JP2012209674A - Color television camera and white balance adjustment method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain appropriate white balance (WB) while restricting S/N deterioration to a possible minimum in any kind of lighting environment.SOLUTION: A camera 100 comprising a color separation prism 1 and image pickup elements 6, 7 and 8 which are disposed facing each other on the respective emission surfaces of the prism 1, includes: lighting control elements 3, 4 and 5 which are respectively disposed between each emission surface and each image pickup element; amplifiers 9, 10 and 11 which respectively amplify the image pickup signal of each image pickup element; and a control unit 13 which determines whether the level of a G image pickup signal obtained by shooting a reference white plate by an image pickup element 7 in a WB adjustment mode while the transmittance of each optical filter is set at maximum and the amplification factor of each amplifier is set to a minimum value, exceeds a reference level, and, if the G image pickup signal level does exceed the reference level, reduces the transmittance of the lighting control element 4 until the G image pickup signal level equals the reference level, or if the G image pickup signal level is less than the reference level, increases the amplification factor of the amplifier 10 until the G image pickup signal level equals the reference level.

Description

  The present invention relates to a color television camera and a white balance adjustment method thereof.

  As a color temperature conversion (white balance adjustment) technique in a conventional color television camera, for example, a technique described in Patent Document 1 is known.

  The color television camera described in Patent Document 1 is arranged so as to oppose a prism that decomposes incident light into R (red), G (green), and B (blue) light, and an emission surface of each light of the prism. And an ND filter of liquid crystal, which is provided between each light emitting surface of each prism and each image sensor, and whose transmittance is changed by an applied voltage. In this color television camera, voltages having different ratios of R, G, and B according to the color temperature of the light source are applied to each ND filter, and appropriate color temperature conversion is performed. According to this color television camera, it is possible to perform color temperature conversion without impairing color reproducibility.

  Further, Patent Document 2 discloses a prism that decomposes incident light into R, G, and B light, an imaging element that is disposed to face an emission surface of each light of the prism, and R light and B of the prism. A red filter and a blue filter, which are provided between the light exit surface and the imaging element opposite to the electrochromic element whose transmittance varies depending on the applied voltage, and the G light exit surface of the prism and In a color television camera including an ND filter with variable transmittance provided between opposing imaging elements, among the R, G, and B imaging signals, the R and B imaging signals have the G imaging signal level. In order to match these levels, a method is described in which the control of the transmittance by the red filter and the blue filter and the control of the amplification factor of the R and B imaging signals are performed together. According to this method, the white balance of the color television signal can be appropriately adjusted without introducing unacceptable noise into the color television signal.

Japanese Utility Model Publication No. 6-70386 JP-A-6-90403

  In the color television camera described in Patent Document 1, when the color temperature of the light source changes, the voltage applied to each ND filter is determined according to the color temperature. Thus, it is not specifically described whether the voltage applied to each ND filter is determined. If the configuration is such that the voltage data to be applied to each ND filter is stored in advance for each color temperature, a memory for storing a large number of data in the camera is required, or a large number of data is stored. Since the work for storing in the memory becomes necessary, the manufacturing cost of the color television camera increases.

  In addition, the color temperature of ambient light in an actual shooting environment varies, and voltage data for dealing with all color temperatures cannot be stored. Therefore, it is necessary to obtain voltage data corresponding to a color temperature other than the representative color temperature from a plurality of representative color temperatures and the corresponding voltage data by interpolation or the like. Temperature conversion cannot be performed.

  In the color television camera described in Patent Document 2, an operator captures a reference white plate by setting an aperture so as to obtain a desired depth of field. At the time of shooting, the color television camera adjusts the transmittance of the ND filter so that the G imaging signal is output at a reference voltage level (eg, 714 millivolts for NTSC) specified by a desired video standard. The color television camera further adjusts the transmittance of the red and blue filters until each of the R and B image signals matches the reference voltage level of the G image signal. For the R and B image pickup signals, SN deterioration is prevented by adjusting the amplification gain in addition to the adjustment of the transmittance of the red and blue filters.

  However, the color television camera described in Patent Document 2 cannot obtain an appropriate white balance if the G image pickup signal does not reach the reference voltage level even when the transmittance of the ND filter is maximized. .

  The present invention has been made in view of the above circumstances, and is a color television capable of obtaining an appropriate white balance while minimizing SN degradation under any lighting environment without causing an increase in cost. An object of the present invention is to provide a John camera and a white balance adjustment method thereof.

  The color television camera of the present invention is a color separation optical unit that separates incident light into three colors of red, green, and blue, and an imaging element that is disposed opposite to the red light emission surface of the color separation optical unit. An image pickup device, a G image pickup device which is an image pickup device arranged opposite to the green light emission surface of the color separation optical unit, and an image pickup element B which is arranged opposite the blue light emission surface of the color separation optical unit. A color television camera having an image pickup device, the R optical filter being disposed between the red light emitting surface and the R image pickup device and having an electrically controllable transmittance, and the green light The G optical filter, which is disposed between the emission surface of the blue light and the G imaging device, and whose transmittance can be controlled electrically, and is disposed between the emission surface of the blue light and the B imaging device, and is electrically B optical filter capable of controlling transmittance and three image pickup devices An amplification factor variable amplifier that amplifies the imaging signal output from each; and a white balance adjustment unit that adjusts the white balance of the imaging signal output from the three imaging elements, the white balance adjustment unit, Set the transmittance of each of the R optical filter, the G optical filter, and the B optical filter to the maximum, and set the amplification factor of each of the three amplifiers to the same value smaller than a settable maximum value, When the transmittance is set to the maximum and the amplification factor is set to the same value, the level of the green component imaging signal obtained by photographing the reference white plate with the G imaging element is the reference level. When the level of the green component imaging signal exceeds the reference level as a result of the determination, the level of the green component imaging signal is the reference level. The first control is performed to make the transmittance of the G optical filter smaller than the maximum value so as to be a bell, and when the level of the green component imaging signal is less than the reference level, the green component imaging signal The second control is performed to increase the amplification factor of the amplifier for amplifying the image pickup signal output from the G image pickup device so as to be equal to the reference level.

  In the color television camera white balance adjustment method according to the present invention, a color separation optical unit that separates incident light into three colors of red, green, and blue, and a red light emission surface of the color separation optical unit are disposed to face each other. An R image pickup device that is an image pickup device, a G image pickup device that is an image pickup device arranged to face the green light emission surface of the color separation optical unit, and a blue light emission surface of the color separation optical unit. A white balance adjustment method in a color television camera having a B image pickup device as an image pickup device, wherein the color television camera is disposed between the red light emitting surface and the R image pickup device, An R optical filter whose transmittance can be controlled, a G optical filter which is disposed between the green light emitting surface and the G image pickup device and can electrically control the transmittance, and the blue light. And the exit surface of the A B optical filter that is disposed between the image pickup device and electrically controllable in transmittance, and an amplifier that amplifies an image pickup signal output from each of the three image pickup devices. A maximum transmittance setting step for setting the transmittance of each of the R optical filter, the G optical filter, and the B optical filter to a maximum in a white balance adjustment mode for adjusting a white balance of an imaging signal output from the imaging device. In the white balance adjustment mode, an amplification factor setting step for setting the amplification factor of each of the three amplifiers to the same value smaller than a maximum value that can be set; and the transmittance is set to a maximum; and In a state where the amplification factor is set to the same value, a green component image signal obtained by photographing a reference white plate with the G image sensor is captured. A determination step for determining whether or not the level of the green component exceeds a reference level; and, as a result of the determination in the determination step, if the level of the green component imaging signal exceeds the reference level, the level of the green component imaging signal is First control is performed to make the transmittance of the G optical filter smaller than the maximum value so as to be the reference level, and when the level of the imaging signal of the green component is less than the reference level, A control step of performing a second control to increase the amplification factor of the amplifier that amplifies the imaging signal output from the G imaging element so that the level of the imaging signal becomes the reference level, than the same value. Is.

  According to the present invention, a color television camera capable of obtaining an appropriate white balance while minimizing SN degradation under any lighting environment without incurring an increase in cost, and a method for adjusting the white balance thereof. Can be provided.

The figure which shows schematic structure of the color television camera 100 for demonstrating one Embodiment of this invention. Flowchart for explaining the operation of color television camera 100 shown in FIG. 1 in the WB adjustment mode. The figure which shows the example of a screen displayed on the display part at the time of WB adjustment mode of the color television camera 100 shown by FIG.

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

  FIG. 1 is a diagram showing a schematic configuration of a color television camera 100 for explaining an embodiment of the present invention.

  The optical system of the color television camera 100 includes a color separation prism 1 that separates incident light into three lights of R, G, and B, and a color that transmits R light provided on the R light exit surface of the color separation prism 1. A filter 2R, a color filter 2G that transmits G light provided on the G light exit surface of the color separation prism 1, and a color filter 2B that transmits B light provided on the B light exit surface of the color separation prism 1; A solid-state imaging device 8 such as a CCD image sensor or a CMOS image sensor that receives light transmitted through the color filter 2R disposed behind the color filter 2R and light transmitted through the color filter 2G disposed behind the color filter 2G is received. A solid-state image sensor 7 such as a CCD image sensor or a CMOS image sensor, and a color filter 2B disposed behind the color filter 2B. A solid-state image pickup device 6 such as a CCD image sensor or a CMOS image sensor that receives received light, and a light control device that is disposed between the color filter 2B and the solid-state image pickup device 6 and whose light transmittance is controlled by an applied voltage. Between the element 3, the color filter 2G and the solid-state image sensor 7, and the light control element 4 whose light transmittance is controlled by the applied voltage, and between the color filter 2R and the solid-state image sensor 8. And a light control element 5 in which the light transmittance is controlled by the applied voltage.

  The light control elements 3, 4, and 5 are configured by optical filters such as electrochromic elements and liquid crystal filters.

  The electric control system of the color television camera 100 includes amplifiers 9, 10, and 11 for amplifying image signals output from the solid-state image sensors 6, 7, and 8 with a set gain (amplification factor), and the light control element 3. , 4, 5, a dimming element driver 12 for controlling the voltage applied to the color television camera 100, a control unit 13 for controlling the color television camera 100, and the R, G, B imaging signals output from the amplifiers 9, 10, 11. An image processing unit 14, a display unit 15, and an operation unit 16 that are used to generate a color television signal by a known method are provided. The control unit 13 functions as a white balance adjustment unit in claims.

  The color television camera 100 uses an imaging signal output from the amplifiers 9, 10, and 11 to generate and output a color television signal by the image processing unit 14 and outputs from the amplifiers 9, 10, and 11. And a WB adjustment mode for adjusting the white balance (WB) of the imaging signal. The operation of the color television camera 100 in the WB adjustment mode will be described below.

  FIG. 2 is a flowchart for explaining the operation of the color television camera 100 shown in FIG. 1 in the WB adjustment mode.

  When the operator operates the operation unit 16 to set the WB adjustment mode, the control unit 13 controls the dimming element driver 12 so that the transmittance of each of the dimming elements 3, 4, and 5 is maximized. The transmittance of each of the light control elements 3, 4 and 5 is set to the maximum by the element driver 12 (step S1).

  Next, the control part 13 sets the gain of each amplifier 9,10,11 to the same value (step S2). The gain value set here is a value that is sufficiently smaller than the maximum value among the gains that can be set for each of the amplifiers 9, 10, and 11, for example, the minimum value among the settable gains, and the maximum value and the minimum value. The intermediate value between them.

  When the process of step S2 is completed, the control unit 13 displays a message that prompts the user to shoot a reference white plate (having a reflectance of 89.9% in the entire visible range) that is generally used in the broadcasting industry. Display on the unit 15.

  In accordance with this message, the operator arranges the standard white plate in front of the prism 1 and adjusts the aperture value of a diaphragm (not shown) arranged in front of the prism 1 so as to obtain a desired depth of field. Then, the photographing of the reference white plate is started (step S3). In this photographing, the user performs photographing so that a desired depth of field is obtained under a bright condition where, for example, the F value is about 2 to 8.

  After the start of imaging in step S3, the imaging signals output from the solid-state imaging devices 6, 7, and 8 are amplified by the amplifiers 9, 10, and 11 with the gain set in step S2, and then input to the control unit 13. The

  The control unit 13 temporarily stores the input R image pickup signal, G image pickup signal, and B image pickup signal in an internal memory, and among these, the level of the G image pickup signal is a reference voltage level specified by a desired video standard (for example, It is determined whether it is 714 millivolts in NTSC (referred to as a reference value in FIG. 2) (step S4). In this case, the reference voltage level may be a voltage range having a certain width including the reference voltage level set in the video standard.

  When the level of the G imaging signal is the reference voltage level (step S4: YES), the control unit 13 performs the process of step S10. When the level of the G imaging signal is not the reference voltage level (step S4: NO), the control unit 13 performs the process of step S5.

  In step S5, the control unit 13 determines whether or not the level of the G imaging signal is higher than the reference voltage level.

  When the level of the G imaging signal is higher than the reference voltage level (step S5: YES), the control unit 13 controls the dimming element driver 12 to adjust the level of the G imaging signal to the reference voltage level. The transmittance of the optical element 4 is reduced from the maximum transmittance to a predetermined value (step S6).

  On the other hand, when the level of the G imaging signal is smaller than the reference voltage level (step S5: NO), the control unit 13 generates message information for prompting the work of increasing the amount of light incident on each of the imaging elements 6, 7, and 8. Then, the message information is displayed on the display unit 15 or is output by voice from a speaker (not shown) (step S7). For example, as shown in FIG. 3, a message such as “Insufficient amount of light. Please perform work to increase the amount of light” is displayed on the display unit 15 and is incident on each of the image sensors 6, 7, and 8. The operator is prompted to increase the amount of light to be emitted.

  The operator who has confirmed this message, for example, further increases the illumination light source, changes the lens attached to the color television camera 100 to a brighter one, or changes the aperture value, thereby changing the imaging elements 6, 6. Work to increase the amount of light incident on 7 and 8. Depending on the shooting environment, it may not be possible to increase the amount of illumination light any more, or it may not be desired to increase the amount of illumination light further depending on the operator's preference. Without the operation, a command icon (“ignore”) displayed together with the message on the message display screen shown in FIG. When the “ignore” icon is selected by the operation unit 16, information indicating that an operation for increasing the amount of incident light was not performed is input to the control unit 13.

  After the notification in step S7, the control unit 13 determines whether or not an operation for increasing the amount of illumination light has been performed (step S8).

  For example, the presence or absence of a change in the aperture setting value is detected, and when the aperture value is changed to the open side, it is determined that an operation for increasing the amount of illumination light has been performed. Alternatively, the level of the imaging signal output from the imaging elements 6, 7, and 8 is monitored, and when the level increases, it is determined that an operation for increasing the amount of illumination light has been performed. In addition, when receiving information indicating that the amount of incident light has not been increased, the control unit 13 determines that the work for increasing the amount of illumination light has not been performed.

  When the determination in step S8 is YES, the control unit 13 performs the process in step S4.

  When the determination in step S8 is NO, the control unit 13 increases the set gain of the amplifier 10 so that the level of the G imaging signal becomes the reference voltage level (step S9). Here, the reason why the set gain of the amplifier 10 is increased is that the transmittance of the light control element 4 is already set to the maximum transmittance and cannot be increased any more.

  Through the processing in steps S6 and S9, the level of the G imaging signal output from the imaging device 7 becomes the reference voltage level.

  After step S6 and step S9, the control unit 13 determines whether or not the level of the R imaging signal obtained during shooting is higher than the level of the G imaging signal (step S10).

  When the level of the R imaging signal obtained during shooting is higher than the level of the G imaging signal (step S10: YES), the control unit 13 adjusts the level of the R imaging signal to be the same as the level of the G imaging signal. The optical element driver 12 is controlled to reduce the transmittance of the dimming element 5 (step S11).

  When the level of the R imaging signal obtained during shooting is smaller than the level of the G imaging signal (step S10: NO), the control unit 13 determines whether the level of the R imaging signal is the same as the level of the G imaging signal. 11 is performed to increase the set gain (step S12).

  After step S11 and step S12, the control unit 13 determines whether or not the level of the B imaging signal obtained during shooting is higher than the level of the G imaging signal (step S13).

  When the level of the B imaging signal obtained during shooting is higher than the level of the G imaging signal (step S13: YES), the control unit 13 adjusts the light control element so that the level of the B imaging signal becomes the level of the G imaging signal. The driver 12 is controlled to reduce the transmittance of the light control element 3 (step S14).

  When the level of the B imaging signal obtained during shooting is smaller than the level of the G imaging signal (step S13: NO), the control unit 13 sets the level of the B imaging signal to the level of the G imaging signal. Control to increase the set gain is performed (step S15).

  The WB adjustment mode is ended by the end of the processes of steps S14 and S15. After the end of the WB adjustment mode, the mode shifts to the imaging mode, and the R, G, B imaging signals according to the adjusted values of the transmittances of the light control elements 3, 4, 5 and the set gains of the amplifiers 9, 10, 11 Are generated, and a color television signal is generated.

  When the shooting environment (color temperature of illumination light) changes due to, for example, taking the color television camera 100 from the indoor to the outdoors, the operator can set the WB adjustment mode again so that the dimming suitable for the shooting environment is performed. The transmittance of the elements 3, 4 and 5 and the set gain of the amplifiers 9, 10 and 11 are adjusted.

  If the level of the R imaging signal is the same as the level of the G imaging signal in the determination of step S10, the control unit 13 performs the process of step S13 without performing the processes of steps S11 and S12. If the level of the B imaging signal is the same as the level of the G imaging signal in the determination of step S13, the WB adjustment is terminated without performing the processing of steps S14 and S15.

  As described above, according to the color television camera 100, when the level of the G imaging signal does not become the reference voltage level (step S8: NO), the control of the set gain of the amplifier 10 that amplifies the G imaging signal is performed. The G imaging signal is matched with the reference voltage level. For this reason, even when the amount of light incident on each image sensor is insufficient, the level of the G image signal can be set to the reference voltage level, and a desired video standard G image signal can be obtained under any shooting environment. Obtainable. This effect can be obtained in the same manner even when steps S7 and S8 are omitted and step S5: NO is followed by step S9.

  In addition, based on the level of the G imaging signal, it is determined whether the level adjustment of the G imaging signal is performed by the transmittance control of the light control element or the gain control of the amplifier. No, it is possible to suppress degradation of SN due to gain increase as much as possible.

  Further, since the level adjustment of the R and B imaging signals is performed by the transmittance control of the light control element or the gain control of the amplifier based on the level of the R and B imaging signals, On the other hand, the gain control is performed only to the minimum necessary, and the degradation of SN due to the gain increase can be suppressed as much as possible.

  Further, according to the color television camera 100, when the level of the G image signal obtained by photographing the reference white plate does not reach the reference value, the operator is notified of the work for increasing the light amount. Therefore, the increase control of the amplification gain of the G imaging signal can be performed only when the amount of light is still insufficient when the operator has performed the work of increasing the amount of light. As a result, even when gain increase is performed, the gain increase range becomes as small as possible, and SN degradation due to gain increase can be minimized.

  Further, according to the color television camera 100, the set gains of the amplifiers 9, 10, and 11 when shooting the reference white plate are set to the minimum values, and the gain is increased only when necessary. If no increase is made, a high SN can be achieved.

  As described above, the following items are disclosed in this specification.

  The disclosed color television camera is a color separation optical unit that separates incident light into three colors of red, green, and blue, and an image sensor R that is disposed to face a red light emission surface of the color separation optical unit. An image pickup device, a G image pickup device which is an image pickup device arranged opposite to the green light emission surface of the color separation optical unit, and an image pickup element B which is arranged opposite the blue light emission surface of the color separation optical unit. A color television camera having an image pickup device, the R optical filter being disposed between the red light emitting surface and the R image pickup device and having an electrically controllable transmittance, and the green light The G optical filter, which is disposed between the emission surface of the blue light and the G imaging device, and whose transmittance can be controlled electrically, and is disposed between the emission surface of the blue light and the B imaging device, and is electrically B optical filter capable of controlling transmittance and three image pickup elements An amplification factor variable amplifier that amplifies the imaging signal output from each of the above, and a white balance adjustment unit that adjusts the white balance of the imaging signal output from the three imaging elements, the white balance adjustment unit, The transmittance of each of the R optical filter, the G optical filter, and the B optical filter is set to the maximum, and the amplification factors of the three amplifiers are set to the same value that is smaller than a settable maximum value. The level of the imaging signal of the green component obtained by photographing the reference white plate with the G imaging element in the state where the transmittance is set to the maximum and the amplification factor is set to the same value. If the level of the green component imaging signal exceeds the reference level as a result of the determination, the level of the green component imaging signal is When the first control is performed to make the transmittance of the G optical filter smaller than the maximum value so as to become a level, and the level of the green component imaging signal is less than the reference level, the green component imaging signal The second control is performed to increase the amplification factor of the amplifier for amplifying the image pickup signal output from the G image pickup device so as to be equal to the reference level.

  In the disclosed color television camera, when the white balance adjustment unit determines that the level of the image signal of the green component is less than the reference level as a result of the determination, the light incident on the three image sensors The user of the color television camera is urged to perform an operation for increasing the amount of the image, the second control is executed when the operation is not performed, and the determination is performed again when the operation is performed. Is what you do.

  In the disclosed color television camera, after the white balance adjustment unit performs the first control or the second control, imaging of a red component obtained by photographing a reference white plate with the R imaging element The transmittance of the R optical filter or the amplification factor of the amplifier that amplifies the imaging signal output from the R imaging device is controlled so that the signal level becomes the reference level, and a reference white plate is obtained by the B imaging device. The transmittance of the B optical filter or the amplification factor of the amplifier that amplifies the imaging signal output from the B imaging element is controlled so that the level of the imaging signal of the blue component obtained by photographing the image becomes the reference level. To do.

  In the disclosed color television camera, the same value set by the white balance adjustment unit includes a minimum amplification factor that can be set for each of the three amplifiers.

  The disclosed white balance adjustment method for a color television camera is arranged so as to oppose a color separation optical unit that separates incident light into three colors of red, green, and blue, and a red light exit surface of the color separation optical unit. An R image pickup device that is an image pickup device, a G image pickup device that is an image pickup device arranged to face the green light emission surface of the color separation optical unit, and a blue light emission surface of the color separation optical unit. A white balance adjustment method in a color television camera having a B image pickup device as an image pickup device, wherein the color television camera is disposed between the red light emitting surface and the R image pickup device, An R optical filter whose transmittance can be controlled, a G optical filter which is disposed between the green light emitting surface and the G image pickup device and can electrically control the transmittance, and the blue light. And exit surface A B optical filter disposed between the image pickup device and electrically controlled in transmittance, and an amplifier for amplifying an image pickup signal output from each of the three image pickup devices; A transmittance maximum setting step for setting the transmittance of each of the two optical filters to a maximum; an amplification factor setting step for setting the amplification factor of each of the three amplifiers to the same value smaller than a settable maximum value; When the transmittance is set to the maximum and the amplification factor is set to the same value, the level of the green component imaging signal obtained by photographing the reference white plate with the G imaging element is the reference level. And when the level of the green component imaging signal exceeds the reference level as a result of the determination in the determination step, the level of the green component imaging signal First control is performed to make the transmittance of the G optical filter smaller than the maximum value so as to be the reference level, and when the level of the imaging signal of the green component is less than the reference level, A control step of performing a second control to increase the amplification factor of the amplifier that amplifies the imaging signal output from the G imaging element so that the level of the imaging signal becomes the reference level, than the same value. Is.

  In the disclosed white balance adjustment method for a color television camera, in the control step, when the level of the green component imaging signal is less than the reference level as a result of the determination in the determination step, the three imaging When the work for increasing the amount of light incident on the element is urged to the user of the color television camera, the second control is executed when the work is not performed, and the work is performed The determination step is performed again.

  According to the disclosed white balance adjustment method for a color television camera, an image signal of a red component obtained by photographing a reference white plate by the R image sensor after performing the first control or the second control. The transmittance of the R optical filter or the amplification factor of the amplifier that amplifies the imaging signal output from the R imaging device is controlled so that the level becomes the reference level, and the reference white plate is photographed by the B imaging device. Controlling the transmittance of the B optical filter or the amplification factor of the amplifier that amplifies the imaging signal output from the B imaging element so that the level of the imaging signal of the blue component obtained in this way becomes the reference level It is.

  In the disclosed white balance adjustment method for a color television camera, the same value set in the gain setting step includes a minimum gain that can be set in each of the three amplifiers.

1 Color separation prism 2R, 2G, 2B Color filter 3, 4, 5 Dimming element 6, 7, 8 Imaging element 9, 10, 11 Amplifier 12 Dimming element driver 13 Control unit 14 Image processing unit 15 Display unit 16 Operation unit

Claims (8)

A color separation optical unit that separates incident light into three colors of red, green, and blue; an R image pickup device that is an image pickup device disposed opposite to a red light emission surface of the color separation optical unit; and the color separation optical unit A color television camera having a G image pickup device which is an image pickup device arranged opposite to the green light emission surface and a B image pickup device which is an image pickup device arranged opposite to the blue light emission surface of the color separation optical unit. Because
An R optical filter that is disposed between the red light exit surface and the R imaging element and is capable of electrically controlling transmittance;
A G optical filter that is disposed between the green light exit surface and the G image sensor and is capable of electrically controlling transmittance;
A B optical filter disposed between the blue light emitting surface and the B image sensor, and having an electrically controllable transmittance;
An amplification factor variable amplifier that amplifies an imaging signal output from each of the three imaging elements;
A white balance adjustment unit that adjusts the white balance of the imaging signals output from the three imaging elements,
The white balance adjustment unit sets the transmittance of each of the R optical filter, the G optical filter, and the B optical filter to a maximum, and sets a gain of each of the three amplifiers to a maximum value that can be set. A green component obtained by photographing a reference white plate with the G imaging device in a state where the same value is set to a small value, the transmittance is set to the maximum, and the amplification factor is set to the same value. It is determined whether or not the level of the imaging signal of the green component exceeds the reference level, and if the level of the imaging signal of the green component exceeds the reference level as a result of the determination, the level of the imaging signal of the green component is the reference level The first control is performed to make the transmittance of the G optical filter smaller than the maximum value so as to be a level, and when the level of the imaging signal of the green component is lower than the reference level, the green color formation is performed. A color television camera that performs second control to increase the amplification factor of the amplifier that amplifies the imaging signal output from the G imaging element so as to be equal to the reference level so that the level of the imaging signal becomes the reference level. . The color television camera according to claim 1,
As a result of the determination, the white balance adjustment unit performs an operation for increasing the amount of light incident on the three image sensors when the level of the image signal of the green component is less than the reference level. A color television camera that prompts the user of the color television camera to execute the second control when the work is not performed and performs the determination again when the work is performed. The color television camera according to claim 1 or 2,
The white balance adjustment unit performs the first control or the second control, and then the level of the red component imaging signal obtained by photographing the reference white plate with the R imaging element becomes the reference level. As described above, the transmittance of the R optical filter or the amplification factor of the amplifier that amplifies the imaging signal output from the R image sensor is controlled, and the blue component obtained by photographing the reference white plate by the B image sensor A color television camera that controls the transmittance of the B optical filter or the amplification factor of the amplifier that amplifies the imaging signal output from the B imaging element so that the level of the imaging signal becomes the reference level. The color television camera according to any one of claims 1 to 3,
The color television camera, wherein the same value set by the white balance adjustment unit is a minimum value of an amplification factor that can be set for each of the three amplifiers. A color separation optical unit that separates incident light into three colors of red, green, and blue; an R image pickup device that is an image pickup device disposed opposite to a red light emission surface of the color separation optical unit; and the color separation optical unit A color television camera having a G image pickup device which is an image pickup device arranged opposite to the green light emission surface and a B image pickup device which is an image pickup device arranged opposite to the blue light emission surface of the color separation optical unit. The white balance adjustment method in
The color television camera is disposed between the red light emitting surface and the R imaging element, and an R optical filter capable of electrically controlling transmittance, the green light emitting surface, and the G G optical filter that is arranged between the image sensor and electrically controllable transmittance, and is arranged between the blue light emitting surface and the B image sensor, and the transmittance can be controlled electrically. A B optical filter, and an amplifier that amplifies an image pickup signal output from each of the three image pickup devices,
A transmittance maximum setting step for setting the transmittance of each of the R optical filter, the G optical filter, and the B optical filter to a maximum;
An amplification factor setting step for setting the amplification factor of each of the three amplifiers to the same value smaller than a maximum value that can be set;
When the transmittance is set to the maximum and the amplification factor is set to the same value, the level of the green component imaging signal obtained by photographing the reference white plate with the G imaging element is the reference level. A determination step of determining whether or not
As a result of the determination in the determination step, when the level of the green component imaging signal exceeds the reference level, the transmittance of the G optical filter is set so that the level of the green component imaging signal becomes the reference level. The G image pickup device is configured to perform first control to be smaller than a maximum value, and when the level of the green component imaging signal is lower than the reference level, the level of the green component imaging signal becomes the reference level. A white balance adjustment method for a color television camera, comprising: a control step of performing a second control to increase an amplification factor of the amplifier that amplifies an imaging signal output from the same value. A white balance adjustment method for a color television camera according to claim 5,
In the control step, as a result of the determination in the determination step, when the level of the image signal of the green component is less than the reference level, an operation for increasing the amount of light incident on the three image sensors is performed. Urge the user of the color television camera to execute the second control when the work is not performed,
A color television camera white balance adjustment method in which the determination step is performed again when the work is performed. A white balance adjustment method for a color television camera according to claim 5 or 6,
After performing the first control or the second control, the R optical filter so that the level of the red component imaging signal obtained by photographing the reference white plate by the R imaging element becomes the reference level. Or the amplification factor of the amplifier that amplifies the imaging signal output from the R imaging device, and the level of the imaging signal of the blue component obtained by photographing the reference white plate by the B imaging device is the reference A white balance adjustment method for a color television camera that controls the transmittance of the B optical filter or the amplification factor of the amplifier that amplifies the imaging signal output from the B imaging element so as to achieve a level. It is the white balance adjustment method of the color television camera of any one of Claims 5-7,
The color television camera white balance adjustment method, wherein the same value set in the amplification factor setting step is a minimum value of the amplification factor that can be set in each of the three amplifiers.

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