JP2008042248A - Electronic camera and its exposure control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electronic camera capable of displaying an image for which suitable exposure control is executed without delay after the camera shifts to a photographing mode. <P>SOLUTION: When the electronic camera 10 is powered off, an aperture 36 and a shutter 38 are opened to execute predetermined exposure, and an electromotive force is generated in a solid-state imaging device 14. The electromotive force is detected as digital data 58 by an amplifier circuit 16, an A/D converter 18, and a signal processor 22 which are driven by an independent power supply, and the signal processor 22 uses its exposure value determining function 24 to previously determine an exposure value in activation corresponding to the electromotive force. When the electronic camera 10 shifts to the photographing mode based on power on or the like, a monitor 49 initially displays an image subjected to proper exposure by an optical system 12 based on a previously determined activation exposure value and output from the solid-state imaging device. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electronic camera and an exposure control method thereof.

  In an electronic camera, exposure control is performed according to the brightness of the subject. In exposure control, it is important to obtain an accurate exposure value while shortening the processing time. In particular, since the brightness of the subject is still unclear when the camera is activated, an automatic exposure (AE) process is performed by estimating the brightness of the subject using an image of one frame immediately after activation, and the evaluation value. Based on the above, it is known to perform exposure control by adjusting the aperture and determining the shutter speed. Alternatively, it is also known that exposure control is performed by adjusting the aperture and determining the shutter speed based on the brightness detected by the sensor using a light control sensor or the like.

In the imaging apparatus described in Patent Document 1, the exposure control processing time is shortened by speeding up the charge reading from a charge coupled device (CCD) as a rough exposure adjustment.
JP-A-7-303206

  However, as described above, when the brightness of a subject is estimated using an image signal of one frame obtained immediately after startup and automatic exposure processing is performed, if the estimated brightness differs from the actual brightness, the image becomes excessive. A phenomenon of brightening or excessive darkening occurs. For this reason, there is a measure that one frame immediately after activation is not displayed on the monitor, but if this is performed, there is a problem that the user feels that the time until activation is long.

  Also, in the method of accurately measuring the brightness of the object field using a sensor such as a light control sensor and using it for exposure control, the sensor must be installed in the camera, which increases the size and cost of the camera. There was a problem that it took.

  Furthermore, in the imaging apparatus described in Patent Document 1, the charge is read from the solid-state image sensor with the aperture closed and shielded, and then the charge is read again from the solid-state image sensor with the aperture opened to the limit. Even if the reading speed of the image sensor is increased, there is a problem that it still takes time to control the exposure.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is an object of the present invention to provide an electronic camera and an exposure control method that perform accurate exposure control with a short processing time.

  In order to solve the above problems, an electronic camera according to the present invention includes two photosensitive elements that generate an image signal by photoelectrically converting light from an object scene during exposure and generating an electromotive force according to the amount of light. Dimensionally arranged solid-state imaging devices, exposure control means for causing the solid-state imaging device to perform predetermined exposure while no image signal is output from the solid-state imaging device, and electromotive force generated in the solid-state imaging device by the predetermined exposure An exposure value determining means for determining an exposure value based on the image, and an image formed from an image signal generated and output to the solid-state imaging device by the exposure performed by the exposure control means to realize the determined exposure value from the beginning. Display means.

  In order to solve the above-described problem, the electronic camera exposure control method according to the present invention generates an image signal by photoelectrically converting light from the object scene and generates an electromotive force according to the amount of light. A step of stopping the output of the image signal from the solid-state imaging device in which the photosensitive elements to be arranged in a two-dimensional manner, a step of causing the solid-state imaging device to perform a predetermined exposure while the output of the image signal is stopped, and a predetermined exposure A step of determining an exposure value based on an electromotive force generated in the solid-state image sensor and an exposure performed by the exposure control means so as to realize the determined exposure value causes the solid-state image sensor to generate an image signal and output the image signal from the element And a step of displaying an image formed by the output image signal on the display means from the beginning.

  According to the present invention, the exposure value determining means is a mode in which no image signal is output from the solid-state image sensor even when the power of the electronic camera is off or when the power is on, that is, a mode other than the shooting mode. In this case, the exposure value is determined in advance, and when the electronic camera enters the shooting mode by turning on the power or shifting from another mode, the exposure control is performed so as to realize the predetermined exposure value. An image formed by the image signal output from the solid-state imaging device thus formed can be displayed on the display means from the beginning. That is, an image obtained by accurately controlling the exposure can be quickly displayed after shifting to the shooting mode. As a result, the sense of delay felt by the user at the time of startup or the like can be eliminated.

  Moreover, since exposure control is performed using a solid-state image sensor, a sensor such as a light control sensor is not required, leading to space saving.

  Embodiments of an electronic camera and its exposure control method according to the present invention will now be described in detail with reference to the accompanying drawings. FIG. 1 is a block diagram showing an embodiment of an electronic camera according to the present invention. The electronic camera 10 according to the present invention has a temporary exposure value at startup (hereinafter referred to as startup exposure value) based on an electromotive force obtained from the electric charge accumulated in the solid-state imaging device 14 since the power is turned off. The camera to be determined will be described below.

  The camera 10 includes an operation unit 26 that is connected to the control unit 20 and supplies various operation signals 88 to the control unit 20 when operated by a user. The control unit 20 is a device that controls various elements in the camera 10 connected thereto. The camera 10 includes a power source (not shown), and power is input only to the entire camera or only a part of the camera by a control signal supplied from the control unit 20 via a signal line. The operation unit 26 includes a power button 28 and a mode switching button 30. When the power button 28 is not pressed, only the optical system 12, solid-state imaging device 14, amplifier circuit 16, A / D converter 18, control unit 20 and digital signal processing circuit 22 described later are powered independently. Supplied. This is called a first power input in the text. On the other hand, when the power button 28 is pressed down, the entire camera is turned on via the control unit 20. This is called a second power input in the text.

  In the embodiment of the present invention, since the predetermined exposure is performed by the diaphragm 36 and the shutter 38 even when the camera is turned off, an electromotive force is generated in the solid-state imaging device 14. This electromotive force is detected by a part of the camera that receives the first power input described above, and the exposure value is determined even when the camera is turned off. Thus, the exposure value determined in advance when the camera is turned off is used as a temporary exposure value when the camera is turned on, that is, immediately after startup. There are two paths from the solid-state imaging device 14 to the digital signal processing circuit 22, which are a path via the amplifier circuit 16 and a path via the CDS 42. Power is supplied by a power input of 1.

  The camera 10 includes an optical system 12 that captures light from the object scene, and 14 that receives irradiation of the light 50 supplied from the optical system 12, and the solid-state imaging device 14 converts the light 50 into an electrical signal by a photodiode. In this embodiment, it is a (Charge Coupled Device; CCD) type solid-state imaging device, but instead of this, a complementary metal oxide semiconductor (C-MOS) type, etc. Alternatively, a MOS type solid-state imaging device may be used.

  FIG. 2 is a configuration diagram of the solid-state imaging device shown in FIG. The solid-state image sensor 14 includes a plurality of photodiodes 100. The photodiode 100 is a diode that facilitates the flow of a photoconductive current by joining two P-type and N-type semiconductors having contradictory properties so that light effectively strikes the junction. In the photodiode 100, when light enters the PN junction, photoelectric conversion occurs and the light is converted into electric charges. The photodiode 100 supplies the converted charge to the vertical CCD 102. The vertical CCD 102 sequentially transfers charges supplied from the photodiodes to the horizontal CCD 104, and the horizontal CCD 104 sequentially transfers charges supplied from the vertical CCDs 102 to the output unit 106. The output unit 106 converts the charge supplied from the horizontal CCD 104 into a voltage and outputs it as an image signal.

  FIG. 12 is a diagram showing a cross-sectional structure of the photodiode shown in FIG. Light 111 from the object scene enters between the light shielding films 105. In FIG. 12, the PN junction 107 is used as the photodiode 100. In the present invention, the electromotive force generated in the PN junction 109 formed by the P-type semiconductor Pwell and the N-type semiconductor Nsub due to the incidence of the light 111 is used for exposure control. Although an electromotive force generated in the upper PN junction 107 in FIG. 12 used as the photodiode 100 may be used, it is preferable to use an electromotive force generated in the PN junction 109.

  In general, when exposure control is performed, the brightness of a subject is usually calculated from an image signal output from a solid-state imaging device, and an exposure value is determined. However, even if no voltage is applied to the PN junction of a photosensitive element such as a photodiode, photoelectric conversion occurs and an electromotive force is generated when light enters. Since this electromotive force varies according to the amount of light, it can also be used as a light amount sensor. If this property is used, even if the camera does not yet have the luminance data of the subject, i.e. immediately after the camera is turned on and started, or immediately after the camera is switched from the playback mode to the shooting mode, An image formed by an image signal output from a solid-state imaging device whose exposure is controlled so as to realize a predetermined exposure value can be displayed on the display unit from the beginning. That is, an image obtained by accurately controlling the exposure can be quickly displayed after shifting to the shooting mode.

  FIG. 13 is a circuit diagram showing a mechanism for detecting an electromotive force from the PN junction shown in FIG. An electromotive force of, for example, about 0 to −0.3 V generated at the PN junction 109 due to the incidence of the light 111 is detected via the switch 113. A terminal 115 that connects the switch 113 to the solid-state imaging device may be a pin that supplies a drive pulse to the vertical CCD connected to the photodiode 100. That is, when the switch 113 selects the terminal 117, a driving pulse given from a timing generator 119 described later is given to the solid-state imaging device 14, and the solid-state imaging device enters a photographing mode. On the other hand, in other cases, such as in the playback mode or when the camera is turned off, the switch 113 selects the terminal 52 and outputs the electromotive force generated at the PN junction 109 to the amplifier circuit 16.

  The amplifier circuit 16 shown in FIG. 1 is connected to the solid-state image sensor 14 via a switch 113 (not shown in FIG. 1), and an A / D (Analog to Digital) conversion of the electric signal 52 coming from the solid-state image sensor 14 is performed. It is a circuit that converts the amplitude to be easily input to the device 18 and supplies it through the signal line 56. The amplifier circuit 16 is also connected to the control unit 20 and is controlled by a control signal 60.

  The A / D converter 18 is connected to the circuit 16 and is a converter that converts analog image data coming from the circuit 16 into digital image data.

  The digital signal processing circuit 22 includes an exposure value determination function 24, determines the startup exposure value from the digital signal coming from the A / D converter 18, and from the digital image signal coming from the A / D converter 46, It is a device that determines the exposure value after activation. Hereinafter, the exposure value determination function 24 at the time of activation will be described. The function 24 determines a preset appropriate exposure value corresponding to the electromotive force value of the digital data 58. For example, the exposure value may be determined according to the correspondence relationship shown in FIGS. That is, the brightness of the subject is divided into regions A, B, and C based on the electromotive force obtained, and appropriate exposure values for each region are shown in FIG. 3 and 4, when the electromotive force obtained is less than 0.6 [V], the exposure value is 17 [EV] in the region A, and when it is 0.6 [V] or more and less than 1.2 [V], the exposure value is 13 [EV]. In the region C, the exposure value is 9 [EV] in the range of 1.2 [V] to less than 1.8 [V]. However, the area and the corresponding exposure value may be arbitrary values. The digital signal processing circuit 22 supplies the determined startup exposure value to the optical system 12 via the signal line 64, the control unit 20, and the signal line 66.

  The electronic camera 10 according to the present invention may not include the amplifier circuit 16 shown in FIG. In that case, the electric signal supplied from the solid-state imaging device 14 is supplied to the A / D converter 18 as it is. Since the amplification circuit 16 does not perform amplification, the exposure value determination function 24 may determine an appropriate exposure value corresponding to the electromotive force of the digital data 58 using the correspondence relationship shown in FIG.

  The optical system 12 includes a lens 34, a diaphragm 36, a shutter 38, and an AE / AF (Auto Exposure / Auto Focus) drive function 40. The AE / AF drive function 40 adjusts the aperture 36 based on the supplied exposure value 66 to adjust the amount of light 50, and performs exposure control for determining the shutter speed of the shutter 38. The AE / AF drive function adjusts the focus by moving the lens 34.

  The aperture 36 and the shutter 38 are completely provided when the power of the camera is off, that is, when power is supplied only to the element that determines the startup exposure value, and when the first power input is performed. It is open or partially open so that it is not completely shielded from light. That is, the solid-state imaging device 14 performs a predetermined exposure.

  A power source (not shown) performs a second power input to the entire camera when the power button 28 is depressed. That is, power is also supplied to the CDS 42, the AGC 44, the A / D converter, the image display unit 48, and the D / A converter 90. In other words, there are two paths from the solid-state imaging device 14 to the digital signal processing circuit 22, which are a path through the amplifier circuit 16 and a path through the CDS 42. Elements on the latter path In addition, power is supplied by a second power input to the entire camera.

  A CDS (Correlated Double Sampling) 42 is a circuit connected to the solid-state imaging device 14 for removing noise. The CDS 42 performs sampling by removing noise from the supplied electric signal 68 and supplies the obtained electric signal to an AGC (Automatic Gain Control) 44 via the signal line 70. The AGC 44 is a circuit that automatically corrects the signal level and automatically adjusts the gain to a constant level. The AGC 44 adjusts the gain according to the signal level of the supplied electric signal 70, and supplies it to the A / D converter 46 via the signal line 74. The A / D converter 46 is a converter similar to the A / D converter 18. The A / D converter 46 converts the electrical signal 74 that is analog data into digital data, and supplies the digital data to the digital signal processing circuit 22 via the signal line 76.

  When the digital data 76 is supplied, the digital signal processing circuit 22 calculates the brightness of the subject from the digital data 76 and performs an exposure value determination process after activation that determines the exposure value based on the brightness of the subject. This exposure value determination is different from the method of determining the startup exposure value based on the electromotive force obtained from the signal charge accumulated in the solid-state imaging device 14 since the power is turned off. The digital signal processing circuit 22 supplies the obtained exposure value after activation to the optical system 12 via the signal line 64, the control unit 20, and the signal line 66.

  When digital image data 76 is supplied, the digital signal processing circuit 22 performs gamma conversion, synchronization processing, image conversion processing, compression / decompression processing, input / output interface processing, image reduction processing, and the like on the digital image data. The digital signal processing circuit 22 supplies the digital data subjected to each processing to the memory 32 via the signal line 82 or to the D / A converter 90 via the signal line 84.

  The memory 32 is a non-volatile memory that can retain stored contents even when the power is turned off. The memory 32 stores the supplied digital data 82.

  The D / A converter 90 is a converter that converts digital data into analog data. The D / A converter 90 converts the supplied digital data 84 into analog data and supplies it to the image display unit 48 via the signal line 92.

  The image display unit 48 includes a monitor 49 and a display controller (not shown). The display controller 48 displays an image by operating the supplied analog data 92 on the display device. As the monitor 49, a liquid crystal monitor is generally used. The liquid crystal monitor is provided with a liquid crystal display controller. The liquid crystal controller performs switching control by arranging liquid crystal molecules and applying voltage based on the digital data 84. By this control, the liquid crystal monitor displays an image. Needless to say, the monitor 49 is not limited to a liquid crystal monitor, and may be sufficiently used as long as it is a display device that is small in size, capable of checking images and suppressing power consumption. The image display unit 48 is controlled by a control signal 86 supplied from the control unit 20.

  The mode switching button 30 of the operation unit 26 is a button for switching between a reproduction mode and a shooting mode. The playback mode is a mode in which the digital data stored in the memory 32 is displayed on the monitor 49. When the reproduction mode is selected, the operation unit 26 creates a reproduction mode signal and supplies it to the digital signal processing circuit 22 via the signal line 88, the control unit 20, and the signal line 64.

  When the shooting mode is selected by the mode switching button 30, the operation unit 26 creates a shooting mode signal and supplies it to the solid-state imaging device 14 via the signal line 88, the control unit 20, and the signal line 54, and is not illustrated. The power supply performs a first power input.

  When the playback mode signal is supplied, the digital signal processing circuit 22 reads the digital data stored in the memory 32 by the compression / decompression process and the input / output interface process, performs the image reduction process, and supplies it to the image display unit 48 To do.

  Each operation of the embodiment of the present invention configured as described above will be described. FIG. 6 is a flowchart of the electronic camera 10 according to the embodiment of the present invention. In step S150, when the power button 28 is not pressed, the power source (not shown) is used to power the optical system 12, the solid-state imaging device 14, the amplifier circuit 16, the A / D converter 18, the control unit 20, and the digital signal processing circuit 22. The first power supply input for supplying is performed. This prepares for determining the startup exposure value.

  In step S152, the solid-state imaging device 14 supplies the electric signal accumulated since the power is turned off to the amplifier circuit 16 via the signal line 52. The amplifier circuit 16 converts the amplitude of the supplied electric signal, and supplies the converted electric signal to the A / D converter 18 via the signal line 56. The A / D converter 18 converts the electrical signal 56 that is analog data into digital data, and supplies the digital data to the digital signal processing circuit 22 via the signal line 58. The digital signal processing circuit 22 uses the exposure value determination function 24 to determine the startup exposure value corresponding to the electromotive force of the supplied electrical signal 58.

  Thereafter, when the power button 28 is pressed, in step S154, a power source (not shown) supplies power to the CDS 42, AGC 44, A / D converter, image display unit 48, and D / A converter 90. The second power input is performed. In step S156, it is confirmed whether or not the camera is in a shooting mode, and a standby state is entered until the camera enters the shooting mode. On the other hand, in the photographing mode, exposure control is performed in step S158. That is, the digital signal processing circuit 22 supplies the determined startup exposure value to the optical system 12 through the signal line 64, the control unit 20, and the signal line 66, and the optical system 12 has an AE / AF drive function. Based on the startup exposure value 66 supplied, the diaphragm 36 is adjusted to adjust the light quantity of the light 50, and exposure control is performed to determine the shutter speed of the shutter 38.

  Further, the image formed by the image signal obtained by such exposure control is displayed on the monitor 49 of the image display unit 48 from the beginning (step S160). As a result, it is possible to quickly display an image with appropriate exposure control on the monitor 49 without causing the user to feel that the start time of the shooting mode is long. Subsequently, in step S162, when the image signal 68 output from the solid-state imaging device 14 undergoes various processes and reaches the signal processing circuit 22 as the digital image signal 74, the luminance of the subject is calculated from the digital image signal 74. Determine the exposure value after startup.

  Thereafter, it is checked again in step S164 whether or not the shooting mode is set. If the shooting mode is maintained, the process returns to step S158 to perform exposure control based on the exposure value after activation. On the other hand, if the shooting mode is not set, the process is terminated.

  As described above, immediately after the second power input to the entire camera or immediately after switching from the playback mode to the shooting mode, the startup exposure value is temporarily used based on the electromotive force obtained from the solid-state imaging device 14, and thereafter As usual, by determining the exposure value after activation from the digital image data, suitable and quick exposure control becomes possible.

  FIG. 7 shows an embodiment in which the electronic camera according to the present invention is applied to a portable information terminal. An optical system 202, a solid-state image sensor 204, an amplifier circuit 206, and an A / D converter 208 are added to the block diagram of the electronic camera 10 in FIG. FIG. 3 is a diagram of a portable information terminal 200 to which are respectively added. That is, it is the portable information terminal 200 having two cameras shown in FIGS. In the figures, similar elements are denoted by the same reference numerals.

  The portable information terminal 200 is characterized in that an electromotive force is obtained from a solid-state image pickup device of a camera that is not used, and the startup exposure value is determined in the same manner as in the embodiment of the electronic camera 10.

  The operation unit 220 includes a camera use button 218 in addition to the power button 28 and the mode switching button 30. The camera use button 218 is a button for determining use of the camera, and at this time, is a button for determining which of the two cameras is used. When the solid-state image sensor 14 is not used, a power supply (not shown) supplies power to the optical system 12, the solid-state image sensor 14, the amplifier circuit 16, the A / D converter 18, and the digital signal processing circuit 22. When the solid-state image sensor 204 is not used, a power source (not shown) supplies power to the optical system 202, the solid-state image sensor 204, the amplifier circuit 206, the A / D converter 208, and the digital signal processing circuit 22. In other words, based on the signal charge accumulated in one of the solid-state image sensors that is not in use, the present embodiment is to obtain the startup exposure value when the other solid-state image sensor enters the photographing mode. This is an example feature.

  The optical system 202, the solid-state imaging device 204, the amplification circuit 206, and the A / D converter 208 are the same as the optical system 12, the solid-state imaging device 14, the amplification circuit 16, and the A / D converter 18, respectively. Each is controlled by a control signal supplied from 20.

  When not in use, the solid-state image pickup devices 14 and 204 convert the electrical signal obtained by converting the light 50 into the photodiode to the electrical signal of one or more photodiodes obtained by converting the amplifier circuit 16 or the light 222. This is supplied to the amplifier circuit 206.

  When the digital data 58 or the digital data 228 is supplied, the digital signal processing circuit 22 uses the exposure value determination function 24 to determine the exposure value from the electromotive force of the digital data.

  When the activation value is determined from the digital data 228, the digital signal processing circuit 22 supplies the activation value to the optical system 12 via the signal line 64, the control unit 20, and the signal line 66. Following this, a power supply (not shown) performs a second power input to the entire camera.

  The digital signal processing circuit 22 supplies the exposure value to the optical system 202 via the signal line 64, the control unit 20, and the signal line 230 when the startup exposure value is determined from the digital data 58. Following this, the power supply inputs a second power to the entire camera, and also supplies power to the solid-state image sensor 204.

  When the mode switching button 30 is used to switch from the playback mode to the shooting mode, the operation unit 220 creates a shooting mode signal and supplies it to either the solid-state image sensor 14 or the solid-state image sensor 204 via the control unit 20. The photographing mode signal may be supplied to a solid-state image sensor of a camera that has not been used most recently.

  By configuring as described above, an electromotive force is obtained from a solid-state image sensor of a camera that is not in use, and an exposure value at startup is determined, so that the image is taken immediately after the second power input to the entire camera or from the playback mode. Even in the case of switching to the mode, suitable exposure control can be quickly performed.

  FIG. 10 is a configuration diagram of an electronic camera 300 in which a light emitting diode (LED) 358 is added to the configuration of the electronic camera 10. The electronic camera 300 is characterized in that the light amount of the LED 358 is adjusted by the electromotive force of the digital data 58 supplied to the signal processing unit 352.

  The signal processing unit 352 has an auxiliary light adjustment function 354, the auxiliary light adjustment function 354 calculates an adjustment value from the electromotive force of the supplied digital data 58, and together with the auxiliary light adjustment signal, the signal line 64, the control unit 20 and The signal is supplied to the D / A converter 360 via the signal line 356. The signal processing unit 352 has an adjustment value corresponding to the electromotive force in advance. For example, the light amount of the LED 358 may be adjusted in three steps according to the electromotive force in about three steps, as shown in FIG. The adjustment value may be set arbitrarily.

  FIG. 14 is a detailed circuit diagram of the D / A converter and the LED shown in FIG. 10, and FIG. 14 shows an amplifier 364 not shown in FIG. The D / A converter 360 has a configuration similar to that of the D / A converter 90 and is a converter that converts supplied digital data into analog data. The D / A converter 360 gains the auxiliary light adjustment signal, which is the supplied digital data, by the amount of the adjustment value supplied at the same time, and converts it into analog data. This gain increase may be performed by an amplifier 364 as shown in FIG. The D / A converter 360 supplies the auxiliary light adjustment signal to the LED 358.

  The LED 358 is auxiliary light installed to enable photographing in a dark place, and the amount of light is determined by the supplied auxiliary light adjustment signal 362.

  The operation unit 314 includes a mode switching button 30 and an auxiliary light button 316, and the auxiliary light button 316 is a button for determining to turn on the LED 358 that is auxiliary light. When the auxiliary light button 316 is pressed, the operation unit 314 has a power supply (not shown) as the optical system 12, the solid-state imaging device 14, the amplification circuit 16, the A / D converter 18, the control unit 20, the digital signal processing circuit 22, and the LED 358. And supplies power to the D / A converter 360.

  By configuring as described above, it is possible to appropriately adjust the light amount of the LED by using the electromotive force obtained from the solid-state imaging device of the camera while the camera is not used.

  The operation of the electronic camera 300 to which the present invention shown in FIG. 10 is applied will be described. In the operation unit 314, the auxiliary light button 316 is pressed, the power source (not shown) is the optical system 12, the solid-state imaging device 14, the amplification circuit 16, the A / D converter 18, the control unit 20, the digital signal processing circuit 22, the LED 358, and Power is supplied to the D / A converter 360.

  Digital data 58 is supplied to the digital signal processing circuit 22 by a method similar to the operation of the electronic camera 10.

  The signal processing unit 352 calculates an adjustment value from the electromotive force of the digital data 58 supplied using the auxiliary light adjustment function 354, and outputs the adjustment value along with the auxiliary light adjustment signal via the signal line 64, the control unit 20, and the signal line 356. Supply to / A converter 360. The D / A converter gains the auxiliary light adjustment signal, which is the supplied digital data, by the amount of the adjustment value supplied at the same time, and converts it into analog data. The D / A converter 360 supplies the converted auxiliary light adjustment signal to the LED 358 via the signal line 362. The LED 358 determines the amount of light based on the supplied auxiliary light adjustment signal 362 and emits light.

  FIG. 11 is a configuration diagram of an electronic camera 350 in which a backlight 304 is added to the configuration of the electronic camera 10. The electronic camera 350 is characterized in that the light amount of the backlight 304 of the monitor 49 is adjusted by the electromotive force of the digital data 58 supplied to the signal processing unit 306.

  The signal processing unit 306 has a display luminance adjustment function 308, calculates an adjustment value based on the electromotive force of the supplied digital data 58, and supplies the adjustment value together with the display luminance signal to the D / A converter 90 via the signal line 84. To do. The signal processing unit 306 has an adjustment value corresponding to the electromotive force in advance, but the adjustment value may be set arbitrarily.

  The D / A converter 90 converts the supplied display luminance signal into analog data. When the D / A converter 90 converts the display luminance signal to analog data, the D / A converter 90 gains the adjustment value supplied simultaneously with the display luminance signal. The D / A converter 90 supplies the display luminance signal 92 converted into analog data to the image display unit 302.

  The image display unit 302 includes a monitor 49 and a backlight 304, and is determined by a display luminance signal 92 to which the light amount of the backlight 304 is supplied.

  The operation unit 312 includes a camera button 310 in addition to the power button 28 and the mode switching button 30. The camera button 310 is a button for determining use of the camera. When the camera button 310 is pressed, the camera use button 64 is created and supplied to the signal processing unit 352 via the signal line 88, the control unit 20, and the signal line 64.

  When the camera use signal 64 is supplied, the signal processing unit 306 stops calculating the adjustment value by the display luminance adjustment function.

  By configuring as described above, the amount of light of the backlight of the monitor 49 can be appropriately adjusted using the electromotive force obtained from the solid-state imaging device of the camera while the camera is not used.

  The operation of the electronic camera 350 to which the present invention shown in FIG. 11 is applied will be described with reference to FIG. FIG. 15 is a flowchart for explaining the operation of the portable information terminal shown in FIG. The digital data 58 is supplied to the signal processing unit 306 in the same manner as the operation of the electronic camera 10.

  First, in step S402, it is confirmed whether or not the camera 350 is activated. If it is running, it will end. If not started, the process proceeds to step S404, and power is supplied to the amplifier 16, the A / D converter 18, and the digital signal processing circuit 306. That is, processing corresponding to the “first power input” in the first embodiment is performed. Thereafter, in step S406, the electromotive force of the solid-state imaging device is read using each of the elements 16 and 18 to which power is turned on. Further, in step S408, the signal processing unit 306 converts the electromotive force into the brightness of the subject. And the set value of the D / A converter 90 is calculated. Thereafter, an image is displayed in step S410. That is, the display luminance signal 92 gained by the adjustment value by the D / A converter 90 is given to the monitor 49 of the image display unit 302, and the backlight 304 emits light with the light amount determined based on the display luminance signal 92. Then, the brightness of the monitor 49 is determined. It should be noted that the brightness of the monitor 49 whose brightness is adjusted is the display brightness other than when shooting with the camera 350 is performed.

  Thereafter, in step S412, as in step S406, the electromotive force of the solid-state imaging device is read, and based on this electromotive force, it is confirmed in step S414 whether the ambient brightness has changed. If it has not fluctuated, the process ends. If fluctuated, the process returns to step S408, and the set value of the D / A converter 90 is calculated.

It is a block diagram which shows the Example of the electronic camera by this invention. It is a block diagram of the solid-state image sensor shown in FIG. FIG. 2 is a diagram illustrating a correspondence relationship between an electromotive force of signal charges accumulated in the solid-state imaging device illustrated in FIG. 1 and brightness of a subject. It is a figure which shows the exposure value at the time of starting corresponding to the electromotive force shown in FIG. It is a figure which shows the electromotive force when not amplifying the signal charge accumulate | stored in the solid-state image sensor shown in FIG. It is a flowchart which shows operation | movement of the electronic camera shown in FIG. It is a block diagram of the portable information terminal which has two electronic cameras by this invention. It is a three-dimensional figure inside the portable information terminal shown in FIG. It is the three-dimensional view of the outer side of the portable information terminal shown in FIG. It is a block diagram of the portable information terminal which has a light emitting diode which is an Example of this invention. It is a block diagram of the portable information terminal which has a backlight in the monitor which is an Example of this invention. It is sectional drawing of the photodiode shown in FIG. FIG. 13 is a circuit diagram showing a mechanism for detecting an electromotive force from the PN junction shown in FIG. FIG. 11 is a detailed circuit diagram of the D / A converter and the light emitting diode shown in FIG. 12 is a flowchart for explaining the operation of the portable information terminal shown in FIG.

Explanation of symbols

10 Electronic camera
12 Optical system
14 Solid-state image sensor
16 Amplifier circuit
18.46 A / D converter
20 Control unit
22 Digital signal signal processing circuit
26 Operation unit
32 memory
42 CDS
44 AGC
48 Image display device
90 D / A converter

Claims (7)

A solid-state image sensor in which photosensitive elements that generate an electromotive force corresponding to the amount of light are two-dimensionally arranged while photoelectrically converting light from an object scene during exposure; and
Exposure control means for causing the solid-state imaging device to perform predetermined exposure while no image signal is output from the solid-state imaging device;
Exposure value determining means for determining an exposure value based on an electromotive force generated in the solid-state imaging device by the predetermined exposure;
Display means for displaying from the beginning an image formed by an image signal generated and output to the solid-state imaging device by exposure performed by the exposure control means so as to realize the determined exposure value. Electronic camera.   2. The electronic camera according to claim 1, wherein the exposure value determining means is driven by an independent power source, and determines the exposure value when power is not supplied to other elements included in the electronic camera. And an electronic camera. First and second solid-state imaging in which photosensitive elements that generate an image signal by photoelectrically converting light from an object scene during exposure and generate an electromotive force according to the amount of the light are arranged two-dimensionally Elements,
First exposure control means for causing the first solid-state imaging device to perform predetermined exposure;
Exposure value determining means for determining an exposure value based on an electromotive force generated in the first solid-state imaging device by the predetermined exposure;
Second exposure control means for exposing the second solid-state imaging device so as to realize the determined exposure value;
An electronic camera comprising: display means for displaying from the beginning an image formed by an image signal generated and output to the second solid-state imaging device by the exposure. A solid-state image sensor in which photosensitive elements that generate an electromotive force corresponding to the amount of light are two-dimensionally arranged while photoelectrically converting light from an object scene during exposure; and
An auxiliary light source that illuminates the scene with light,
Exposure control means for causing the solid-state imaging device to perform predetermined exposure;
Exposure value determining means for determining an exposure value based on an electromotive force generated in the solid-state imaging device by the predetermined exposure;
An electronic camera comprising: a dimming unit for dimming the auxiliary light source so as to realize the determined exposure value.   5. The electronic camera according to claim 4, wherein the auxiliary light source is a light emitting diode. A solid-state image sensor in which photosensitive elements that generate an electromotive force corresponding to the amount of light are two-dimensionally arranged while photoelectrically converting light from an object scene during exposure; and
Display means for displaying an image formed by the image signal;
Exposure control means for causing the solid-state imaging device to perform predetermined exposure;
Brightness determining means for determining the brightness of the display means based on an electromotive force generated in the solid-state imaging device by the predetermined exposure;
An electronic camera comprising: brightness adjusting means for adjusting the brightness of the display means to the determined brightness. Light from the object scene is photoelectrically converted to generate an image signal, and output of the image signal from the solid-state imaging device in which photosensitive elements that generate an electromotive force corresponding to the amount of the light are two-dimensionally arranged is stopped. Process,
A step of causing the solid-state imaging device to perform predetermined exposure while the output of the image signal is stopped;
Determining an exposure value based on an electromotive force generated in the solid-state imaging device by the predetermined exposure;
A step of generating an image signal on the solid-state imaging device by the exposure performed by the exposure control means so as to realize the determined exposure value, and outputting the image signal from the device;
And a step of displaying an image formed by the output image signal on the display means from the beginning.