JPS6240918B2 - - Google Patents

Description

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

Color TV currently used for broadcasting stations
Most cameras are of the three-tube type, and require a series of adjustment operations to ensure good color image quality when replacing the imaging tube, during regular maintenance, or before use. Traditionally, these have mainly been used to illuminate test patterns to check adjustment items such as resolution, registration, and gray scale.
An image of this test pattern is formed on the image pickup tube using an image pickup lens, and after being framed to regular dimensions, the CCU (central
This is done by adjusting the controllers (some of which are located on the camera side) of the control unit. A commonly used method for projecting 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 set 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, it is sometimes necessary to check them using test patterns even during use, 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 a color TV camera (in the normal case). Due to insufficient performance, it is only used in supplementary applications.

One of the reasons why this performance is insufficient is that a pattern image with a desired color temperature cannot be easily formed on the image pickup tube.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a television camera equipped with a test pattern projector that allows a test pattern image having a desired color temperature to be easily obtained.

This objective is achieved by forming a plurality of color component beams in the test pattern projector, adjusting the intensity of at least one of the color component beams, and integrating these beams again.

Note that the color component light does not mean only a monochromatic light beam, but may also be a light beam that is a mixture of a plurality of monochromatic lights.

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

As mentioned above, there are two methods of pattern projection, and these two methods will be explained using FIG.

FIG. 1 is a diagram illustrating a conventional method of projecting a test pattern using external light illumination. A light source 1 illuminates a reflective test pattern chart 2 for, for example, gray scale adjustment, and the chart 2 is converted into a three-color separation prism system Y using a zoom lens composed of a zoom section 1 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 aperture 4 of the zoom lens X adjusts the brightness on the light receiving surface of the image pickup tube.

Another method is also shown in FIG. That is, in the imaging method using the built-in pattern projector, a transmission type test pattern chart 2' is illuminated by a light source 1' such as a tungsten incandescent light bulb through a condenser lens 9. The light passing through the chart 2' is reflected by the reflecting mirror 12 and then 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.
The light then passes through a three-color separation prism system Y, where it is color-separated into red, green, and blue region 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. However, it is not possible to use flat-wound, so-called high color temperature light bulbs such as optical light bulbs, and we use regular tungsten incandescent light bulbs with a color temperature of 2550 ± 50K, so they are not suitable for outdoor lighting. It is about 450 times lower than that of light source 1.

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 using external light illumination.

By the way, the variation in the imaging state (i.e. the ratio of the brightness of red, green and blue region light on the light receiving surface of each image pickup tube) due to the variation in color temperature of the light source 1' is 2550〓 of red, green and blue.
If the brightness ratio of blue is 1:1:1, in the case of ±50〓 it is 0.98:1: in the case of 1.04-50〓 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 adjusting the sensitivity characteristics of , that is, increasing the red sensitivity, the color image quality obtained becomes reddish, and when -50〓, it 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 described above, the current built-in pattern projector does not match the projection state of the test pattern under external light illumination due to a number of factors, and therefore, the reality is that it is only used in an auxiliary manner.

Hereinafter, reference examples useful for understanding the present invention will be described first, and then embodiments of the present invention will be described using FIGS. 15 and 16.

This reference example is exactly the same as that in FIG. 1 except that the light source section 1' in FIG. 2 is replaced with the light source section in FIG.
In the figure, reference numerals 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.

21R.GB is a light source such as a tungsten light bulb, and it does not matter whether they are the same or different types. A red filter 22R that mainly transmits red region light, a green filter 22G that mainly transmits green region light, and a blue filter 22 that mainly transmits blue region light.
B are arranged respectively. Figure 3 shows an example of the spectral transmission characteristics of the red, green, and blue filter 22R.GB.
Shown below. When the color temperature of the light source 21R.GB is low, there is a shortage of light in the blue region, so if you use a filter with the characteristics shown in the figure, the green filter 22G will also transmit the light in the blue region, making up for the shortage. good.

The light emitted from the light source 21R.GB passes through the red, green, and blue filters 22R.GB, and then passes through the light transmission bodies 23, 2.
3′, 23″ light entrance ports 23A, 23′A, 23″A
, propagates inside the optical transmission bodies 23, 23', 23'' by total reflection, etc., and red, green, and blue region light is mixed and diffused from the light exit 25, which is bundled into one by the tube 24. radiate.

At this time, the amount of light in each of the red, green, and blue region lights is
For example, the light source 21R.GB as shown in FIG.
A variable resistor 41R.GB is provided in the electrical circuit of the light source 21R.GB, and by changing this resistance value, the voltage or current supplied to the light source 21R.GB can be changed independently for each light source, thereby adjusting the brightness of each light source 21R.GB. By adjusting , the amount of light in the red, green, and blue regions 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. Since the light source section of this embodiment has a light amount adjustment function for red, green, and blue region light, the color filter 10 and the ND filter 11 for adjusting the light amount of the built-in pattern projector shown in FIG. 1 are unnecessary. Note that if the light source 21R.GB itself has the characteristics of the color filter 22R.GB, 22R.GB can be omitted.

FIG. 5 shows another reference example, in which a light source 21R.GB illuminates a diffuser plate 51 through red, green, and blue filters 22R.GB, and this diffuser plate 51 is installed at the position of 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. Furthermore, if the light sources 21R.GB are arranged as shown, they will be small and will be easy to sort when replacing the condenser lens 9 with another one.

FIG. 6 shows a third reference example in which a light source 21 is used with half mirrors or dichroic mirrors 61 and 62.
The RGB light is combined to illuminate the diffuser plate 51. The other details are the same as in FIG. 5. The method of adjusting the light amount in the reference example in FIGS. 5 and 6 is the same as in the reference example in FIG.

FIG. 7 shows a fourth embodiment in which two light sources 71 and 71' are used, and 72 and 72' are color correction filters having spectral characteristics as shown in FIG. The lights 71' are combined to illuminate the diffuser plate 51. In this case, by independently changing the voltage or current of the two light sources 71 and 71', the color temperature of the light sources can be changed appropriately to obtain the desired balance of light in the red, green, and blue regions, and the total amount of light can be adjusted. An aperture is provided in the ND filter 11 or the pattern projection optical system for adjustment.

In the first to fourth reference examples above, multiple optical component light fluxes were obtained by using multiple light sources, but by dividing the light flux from one light source, multiple light component light fluxes were obtained. It is possible to obtain color component light. The fifth reference example will be explained below.

123, 123', 123'' and 12 in Figure 9
7, 127', 127'' are optical transmission bodies such as optical fiber bundles, and one end of each is bound into a single bundle by tubes 124 and 128. Optical transmission bodies 123, 123', 123″ and 127,1
27', 127'' exit, human firing end 123A, 123
A', 123A'', 127A, 127A', 127
As shown in the figure, A'' is arranged to face each other, and between the light transmitting bodies 123 and 127 is a red filter 122 that mainly transmits light in the red region.
R and a diaphragm 126 for adjusting the amount of light are provided. Similarly, between 123' and 127', a green filter 122G and an aperture 126' are installed between 123'' and 127'.
7″, there are blue filters 122B and 12
6'' are arranged respectively.

Light emitted from a light source 121 such as a tungsten light bulb enters the inside of the light transmitting bodies 123, 123', 123'' through the light entrance 125 of the tube 124 that bundles the light transmitting bodies 123, 123', 123''. is propagated by total reflection etc., and each light exit 12
Injection from 3A, 123A', 123A'', respective red, green, blue filters 122R, 122G, 12
2B and light amount adjustment diaphragm 126, 126', 12
6″ and the other opposing optical transmission body, the light entrance 127 of 127, 127′, 127″.
A, 127A', 127'' respectively, propagates inside the optical transmission bodies 127, 127', 127'' by total reflection, etc., and exits from the light exit 129 which is bundled into one by the tube 128.・Blue region light is mixed and emitted diffusely. At this time, the amount of light of each of the red, green, and blue region lights is adjusted by each light amount adjusting diaphragm 126, 12.
Adjustment can be made arbitrarily by changing the aperture diameter of 6′, 126″.
6', 126'' are the light exit ports 123A, 123A', 123A'' of the opposing optical transmission bodies and the light entrance port 1.
This can be omitted if the light amount is adjusted by changing the distance between 27A, 127A', and 127A''.

Then, the light exit port 129 of the light transmitting body may be installed at the position of the light source 1' of the built-in pattern projector shown in FIG. Since the light source section of this embodiment has a light intensity adjustment function for red, green, and blue region light, the built-in pattern projector color filter 10 and the light intensity adjustment function shown in FIG.
The ND filter 11 becomes unnecessary.

An example of the spectral characteristics of the red/green/blue filter 122R.GB is shown in FIG. light source 12
When the color temperature of the green filter 122G is low, there will be a shortage of light in the blue region, so using a filter as shown in the figure is convenient because the green filter 122G also transmits the light in the blue region, thereby catching the shortage.

FIG. 11 shows a sixth reference example, in which a light source 131, a red reflecting dichroic mirror 132, a blue transmitting dichroic mirror 133, a green reflecting dichroic mirror 134 and a diffuser plate 135 are arranged in sequence. ，
134 are arranged at an angle as shown in FIG. 11, and their spectral characteristics are as shown in FIG. 12.

The red region light emitted from the light source 131 is reflected by the dichroic surface of the red reflective dichroic mirror 132,
After being reflected by 132A, reflecting mirrors 137, 137'
The light is reflected by the blue-transmitting dichroic mirror 133 , is reflected by the dichroic surface 133 A, passes through the green-reflecting dichroic 134 , and enters the diffuser plate 135 .

The green light emitted from the light source 131 passes through the red reflecting dichroic mirror 132 and then enters the blue transmitting dichroic mirror 133, where it is reflected by the dichroic surface and reflected by the reflecting mirrors 138, 138'.
Green reflective dichroic mirror 134 after reflection
The light is incident on the dichroic surface 133A and is reflected on the diffuser plate 135.

On the other hand, the blue light emitted from the light source 131 passes through a red reflecting dichroic mirror 132, a blue transmitting dichroic mirror 133, and a green reflecting dichroic mirror 134, and enters a diffuser plate 135.

Then, the diffuser plate 135 is placed at the position of the light source 1' in FIG.

The apertures of the light amount adjusting diaphragms 136 and 136' arranged in the red region optical path and the green region optical path and the light source 1
By adjusting the voltage applied to 31,
The light intensity of each of the green and blue region lights can be adjusted to an arbitrary value.

Incidentally, the diffuser plate 135 can be omitted by appropriately replacing the condenser lens 9 and its position in FIG. 1.

FIG. 13 shows a seventh reference example, in which the light emitted from a light source 171 is separated into two parts by a half mirror 173, each light is reflected by reflecting mirrors 175 and 175', and then combined by a half mirror 174. , diffuser plate 1
77. The diffuser plate 177 is placed at the position of the light source 1' in FIG.

A color filter 17 having characteristics as shown in FIG. 13 is provided in the optical path separated into two by a half mirror 173.
2,172' and a light amount adjusting diaphragm 176, 176' are arranged, and by adjusting the aperture and the voltage applied to the light source 131, the light amount of each of the red, green, and blue region lights can be adjusted to an arbitrary value. This is how it was done.

FIG. 15 shows an embodiment of the invention.
251 is a tungsten lamp, and 252 is a filament of this lamp 251. A lens 253 forms an image 252' of the filament 252. 254 is a lens whose front focal plane is at the position of the filament image 252'. 256 is a test pattern located at the back focal plane of the lens 254. 255 is an image pickup tube 25 that captures the image of the test pattern.
This lens is formed on the imaging surface 258 of No. 7 and corresponds to lenses 8 and 7 of FIG. Further, 252'' is a filament image formed at the pupil position of the lens 255.A filter as shown in FIG. are arranged. That is, 261R is a red transmission filter, 261G is a green transmission filter, and 261B is a red transmission filter.
is a blue transparent filter. 262R is a light shielding plate that can go in and out of the surface of the red transmission filter 261R, 262G is a light shielding plate that can go in and out of the surface of the green transmission filter 261G, and 262B is a light shielding plate that can go in and out of the surface of the blue transmission filter 261B. Therefore, the color temperature can be adjusted by individually adjusting the amount of inflow and outflow of these light shielding plates. Note that the filter 261 and the light shielding plate 262 may be placed at the position of the filament 252''. In this case, the color temperature correction means is placed in the projection optical path. However, this means may be placed anywhere in the projection optical path. It is not necessarily a good idea, but it is desirable to arrange it at least before the half mirror 12 in FIG.

According to the present invention described above, it is possible to obtain a test pattern image having a desired color temperature even though it is a built-in test pattern projector, so there is an effect that adjustment of the television camera can be carried out at any time and at any place. Moreover, it is extremely convenient because it does not require any major modification of the form of the conventional device.

[Brief explanation of the drawing]

Fig. 1 is an optical layout diagram of a conventional television camera, Fig. 2 is a diagram showing the light source section of the first reference example, Fig. 3 is a diagram showing the spectral transmittance of the filter in Fig. 1, and Fig. 4 is a diagram showing the spectral transmittance of the filter in Fig. 1. Circuit diagram for controlling the amount of light emitted from the light source in Figure 1, No. 5
The figure shows the light source part of the second reference example, and Figure 6 shows the light source part of the third reference example.
FIG. 7 is a diagram showing the light source section of the fourth reference example. FIG. 8 is a diagram showing the spectral transmittance of the dichroic mirror of FIG. 7. FIG. 9 is a diagram showing the spectral transmittance of the dichroic mirror of FIG. 5. FIG. 10 is a diagram showing the spectral transmittance of the filter in FIG. 9, FIG. 11 is a diagram showing the light source section in the sixth reference example, and FIG. 12 is a diagram showing the spectral transmittance of the filter in FIG. 10. A diagram showing the spectral transmittance, Figure 13 is the 7th
FIG. 14 is a diagram showing the spectral transmittance of the dichroic mirror of FIG. 13, FIG. 15 is an optical layout diagram of the embodiment of the present invention, and FIG. 16 is a diagram showing the light source section of the reference example. This is a diagram showing a filter. In the diagram, X is an objective lens, Y is a color separation prism,
3R.GB is an image pickup tube, 1 and 1' are light sources, 12 is a mirror, 21R.GB is a lamp constituting a light source unit, 22R.GB is a filter, and 23 is a fiber.

Claims (1)

[Claims] 1 Guide the light from the test pattern illuminated by the light source device into the objective lens optical path using a light polarizer,
In a television camera incorporating a test pattern projector that forms an image of a test pattern on a photographing device, means for dividing a pupil of an optical system of the test pattern projector into a plurality of different color regions, and limiting the color region. A television camera characterized by comprising color temperature adjustment means.