JPS6129195B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a television camera with a built-in pattern projector, in which a test pattern projector is fixedly or removably attached to the objective lens of the television camera.

Currently, most color TV cameras used for broadcasting are of the three-tube type, and when replacing the image pickup tube, during regular maintenance, or before starting operation, a series of adjustment operations are required to ensure good color image quality. Requires. Conventionally, test patterns such as resolution, registration, grayscale, etc. are illuminated with flat light, and after facing the imaging lens and framing to the regular dimensions, the CCU adjuster ( (Some of it is on the camera side)
We are doing this by moving. A commonly used method for imaging this type of test pattern is to illuminate a transmissive or reflective test pattern with external light. However, in the case of this method, it is necessary to exchange patterns and perform setting operations each time, which requires a lot of effort and time.

On the other hand, although the stability of color TV cameras has been significantly improved, there are cases where it is necessary to check using test patterns even during operation, which is difficult to do with the above-mentioned method.

In order to improve the operability of color TV cameras by improving these problems, a method has been developed in which a test pattern projector is built into the zoom lens, which is the objective lens of color TV cameras (usually). Due to insufficient performance, it is only used in supplementary applications.

Next, the reason will be explained using drawings.

Referring to FIG. 1, a conventional method of imaging a test pattern using external light illumination will be described. A light source 1 illuminates a reflective test pattern chart 2 such as gray scale, and the chart 2 is separated into a three-color separation prism system Y using a zoom lens X consisting of a zoom section and a relay section.
After color separation into red, green, and blue region light,
An image is formed on the _RGB light receiving surface of each image pickup tube 3. At this time, Chart 2 normally sets the light source 1 so that the color temperature is 3000 and the illuminance is 2000 lux, which are the standard imaging conditions.
The brightness on the light-receiving surface of the image pickup tube is adjusted by the aperture 4 of the zoom lens.

On the other hand, the imaging method using the built-in pattern projector is
A transmission type test pattern chart 2', such as a gray scale, is illuminated through a condenser lens 9 using a light source 1' such as a tungsten incandescent lamp. The light passing through the chart 2' is reflected by the reflecting mirror 12.
After being reflected, the light enters the projection lens 8. The light emitted from the projection lens 8 is reflected by the prism-shaped half mirror 6 disposed between the relay lens front group 5 and the relay lens rear group 7 of the relay section of the zoom lens X, and then reflected by the relay lens rear group 7 and the relay lens rear group 7. The light passes through a three-color separation prism system Y and is color-separated into red, green, and blue light, and reaches the _RGB light receiving surface of each image pickup tube 3. At this time, the projection lens 8 and the relay lens rear group 7 form an image of the chart 2' on the light receiving surface of each of the image pickup tubes 3, _RGB , for red, green, and blue region light.

Here, the power supply for the light source 1 of the built-in pattern projector is usually a stabilized DC voltage of 24 V and a current capacity of 0.75 A, which is the same as the circuit power supply of the color TV camera, so the light source 1' is a halogen bulb or filament. Since it is not possible to use high color temperature light bulbs such as flat-wound optical light bulbs, ordinary tungsten incandescent light bulbs with a color temperature of 2550 ± 50 are used for outdoor lighting. It is about 450 times lower than that of light source 1 in . In addition, the spectral transmittance characteristics of the zoom lens . On the other hand, the built-in pattern projection optical system does not absorb as much light in the blue region as the Zoom Lens X because the overall thickness of the glass is much thinner than that of the Zoom Lens X and because high refractive index glass is used relatively less. .

Based on the above, when comparing the imaging state of the test pattern with external light illumination and the imaging state of the test pattern with the built-in pattern projector, it is found that the brightness of both methods on the light receiving surface of the green region light imaging tube _3G is equal. Then, the latter method becomes brighter on the light receiving surface of the red region light imaging tube _3R , and the former method becomes brighter on the light receiving surface of the blue region light imaging tube _3B . Therefore, a color filter (spectral characteristic correction filter) 10 and an ND filter 11 for adjusting the light amount so that the brightness of the former method matches that of the latter method are arranged near the condenser lens 9 of the built-in pattern projector. has been done.

However, in the built-in pattern projector as described above, it may be difficult to find an appropriate color correction filter 10, or the color temperature of the tungsten bulb that is the light source 1', or each optical element such as the lens or reflective mirror of the pattern projection optical system. Due to variations in coating, etc., it has been extremely difficult to completely match the imaged state of the test pattern by external light irradiation.

By the way, the variation in the imaging state (that is, the ratio of the brightness of red, green, and blue region light on the light receiving surface of each image pickup tube) due to variations in the color temperature of the light source 1' is 2550〓 red. green.
If the brightness ratio of blue is 1:1:1, in the case of +50〓, it is 0.98:1:1.04, and in the case of -50K, it is 1.03:
1:0.96, which far exceeds the operationally acceptable adjustment range of 0.1 to 0.2%, and compared to the color image quality obtained by adjusting the sensitivity characteristics of each image pickup tube with 2550〓, the color image quality of each image pickup tube is +50〓. When the sensitivity characteristics of the color image are adjusted, that is, when the red sensitivity is improved, the color image quality obtained becomes reddish, and in the case of -50〓, the color image quality becomes bluish, which is inconvenient for practical use.

On the other hand, it is not practical to select the color temperature of light bulbs more strictly than ±50〓 from the viewpoint of supply quantity and price.

As mentioned above, the current built-in pattern projector does not match the imaged state of the test pattern by external light illumination due to a number of factors, and therefore, the reality is that it is only used in an auxiliary manner.

The object of the present invention is to eliminate the above-mentioned drawbacks, to put a built-in pattern projector into practical use, and to improve the operability of a color TV camera.

This purpose is to make the light source device a plurality of individual light source units, and by making the light source units individual, it is possible to adjust the test pattern illumination light to a desired scene and color temperature.

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 2 shows a first embodiment of the light source section of a television camera according to the present invention, which can be used in place of the light source 1' of the built-in pattern projector shown in FIG.

23, 23', and 23'' are optical transmission bodies such as optical fiber bundles, and one end of each is bundled into one by a tube 24.

21 _RGB is a light source such as a tungsten light bulb, and it does not matter if they are the same or different types. Between the light source 21 _RGB and the light transmitters 23, 23', 23'' are a red filter 22R that mainly transmits red region light, a green filter 22G that mainly transmits green region light, and a blue filter _22G that mainly transmits blue region light. Filters 22 _B are arranged respectively. Red, green, and blue filters 22 An example of _{RGB spectral} transmission characteristics is shown in the third example.
As shown in Figure. Light source 21 If _{the RGB} color temperature is low, the blue region light will be insufficient, so
Using a filter with the characteristics shown in the figure is convenient because the green filter _22G also transmits light in the blue region, thereby making up for the deficiency.

Light source 21 The light emitted from _RGB is red. green. The blue filter 22 passes through _RGB , and the light transmitter 23,
23', 23'' light entrance apertures 23 _A , 23' _A , 23'' _A
, propagates inside the optical transmission bodies 23, 23', 23'' by total reflection, etc., and from the light exit 25 bundled into one by the tube 24, red, green, and blue region lights are mixed and diffused. radiate.

At this time, red. green. The amount of light of each blue region light is
For example, the light source 21 _RG as shown in FIG.
A variable resistor 41 _RGB is provided in the electric circuit of _B , and by changing this resistance value, the light source 21 _RGB
By adjusting the brightness of each light source 21 _RGB by independently changing the voltage or current supplied to each light source, red. green. The amount of light in the blue region can be adjusted as desired. Note that FIG. 4 shows the case where the power supply to the light source is a DC constant voltage power supply, and FIG. 4 shows the case where the power supply to the light source is a DC constant current power supply.

Then, the light exit port 25 may be installed at the position of the light source 1' of the built-in pattern projector shown in FIG. The light source part of the present invention has a red color. green. Since there is a light intensity adjustment function for blue region light, the color filter 10 of the built-in pattern projector (shown in Figure 1) and the ND filter 11 for _light intensity adjustment are _unnecessary . If it has, 22 _RGB can be omitted.

FIG. 5 shows another embodiment in which the light source 21 is red with _RGB . green. A diffuser plate 51 is illuminated through the blue filter 22 _RGB , and the diffuser plate 51 is installed at the position of the light source 1' in FIG. At this time, if the diffusivity of the diffusion plate 51 is not good, projection unevenness is likely to occur in the pattern projector, so in this case it is necessary to replace the condenser lens 9 with one that does not cause unevenness. Also, if the light source 21 _RGB is arranged as shown, it will be small and easy to sort when replacing the condenser lens 9 with another one.

FIG. 6 also shows another embodiment, in which the light source 21 _RG is made of half mirrors or dichroic mirrors 61 and 62.
_{．． The B} lights are combined to illuminate the diffuser plate 51. Others are the same as in FIG. 5. The method of adjusting the amount of light in the embodiments in FIGS. 5 and 6 is the same as in the embodiment in FIG. 2.

FIG. 7 shows an example in which two light sources 71, 71' are used, and 72, 72' are color correction filters having spectral characteristics as shown in FIG. The light is combined to illuminate the diffuser plate 51. In this case two light sources 7
By independently changing the voltage or current of 1,71', the color temperature of the light source can be changed appropriately to obtain the desired red color. green. A balance of light in the blue region is obtained, and the total amount of light is adjusted by providing an ND filter 11 (FIG. 1) or an aperture in the pattern projection optical system.

As described above, according to the present invention, it is possible to easily match the imaging state of a test pattern using conventional external light illumination and the imaging state of the built-in pattern projector, and thereby the built-in pattern projection With the aim of putting this machine into practical use, the operability of color TV cameras was significantly improved.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a television camera to which a conventional external pattern projection method and a built-in pattern projection method are applied in the same drawing, and FIG. 2 is a diagram showing a light source device for test pattern illumination applied to the television camera of the present invention. FIG. 3 is a diagram showing the wavelength transmittance of the filter shown in FIG. 2, where the vertical axis represents the transmittance and the horizontal and vertical directions represent the wavelength. FIG. 4 is a light intensity adjustment circuit diagram of each light source unit, FIG. 5 is a diagram showing the second embodiment, FIG. 6 is a diagram showing the third embodiment, FIG. 7 is a diagram showing the fourth embodiment, and FIG. FIG. 8 is a diagram showing the wavelength transmittance of the filter shown in FIG. 7. In the figure, X is an objective lens, Y is a color separation prism,
3 _RGB is an image pickup tube, 1 and 1' are light sources, 12 is a mirror, 21 _RGB is a lamp constituting a light source unit, 22 _RGB is a filter, and 23 is a fiber.

Claims (1)

[Claims] 1. A television camera incorporating a pattern projector that forms an image of the test pattern on an imager by introducing light from a test pattern illuminated by a light source device into an optical path of an objective lens through an optical deflector. Each light source device has a light source, a plurality of light source units of different colors, and a light mixing means for mixing and emitting light from these light source units,
A television camera configured to adjust the amount of light incident on the light mixing means from the light source unit.