JP2010104016A - Imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a triple-plate type solid-state imaging apparatus for constantly maintaining a white balance change even when internal temperature elevation or use environmental temperature change occurs. <P>SOLUTION: According to one embodiment of the present invention, an imaging apparatus (1) includes: a first CCD 7R for converting a first color component according to additive color mixture into an electric signal; a second CCD 7G for converting a second color component different from the first color component into a second electric signal; a third CCD 7B for converting a third color component different from the first and the second color components into a third electric signal; and a heat radiating plate 11 including first to third radiators for radiating heat from the first to the third CCDs, wherein the first to the third radiators are maintained at the same temperature. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to improvement of white balance (temperature compensation) in an imaging device using an imaging device, for example, a three-plate CCD.

  In an image pickup apparatus using a three-plate CCD, it is known that white balance tends to be lost as the temperature of each of the R, G, and B CCDs increases.

  Against this background, a method for suppressing a change in white balance in an imaging apparatus using a CCD has already been proposed.

  In Patent Document 1, in a single-plate solid-state image pickup device, an image pickup device is attached to a substrate to dissipate heat from the substrate, and the temperature of the R, G, B image pickup device is made uniform to eliminate white balance deviation. It is disclosed.

  Patent Document 2 discloses that in a solid-state image sensor of a three-plate CCD using a color separation prism, each image sensor (R, G, B) is cooled using an electronic cooling element.

  Patent Document 3 discloses an image processing apparatus that corrects a white balance shift due to a temperature change in a CMOS sensor in accordance with a temperature at factory adjustment and a current temperature difference.

Japanese Patent Laid-Open No. 1-259692 Japanese Patent Laid-Open No. 5-207486 JP 2008-72439 A

  The solid-state imaging device disclosed in Patent Document 1 is a single-plate type, and when the R, G, and B imaging devices are provided independently, the temperature rises for each device or changes in sensitivity for each device accompanying the temperature rise. There is no mention of eliminating the resulting white balance deviation.

  It is known that the electronic cooling element disclosed in Patent Document 2 is very expensive and the overall size (volume) increases.

  The image processing apparatus disclosed in Patent Document 3 corrects the white balance according to the difference between the factory adjustment temperature and the current (installation environment) temperature when driving the CMOS sensor. No mention is made of eliminating a white balance shift caused by a difference in temperature rise between elements when each image sensor is provided independently.

  An object of the present invention is to provide a three-plate solid-state imaging device capable of maintaining a constant white balance change even when an internal temperature rise or a change in use environment temperature occurs.

  The present invention has been made on the basis of the above-described problem. The first element for converting the first color component according to the additive color mixture into an electrical signal, and the second color different from the first color component according to the additive color mixture. A second element that converts a component into a second electrical signal, and a third element that converts a third color component different from the first and second color components into a third electrical signal according to additive color mixing A first output adjusting device that changes a gain of an output signal output from the first element based on a change in ambient or its own temperature, and a gain of an output signal output from the second element in the surrounding or itself A second output adjustment device that changes based on a change in temperature of the second output adjustment device; a third output adjustment device that changes the gain of an output signal output from the third element based on a change in the surrounding or its own temperature; Provided with an imaging device characterized by having A.

  According to the present invention, the output characteristics of the CCD sensor for each color fluctuate due to the ambient temperature change or the temperature rise of the CCD sensor itself, and the problem that white balance is shifted and correct color reproduction cannot be realized is improved. be able to.

  Further, for example, by radiating the temperature rise of all the individual CCD sensors with a single heat radiating plate, it is possible to reduce variations in the output of the individual CCD sensors due to temperature changes.

  Furthermore, by correcting the variation in the output of each CCD sensor with respect to the temperature rise of the individual CCD sensor based on the temperature detected by the temperature sensor provided in the vicinity of the CCD sensor, it is possible to obtain an imaging device with more stable white balance. it can.

1 is a schematic diagram showing an example of a three-plate CCD image pickup apparatus to which an embodiment of the present invention is applied. Schematic which shows an example of the signal processing part used for the 3 plate type CCD imaging device shown in FIG. FIG. 2 is a schematic diagram illustrating an example of a three-plate CCD sensor used in the imaging apparatus illustrated in FIG. 1. Schematic which shows an example of the characteristic of the shape of a hot plate in the imaging device with which embodiment shown in FIG. 1 is summarized. Schematic which shows an example of another embodiment of the heat sink shown in FIG. Schematic which shows an example of another embodiment of the heat sink shown in FIG. Schematic which shows an example of the relationship between the output of a CCD sensor using the signal processing circuit shown in FIG. 2, and amplifier gain (correction signal level). Schematic which shows an example of the relationship between the output of a CCD sensor using the signal processing circuit shown in FIG. 2, and amplifier gain (correction signal level). FIG. 3 is a schematic diagram illustrating an example for explaining the signal processing circuit shown in FIG. 2 in more detail; Schematic which shows an example of another embodiment of the signal processing circuit which showed an example in FIG.

  Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 shows an example of a three-plate CCD image pickup apparatus to which an embodiment of the present invention is applied.

  An imaging apparatus 1 shown in FIG. 1 has a lens 3 that receives image light from an imaging target, and image light input from the lens 3 is R (Red, G), G (Green), which is an additive color mixture of three subtractive colors. And a prism 5 that decomposes into B (Blue), and a three-plate CCD sensor 7 (R, G, B) that converts image light for each of R, G, and B colors separated by the prism 5 into input image signals. Including. The lens 3 is detachably formed with respect to the prism 5 and the three-plate CCD sensor 7 by the cabinet 3a, and is useful when the lens 3 needs to be replaced. Also, the prism 5 and the three-plate CCD sensor 7 are integrally formed, and the three-plate CCD sensor is formed by the heat conducting sheet 9 and the heat radiating plate 11 integrated with the prism 5 and the three-plate CCD sensor 7 via the heat conducting sheet 9. The heat from 7 is dissipated. In addition, the one end part of the heat sink 11 is connected with the cabinet 3a formed with a metal in many cases, and heat dissipation efficiency is improved (a high heat dissipation amount is ensured).

  The input image signal output from each of the three-plate CCD sensor 7 (R, G, B) is outlined in FIG. 2, but is amplified to a predetermined gain by the process circuit block 13 and then A / D converted. Then, predetermined signal processing is performed by the signal processing circuit block 15 and output as an R signal output, a G signal output, and a B signal output. The process circuit block 13 is a CDS (Correlated Double Sampling) that removes noise components from the input image signals output from the R, G, and B CCD sensors, and a predetermined gain for the output of the CDS circuit. A gain control amplifier (GCA) that provides a digital signal and an A / D converter that converts the analog input image signal into a digital signal and outputs the digital signal.

  The signal processing circuit block 15 includes a shading correction unit that corrects a light amount difference between the image light passing through the center of the lens 3 and the image light passing through the periphery of the lens 3 among the signals output from the CCD sensors 7 and an input. A gamma (γ) correction unit for correcting the contrast of the image signal is included.

  Although not shown, the R, G, B image signals output from the signal processing circuit block 15 are connected to a subsequent stage via an image output circuit (camera link driver), for example, a display device (monitor device) or an image. The data is output to a data storage unit (mass storage unit) or the like.

  FIG. 3 shows an example of the positional relationship between the reflecting surface of the prism 5 that makes the input image light enter each channel of the CCD sensor 7, that is, the CCD sensors 7R, 7G, and 7B for each color, and the prisms of the respective colors.

  Of the input image light incident on the prism 5, for example, the B channel, that is, the blue image component that should be received by the CCD 7B is reflected by the first wavelength selection film 5B and reflected by the light incident surface 5I. Not guided to the light receiving surface. Of the input image light incident on the prism 5, for example, an R channel, that is, a red image component to be received by the CCD 7R is transmitted through the first wavelength selection film 5B and reflected by the second wavelength selection film 5R. The light is reflected again by the back surface of the first wavelength selection film 5B and guided to a light receiving surface (not described in detail) of the CCD 7R. Of the input image light incident on the prism 5, the G channel, that is, the green image component to be received by the CCD 7G is transmitted through the first wavelength selection film 5B and the second wavelength selection film 5R, and the details of the CCD 7G. Guided to a light receiving surface not described. Further, each CCD sensor 7R, 7G, 7B integrally has individual heat radiating plates 7a, 7b, 7c for radiating the heat released from each.

  FIG. 4 shows the characteristics of the shape of the hot plate in the imaging apparatus to which the embodiment shown in FIG. 1 is summarized.

  As shown in FIG. 4, the heat radiating plate 11 has a prism 5 and a three-plate type from the side of the prism 5 and the three-plate CCD sensor 7 through a heat conducting sheet 9 provided integrally with the prism 5 and the three-plate CCD sensor 7. Connected to each of the CCD sensors 7. In addition, the heat radiating plate 11 is provided for each of the individual heat radiating plates 7a, 7b so as to equalize the heat from the individual heat radiating plates 7a, 7b, 7c provided in the individual CCD sensors 7R, 7G, 7B of the three-plate CCD sensor 7. , 7c are provided for each CCD sensor, but are integrated with each other (regions in contact with the CCD sensors 7R, 7G, 7B via the heat conductive sheet 9 are formed on a single plate having a large area. )

  With this configuration, the temperature rise values of the blue (B) CCD 7B, the green (G) CCD 7G, and the red (R) CCD 7R are the same, the difference in sensitivity between the individual CCDs due to the temperature is reduced, and the white balance of the imaging device 1 is improved. Stabilized.

  FIG. 5 shows an example of another embodiment of the heat dissipation plate shown in FIG.

  As shown in FIG. 5, the heat radiating plate 11 has a prism 5 and a three-plate type from the side of the prism 5 and the three-plate type CCD sensor 7 via a heat conductive sheet 9 provided integrally with the prism 5 and the three-plate type CCD sensor 7. Connected to each of the CCD sensors 7. In addition, the heat sink 11 corresponds to the individual CCD sensors 7R, 7G, and 7B according to the individual heat sinks 7a, 7b, and 7c provided on the individual CCD sensors 7R, 7G, and 7B of the three-plate CCD sensor 7. Provided independently. In this case, it is not always necessary to be connected to the cabinet 3a as shown in FIG. 1 on the assumption that the heat from the CCD sensors R, 7G, and 7B is relatively small.

  With this configuration, the temperature rise values of the blue (B) CCD 7B, the green (G) CCD 7G, and the red (R) CCD 7R are the same, the difference in sensitivity between the individual CCDs due to the temperature is reduced, and the white balance of the imaging device 1 is improved. Stabilized.

  FIG. 6 shows an example of still another embodiment of the heat dissipation plate shown in FIG.

  As shown in FIG. 6, the heat radiating plate 11 includes individual heat radiating plates 7 a (provided on the red (R) CCD sensor 7 R and the blue (B) CCD sensor 7 B among the prism 5 and the three-plate CCD sensor 7. Only the sensors 7R) and 7c (sensor 7B) are provided independently through the heat conductive sheet 9 (two locations). In this case, on the premise that the heat from the CCD sensor 7G is relatively small, it is not necessary to be connected to the cabinet 3a as shown in FIG.

  With this configuration, the blue (B) CCD sensor 7B and the red (R) CCD sensor 7R are based on the green (G) CCD sensor 7G, which has a smaller number of reflections by the prism 5 than other CCD sensors. By suitably controlling the temperature rise, that is, by correcting the R component and the B component in a state where the G component is fixed, it is possible to prevent color unevenness (white balance deviation) from occurring.

  7 and 8 respectively show the relationship between the output of the red (R) CCD sensor and the blue (B) CCD sensor and the amplifier gain (correction signal level) using the signal processing circuit shown in FIG.

  FIG. 7 illustrates a red (R) CCD sensor (CCD 7R in FIG. 1) as an example, but shows an example in which the image level, that is, the CCD output is increased as the ambient temperature and the temperature of the CCD sensor itself increase. (Example using a thermistor whose resistance increases as temperature rises).

  In the example shown in FIG. 7, although not shown, for example, the gain control amplifier in the process circuit block 13 causes the increase in the CCD output accompanying the increase in the ambient temperature and the temperature of the CCD sensor itself to be substantially “0”. Gain is controlled.

  FIG. 8 illustrates a blue (B) CCD sensor (CCD 7B in FIG. 1) as an example, but shows an example in which the image level, that is, the CCD output decreases as the ambient temperature and the temperature of the CCD sensor itself increase. (Example using a thermistor whose resistance value decreases with increasing temperature).

  In the example shown in FIG. 8, although not shown, for example, the gain control amplifier in the process circuit block 13 causes the decrease in the CCD output accompanying the increase in the ambient temperature and the temperature of the CCD sensor to be substantially “0”. Gain is controlled.

  The example shown in FIGS. 7 and 8 is an example. For example, when the output of the blue (B) CCD sensor increases due to the ambient temperature and the temperature increase of the CCD sensor itself, the example shown in FIG. It goes without saying that the amplifier gain (correction signal level) is reduced according to the above. Further, for example, when the output of the red (R) CCD sensor decreases due to the ambient temperature and the temperature increase of the CCD sensor itself, the amplifier gain (correction signal level) is increased in accordance with the example shown in FIG. The In other words, by using a thermistor that shows the opposite temperature characteristics according to whether the output gain increases or decreases as the temperature rises, fluctuations in the output level of each CCD with respect to temperature are canceled out, and the white balance is stabilized. Can be

  FIGS. 9A, 9B, and 9C are circuit examples illustrating the signal processing circuit shown in FIG. 2 in more detail.

  As shown in FIG. 9B, the noise component of the output of the green (G) CCD sensor 7G of the three-plate CCD sensor 7 schematically shown in FIGS. 1 and 3 is removed by the G CDS circuit 17G. Thereafter, the signal is amplified to a predetermined level by a gain control unit 19G including a series resistor RG1, a negative feedback amplifier G-GCA, and a feedback resistor RG2.

  On the other hand, as shown in FIG. 9A, the output of the red (R) CCD sensor 7R of the three-plate CCD sensor 7 schematically shown in FIGS. 1 and 3 is converted into a noise component by the R CDS circuit 17R. Is removed, and is amplified to a predetermined level by a gain control unit 19R including series resistors RR1 and RR3, a negative feedback amplifier R-GCA, a feedback resistor RR2, and a thermistor RTH. The thermistor RTH is grounded between the series resistors RR1 and RR3.

  On the other hand, as shown in FIG. 9C, the noise component is removed from the output of the blue (B) CCD sensor 7B of the three-plate CCD sensor 7 schematically shown in FIGS. 1 and 3 by the B CDS circuit 17B. After that, the gain is amplified to a predetermined level by a gain control unit 19B including a series resistor RB1, a negative feedback amplifier B-GCA, a feedback resistor RB2, and a thermistor BTH provided in series with the feedback resistor RB2.

  The gain control units shown in FIGS. 9A, 9B and 9C can be suitably combined with any color, for example, a green (G) CCD sensor 7G. The gain control section shown in FIG. 9 (A) may be used for both the R output and the B output, or the gain control section shown in FIG. 9 (C) may be used. Further, the gain control unit shown in FIG. 9A may be used for all the CCD sensors 7R, 7G, and 7B of R, G, and B, or the gain control unit shown in FIG. It may be used.

  When the prism 5 and the CCD sensor 7 shown in FIG. 3 are used, the input image light input through the lens 3 is converted into an input image signal for each of R, G, and B colors. In the embodiment shown in the figure, since the number of reflections of the green image component guided to the G channel, that is, the CCD 7G, by the prism 5 is the smallest, the green (G) CCD sensor 7G is shown in FIG. As shown in the above, by correcting the R component and the B component in a configuration that does not include the thermistor, that is, in a state where the G component is fixed, it is possible to more stably prevent color unevenness (white balance deviation) from occurring. .

  FIG. 10 shows another embodiment of the signal processing circuit shown as an example in FIG.

  The signal processing circuit shown in FIG. 10 has the CCD sensor 7R, 7G for each color component (R, G, B) for the input image signal output from each of the three-plate CCD sensor 7 (R, G, B). And a process circuit 25 including CDS circuits 21R, 21G and 21B for removing noise components from the input image signals output from 7B and variable amplifier circuits 23R, 23G and 23B for giving a predetermined gain to the output of each CDS circuit. Including. Outputs from the process circuit 25, that is, the variable amplifier circuits 23R, 23G, and 23B for each color component are input to the signal processing circuit block 15 described with reference to FIG.

  The gain (adjustment amount) of each variable amplifier circuit 23R, 23G, and 23B of the process circuit 25 acquires the output of the temperature sensor 27 provided in the vicinity of the prism 5 and the three-plate CCD sensor 7 and individually for each color component. An instruction value for correcting the outputs of the CCD sensors 7R, 7G, and 7B is set, and is set by the microcomputer unit 29 that determines the presence / absence of correction by the variable amplifier circuits 23R, 23G, and 23B and the correction value. In other words, the temperature around the CCD sensor 7 is detected by the temperature sensor 27, and the temperature detected by the temperature sensor 27 is detected by the microcomputer unit 29 in which the output levels of the individual CCDs R, G, and B according to the temperature are stored in advance. Accordingly, the microcomputer 29 controls the gain of the process circuit 25 separately for each of R, G, and B, so that the output of each of the CCD sensors 7R, 7G, and 7B can be more finely corrected, and the white balance is further improved. It can be maintained well.

  As described above, by using one of the embodiments of the present invention, the output characteristics of the CCD sensor for each color fluctuate due to the ambient temperature change or the temperature rise of the CCD sensor itself, and the white balance It is possible to improve the problem that the correct color reproduction cannot be realized.

  Further, for example, by radiating the temperature rise of all the individual CCD sensors with a single heat radiating plate, it is possible to reduce variations in the output of the individual CCD sensors due to temperature changes.

  Furthermore, by correcting the variation in the output of each CCD sensor with respect to the temperature rise of the individual CCD sensor based on the temperature detected by the temperature sensor provided in the vicinity of the CCD sensor, it is possible to obtain an imaging device with more stable white balance. it can.

  It should be noted that the content of the present invention is not limited to the form described here, and it goes without saying that various other forms can be taken without departing from the spirit of the invention. In addition, the embodiments may be implemented by appropriately combining them as much as possible, or by deleting a part thereof. In that case, various effects resulting from the combination or deletion can be obtained.

  DESCRIPTION OF SYMBOLS 1 ... 3 plate CCD type imaging device, 3 ... Lens, 3a ... Lens holder (cabinet), 5 ... Prism, 7 ... CCD sensor, 7R, 7G, 7B ... Individual CCD sensor ((R) CCD sensor 7R, (G) CCD sensor 7G, (B) CCD sensor 7B), 9 ... heat conduction sheet, 11 ... heat sink, 13 ... process circuit block, 15 ... signal processing circuit block, 17R, 17G, 17B ... CDS circuit, 19R, 19G, 19B ... gain control units 19, 21R, 21G, 21B ... CDS circuit, 23R, 23G, 23B ... variable amplifier unit, 25 ... process circuit, 27 ... temperature sensor, 29 ... microcomputer unit.

Claims (12)

A first element that converts a first color component according to additive color mixing into an electrical signal;
A second element that converts a second color component different from the first color component into a second electrical signal in accordance with additive color mixing;
A third element that converts a third color component different from the first and second color components into a third electrical signal according to additive color mixing;
A first output adjusting device that changes a gain of an output signal output from the first element based on a change in ambient or its own temperature;
A second output adjusting device that changes a gain of an output signal output from the second element based on a change in ambient or its own temperature;
A third output adjusting device that changes a gain of an output signal output from the third element based on a change in ambient or its own temperature;
An imaging device comprising:   At least one of the first output adjustment device, the second output adjustment device, and the third output adjustment device includes an element that changes in resistance value due to a temperature rise. The imaging device according to claim 1.   The imaging apparatus according to claim 2, wherein the element whose resistance value changes as the temperature rises is an element whose resistance value decreases as the temperature rises.   The imaging device according to claim 2, wherein the element whose resistance value changes as the temperature rises is an element whose resistance value increases as the temperature rises.   The imaging apparatus according to claim 2, wherein at least two of the first output adjustment device, the second output adjustment device, and the third output adjustment device are provided. A first heat radiator that dissipates heat from the first element;
A second radiator that dissipates heat from the second element;
A third radiator for radiating heat from the third element;
The imaging apparatus according to claim 2, further comprising:   The imaging apparatus according to claim 6, wherein each of the first heat radiator, the second heat radiator, and the third heat radiator is connected to each other.   The imaging apparatus according to claim 6, wherein at least two of the first heat radiator, the second heat radiator, and the third heat radiator are connected to each other. A first element that converts a first color component according to additive color mixing into an electrical signal;
A second element that converts a second color component different from the first color component into a second electrical signal in accordance with additive color mixing;
A third element that converts a third color component different from the first and second color components into a third electrical signal according to additive color mixing;
A temperature detecting device for detecting a temperature in the vicinity of the first element, the second element, and the third element;
The temperature sensing device has at least one of a gain of an output signal output from the first element, a gain of an output signal output from the second element, and a gain of an output signal output from the third element. A control unit that changes based on the temperature to be detected;
An imaging device comprising: A first radiator that dissipates heat from the first element;
A second radiator that dissipates heat from the second element;
A third radiator for radiating heat from the third element;
The imaging apparatus according to claim 9, further comprising:   The imaging device according to claim 10, wherein each of the first heat radiator, the second heat radiator, and the third heat radiator is connected to each other.   The imaging device according to claim 10, wherein at least two of the first heat radiator, the second heat radiator, and the third heat radiator are connected to each other.

Images