexed signal in a direction perpendicular to the scanning direction of the image pickup tube 1, and a color demodulation circuit 12 captures an arbitrary specific color in advance before imaging. The fundamental wave component of the color multiplexed carrier wave obtained by the color multiplex carrier wave is stored for at least one field period, and the stored fundamental wave component is used as a reference wave to perform color demodulation during the image removal operation.

Embodiment FIG. 1 shows a block system diagram of an embodiment of the apparatus of the present invention. In the figure, the same components as those in FIGS. 5 and 9 are given the same numbers and their explanations are omitted.

Similar to the apparatus shown in FIG. 9, this device captures an image of any specific color prior to imaging, stores the fundamental wave component of the color multiplex carrier wave in the storage device 17 of the color demodulation circuit 12, and stores the fundamental wave component during the decoy image operation. Using the signal as a reference wave, a synchronous detection circuit 15 synchronously detects the fundamental wave and performs color demodulation. In this way, since only the fundamental wave component is used during color demodulation, in general, to reproduce the fundamental wave component and the second harmonic component, the number of scanning lines is 4 for each group of G, C, and W under the sampling theorem. The device of the present invention can do what is required with just two wires. As a result, the number of scanning lines of the image pickup tube 21 may be one for each filter strip, as shown in FIG. 2, and the number of scanning lines can be reduced compared to the apparatus shown in FIG.

On the other hand, points b11° b12 .
The writing of .

Other operations and effects are the same as those of the devices shown in FIGS. 5 and 9, so their explanations will be omitted.

Note that when the scanning direction of the image pickup tube is set vertically, the longitudinal direction of the stripes of the color stripe filter is also set vertically, and data is written in the memory 4 in the vertical direction and read in the direction perpendicular to this. If you do it the same way.

Effects of the Invention According to the apparatus of the present invention, since the image pickup tube is scanned in the longitudinal direction of the stripes of the color live filter, color multiplexing is performed using a relatively low carrier wave, which results in a low S/N ratio. It is possible to obtain good color reproducibility by increasing the luminance signal band by 1Q, and it is also possible to obtain good horizontal resolution by widening the luminance signal band by 1Q. Generally speaking, to reproduce the fundamental wave component and the second harmonic component, four scanning lines are required for each set of G, C, and W under the condition of quantity numbering theorem. However, it has the advantage that the number of scanning lines can be reduced by 1/2 of that.

[Brief explanation of the drawing]

FIGS. 1 and 2 are a block diagram of an embodiment of the device of the present invention and a schematic diagram showing the relationship between the color stripe filter and the scanning line used in the device of the present invention, and FIG. 3 is a schematic diagram showing the relationship between the color stripe filter and the scanning line, and FIG. 4 is a diagram for explaining the state, FIG. 4 is an input signal waveform diagram of the color demodulation circuit in the device of the present invention, and FIGS. 5 and 6 are block diagrams of an example of the device previously proposed by the applicant, respectively. and a schematic diagram showing the relationship between the stripe filter and the scanning line used in the device, FIG. 7 is a diagram for explaining the state of writing to the field memory of the device, and FIG. 8 is an input diagram of the color demodulation circuit in the device. The signal waveform diagrams in FIGS. 9 and 10 are block diagrams of other examples of the device previously proposed by the applicant, and schematic diagrams showing the relationship between color stripe filters and scanning lines used in the device. 1a... Color stripe filter, 3, 7... AD converter, 4, 8... Field memory, 5, 9... D
A converter, 10... Output terminal, 12... Color demodulation circuit, 13... Low pass filter, 14... Bandpass filter,
15... Synchronous detection circuit, 16... Matrix circuit,
17...Storage device, 18...Reference signal generator. Drain l Figure f Al Figure 3 [Continued from page 81 11] Inventor Asakura Biography Moriyamachi, Kanayō Ward, Yokohama City

Claims (1)

[Claims] A color stripe filter is arranged with the longitudinal direction of its stripes parallel (substantially parallel) to the scanning direction of the imaging tube, a color multiplexed signal is obtained in a direction perpendicular to the scanning direction, and an arbitrary specific color is imaged in advance before imaging. What is claimed is: 1. A color imaging device, comprising: storing a fundamental wave component of a color multiplexed carrier wave obtained by a color multiplexing carrier wave for at least one field period, and performing color demodulation using the stored fundamental wave component as a reference wave during an imaging operation.