JP2010109578A - Imaging apparatus and liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging apparatus in which the responsiveness of a liquid crystal display means is improved. <P>SOLUTION: The imaging apparatus includes a CCD 306 for photographing an object and a liquid crystal panel 321 for displaying an image photographed by the CCD 306. The imaging apparatus further includes a CPU 314 for controlling a video signal amplitude to be input to the liquid crystal panel 321 to the range of the high responsiveness of the liquid crystal panel 321 under an environmental temperature at which the responsiveness of the liquid crystal panel 321 decreases. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an imaging device and a liquid crystal display device, and more particularly, to an imaging device and a liquid crystal display device that are characterized by a technique for improving the response of liquid crystal display means.

  In an imaging apparatus such as a digital camera, a framing operation is first performed when photographing a subject. The framing operation is an operation for determining a photographing range of a subject using an optical finder or an electronic finder of a camera.

  In recent years, with the miniaturization of cameras, the number of digital cameras equipped with optical viewfinders has decreased, and mainly, the number of cameras that can perform framing operations only with an electronic viewfinder using a liquid crystal panel has increased.

  Since the optical viewfinder uses an optical system independent of the photographing optical system except for a single-lens camera, an error occurs between the photographing range indicated by the viewfinder and the actual photographing range.

  On the other hand, many electronic finders display images incident on the image sensor on a liquid crystal panel, and since the shootable range shown by the finder is in principle the same as the actual shooting range, there is no parallax and accurate Framing can be performed.

  However, the liquid crystal panel has a long response time when the image luminance changes, and particularly at low temperatures, the response becomes slow enough to be perceived by human eyes.

  In order to improve the response of the liquid crystal panel, for example, in Patent Document 1, when the luminance of an image displayed on the liquid crystal panel changes, the response speed is increased by increasing the liquid crystal applied voltage only in the first frame. The proposal which raises is made.

  The technique described in Patent Document 1 has a table in which the optimum liquid crystal application voltage is set for each according to the amount of change in image brightness, and the set value is a voltage generated by increasing the liquid crystal application voltage. The voltage level is set to suppress overshoot of the waveform as much as possible.

  Here, FIG. 1 is a diagram showing the response speed of the liquid crystal panel when the display image transitions from low luminance to high luminance. FIG. 2 is a diagram illustrating the response speed of the liquid crystal panel when the display image shifts from high luminance to higher luminance.

  1 and 2, reference numeral 101 denotes an optical response waveform, and reference numerals 102 and 202 denote response times of the liquid crystal panel.

  As proposed in the above-mentioned Patent Document 1, since the response of the liquid crystal panel is extremely poor when the luminance changes in an area where the responsiveness of the liquid crystal panel is poor, for example, when changing from medium luminance to high luminance as shown in FIG. Therefore, it is not possible to expect a great effect of improving responsiveness only by increasing the liquid crystal applied voltage.

  In addition, when the voltage applied to the liquid crystal is temporarily increased, an overshoot occurs in the light transmittance waveform, and the brightness change is observed by the user (photographer) as flicker.

  In the technique described in Patent Document 1, a table for suppressing overshoot is prepared. However, it is difficult to completely suppress a change in luminance due to variations in individual liquid crystal panels. In addition, it is necessary to set the liquid crystal applied voltage to be larger than that during normal use, and there is a concern about increase in power consumption and generation of noise.

  In Patent Document 2, the luminance of an image displayed on a liquid crystal panel is read by a sensor, and the reading value of the sensor is compared with the video signal level input to the panel, thereby delaying the luminance change due to the responsiveness of the liquid crystal panel. Proposals for correction have been made.

  Due to the responsiveness of the liquid crystal panel, the luminance of the image displayed on the liquid crystal panel changes moderately as compared with the video signal level.

In the technique described in Patent Document 2, the reading value of the sensor is fed back, and the luminance of the video signal is increased so that the desired luminance is displayed on the liquid crystal panel. As a result, the brightness change of the liquid crystal panel is made steep, and the process of making the response of the brightness change of the video signal and the brightness change of the liquid crystal panel as close as possible is performed.
JP 2002-062850 A JP 2002-244107 A

  However, in the technique described in Patent Document 2, as in the technique described in Patent Document 1, when the luminance changes in a region where the response of the liquid crystal panel is poor, the response of the liquid crystal panel is large only by increasing the video signal voltage. We cannot expect improvement. In addition, it is necessary to provide a sensor for detecting luminance in the imaging device, which leads to an increase in size and cost of the device.

  An object of the present invention is to provide an imaging device and a liquid crystal display device capable of improving the responsiveness of liquid crystal display means.

  In order to achieve the above object, in the imaging apparatus according to claim 1, the responsiveness of an imaging unit that images a subject, a liquid crystal display unit that displays an image captured by the imaging unit, and the liquid crystal display unit decreases. And control means for controlling the amplitude of the video signal input to the liquid crystal display means within a range in which the responsiveness of the liquid crystal display means is high under an environmental temperature.

  9. The liquid crystal display device according to claim 8, wherein the liquid crystal display means displays an image taken by the photographing means, and the video signal amplitude input to the liquid crystal display means under an environmental temperature at which the responsiveness of the liquid crystal display means decreases. And control means for controlling the liquid crystal display means within a range in which the responsiveness of the liquid crystal display means is high.

  According to the imaging apparatus of the present invention, the responsiveness of the liquid crystal display means can be improved.

  Hereinafter, the present invention will be described in detail with reference to the drawings.

  FIG. 3 is a block diagram showing an electrical configuration of the digital camera as the imaging apparatus according to the embodiment of the present invention.

  Hereinafter, the configuration will be described together with the operation.

  3, the lens barrel 301 includes a focusing motor 302, a lens 303, an iris motor 304, an aperture 305, and a CCD (imaging means) 306.

  Light from the subject enters through the lens 303 and reaches the CCD 306 through the stop 305. A lens 303 disposed in parallel with the light receiving surface of the CCD 306 is translated by a focusing motor 302 to adjust the distance between the lens 303 and the CCD 306 and form a subject image on the CCD 306.

  Although not shown, a plurality of lenses 303 are actually installed, and the focal length of the subject imaged on the CCD 306 can be adjusted by changing the distance between the lenses.

  The rotation speed of the focusing motor 302 is read by a photo interrupter (not shown) so that the position where the lens 303 exists can be recognized. The focusing motor 302 can control the number of rotations by a motor driver 307 and can move the lens 303 to a desired position.

  Since the amount of incident light and the angle of light incident on the lens 303 change depending on the distance and angle between the digital camera and the subject, a focus detection operation for adjusting the distance between the lens 303 and the CCD 306 is required each time shooting is performed.

  The iris motor 304 is a motor that controls the diaphragm 305. By controlling the aperture diameter of the diaphragm 305 according to the brightness of the subject, the iris motor 304 controls the amount of light incident on the CCD 306, and can perform shooting that provides an optimal exposure. it can.

  The subject image formed on the CCD 306 is subjected to photoelectric conversion, and converted into a charge amount proportional to the amount of light obtained by each pixel of the CCD 306. A large amount of charge is obtained in a bright part of the subject image, a charge amount in a dark part of the subject image is small, and the density of the subject image can be obtained as a difference in the amount of charge.

  The CCD 306 is composed of hundreds to tens of millions of pixels, and a microlens and a color filter are arranged in each pixel. By arranging red, green, and blue color filters, it is possible to obtain the light amounts of the three primary colors and obtain a full color image.

  The charge from the CCD 306 is input to the AFE 308 through a wiring pattern on a printed board (not shown).

  The AFE 308 incorporates analog signal processing circuits such as a CDS circuit for removing fixed pattern noise generated in the CCD 306 and an A / D conversion circuit for analog-digital conversion of signals from the CCD 306.

  The AFE 308 incorporates a TG circuit that generates a timing signal for reading an electrical signal from the CCD 306.

  The TG circuit generates a timing signal for controlling the CCD 306, and charges are transferred from the CCD 306 to the AFE 308 in accordance with the timing signal. The read charge is subjected to noise component reduction processing by the CDS circuit, and the analog charge amount is converted into a digital signal by the A / D conversion circuit.

  The converted digital signal is temporarily stored in a device capable of high-speed transmission / reception such as SDRAM 309 via the bus signal line 313. From there, reading to a CPU (control means) 314 is sequentially performed, and various image processing such as edge enhancement, noise removal, and white balance are performed.

  Since the image data for which various types of image processing have been completed is large-capacity data of about several megabytes, the nonvolatile memory 311 that can be inserted into the flash memory 310 or the card connector 312 after image compression processing by the JPEG method or the like is performed. Saved in etc.

  By storing the image data in the portable non-volatile memory 311, it is possible to read an image captured by the digital camera with another device such as a personal computer or a printer. Thereby, it is possible to view an image on a large-screen display or to print it as a photograph by printing it out on photographic paper.

  As described above, in the digital camera having the liquid crystal panel (liquid crystal display means) 321 for outputting the image via the nonvolatile memory 311, the photographed image is immediately sent via the liquid crystal panel driver 320 to the liquid crystal panel 321. You can check on the screen.

  Since the liquid crystal panel 321 is built in the digital camera, it is often small and has a low resolution, and it is difficult for a plurality of people to view images simultaneously.

  Therefore, there are many digital cameras in which a video encoder 317 and a video amplifier 318 are mounted inside the digital camera so that video is directly output from the digital camera to the TV monitor 319.

  Since the TV monitor 319 has a larger screen and higher resolution than the liquid crystal panel 321, it can sufficiently express the resolution of the image of a digital camera with an increased number of pixels, and the image can be displayed together with many people. You can also enjoy browsing.

  Note that an operation switch 322 and an external connection terminal 323 are also connected to the CPU 314.

  Next, the operation of the digital camera in FIG. 3 will be described.

(First embodiment)
FIG. 4 is a flowchart showing a procedure of video signal amplitude control processing executed by the digital camera of FIG. 3 to control the video signal amplitude according to the detected temperature. FIG. 5 is a front perspective view of the digital camera of FIG. FIG. 6 is a rear perspective view of the digital camera of FIG.

  As shown in FIG. 5, the digital camera includes a lens barrel 301, an external connection terminal 323, a zoom lever 501, a release switch 502, a power switch 503, an optical viewfinder 504, and a strobe 505.

  As shown in FIG. 6, the digital camera includes a mode switch 601 in addition to the liquid crystal panel 321 and the operation switch 322.

  The flowchart of FIG. 4 is executed under the control of the CPU 314 in FIG.

  In FIG. 4, first, in step S <b> 401, the CPU 314 confirms whether the digital camera has shifted to the shooting mode.

  In FIG. 6, since the mode of the imaging device is displayed on the liquid crystal panel 321, the operation switch 322 can be pressed to shift to a desired mode. Digital cameras usually have a shooting mode such as a still image shooting mode and a movie shooting mode, and a playback mode for checking the shot image. Check if.

  In step S401, when the digital camera is in a photographing mode to which the present invention is applied, the process proceeds to step S402 (temperature detection means), and the CPU 314 performs temperature detection. Since digital cameras use devices whose characteristics change with temperature, such as the CCD 306, many are equipped with temperature detection means such as a thermistor.

  In the present embodiment, the CPU 314 detects the temperature based on temperature information from a thermistor mounted on a mounting board inside a digital camera (not shown), and the process proceeds to step S403.

  FIG. 7 is a diagram showing an optical response waveform of the liquid crystal panel in FIG. 3 when the environmental temperature is 0 ° C. (low temperature) and 25 ° C. (normal temperature).

  In this embodiment, a description is given of the case where a normally black liquid crystal panel is used.

  In the normally black method, light is not transmitted when no voltage is applied to the liquid crystal, and the light transmittance of the liquid crystal panel 321 increases as the voltage applied to the liquid crystal is increased.

  On the other hand, in the case of a normally white liquid crystal panel, the light transmittance is maximized when no voltage is applied to the liquid crystal, and the light transmittance of the liquid crystal panel 321 decreases as the voltage applied to the liquid crystal is increased. .

  Since the relationship between the applied voltage and the transmittance of the normally white method is opposite to that of the normally black method, the present invention only requires changing the voltage application direction in the normally black method. It can also be applied to liquid crystal panels.

  Here, FIG. 7A shows an optical response waveform of the liquid crystal panel 321 when the environmental temperature is 25 ° C., and FIG. 7B shows an optical response waveform of the liquid crystal panel 321 when the environmental temperature is 0 ° C. The liquid crystal panel 321 has greatly different optical response speeds in a normal temperature environment and a low temperature environment due to the characteristics.

  The rise times (τr) 702 and 704 of the liquid crystal panel 321 are normally defined by the time until the light transmittance of the liquid crystal panel 321 increases from 10% to 90%, and the fall times (τd) 701 and 703 are It is defined by the time until the light transmittance decreases from 90% to 10%.

An example of the optical response speed of the 3-inch diagonal liquid crystal panel 321 used in the digital camera is shown below.
τr (25 ° C.) = 35 ms
τd (25 ° C.) = 30 ms
τr (0 ° C) = 80 ms
τd (0 ° C) = 60 ms
As can be seen from the above, both the rise time and the fall time have a difference of more than double in the response speed under the environment of 25 ° C. and 0 ° C. For this reason, when the digital camera is used in a low temperature environment, the response speed of the liquid crystal panel 321 is greatly reduced. Therefore, even when attempting to shoot a moving subject, an afterimage of the subject remains on the liquid crystal panel 321 for a long time. Framing becomes very difficult.

  In the present invention, the amplitude of the video signal input to the liquid crystal panel 321 is corrected to a range in which the response speed of the liquid crystal panel 321 is fast so that the afterimage of the subject does not remain even at low temperatures and the subject can be easily framed. The process of (control) is performed.

  That is, the CPU 314 controls the amplitude of the video signal input to the liquid crystal display panel 321 within a range where the response of the liquid crystal display panel 321 is high under an environmental temperature at which the response of the liquid crystal display panel 321 decreases.

  FIG. 8 is a diagram showing processing for correcting the video signal amplitude to a video signal voltage range in which the responsiveness of the liquid crystal panel in FIG.

  Here, FIG. 8A shows an optical response waveform of the liquid crystal panel 321 when the environmental temperature is 25 ° C. (normal temperature), and the amplitude control to the video signal (25 ° C.) is not performed at normal temperature. The video signal (25 ° C.) matches the luminance gradation (luminance 0% to luminance 100%) that can be expressed by the liquid crystal panel 321, and the black level of the video signal (25 ° C.) is 0% luminance and white level of the liquid crystal panel 321. Is set so that the luminance of the liquid crystal panel 321 is 100%.

  By setting the amplitude of the video signal (25 ° C.) in this way at room temperature, the gradation reproducible range of the liquid crystal panel 321 is maximized and visibility is improved.

  FIG. 8B shows an optical response waveform of the liquid crystal panel 321 when the environmental temperature is 0 ° C. (low temperature). When the temperature is low, amplitude correction processing of the video signal (0 ° C.) is performed. In the example of FIG. 8B, the black level of the video signal (0 ° C.) is set to 15% luminance of the liquid crystal panel 321 and the white level is set to 85% luminance of the liquid crystal panel 321.

  In the example of FIG. 8, the rise time 802 and the fall time 801 of the liquid crystal panel 321 when the temperature is low (0 ° C.) are both about twice that at normal temperature (25 ° C.). By limiting the amplitude of (0 ° C.), the following response speed is realized.

  That is, by using only the part with a fast response speed of the liquid crystal panel 321, the fall time τd (25 ° C.) 701 at the ambient temperature of 25 ° C. and the fall at the ambient temperature of 0 ° C. after the video signal amplitude correction processing. The time τd (0 ° C.) 801 has almost the same response speed.

  Further, the rise time τr (25 ° C.) 702 when the ambient temperature is 25 ° C. and the rise time τr (0 ° C.) 802 when the ambient temperature is 0 ° C. after the video signal amplitude correction processing are substantially equal in response speed, and even at low temperatures. The response speed is almost equivalent to that at room temperature.

  When the amplitude of the video signal (0 ° C) is limited, the black level voltage rises (the light transmittance increases), so that the black floats (black that should be expressed with 0% brightness has brightness, and black appears bright) ) Occurs and white level voltage decreases, resulting in white sinking (decrease in white brightness). That is, the contrast (white luminance / black luminance) of the liquid crystal panel 321 decreases.

  Thus, in terms of appearance, there is a slight deterioration. However, when the response speed of the liquid crystal panel 321 is greatly reduced at low temperatures, such as in a low temperature environment, the moving subject becomes an afterimage and is blurred, and the visibility is greatly reduced, the liquid crystal is more than a slight decrease in contrast. Priority is given to improving the response speed of the panel 321.

  Thereby, visibility can be improved significantly. In particular, a great effect can be expected in a digital camera that needs to follow a moving subject.

  FIG. 9 is a diagram showing a video signal amplitude correction table showing the relationship between the environmental temperature and the amplitude of the video signal input to the liquid crystal panel in FIG.

  This video signal amplitude correction table shows the relationship between the ambient temperature and the corrected video signal amplitude set in advance so that an afterimage does not stand out on the liquid crystal display panel 321.

  The smaller the video signal amplitude is, the better the response of the liquid crystal panel 321 is, but at the same time the contrast is lowered, so it is necessary to set an optimum applied voltage according to the environmental temperature.

  The correction table of FIG. 9 is an example, and the relationship between the environmental temperature and the applied voltage level varies depending on the characteristics of the liquid crystal panel 321, so that a specific applied voltage must be set for each type of the liquid crystal panel 321.

  In the present embodiment, the environmental temperature is set in increments of 1 ° C. for simplicity. However, for example, environmental temperatures: 25 ° C., 24.8 ° C., 24.6 ° C. −18.8 ° C., −20 ° C., etc. are set in detail, and the video signal at each environmental temperature is set. It is desirable to have an amplitude correction table in order to increase the correction accuracy.

  Under normal temperature (around 25 ° C.), the appearance of the liquid crystal panel 321 is enhanced by increasing the video signal amplitude as much as possible and maintaining a large contrast value. At room temperature, the responsiveness of the liquid crystal panel 321 is high even when the video signal amplitude is large. Therefore, even when shooting a moving subject, the afterimage of the subject can be taken without much recognition by the photographer. .

  At low temperatures (below 0 ° C.), the responsiveness of the liquid crystal panel 321 is extremely reduced, so that the video signal amplitude is narrowed and the responsiveness of the liquid crystal panel display is increased. By setting the applied voltage so that this responsiveness is equivalent to that at room temperature, it is possible to shoot without worrying about the occurrence of afterimages when shooting moving subjects even at low temperatures.

  When a moving subject is photographed without applying the present invention, a large afterimage is generated on the subject, and the appearance of the liquid crystal panel display is extremely lowered. For example, if the subject is a person, details such as facial expressions may be blurred due to afterimages, making it impossible to distinguish whether the person being photographed is laughing or not, and may miss a photo opportunity. Becomes larger.

  In order to avoid such a situation, the present invention places an emphasis on preventing the occurrence of an afterimage of a subject having a large adverse effect on the photographing operation while allowing a slight contrast reduction by limiting the video signal amplitude. This is intended to improve the shooting environment below.

  Returning to FIG. 4, in step S402, after detecting the temperature, the CPU 314 proceeds to step S403, and refers to the video signal amplitude correction table shown in FIG. 9 based on the environmental temperature detected in step S402.

  Next, the CPU 314 sets the white level and black level voltages to change (limit) the video signal amplitude (step S404). Next, the CPU 314 corrects the video signal amplitude input to the liquid crystal panel 321 within the range of white level-black level (step S405), and outputs the video to the liquid crystal panel 321 (step S406). Then, this process ends.

(Second Embodiment)
Next, a second embodiment of the present invention will be described.

  FIG. 10 is a flowchart showing a procedure of video signal amplitude control processing executed by the digital camera of FIG. 3 to control video signal amplitude according to the detected temperature and zoom magnification.

  In FIG. 10, step S401 and step S402 in the flowchart of the first embodiment shown in FIG. 4 correspond to step S1001 and step S1002 of the present embodiment, and thus description thereof is omitted.

  In step S1003, when the zoom lever 501 shown in FIG. 5 is operated and a zooming operation is performed, the CPU 314 detects the zoom magnification.

  The digital camera shown in FIG. 5 has a configuration in which when the zooming operation is performed, the lens barrel 301 is extended or contracted so that the intervals of the plurality of lenses 303 included in the digital camera can be adjusted. ing. Therefore, it is possible to change the subject range imaged on the CCD 306 by the zooming operation.

  When shooting a subject that is far away from the photographer, it is possible to form a large image on the CCD 306 even if the subject is far away from the photographer by the zooming operation as described above.

  When the lens barrel 301 is operated in the direction that widens the image formation range on the CCD 306, the lens barrel 301 is positioned at the wide end, and the lens barrel is operated in the direction that narrows the image formation range on the CCD 306. If so, the lens barrel is said to be at the telephoto end. The zoom magnification is defined by the following equation.

Zoom magnification = √ ((Shooting area at tele end) / (Shooting area at wide end))
Even a normal camera often has a lens barrel that can change the zoom magnification to about 3 to 5 times. However, it is possible to control a camera that cannot be zoomed, or an extremely high magnification such as 10 to 20 times. Some cameras have a lens barrel.

  When taking a photo at a high magnification, it is necessary to be careful because slight vibration of the hand holding the camera leads to shaking (camera shake) of the shot image. When the lens barrel is set on the high-magnification side, camera shake is much more likely to occur than on the wide-angle side.

  Since the shooting range is narrower on the high magnification side than on the wide-angle side, the shooting range is greatly changed even if the hand holding the camera is slightly shaken. This tendency becomes more prominent as the zoom magnification becomes larger. Usually, when photographing at a high magnification such as 10 to 20 times, the photographing can be performed with the camera stationary using a tripod or the like. Many.

  In order to avoid such camera shake, some cameras have high sensitivity shooting and a camera shake correction mechanism. In the digital camera, the adjustment of the photographing sensitivity can be realized relatively easily by adjusting the gain of the image captured from the CCD 306 by the AFE 308.

  However, if the gain is increased in order to increase the shooting sensitivity, the noise gain also increases, and the noise of the captured image increases as the shooting sensitivity is increased.

  There are several methods for correcting camera shake. Generally, a method of detecting the amount of camera shake of a photographer holding the camera with a gyro and moving a part of the lens 303 or the CCD 306 in a direction to cancel the camera shake is common. is there.

  In order to perform the camera shake correction, a gyro for detecting the amount of camera shake, and a driving device that precisely drives the lens 301 and the CCD 306 are required. In addition, the correction amount has a limit. Therefore, when the zoom magnification becomes 10 to 20 times, there are many cases where correction is not possible when the amount of camera shake is large.

  As described above, there are many scenes in which camera shake cannot be suppressed when shooting at a high magnification zoom, and the display on the liquid crystal panel 321 is also shaken in the same manner, resulting in an afterimage, which is similar to that at the time of use at a low temperature. Visibility deteriorates.

  In the present embodiment, the afterimage of the liquid crystal panel display that occurs when using a high-magnification zoom is reduced, and the visibility of the liquid crystal panel 321 is improved.

  In the flowchart of FIG. 10, when the zooming of the digital camera is detected in step S1003, the CPU 314 proceeds to step S1004 (zoom magnification calculation means) and calculates the zoom magnification.

  In FIG. 3, a focusing motor 302 drives a plurality of lenses 303 of the digital camera. The rotation speed of the focusing motor 302 is detected by a photo interrupter (not shown). The amount of extension of the lens barrel 301 shown in FIG. 5 is calculated from the rotation speed of the focusing motor 302, and the zoom magnification is calculated therefrom.

  After calculating the zoom magnification, the CPU 314 proceeds to step S1005 and refers to the video signal amplitude correction table.

  FIG. 11 is a diagram showing a video signal amplitude correction table showing the relationship between the zoom magnification, the environmental temperature, and the video signal amplitude input to the liquid crystal panel of the digital camera of FIG.

  Generally, as the zoom magnification of a digital camera increases, the amount of camera shake increases. Therefore, as the zoom magnification increases, the white level voltage of the video signal is decreased and the black level voltage is increased.

  By performing such processing, only a portion with a quick response of the liquid crystal panel 321 can be used, and the response of an image displayed on the liquid crystal panel 321 is improved. Therefore, an afterimage of the liquid crystal panel 321 generated by camera shake that occurs during zooming of the digital camera is alleviated, and the visibility of the liquid crystal panel 321 is improved.

  In the present embodiment, for the sake of simplicity, the zoom magnification is set in four ways: 1 to 5 times, 5 to 10 times, 10 to 15 times, and 15 to 20 times. However, for example, zoom magnification: 1 ×, 1.2 ×, 1.4 ×... 19.8 ×, 20 ×, etc., the zoom magnification is set finely, and video signal amplitude correction at each zoom magnification. It is desirable to have a table to increase the correction accuracy.

  Returning to FIG. 10, in step S1005, the CPU 314 refers to the video signal amplitude correction table, and then proceeds to step S1006 to set the white level and black level voltages and change (limit) the video signal amplitude. .

  Next, the CPU 314 corrects the video signal amplitude input to the liquid crystal panel 321 within the range of white level-black level (step S1007), and outputs the video to the liquid crystal panel 321 (step S1008). Then, this process ends.

(Other embodiments)
The embodiment of the present invention has been specifically described above, but the present invention is not limited to the above-described embodiment, and various modifications based on the technical idea of the present invention are possible.

  For example, in the embodiment of the present invention, a normally black liquid crystal panel is described as a display device, but the present invention can also be applied to a normally white liquid crystal panel.

  Further, for example, the second embodiment of the present invention corresponds to a case where the display on the liquid crystal panel is easily disturbed when the digital camera is used at a high magnification zoom. However, the present invention is not limited to this, and the present invention can be applied to a case where a fast-moving subject is photographed and a camera shake is likely to occur and an afterimage is likely to occur on a display on a liquid crystal panel. Can do.

  In addition, for example, when an image is slid at high speed, such as during a slide show, not only during shooting but also during playback of a shot image, by applying the present invention, an afterimage of image display on a liquid crystal panel is generated. Can be suppressed.

It is a figure which shows the response speed of a liquid crystal panel when a display image changes from low brightness to high brightness. It is a figure which shows the response speed of a liquid crystal panel when a display image transfers to higher brightness from high brightness. It is a block diagram which shows the electric constitution of the digital camera as an imaging device which concerns on embodiment of this invention. 4 is a flowchart showing a procedure of video signal amplitude control processing executed by the digital camera of FIG. 3 to control video signal amplitude according to detected temperature. FIG. 4 is a front perspective view of the digital camera of FIG. 3. FIG. 4 is a rear perspective view of the digital camera of FIG. 3. It is a figure which shows the optical response waveform of the liquid crystal panel in FIG. 3 in case environmental temperature is 0 degreeC (low temperature) and 25 degreeC (normal temperature). It is a figure which shows the process which correct | amends an image signal amplitude in the voltage range with a quick responsiveness of the liquid crystal panel in FIG. It is a figure which shows the video signal amplitude correction table which shows the relationship between environmental temperature and the video signal amplitude input into the liquid crystal panel in FIG. 4 is a flowchart showing a procedure of video signal amplitude control processing executed by the digital camera of FIG. 3 to control video signal amplitude according to detected temperature and zoom magnification. It is a figure which shows the video signal amplitude correction table which shows the relationship between the zoom magnification of the digital camera of FIG. 3, environmental temperature, and the video signal amplitude input into a liquid crystal panel.

Explanation of symbols

301 Lens tube 303 Lens 306 CCD
314 CPU
320 LCD panel driver 321 LCD panel

Claims (11)

Photographing means for photographing the subject;
Liquid crystal display means for displaying an image photographed by the photographing means;
A control means for controlling the video signal amplitude input to the liquid crystal display means within a high responsiveness range of the liquid crystal display means under an environmental temperature at which the responsiveness of the liquid crystal display means is reduced;
An imaging apparatus comprising: Temperature detection means,
The image pickup apparatus according to claim 1, wherein the control unit controls the video signal amplitude based on temperature information detected by the temperature detection unit.   The imaging apparatus according to claim 1, further comprising a correction table that is set in advance so that an afterimage is not conspicuous on the liquid crystal display unit and indicates a relationship between the environmental temperature and the controlled video signal amplitude. A zoom magnification calculating means for calculating the zoom magnification;
4. The imaging apparatus according to claim 1, wherein the control unit controls the video signal amplitude based on the zoom magnification calculated by the zoom magnification calculating unit.   5. The control unit according to claim 4, wherein the control unit controls the video signal amplitude based on the temperature information detected by the temperature detection unit and the zoom magnification detected by the zoom magnification calculation unit. Imaging device.   5. The imaging apparatus according to claim 4, further comprising a correction table that is set in advance so that an afterimage is not conspicuous on the liquid crystal display means and indicates the relationship between the environmental temperature and the controlled video signal amplitude with respect to the zoom magnification. .   7. The imaging apparatus according to claim 3, wherein the correction table is calculated based on an optical response waveform of the liquid crystal display means. Liquid crystal display means for displaying an image photographed by the photographing means;
A control means for controlling the video signal amplitude input to the liquid crystal display means within a high responsiveness range of the liquid crystal display means under an environmental temperature at which the responsiveness of the liquid crystal display means is reduced;
A liquid crystal display device comprising: Temperature detection means,
9. The liquid crystal display device according to claim 8, wherein the control means controls the video signal amplitude based on temperature information detected by the temperature detection means.   10. The liquid crystal display device according to claim 8, further comprising a correction table that indicates a relationship between the environmental temperature and the controlled amplitude of the video signal, which is set in advance so that an afterimage is not conspicuous on the liquid crystal display means.   11. The liquid crystal display device according to claim 10, wherein the correction table is calculated based on an optical response waveform of the liquid crystal display means.

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