JPS636944Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a color television imaging device.
In particular, in an imaging device provided with a color stripe filter that periodically selects and decomposes specific colored light rays and has a common color energy component for each filter strip, the color energy component is substantially the same as the common color energy component. It is an object of the present invention to provide a color television imaging device that eliminates color modulation of bias light by applying component light as bias light to an image sensor, and that can simplify the circuit system in this regard. .

In a color television imager, a color stripe filter of the type in which each filter strip has a common color energy component is provided as a color stripe filter for synchronously selecting and separating particular color rays from an incoming light beam. There is an imaging device that incorporates an imaging tube. Further, in a color television image pickup apparatus, a means is provided for applying bias light to an image pickup element in order to solve the so-called afterimage phenomenon.

There are two ways to apply bias light to the image sensor: one is to irradiate the bias light from the front of the target, and the other is to irradiate it from the back of the target. However, there were various drawbacks associated with bias light irradiation.

1 and 2 both show a color television imaging device equipped with the color stripe filter described above, and FIG. 1 employs a method of applying bias light from the front side of the target.
In FIG. 2, a method is adopted in which bias light is irradiated from the back side of the target.

In FIGS. 1 and 2, reference numeral 1 denotes an image pickup tube, and a color stripe filter 3 and a target 4 are laminated on the back side of a face plate 2 of the image pickup tube.
As shown in an enlarged view in FIG. 3, this color stripe filter 3 includes filter strips 3-1, 3-2,
The color energy components of 3-3, 3-4, ... are G
(record), C _Y (cyan), W (white), G...
It is a C _Y /W type filter, where C _Y is G+B (blue),
Since W is R (red) + G + B, each filter strip has G as a common color energy component.

The optical image of the subject 5 passes through the imaging lens 6, the half mirror 7 (in the case of FIG. 1), and the reflective infrared cut filter 8, is modulated by the color stripe filter 3 of the imaging tube 1, and is imaged onto the target 4. Ru. As a result of this imaging, a video signal is output from the image pickup tube 1. This video signal is amplified by a preamplifier 9, then separated and demodulated into R, G, and B by a color separation circuit 10, and subjected to necessary waveform processing in a process circuit 11. is encoded by the encoder 12,
It is output from terminal 13 as an NTSC color television signal.

Further, 15 is a bias light source, which is generally an incandescent light bulb, and its spectral energy ranges from the entire visible light region to the infrared region.

In FIG. 1, bias light from a bias light source 15 is reflected by a half mirror 7, passes through a reflective infrared cut filter 8 and a color stripe filter 3, and illuminates the front surface of a target 4. This bias light is
Like the light from the subject 5, it will be modulated by the color stripe filter 3, and the modulated signal will be added to the video signal from the subject 5. Therefore, it is necessary to remove the signal component using bias light in the process circuit 11 at the subsequent stage, but since the bias light is white light, each of the filter strips 3-1, 3-2, 3 of the color stripe filter 3 described above −
The levels modulated by 3, . . . differ for each filter strip as shown in FIG. However, it has the disadvantage that adjustment is troublesome.

Furthermore, in the apparatus shown in FIG. 2, the bias light from the bias light source 14
5, and is further reflected and scattered within the tube of the focusing electrode 16 to illuminate the back side of the target 4. Here, since both the target 4 and the color stripe filter 3 are extremely thin, the bias light passes through them and exits to the lens side. The near-infrared component (including the red component) of the light exiting to the lens side is reflected by the filter 8, passes through the color stripe filter 3 again, and illuminates the front surface of the target 4. For this reason, each filter strip 3-1, 3- of the color stripe filter 3
2, 3-3 The modulation level for the filter strip 3-3 having a medium red energy component is different from that of the other filter strips, and the process circuit 1
1 requires a separate setup adjustment as before.

Furthermore, since the bias light is scattered light, the light that illuminates one point on the target 4 is not entirely occupied by the light that has passed through one filter strip in the color stripe filter 3, but rather, for example, in the color stripe filter 3. It is composed of light that has passed through two adjacent filter strips separately. Therefore,
When white light is used as bias light, primary and secondary modulation components will appear as bias light components from the image pickup tube, and the process circuit 11
In this case, signal level correction for the above-mentioned primary and secondary modulation components is also required, and a so-called color mixing phenomenon occurs.

The present invention eliminates the above-mentioned drawbacks, and an embodiment thereof will be described below with reference to the drawings.

FIG. 5 shows an embodiment of a color television imaging device according to the present invention. In the figure, Figures 1 and 2
Components that are the same as those shown in the figures are given the same reference numerals, and their explanations will be omitted.

A trimming filter 20 is provided in front of the white bias light source 14 and has a characteristic of allowing only color components corresponding to the common energy components of the color stripe filters 3 to pass through. In this embodiment, as the color stripe filter 3, G.
Since C _Y and W filters are used and the common energy component is G, the trimming filter 20 has the characteristic of passing only the green component of the white light from the light source 14 and cutting out other color components. I'm using the one from That is, as the bias light, light whose main color energy component is contained in all the stripes of the color stripe filter 3 is used.

Therefore, the green component light that has passed through the trimming filter 20 is reflected by the half mirror 7 and illuminates the front side of the target 4 as bias light. This green component light commonly passes through each of the filter strips 3-1, 3-2, 3-3, . irradiate.

Therefore, the signal component caused by the bias light becomes a green component with a constant level as shown in FIG. It would be best to remove it. Therefore, in the white balance adjustment that determines the image quality of a color television camera, there is no need to adjust all of the R, G, and B colors individually, and only G needs to be adjusted, thereby reducing the number of adjustment steps. Further, in connection with this, the process circuit 11A itself has a simple structure in which circuit portions for R and B are not required.

Furthermore, the bias light is passed through a color stripe filter 3.
Because the color corresponds to the common color energy of each filter strip, the bias light component is As a result, primary and secondary modulation components do not appear. Therefore, even when capturing images of particularly dark scenes, there is no confusion with low-level color modulation caused by bias light, and the balance between primary and secondary components is maintained, resulting in improved color reproducibility.
The S/N ratio also improves.

According to the above embodiment, since G, C _Y , and W filters are used as the color stripe filter 3, green, which is a color energy component common to each filter strip, is selected as the bias light. But another color stripe filter, e.g. R.
When using Y _L and W filters, red light, which is a common color energy component, and B
When using C _Y and W filters, it is sufficient to use blue light, which has a common color energy component, as bias light, and also W-C _Y or W-Y _L
When using a frequency separation type filter, green light, which is a common color energy component, may be used as bias light. Therefore, the trimming filter 20 with predetermined characteristics may be selected and used depending on the type of color stripe filter 3 of the image pickup tube.

FIG. 6 shows a configuration in which a colored rubber cap 21 is used in place of the trimming filter 20 of FIG. 5 and is placed over the bias light source 14 to allow only a specific color to pass through.

Further, the same effect can be obtained even when the bias light source 14 and the trimming filter 20 or the bias light source 14 covered with the colored rubber cap 21 are disposed on the rear side of the image pickup tube 1 as shown in FIG. .

Furthermore, an LED or the like which itself emits light of a specific color may be used as the bias light source, and in this case, the trimming filter 20, colored rubber cap 21, etc. are not necessary.

As described above, according to the color television imaging device of the present invention, in particular, a color television having an image pickup element provided with a color stripe filter having a common color energy component for each filter strip. Since the imaging device is configured to use light with substantially the same color energy component as the above-mentioned common color energy component as bias light, color modulation due to the bias light does not occur, and the removal of the bias light component is similar to the above-mentioned common color energy component. It is only necessary to perform the adjustment for the color energy component of , the so-called color mixing phenomenon can be avoided, and color reproducibility and S/N ratio can be improved.

[Brief explanation of the drawing]

1 and 2 are diagrams showing examples of conventional color television imaging devices, FIG. 3 is a diagram showing an example of a color stripe filter in which each filter strip has a common color energy component, and FIG. A and B are diagrams showing bias light components in the conventional example and in the present invention, respectively, FIG. 5 is a diagram showing an embodiment of the color television imaging device according to the present invention, and FIG. 6 is a modification of the present invention device. FIG. 1... Image pickup tube, 2... Face plate, 3...
...Color stripe filter, 4...Target, 6
...Imaging lens, 8...Reflective infrared cut filter, 10...Color separation circuit, 11, 11A...Process circuit, 12...Encoder, 14...Bias light source, 20...Trimming filter, 21...
Colored rubber cap.

Claims (1)

[Scope of utility model registration request] an image sensor that captures an image of a subject and receives an electrical signal;
an imaging lens that forms an optical image of a subject on the imaging element; a plurality of color stripe filters that periodically select and decompose specific color rays from among the rays that have passed through the imaging lens and that have a common color energy component; A color television imaging device comprising bias light source means for applying light having substantially the same color energy component as the common color energy component to the image pickup element as bias light.