JP2009116036A - Liquid crystal display, liquid crystal display program and liquid crystal display method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display etc., that enables higher quality display inexpensively in a low-temperature environment. <P>SOLUTION: The liquid crystal display comprises an LCD, a backlight for lighting the LCD from behind, a (S2) sensor detecting temperature of the LCD or its ambient temperature, and a control part which turns on the backlight (S7) and brings the LCD in a black display state (S8) when the temperature sensor detects the temperature being lower than predetermined temperature (S3). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a liquid crystal display device, a liquid crystal display program, and a liquid crystal display method for performing display using a liquid crystal display element.

  Liquid crystal display devices that perform display using a liquid crystal display element have been used in various devices in the past. However, with recent improvements in liquid crystal display technology, the number of devices that employ liquid crystal display devices has increased.

  As a device using such a liquid crystal display device as a display unit, for example, a digital camera mainly for taking still images, a video camera for mainly taking moving images, a mobile phone, a personal digital assistant (PDA) (Personal Digital Assistant)), an electronic dictionary, a television receiver (including a portable television receiver provided with a so-called one-segment tuner, etc.), a monitor of a personal computer, and the like.

  Among these examples, digital cameras, video cameras, mobile phones, personal digital assistants, electronic dictionaries, portable television receivers, etc. are often used not only indoors but also outdoors. Often exposed to

  However, it is known that the liquid crystal display element has different response characteristics depending on the temperature. In particular, in a low temperature environment, the liquid crystal substance tends to increase in viscosity and slow down in response.

  When an image, particularly a moving image, is displayed using such a liquid crystal display element in a low-temperature environment such as winter or in a cold region, the next image is deleted before the previous frame image is completely erased due to a delay in response. The display starts and becomes an afterimage (for example, the image is observed as if it has flowed), the target gradation brightness is not reached within a predetermined time, the contrast decreases, or the intermediate gradation is displayed correctly Otherwise, the display quality of the video will be degraded.

  As means for solving such a problem at low temperatures, for example, Japanese Patent Application Laid-Open No. 6-289370 provides a terminal for connecting a heater power source to a black matrix in liquid crystal in an active matrix liquid crystal display device. A technique for generating heat is described.

Also, for example, in Japanese Patent Application Laid-Open No. 2004-226594, a temperature sensor is used in a liquid crystal display device that prevents motion blur by writing an image signal and a black display signal to a liquid crystal display panel within one frame period. A technique for variably controlling the ratio of the black display period according to the detected temperature is described.
JP-A-6-289370 JP 2004-226594 A

  However, in the device described in JP-A-6-289370, the structure of the liquid crystal display element itself must be changed (a heater member or the like must be incorporated in the liquid crystal display element), which increases the manufacturing cost. In addition, it cannot be applied to a conventional liquid crystal display element in which no heater member is provided.

  In addition, in Japanese Patent Application Laid-Open No. 2004-226594, it is necessary to lengthen the black display period within one frame period in a low temperature environment in order to cope with a delay in response at low temperatures. In this case, since the amount of transmitted light taking the time average is reduced, the luminance of the display image is lowered, and the contrast is lowered. Furthermore, since the black display period must be limited to less than one frame period no matter how long, the display quality can be expected in a low temperature environment where the liquid crystal response period reaches or exceeds one frame period. Can not.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a liquid crystal display device, a liquid crystal display program, and a liquid crystal display method that enable high-quality display at low cost even in a low temperature environment. .

  In order to achieve the above object, a liquid crystal display device according to a first aspect of the present invention includes a liquid crystal display element and a temperature detection unit that detects whether or not the temperature of the liquid crystal display element or its vicinity is equal to or lower than a predetermined temperature. A control unit that controls the liquid crystal display element to be in a black display state when the temperature detection unit detects that the temperature is equal to or lower than a predetermined temperature.

  The liquid crystal display device according to a second aspect of the present invention is the liquid crystal display device according to the first aspect of the present invention, further comprising a backlight for illuminating the liquid crystal display element from the back side, and the controller is configured to detect the temperature. When it is detected by the unit that the temperature is not more than the predetermined temperature, the backlight is controlled to be further turned on.

  Furthermore, a liquid crystal display device according to a third aspect of the invention is the liquid crystal display device according to the second aspect of the invention, wherein the backlight is configured so that the luminance can be changed, and the control unit is controlled by the temperature detection unit. When the backlight is turned on when it is detected that the temperature is equal to or lower than a predetermined temperature, control is performed so that the backlight is turned on at the maximum luminance.

  A liquid crystal display device according to a fourth aspect of the invention is the liquid crystal display device according to the first aspect of the invention, wherein the liquid crystal display element is a normally black liquid crystal display element, and the control unit places the liquid crystal display element in a black display state. This control is performed by controlling the liquid crystal display element to be turned off.

  A liquid crystal display device according to a fifth invention is the liquid crystal display device according to the first invention, wherein the liquid crystal display device includes a battery and a power supply unit for supplying power to the liquid crystal display device, and the remaining amount of the battery is less than a predetermined value. A remaining battery level detection unit for detecting whether or not the control unit detects that the remaining battery level is less than a predetermined value by the remaining battery level detection unit. Even when the temperature detection unit detects that the temperature is equal to or lower than the predetermined temperature, the liquid crystal display element is not controlled to be in a black display state.

  A liquid crystal display device according to a sixth aspect of the invention is the liquid crystal display device according to the first aspect of the invention, wherein when the control unit controls the liquid crystal display element to be in a black display state, the liquid crystal display device is further in a black display state. Control is performed so that information indicating the presence is displayed on the liquid crystal display element.

  A liquid crystal display device according to a seventh aspect of the invention is the liquid crystal display device according to the second aspect of the invention, further comprising an external light quantity measuring unit that measures the quantity of external light irradiated to the liquid crystal display element, and the control unit is When the amount of external light measured by the external light quantity measurement unit is greater than or equal to a predetermined value, the backlight is turned on even when the temperature detection unit detects that the temperature is below the predetermined temperature. It controls to not.

  A liquid crystal display program according to an eighth invention is a liquid crystal display program for causing a computer to control a liquid crystal display device including a liquid crystal display element and a temperature detection unit, and based on the detection result of the temperature detection unit. A temperature determining step for determining whether or not the temperature of the liquid crystal display element or its vicinity is equal to or lower than a predetermined temperature, and when the temperature determining step determines that the temperature is equal to or lower than the predetermined temperature, the liquid crystal display element is blackened. And a control step for controlling the display state to be executed.

  A liquid crystal display method according to a ninth aspect of the present invention is a liquid crystal display method for controlling a liquid crystal display device including a liquid crystal display element and a temperature detection unit, and the liquid crystal display element or the same based on the detection result of the temperature detection unit A temperature determination step for determining whether or not the temperature in the vicinity is equal to or lower than a predetermined temperature, and when the temperature determination step determines that the temperature is equal to or lower than the predetermined temperature, the liquid crystal display element is set to a black display state. And a control step for controlling.

  According to the liquid crystal display device, the liquid crystal display program, and the liquid crystal display method of the present invention, higher quality display can be achieved at low cost even in a low temperature environment.

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

[Embodiment 1]
FIGS. 1 to 3 show Embodiment 1 of the present invention. FIG. 1 is a block diagram showing the configuration of an imaging apparatus to which a liquid crystal display device is applied. FIG. 2 shows the principle of black display in the liquid crystal display device. FIG. 3 is a flowchart showing the operation of the liquid crystal display device.

  The present embodiment is for an imaging device to which an image display device is applied.

  That is, as shown in FIG. 1, the imaging apparatus includes a photographing lens 1, an aperture 2, a shutter 3, an imaging element 4, an imaging circuit 5, an A / D converter 6, and an image processing unit 7. , Buffer memory 8, compression / decompression unit 9, interface (I / F) 10, recording medium 11, finder image generation unit 12, menu image storage unit 13, liquid crystal drive circuit 14, backlight 15, A liquid crystal display element (LCD) 16, a light source controller 17, a liquid crystal drive circuit 18 and a backlight 19, a liquid crystal display element (LCD) 20 and an electronic viewfinder (EVF) 22 including an eyepiece lens 21, and an AF mechanism 25. A flash control circuit 26, a flash 27, a temperature sensor 28, an operation unit 29, a power supply unit 30 including a battery 31, a nonvolatile memory 32, and a system controller. And a 3, a.

  The taking lens 1 is for forming an optical image of a subject on the image pickup surface of the image pickup device 4.

  The diaphragm 2 is for adjusting the amount of light passing through by defining the passing range of the subject light flux from the photographing lens 1.

  The shutter 3 is for adjusting the exposure time by defining the passage time of the subject luminous flux from the photographing lens 1.

  The imaging device 4 is configured as, for example, a CCD or a CMOS, and photoelectrically converts an optical image formed by the photographing lens 1 and outputs it as an electrical signal.

  The imaging circuit 5 amplifies the electrical signal output from the imaging device 4 to perform analog processing, and outputs it as an analog image signal.

  The A / D converter 6 converts the analog image signal from the imaging circuit 5 into a digital image signal (hereinafter also referred to as “image information” as appropriate). Note that the imaging lens 1 to the A / D converter 6 described above constitute an imaging unit of this imaging apparatus.

  The digital image signal from the A / D converter 6 is stored in the buffer memory 8 via the image processing unit 7. The buffer memory 8 is configured as, for example, a volatile built-in memory, and specifically, is configured by a high-speed memory such as SDRAM (Synchronous Dynamic Random Access Memory). The buffer memory 8 is also used as a work area for image processing described later.

  The image processing unit 7 performs various digital image processing such as color information conversion processing and pixel number conversion processing on the image information temporarily stored in the buffer memory 8, and stores the processed image information in the buffer memory 8. To remember again.

  The compression / decompression unit 9 reads out image information subjected to various types of image processing by the image processing unit 7 from the buffer memory 8 and performs compression processing such as JPEG compression. The compression / decompression unit 9 also reads a compressed image recorded on the recording medium 11 via the interface 10, decompresses it, and temporarily stores it in the buffer memory 8.

  The interface 10 mediates exchange of information between the compression / decompression unit 9 and the recording medium 11.

  The recording medium 11 is configured as a detachable memory card, for example, and specific examples include smart media, SD card, xD picture card, and the like. Note that the compression / expansion unit 9 to the recording medium 11 described above constitute a recording unit of the imaging apparatus.

  The finder image generation unit 12 converts the digital image signal from the A / D converter 6 into an image corresponding to the number of pixels for finder display when the captured image is displayed in live view.

  The menu image storage unit 13 stores a menu image for finder display. The menu image storage unit 13 is configured to transfer a designated menu image to the buffer memory 8 under the control of the system controller 33.

  The finder image generation unit 12 and the menu image storage unit 13 via the buffer memory 8 are respectively connected to the liquid crystal drive circuit 14 and the liquid crystal drive circuit 18.

  The liquid crystal driving circuit 14 drives the LCD 16 based on the image from the finder image generation unit 12 and the menu image from the buffer memory 8 to display.

  The LCD 16 is arranged on the back side of the imaging apparatus, for example, and is configured as a direct-view type. The LCD 16 is driven by the liquid crystal driving circuit 14 and performs various displays such as an image and a menu screen. As is well known, the LCD 16 and the LCD 20 described later are not self-luminous display elements, but control the amount of transmitted light by controlling the polarization component of the light. For example, gradation expression of a monochrome liquid crystal display element is realized only by controlling the amount of transmitted light. In addition, gradation expression of a color liquid crystal display element is realized by performing monochrome gradation expression for each color of RGB. Further, black display is realized by controlling so as to block all transmitted light in both monochrome and color liquid crystal display elements. Note that, here, “black display” is simply described, but depending on the liquid crystal display element, the color may not necessarily be “black”. Therefore, more accurately, “display with the least amount of light reaching the viewer side (“ display with the least amount of transmitted light ”when the liquid crystal display element is a transmission type”, and “when the liquid crystal display element is a reflection type,“ It should be called “display with the least amount of reflected light”) ”, but instead of this wording, it will be called“ black display ”.

  The backlight 15 is disposed on the back side of the LCD 16 and illuminates the LCD 16 from the back side, and the light emission luminance can be adjusted in a plurality of stages.

  The light source controller 17 controls the backlight 15 and the backlight 19 provided in the EVF 22 to emit light.

  The liquid crystal driving circuit 18 drives the LCD 20 to display based on the image from the finder image generation unit 12 and the menu image from the buffer memory 8.

  The LCD 20 is provided in the EVF 22 and is driven by the liquid crystal driving circuit 18 to perform various displays such as images and menu screens.

  The backlight 19 is disposed on the back side of the LCD 20 and illuminates the LCD 20 from the back side, and the light emission luminance can be adjusted in a plurality of stages.

  The eyepiece 21 enlarges and projects the display on the LCD 20 onto the observer's eyes.

  The liquid crystal driving circuit 18, the backlight 19, the LCD 20, and the eyepiece lens 21 constitute an EVF 22, and the imaging apparatus includes an electronic viewfinder (EVF) 22 instead of the optical viewfinder. ing.

  The finder image generation unit 12 to the eyepiece lens 21 described above constitute a display unit of this imaging apparatus.

  When displaying an image recorded on the recording medium 11, image information read from the recording medium 11 and expanded by the compression / expansion unit 9 is supplied to the liquid crystal drive circuits 14 and 18 via the buffer memory 8. Are displayed on the LCDs 16 and 20.

  The AF mechanism 25 adjusts the focus by moving the focus lens included in the photographing lens 1 in the optical axis direction by a focus motor (not shown) based on the control of the system controller 33. In the case where the photographing lens 1 is configured as an electric zoom, a zoom mechanism or the like may be further provided to perform zooming with a zoom motor or the like.

  The system controller 33 drives the diaphragm 2 and adjusts the diaphragm through a diaphragm control mechanism (not shown).

  Further, the system controller 33 drives the shutter 3 via a shutter control mechanism (not shown) to expose the image sensor 4.

  The control of the diaphragm 2 and the control of the shutter 3 are performed based on the input setting from the user via the operation unit 29, or the luminance of the subject is calculated based on the image signal from the image processing unit 7, This is done based on automatic setting according to the result of referring to the program diagram.

  The strobe 27 is for irradiating the subject with illumination light as necessary, and includes an arc tube serving as a light source.

  The strobe control circuit 26 includes a strobe capacitor (not shown) capable of accumulating a predetermined amount of charge, and charges the strobe capacitor based on the control of the system controller 33. The discharge tube of the strobe 27 is caused to emit light with a predetermined light amount by discharging only the amount of electric charge.

  The temperature sensor 28 is a temperature detection unit that measures the temperature in the imaging apparatus, particularly in the vicinity of the LCD 16 and the LCD 20, and outputs the measured temperature to the system controller 33. Although the common temperature sensor 28 is used here, a temperature sensor dedicated to the LCD 16 and a temperature sensor dedicated to the LCD 20 may be provided independently. Although a temperature sensor is used here, a switch that turns on / off with a predetermined temperature as a boundary value may be used.

  The operation unit 29 selects a power button for turning on / off the power of the imaging apparatus, a release button for taking an image, a recording (shooting) mode and a playback mode, or a full mode in the recording mode. A mode setting button for selecting a mode, a program shooting mode, a manual shooting mode, a scene-specific shooting mode, and the like are included. The operation unit 29 includes a push button, a slide switch, a cross key, and the like as specific operation modes of various buttons. An operation input from the operation unit 29 is output to the system controller 33.

  The power supply unit 30 supplies power to each unit in the imaging apparatus. The power supply unit 30 includes a battery 31 and is configured to receive power from the external power supply by connecting to an external power supply. . The system controller 33 performs power management for the entire imaging apparatus, and the power supply unit 30 is controlled by the system controller 33. Further, the power supply unit 30 detects the voltage of the battery 31 and transmits the detection result to the system controller 33. The system controller 33 detects the remaining battery level based on the battery voltage from the power supply unit 30. That is, the power supply unit 30 and the system controller 33 constitute a battery remaining amount detection unit.

  The non-volatile memory 32 is configured by a rewritable non-volatile recording medium such as a flash memory, for example, and a basic control program for controlling the image pickup apparatus, and various data and parameters used in the image pickup apparatus. Etc. are memorized. Since the nonvolatile memory 32 is rewritable, it can cope with so-called firmware update.

  The system controller 33 is a control unit that reads the above-described basic control program from the nonvolatile memory 32 and controls the entire imaging apparatus including the above-described units.

  Note that the imaging apparatus according to the present embodiment includes a direct-view liquid crystal display unit (backlight 15, LCD 16 and the like) disposed on the back surface and a liquid crystal display unit (backlight 19, liquid crystal display) disposed on the EVF 22 as display units. LCD 20 and the like) are provided.

  The system controller 33 controls these two liquid crystal display units. For example, when displaying the liquid crystal display unit on the back side, the liquid crystal display unit of the EVF 22 is not displayed or the liquid crystal display unit of the EVF 22 is displayed. In such a case, the display state is controlled such that the liquid crystal display unit on the back side is not displayed, or two liquid crystal display units are displayed simultaneously, or both the two liquid crystal display units are not displayed. It is like that.

  Next, black display realized by the LCD 16 or the LCD 20 will be described with reference to FIG. Note that the liquid crystal display element is configured by dividing a portion to be shielded into a plurality of pixels, and in FIG. 2, for simplicity of explanation, one pixel is schematically illustrated. Shall.

  In FIG. 1, the liquid crystal display unit is illustrated so as to include the backlights 15 and 19 and the LCDs 16 and 20, but more specifically, the first polarization is on the optical path from the backlights 15 and 19 to the LCDs 16 and 20. A plate 41 is provided with a second polarizing plate 42 on the optical path of light emitted from the LCDs 16 and 20. Although these two polarizing plates 41 and 42 are drawn apart from the LCDs 16 and 20 in FIG. 2, they are actually bonded to the LCDs 16 and 20, for example, and are in close contact with each other. .

  Of the two polarizing plates described above, the first polarizing plate 41 transmits, for example, only polarized light in the vertical direction (vertical polarization transmission axis) and absorbs polarized light in the horizontal direction. .

  The LCDs 16 and 20 change the state of rotating the polarized light corresponding to the electric signal.

  Furthermore, the second polarizing plate 42 transmits, for example, only polarized light in the horizontal direction (horizontal polarization transmission axis) and absorbs polarized light in the vertical direction. Therefore, the amount of light transmitted through the second polarizing plate 42 changes depending on the degree of rotation of the polarized light from the LCDs 16 and 20.

  In such a configuration, it is assumed that the illumination light emitted from the backlights 15 and 19 does not have a specific polarization direction.

  When this illumination light is incident on the first polarizing plate 41, only vertically polarized light is transmitted, and horizontally polarized light (that is, approximately half the amount of light) is absorbed. In general, most of the polarized light absorbed by the first polarizing plate 41 is converted into thermal energy.

  The vertically polarized light transmitted through the first polarizing plate 41 is incident on the LCDs 16 and 20. Here, it is assumed that the LCDs 16 and 20 are driven so as not to rotate the polarization direction of incident light. Therefore, the light incident on the LCDs 16 and 20 is emitted from the LCDs 16 and 20 as vertically polarized light.

  When this vertically polarized light is incident on the second polarizing plate 42, it is absorbed as it is because there is no horizontally polarized component. Most of the polarized light absorbed by the second polarizing plate 42 is converted into thermal energy as described above.

  And since there is no light which permeate | transmits the 2nd polarizing plate 42, black display is implement | achieved.

  Thus, when displaying black, the thermal energy converted from the illumination light by the first polarizing plate 41 and the second polarizing plate 42 is applied to the LCDs 16 and 20 as described above. Therefore, it is transmitted to the LCDs 16 and 20 with high efficiency. Thus, during black display, the LCDs 16 and 20 are heated by receiving heat energy, and the temperature rises.

  By performing black display in this way, light energy can be absorbed and converted into heat energy, so that it is not necessary to provide a special structure such as a heater member in the LCDs 16 and 20, and the temperature of the liquid crystal is increased. (Such an operation will be referred to as a “pseudo heater operation” below).

  In the above description, the illumination light emitted from the backlights 15 and 19 has been described as having no specific polarization direction. However, the illumination light generated in the backlights 15 and 19 is perpendicular to the first polarizing plate 41. If it is aligned with the polarization transmission axis, light loss in the first polarizing plate 41 does not occur, so that a liquid crystal display device with higher luminance can be obtained, which is a desirable configuration. However, even in this case, the above description can be applied almost as it is except that the amount of heat generated by the first polarizing plate 41 during black display is substantially zero.

  Further, in the above description, the case where the LCDs 16 and 20 are heated by the light from the backlights 15 and 19 has been described. However, if there is external light, the LCDs 16 and 20 can be displayed in black so that the external light can also be used. The LCDs 16 and 20 can be heated. Also in this case, the above-described explanation can be applied almost as it is, only that the incident and exit directions of the light beam are opposite to those in the example shown in FIG. In particular, when the liquid crystal display element is of a reflective type, the light source for performing the pseudo heater operation is basically only this outside light (however, when a separate illumination light source is provided) As in the case of the backlight in the transmissive liquid crystal, illumination with this illumination light source may be performed).

  By the way, the liquid crystal display element includes a normally white type and a normally black type.

  Among these, normally white liquid crystal display elements display white when no voltage is applied to the liquid crystal. Therefore, in order to realize black display, it is necessary to apply a voltage to the liquid crystal. A typical example of such a normally white liquid crystal display element is a TN (Twisted Nematic) liquid crystal.

  On the other hand, a normally black liquid crystal display element displays black when no voltage is applied to the liquid crystal. Therefore, it is not necessary to apply a voltage to the liquid crystal when realizing black display. A typical example of such a normally black liquid crystal display element is a VA (Vertical Alignment) liquid crystal.

  Therefore, when a normally black liquid crystal display element is used to form a liquid crystal display device, the above-described pseudo heater operation can be realized by emitting only the backlight without applying a voltage to the liquid crystal. . Compared to the case where a liquid crystal display device is configured using a normally white type liquid crystal display element, it is possible to reduce power consumption by the amount that voltage application to the liquid crystal is not required. From this point of view, the configuration is advantageous.

  Next, with reference to FIG. 3, the flow of the pseudo heater operation with black display will be described.

  This operation is started when the power of the imaging apparatus is turned on via the operation unit 29. However, this operation is performed on the display unit to be displayed. That is, when the display target is the rear display unit (backlight 15 and LCD 16), the rear display unit is performed. When the display target is the EVF 22 (backlight 19 and LCD 20), the EVF 22 is processed. When the display target is both of these, it is performed on both display units.

  When the operation starts, first, the system controller 33 functions as a power supply state determination unit, and checks the state of the power supply unit 30 to determine whether or not the remaining amount of the battery 31 is equal to or greater than a first predetermined value. (Step S1). Here, the first predetermined value is a threshold for determining whether or not to perform black display, that is, black display can be performed when the remaining battery level is equal to or greater than the first predetermined value. Yes, it is a threshold value for determining that black display is not performed when it is less than the first predetermined value.

  Here, when the power supply unit 30 is supplied with power from an external power supply, or when the remaining amount of the battery 31 is equal to or greater than the first predetermined value, the system controller 33 checks the output of the temperature sensor 28. In step S2, it is determined whether or not the temperature in the vicinity of the LCDs 16 and 20 is equal to or lower than a predetermined temperature necessary for maintaining the liquid crystal display quality (the system controller 33 functions as a black display image output determination unit). (Step S3). Here, the predetermined temperature for maintaining the liquid crystal display quality cannot be specified because it differs depending on the configuration of the liquid crystal display element, but an example is 5 ° C.

  Here, when the detected temperature is equal to or lower than the predetermined temperature, the quality of the liquid crystal display cannot be ensured, and thus it is basically necessary to perform a pseudo heater operation with black display. However, depending on the use conditions of the user, even if the display quality is inferior, it may be desired to display immediately.

  In view of this, the display quality of the liquid crystal display device is inferior due to the current temperature drop, but the menu image storage unit displays a menu image for prompting the user to select whether or not to immediately perform the liquid crystal display. 13 and displayed on the LCD 16 or LCD 20 and waits for a user input from the operation unit 29 (the system controller 33 functions as a menu image determination unit) (step S4).

  Here, when there is no immediate selection of the liquid crystal display from the user, that is, when there is an input from the user that the liquid crystal display is not displayed immediately, or there is no input from the user even after a predetermined time has elapsed. The system controller 33 checks the state of the power supply unit 30 to determine whether or not the remaining amount of the battery 31 is greater than or equal to a second predetermined value (here, second predetermined value> first predetermined value). Is determined (step S5). Here, the second predetermined value drives the LCD 16 (LCD 20) to a black display state, but the threshold value for determining whether the backlight 15 is turned on or off, that is, the remaining battery level is the first predetermined value. It is possible to turn on the backlight 15 when it is equal to or greater than a predetermined value of 2, and when it is less than the second predetermined value, it is a threshold value for determining that the backlight 15 is not turned on (note that Since the LCD 20 is provided in the EVF 22, the backlight 19 is basically turned on as described later).

  Here, when it is determined that the remaining battery level is equal to or greater than the second predetermined value, it is determined whether the amount of external light applied to the LCD 16 is equal to or greater than the predetermined value (step S6).

  When it is determined that the amount of external light is less than the predetermined value, the backlight 15 has the maximum luminance (the maximum luminance is used here for increasing the temperature of the LCD 16 in as short a time as possible). When it is turned on (step S7) and it is determined that the amount of external light is greater than or equal to the predetermined value, or when it is determined in step S5 that the remaining battery level is less than the second predetermined value, the backlight 15 is turned on. The black display on the LCD 16 is started without being turned on (step S8). As described above, the black display is performed by applying a drive signal when the LCDs 16 and 20 are normally white liquid crystal, but when the LCDs 16 and 20 are normally black liquid crystal, the drive signal is applied. Will do without.

  Here, for example, when the external light is direct sunlight, the amount of light per unit area is often larger than the amount of light generated from the backlight 15 per unit area. Therefore, when the amount of external light is sufficient, it can be expected that even if the backlight 15 is turned off, the LCD 16 generates heat and the temperature rises due to the external light applied to the LCD 16. Therefore, when the external light is sufficient, the backlight 15 is turned off to save power. Note that the amount of external light applied to the LCD 16 may be detected by providing an external light amount measurement unit such as a dedicated luminance sensor in the vicinity of the LCD 16, but in this embodiment, the liquid crystal display device is used as an imaging device. Since it is applied, an AE sensor or the like often provided in the imaging apparatus originally may be used as the external light quantity measuring unit, or the imaging element 4 may be used as the external light quantity measuring unit. The amount of ambient light may be estimated based on the obtained image.

  Since the LCD 20 of the EVF 22 is disposed inside the eyepiece lens 21 and is hardly exposed to external light such as direct sunlight, the processing of steps S5 and S6 is performed for the EVF 22. Omitted, the backlight 19 is always turned on at the maximum brightness in step S7, and black display on the LCD 20 is started in step S8.

  When this black display is started, the system controller 33 further reads out a menu image such as “Please wait” from the menu image storage unit 13 and displays it on the LCDs 16 and 20 via the buffer memory 8 as an OSD (On Screen Display) display. (The system controller 33 functions as a menu image determination unit) (step S9). This is because when the black display is performed, the screen is in a black state, so that the user is performing the black display or the system of the imaging apparatus is not activated (for example, the power is off) (or This is to notify the user that the display is black, since it is difficult to determine whether the system is down. However, since this menu is brighter than black (that is, the heat energy for the transmitted light is not generated because it transmits light), this menu image is displayed to prevent the simulated heater effect from being reduced as much as possible. Is preferably performed in an area as small as possible (for example, an area of 1/10 or less of the entire screen). Further, when the menu image is displayed, if the displayed characters and the like are moved within the screen, the entire screen may be heated uniformly. Further, it is not necessary to always display the menu image. For example, a so-called blinking display may be performed such that the menu image is displayed for 0.5 seconds and then not displayed for 0.5 seconds. In this case, since it is possible to secure the time for the entire screen to display black, the heating efficiency can be increased somewhat.

  In addition, although the example which displays character information was demonstrated here, of course, it is not restricted to this, You may display with the icon etc. which understand that it is black display, and there is a function to emit a sound. For example, the user may be notified by voice.

  Then, it is determined whether or not a predetermined time (for example, 1 minute) has elapsed (step S10). If it has not yet elapsed, the process returns to step S8 to continue black display.

  On the other hand, if it is determined that the predetermined time has elapsed, the process returns to step S1 to perform the processing as described above. Here, the loop of steps S8 to S10 is rotated for a predetermined time, but the output of the temperature sensor 28 is always monitored during this predetermined time, and it is detected that the predetermined temperature has been reached. In this case, it is possible to return to step S1 through this loop.

  If it is determined in step S1 that the remaining battery level is less than the first predetermined value, the system controller 33 determines that the remaining battery level is not sufficient and the system controller 33 stores the low battery icon or the like from the menu image storage unit 13. The low battery warning display is performed by controlling to read the menu image and display it on the LCDs 16 and 20 via the buffer memory 8 (step S11). The low battery warning display is not limited to the icon display, and may be performed by displaying a sentence, or a warning sound or the like may be generated by voice.

  If it is determined that the process of step S11 is to be performed, that the temperature is higher than the predetermined temperature in step S3, or that liquid crystal display is to be performed immediately in step S4, the backlights 15 and 19 are turned on. (Step S12), display is performed on the LCDs 16 and 20 (Step S13), and it is determined whether or not to end the liquid crystal display (Step S14).

  If it is determined in step S14 that the liquid crystal display is not yet finished, the process returns to step S13 to continue the liquid crystal display. On the other hand, if it is determined that the liquid crystal display is finished, the process is terminated. .

  As described above, the pseudo heater operation by the black display can be performed on any of the direct-view type rear LCD 16 and the EVF 22 LCD 20 as long as it is a liquid crystal using a polarizing plate. it can.

  In the above description, the predetermined temperature in step S3, which is a threshold for determining whether or not to perform black display, is common to the direct-view rear LCD 16 and the LCD 20 of the EVF 22, but these two LCDs are arranged. In this case, it is preferable to use different values as the predetermined temperature, because the positions of the liquid crystals are different and it is possible to use different types of liquid crystals.

  In addition, the liquid crystal display unit on the back side can turn off the backlight when the pseudo heater operates when the amount of external light is sufficient, whereas the liquid crystal display unit of the EVF 22 Will basically turn on the backlight. Therefore, the first predetermined value in step S1 may be different for the liquid crystal display unit on the back side and the liquid crystal display unit of the EVF 22.

  Furthermore, in order to perform the pseudo heater operation as described above, any device having a liquid crystal display element (more preferably, a device further having a backlight) can be applied. Even if it exists, it becomes possible to cope by upgrading the firmware stored in the nonvolatile memory 32 or the like. Therefore, the present invention can be applied to a very wide range of devices including devices that have already been manufactured or sold.

  In the above description, an imaging apparatus (for example, a digital camera) is exemplified as an apparatus to which the liquid crystal display device is applied. However, the present invention is not limited to this, and can be widely applied to apparatuses having a liquid crystal display unit. Is possible. Specific examples of such devices include a digital camera, a video camera, a mobile phone, a personal digital assistant, an electronic dictionary, and a portable television receiver.

  In addition, although the liquid crystal display device has been mainly described above, a liquid crystal display program for causing a computer to perform similar processing or a liquid crystal display method for performing similar processing may be used.

  According to the first embodiment, the temperature at which the liquid crystal display element can be heated and the display quality can be ensured by performing the pseudo heater operation by black display without adding a special configuration such as a heater member. Therefore, even when the temperature is low, the response delay of the liquid crystal can be reduced and higher quality display can be performed.

  Further, by turning on the backlight with the maximum luminance, the temperature of the liquid crystal display element can be increased in as short a time as possible, and the time until the start of use can be shortened and the usability can be improved.

  Further, by using a normally black liquid crystal display element as the liquid crystal display element, power consumption can be reduced.

  Further, since the black display is performed only when the remaining battery level is equal to or higher than the first predetermined value when the battery is driven, the displayable time is not shortened unnecessarily when the remaining battery level is low.

  Furthermore, since the backlight of the rear display unit is turned off when the remaining battery level is less than the second predetermined value, even when the remaining battery level is low, black display is achieved while reducing power consumption. This makes it possible to perform a pseudo heater operation.

  In addition, when the amount of external light is sufficient, only the black display is performed and the pseudo heater effect is obtained by the external light, so that the power consumption can be reduced. In particular, when the image display device is applied to an imaging device, it is possible to use a photometric function or the like provided in the imaging device. It is possible to extend the operation time without increasing.

  Since the OSD display for notifying the user of the black display and the voice notification are performed during the black display, the user is not confused even in the black display, and the user interface is improved.

  In addition, even if the device is already manufactured, it is advantageous in that the technology of the present embodiment can be used when the device is compatible with rewriting of firmware or the like.

  Note that the present invention is not limited to the above-described embodiments as they are, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Moreover, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, you may delete a some component from all the components shown by embodiment. Furthermore, the constituent elements over different embodiments may be appropriately combined. Thus, it goes without saying that various modifications and applications are possible without departing from the spirit of the invention.

1 is a block diagram illustrating a configuration of an imaging device to which a liquid crystal display device according to Embodiment 1 of the present invention is applied. FIG. 3 is a diagram showing the principle of black display in the liquid crystal display device of the first embodiment. 6 is a flowchart showing the operation of the liquid crystal display device of the first embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Shooting lens 2 ... Aperture 3 ... Shutter 4 ... Image sensor (external light quantity measurement part)
DESCRIPTION OF SYMBOLS 5 ... Imaging circuit 6 ... A / D converter 7 ... Image processing part 8 ... Buffer memory 9 ... Compression / decompression part 10 ... Interface (I / F)
DESCRIPTION OF SYMBOLS 11 ... Recording medium 12 ... Finder image generation part 13 ... Menu image memory | storage part 14, 18 ... Liquid crystal drive circuit 15, 19 ... Backlight 16, 20 ... Liquid crystal display element (LCD)
17 ... Light source control unit 21 ... Eyepiece lens 22 ... EVF
25 ... AF mechanism 26 ... Strobe control circuit 27 ... Strobe 28 ... Temperature sensor (temperature detector)
29 ... Operation part 30 ... Power supply part (remaining battery level detection part)
31 ... Battery 32 ... Non-volatile memory 33 ... System controller (control unit, remaining battery level detection unit)
41, 42 ... Polarizing plate

Claims (9)

A liquid crystal display element;
A temperature detector for detecting whether or not the temperature of the liquid crystal display element or its vicinity is equal to or lower than a predetermined temperature;
A control unit for controlling the liquid crystal display element to be in a black display state when the temperature detection unit detects that the temperature is equal to or lower than a predetermined temperature;
A liquid crystal display device comprising: A backlight for illuminating the liquid crystal display element from the back side;
2. The control unit according to claim 1, wherein when the temperature detection unit detects that the temperature is equal to or lower than the predetermined temperature, the control unit controls the backlight to be further turned on. Liquid crystal display device. The backlight is configured to be able to change the brightness,
The controller is configured to control to turn on the backlight at the maximum brightness when the temperature detector detects that the temperature is equal to or lower than the predetermined temperature. Item 3. A liquid crystal display device according to Item 2. The liquid crystal display element is a normally black liquid crystal display element,
2. The liquid crystal display according to claim 1, wherein the control unit controls the liquid crystal display element to be in a black display state by controlling the driving of the liquid crystal display element to be turned off. apparatus. A power supply unit including a battery for supplying power to the liquid crystal display device;
A remaining battery level detection unit for detecting whether or not the remaining battery level is less than a predetermined value;
Further comprising
When the control unit detects that the remaining battery level is less than a predetermined value by the remaining battery level detection unit, the temperature detection unit detects that the remaining battery level is equal to or lower than the predetermined temperature. However, the liquid crystal display device according to claim 1, wherein the liquid crystal display element is not controlled to be in a black display state.   When the control unit controls the liquid crystal display element to be in a black display state, the control unit further controls to display information indicating the black display state on the liquid crystal display element. The liquid crystal display device according to claim 1. It further comprises an external light quantity measurement unit that measures the quantity of external light irradiated to the liquid crystal display element,
When the external light amount measured by the external light amount measurement unit is equal to or greater than a predetermined value, the control unit may detect that the temperature detection unit detects that the external light amount is equal to or less than the predetermined temperature. The liquid crystal display device according to claim 2, wherein the backlight is controlled not to be lit. A liquid crystal display program for causing a computer to control a liquid crystal display device including a liquid crystal display element and a temperature detection unit,
On the computer,
A temperature determination step for determining whether the temperature of the liquid crystal display element or the vicinity thereof is equal to or lower than a predetermined temperature based on a detection result of the temperature detection unit;
A control step for controlling the liquid crystal display element to be in a black display state when it is determined by the temperature determination step that the temperature is equal to or lower than a predetermined temperature;
LCD program for running A liquid crystal display method for controlling a liquid crystal display device including a liquid crystal display element and a temperature detection unit,
A temperature determination step for determining whether the temperature of the liquid crystal display element or the vicinity thereof is equal to or lower than a predetermined temperature based on a detection result of the temperature detection unit;
A control step for controlling the liquid crystal display element to be in a black display state when it is determined by the temperature determination step that the temperature is equal to or lower than a predetermined temperature;
A liquid crystal display method comprising:

Images