JP2009194446A - Video camera system using field sequential color system display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a video camera system employing a field sequential color system display device which performs both color adjustment and focusing by color display up to a normal moving speed, and also performs focusing by monochrome display in the situation of high speed movement. <P>SOLUTION: An FSC system liquid crystal display device 3 is provided with a color/monochrome display mode switching means 100 which can switch from a color display mode to a monochrome display mode where the prime color light sources of a backlight 30 are lighted simultaneously in a specific field of one frame and the specific field is set as a monochrome display field, and the other field is set as a black field by lighting out the backlight or displaying black in the other field. The video camera system uses this device as its monitor. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a video camera system using a field sequential color system display device.

  The field sequential color liquid crystal display device does not need to divide the pixel into sub-pixels for displaying the three primary colors (red R, green G, and blue B), so the aperture ratio is higher than that of the liquid crystal display device using the micro color filter method. Even if TFTs made of inexpensive amorphous silicon can be used, a small and high-definition display device can be configured. And since each color of R, G, B is displayed by the same pixel, when applied to a monitor of a video camera, there is an advantage that focusing (focus adjustment) becomes easy. That is, in the professional video camera, each color is imaged at the same pixel position by RGB three-plate imaging, but in the micro color filter type display device, R, G, and B are displayed at different positions as sub-pixels, so the contour of the subject is Contrast with the imperfections that are unclear. In some professional cameras, in order to prioritize focusing over color adjustment, there is an example in which a monochrome display device is purposely employed instead of a micro color filter type display device as a monitor.

However, the field sequential color display device has a problem of color breakup as a disadvantage caused by the method itself. When photographing a subject moving in the screen or panning the camera, RGB is decomposed at the contour portion of the object and the rainbow is displayed. It looks like a color. This is a method according to Patent Document 1 and the like, and the moving speed that normally appears in TV broadcasting can be suppressed to a level that does not cause a problem. However, even with high-speed moving object shooting and high-speed panning, color breaks are inevitably seen. This will interfere with focusing. However, since there is no time for color adjustment in these high-speed moving body imaging, it is only necessary to perform color adjustment in advance with a stationary or low-speed moving body and to focus only on the high-speed moving body.
JP 2007-264211 A

  As described above, the imaging system using the micro color filter type liquid crystal display device cannot solve the focusing problem for both stationary and moving body imaging, while the system using the field sequential color type liquid crystal display device moves. Focusing problem could not be solved by body imaging.

  In order to solve the above problems (problems), the present invention uses a small and high-definition liquid crystal display device, which is an advantage of the field sequential color system, as a monitor (video image monitor) of an image taken by a video camera. A video camera system that allows both color adjustment and focus adjustment in color display up to the normal movement speed, and can be adjusted in black and white display in high-speed movement conditions by providing a function to switch between color display and monochrome display. Is to provide.

That is, the present invention is as follows.
(Claim 1)
In a video camera system using a field sequential color liquid crystal display device having a primary color light source of three or more primary colors as a backlight for a monitor of the video camera, the liquid crystal display device has each of the backlights in a specific field in one frame. The color to the monochrome display mode in which the primary color light source is turned on at the same time to make the specific field a white display field and the other field is turned off or black is displayed in the other field to make the other field a black field. A video camera system using a field sequential color system display device, characterized by comprising color / monochrome display mode switching means capable of switching from a display mode.
(Claim 2)
The liquid crystal display device further includes
Display methods from video cameras other than the field sequential color method
In the color display mode, the field sequential color system, in which one frame consists of each primary color field and multiple black fields,
In the black and white display mode, one frame is converted into a field sequential black and white system composed of one or a plurality of continuous white display fields and one or a plurality of continuous black fields.
The video camera system according to claim 1, further comprising a display system conversion unit.
(Claim 3)
The liquid crystal display device further includes
In the monochrome display mode, the primary color information from the video camera is mixed at a ratio corresponding to the primary color chromaticity coordinates designated by the video camera to generate white display information, and the frame image is generated for each white display information. A primary color light source in the white display field is detected by detecting the brightest gradation from among them, and adding the primary color light transmittance ratio of the liquid crystal at the gradation voltage to a ratio according to the primary color chromaticity coordinates of the backlight. Adjust the amount of light
3. The video camera system according to claim 1, further comprising gradation detection and light amount adjustment means.
(Claim 4)
3. The video camera system according to claim 1, wherein a field sequential color display device is used as a digital mirror device display device instead of the liquid crystal display device.

  According to the present invention, a small and high-definition liquid crystal display device, which is an advantage of the field sequential color system, is used as a monitor of a video camera, and this has a function of switching between color display and black-and-white display. Until then, both color adjustment and focus adjustment are possible in color display, and in high-speed movement situations, black-and-white display is possible.

  The video camera system of the present invention (abbreviated as the system of the present invention) is a field sequential color used as a monitor in addition to a high-performance video camera 1 used for broadcasting business and its recording device 2 as shown in FIG. (Abbreviated as FSC) type liquid crystal display device 3. A video transmission device may be provided instead of the recording device 2. The FSC type liquid crystal display device 3 includes a backlight composed of three primary color light sources. Note that a light source with a primary color other than the three primary colors may be added. Further, in the case of the FSC system, a digital mirror device (abbreviated as DMD) display device or the like may be used instead of the liquid crystal display device.

Unlike the viewfinder, the monitor is used to monitor and check the video information that is recorded or transmitted. All adjustments that are performed in the field, such as screen configuration, exposure adjustment, color adjustment, and focusing, are performed while watching the monitor. It is.
Hereinafter, a case where the display device used as the monitor in the present invention is an FSC liquid crystal display device will be described.

  FIG. 2A shows the light emission timing of the primary color light source of the FSC liquid crystal display device with reduced color breakup according to Patent Document 1. The white balance is a light intensity ratio between each primary color light source in terms of light intensity and / or emission time width in consideration of the transmittance of the liquid crystal with respect to the wavelengths of the primary color lights of red (R), green (G), and blue (B). It is obtained by adjusting. Here, the light quantity is the product of the light emission time and the light intensity. The three primary colors are not limited to RGB, but may be other three primary colors such as cyan, magenta, and yellow, and the number N of primary colors of the N primary colors is not limited to three and may be four or more. .

  The light quantity ratio is adjusted as described above with reference to R, G, and B primary color light sources (R light source, G light source, and B) that constitute the backlight 30 that illuminates the display panel 20 from behind, as shown in FIG. The light intensity can be controlled for each primary color light source and for each field with respect to the primary light sources (X light sources) 7) for the light sources 4), 5 and 6 or for other primary colors X added as necessary. In addition, it can be executed by providing the light control means 10. Such dimming means 10 can be constituted by a small-scale dimming control circuit using an IC (a circuit for controlling the current applied to the primary color light source and the on / off timing of the current), and the cost burden is light. Reference numeral 40 denotes a dimmer that integrates a plurality of dimming means 10.

Further, in FIG. 2A, in the field marked K, each primary color light source of the backlight is not caused to emit light (turns off), and thus becomes black. Note that a black field can also be realized by displaying all pixels on the field screen in black (driving the liquid crystal to the black side) regardless of whether the backlight is turned off or not.
In the example of FIG. 2A, one frame is composed of 6 fields of R, G, B, K, K, and K. As the number of continuous K fields increases, the effect of reducing the color breakup becomes stronger, but the display becomes darker because the time of the light emitting field becomes shorter.

In the present invention, a function capable of selecting a field configuration as shown in FIG. 2B is added to the FSC display device with reduced color breakup as shown in FIG. The W field is a white display field and displays video luminance information. Since the light emission of the R, G, and B light sources is only combined into one field, the screen brightness of the display device does not change.
For such a selection function, for example, as shown in FIG. 3, a color / monochrome display mode switching means 100 is provided in the dimmer 40, and the dimming control circuit 10 according to the switching to the monochrome display mode thereby. For example, the primary color light sources of the backlight 30 are simultaneously turned on in a specific field in one frame (the specific field becomes the W field), and the backlight 30 is turned off in the other fields (the other fields). (The field becomes the K field).

  In FIG. 2B, since the W field in one frame is only one field and the remaining five fields are black, the light emission time is 1/6 or less of one frame, which is almost the same as the impulse-type display CRT. The time ratio is achieved. That is, even if a liquid crystal display device is used, it is possible to achieve moving image blur characteristics equivalent to those of a CRT. Although the motion blur characteristic is slightly sacrificed, the display luminance can be increased by reducing the number of K fields to the W field.

In the present invention, when the video camera is other than the FSC system, the display system conversion means having the function of converting the display system of the video from the video camera as follows is displayed on the monitor (the display device of the present invention). ), It is possible to obtain a sharp display with no color breakage and less moving image blur, so that high-speed panning of a video camera or high-speed moving object shooting is easy to focus.
(a1) In the color display mode, a function in which one frame is converted to a field sequential color system composed of a field of each primary color and a plurality of black fields.
(a2) In the monochrome display mode, a function of converting one frame into a field sequential monochrome system in which one frame is composed of one or a plurality of continuous white display fields and one or a plurality of continuous black fields.

  FIG. 4 is a schematic diagram showing an example of the embodiment of the present invention having the display method conversion means. The display method conversion means has the function of converting to the FSC method as in the above (a1) and (a2). A display system conversion circuit 11 having a switching circuit 15 for switching between three options of a path bypassing the circuit 11, a color input path to the circuit 11, and a monochrome input path on the input side of the circuit 11, On the output side of the circuit 11, a switching circuit 15a that switches between two options of a path that bypasses the circuit 11 and an output path from the circuit 11 is provided. In this example, as the most preferable mode, gradation detecting and light amount adjusting means 12 (which will be described later) is provided.

  By the way, as the gradation information displayed in the W field, if the video signal is composed of the luminance Y and the color difference signal, the value of the luminance signal Y can be used as it is. If the video signal is composed of RGB, The luminance Y value calculated at a ratio determined by the relationship between the chromaticity coordinates of the three primary colors specified by the video signal and the chromaticity coordinates of the white color is used. In the NTSC standard, the ratio is Y = 0.30r + 0.59g + 0.11b, and in the sRGB standard, Y = 0.21r + 0.72g + 0.07b. Here, r, g, and b on the right side of the equation are gradation values for each primary color.

In general, however, the liquid crystal has different transmittance characteristics at each wavelength of R, G, and B. Therefore, even if the light quantity ratio of each color light source has white balance when R, G, and B are divided into different fields, W It is difficult to say that the light intensity ratio in the field is appropriate. FIG. 5 shows the transmittance characteristics of each wavelength.
For example, if 3V is applied to the liquid crystal in the W field, the blue transmittance is large and the red transmittance is small. Since the transmittance ratio varies depending on the voltage applied to the liquid crystal, the coloring is different at different points of the gradation of the display image.

When R, G, and B are separated into separate fields, the light quantity ratio of each primary color light source is obtained by adding the ratio of the maximum transmittance of each color to the ratio determined by the chromaticity coordinates, so that the transmittance is If they are different in three colors, they will be colored and cannot be used.
Therefore, in the present invention, as the most preferred embodiment, in order to minimize color tinting, the maximum gradation of the image displayed in the W field is detected, and the RGB transmittance ratio at the voltage corresponding to the gradation is determined as W. It is used to determine the light quantity ratio in the field. By doing so, the brightest point on the screen does not cause coloration and becomes completely white, and only a little coloration appears only for dark gradations.

The gradation detection and light quantity adjusting means 12 shown in FIG. 4 is configured by a circuit having the following functions in order to minimize the above-mentioned coloring.
(b1) In the black and white display mode, the primary color information from the video camera 1 is mixed at a ratio corresponding to the primary color chromaticity coordinates designated by the video camera 1, and white display information is generated. A function that detects the brightest gradation in a frame image.
(b2) Adjusting the light intensity of the primary color light source in the W field by adding the primary color light transmittance ratio of the liquid crystal at the voltage corresponding to the detected gradation to the ratio according to the primary color chromaticity coordinates of the backlight 30 Function to do.

In the example of FIG. 4, switching means 16 is provided that enables selection between the case where the gradation detection and light quantity adjustment means 12 is used and the case where it is not used. The gradation detection and light quantity adjusting means 12 is operable only when the dimmer 40 is in the monochrome display mode (the state where the color / monochrome display mode switching means 100 is switched to the monochrome display mode).
It should be noted that the switching means 16 may be omitted when the switching means 16 is always set to the side where the gradation detection and light quantity adjustment means 12 is used.

In the above function (b2), “additional” specifically includes the following contents. That is, for example, the light quantity ratio of R, G, and B in FIG. 2A is the ratio of lumen (L) when an LED is used, and L _R : L _G : L _B = 0.274: 0.644: For example, when the liquid crystal having the transmittance characteristics shown in FIG. 4 is used and the maximum gradation corresponds to the gradation when 3 V is applied, the transmittance of red, blue, and green there is used. The light quantity ratio corrected by multiplying the reciprocal of 0.42: 0.56: 0.78, which is the ratio, L _R : L _G : L _B = 0.65: 1.15: 0.11 in the corresponding W field The primary color light source light quantity ratio is set as follows.

Example 1
In the video camera system of FIG. 1, a monitor in which the FSC liquid crystal display device 3 is configured as shown in FIG. 5 is used as a monitor, and color video input other than the FSC system is input by the display system conversion circuit 11 as shown in FIG. The image was converted to a field-structured FSC image, and the backlight 30 was controlled by the dimmer 40, and displayed in color on the monitor screen. On the other hand, the color / monochrome display mode switching means 100 in the dimmer 40 converts the color display into a monochrome image having a field configuration as shown in FIG. 2B. The switching means 16 performs gradation detection and light quantity adjustment means. A route not using 12 was selected, and the backlight 30 was controlled by the dimmer 40 and displayed in black and white on the monitor screen.

As a result, no color break was observed in the color display mode during low-speed moving object shooting and low-speed panning, while focusing was easy in the monochrome display mode during high-speed moving object shooting and high-speed panning. However, the white color display in the black-and-white display mode has a considerably blue color change.
(Example 2)
In the video camera system of FIG. 1, a monitor in which the FSC liquid crystal display device 3 is configured as shown in FIG. 5 is used as a monitor, and color video input other than the FSC system is input by the display system conversion circuit 11 as shown in FIG. The image is converted into a field-structured FSC image, and the backlight 30 is controlled by the dimmer 40 and displayed in color on the monitor screen. On the other hand, the color / monochrome display mode switching means 100 in the dimmer 40 is used for color display. 2B is converted into a black and white image having a field configuration shown in FIG. 2B, and the switching means 16 selects a path using the gradation detection and light quantity adjusting means 12, adjusts the primary field light source light quantity ratio in the W field, and then adjusts the light intensity. The backlight 30 was controlled by the device 40 and displayed in black and white on the monitor screen.

  As a result, no color break was observed in the color display mode during low-speed moving object shooting and low-speed panning, while focusing was easy in the monochrome display mode during high-speed moving object shooting and high-speed panning. In the white display in the monochrome display mode, the coloring is greatly reduced.

It is the schematic which shows an example of this invention system. It is explanatory drawing which shows an example of the field structure of the color display mode (a) and monochrome display mode (b) mutually switched by the system of this invention. FIG. 7 is a schematic view showing one example of light control means used in the present invention (a color / monochrome display mode switching means added to the reference example of FIG. 6). FIG. 2 is a schematic diagram showing an example of the most preferred embodiment of the present invention. FIG. 6 is a characteristic diagram illustrating an example of wavelength dependency of liquid crystal transmittance. FIG. 2 is a schematic view showing an example of a light control means used as a reference of the present invention.

Explanation of symbols

1 Video camera (eg high-performance video camera for broadcasting business)
2 Recording device 3 Field sequential color liquid crystal display device 4 Primary color light source (R light source)
5 Primary color light source (G light source)
6 Primary color light source (B light source)
7 Primary color light source (X light source, X is a primary color other than RGB)
10 Light control means (light control circuit)
11 Display conversion circuit
12 Gradation detection and light intensity adjustment means
15,15a, 16 switching circuit
20 Display panel
30 Backlight
40 Dimmer
100 color / monochrome display mode switching means

Claims (4)

  In a video camera system using a field sequential color liquid crystal display device having a primary color light source of three or more primary colors as a backlight for a monitor of the video camera, the liquid crystal display device has each of the backlights in a specific field in one frame. The color to the monochrome display mode in which the primary color light source is turned on at the same time to make the specific field a white display field and the other field is turned off or black is displayed in the other field to make the other field a black field. A video camera system using a field sequential color system display device, characterized by comprising color / monochrome display mode switching means capable of switching from a display mode. The liquid crystal display device further includes
Display methods from video cameras other than the field sequential color method
In the color display mode, the field sequential color system, in which one frame consists of each primary color field and multiple black fields,
In the black and white display mode, one frame is converted into a field sequential black and white system composed of one or a plurality of continuous white display fields and one or a plurality of continuous black fields.
The video camera system according to claim 1, further comprising a display system conversion unit. The liquid crystal display device further includes
In the monochrome display mode, the primary color information from the video camera is mixed at a ratio corresponding to the primary color chromaticity coordinates designated by the video camera to generate white display information, and the frame image is generated for each white display information. A primary color light source in the white display field is detected by detecting the brightest gradation from among them, and adding the primary color light transmittance ratio of the liquid crystal at the gradation voltage to a ratio according to the primary color chromaticity coordinates of the backlight. Adjust the amount of light
3. The video camera system according to claim 1, further comprising gradation detection and light amount adjustment means.   3. The video camera system according to claim 1, wherein a field sequential color display device is used as a digital mirror device display device instead of the liquid crystal display device.

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