JP2004219715A - Liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display wherein burning of a liquid crystal display panel can be suppressed. <P>SOLUTION: In the liquid crystal display, when environmental temperature T of the surroundings of the liquid crystal panel monitored by a temperature sensor is a prescribed temperature TC a little higher than the normal temperature or more and temperature change per unit time of temperature rise of a prescribed value or more is detected, the screen of the liquid crystal display panel is renewed to a burning preventing image, for example, whose full surface is uniformly black. When the environmental temperature T reaches a threshold temperature TM (>TC), the screen is immediately renewed to the burning preventing image. When the environmental temperature T is TL≤T<TM and a fixed period t2 lapses in the range where irreversible burning is not generated and display renewal is not performed, the screen is renewed to the burning preventing image. By these processes, burning of the liquid crystal panel can be suppressed. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a liquid crystal display device having a liquid crystal display panel having a memory function and performing display using selective reflection of a cholesteric liquid crystal phase.
[0002]
[Prior art]
In recent years, as a medium for reproducing digital information into visible information, a selective reflection type liquid crystal display element (panel) using a liquid crystal exhibiting a cholesteric phase at room temperature (mainly a chiral nematic (CN) liquid crystal) has been displayed without applying a voltage. Various development studies have been made with a focus on the advantage of low power consumption due to having a memory property capable of maintaining the above, and of being inexpensive to manufacture.
[0003]
Liquid crystal display devices using this liquid crystal display panel are disclosed in Patent Documents 1 to 3, for example.
[0004]
[Patent Document 1]
JP 2000-147465 A
[Patent Document 2]
JP 2000-284760 A
[Patent Document 1]
JP 2000-330526 A
[0005]
[Problems to be solved by the invention]
However, Patent Documents 1 to 3 do not take into account image sticking, which is one of the problems of the chiral nematic liquid crystal display panel.
[0006]
This burn-in means that if the display is changed to another image after the image is displayed and the liquid crystal is left in a state where it is written in the planar state and the focal conic state, the history of the previous display image is observed. It is a phenomenon that is done. Image sticking is not preferable because display quality is impaired.
[0007]
According to the study of the present inventors, the seizure is more likely to occur as the standing time is longer and as the environmental temperature around the liquid crystal display element is higher. In particular, the influence of the environmental temperature is great, and the higher the temperature is, the more the burning occurs in a short time. In the case of image sticking in a room, for example, the entire surface of the panel is set in a focal conic state and left at room temperature to be alleviated, and the image sticking can be eliminated by maintaining the state for a predetermined time. However, the seizure in a high-temperature environment requires a long time to be eliminated by leaving it at room temperature, and the higher the temperature, the more difficult it is to eliminate the seizure. That is, if the ambient temperature is too high, seizure becomes substantially irreversible.
[0008]
The present invention has been made in view of the above problems, and has as its object to provide a liquid crystal display device capable of suppressing image sticking of a liquid crystal display panel.
[0009]
[Means for Solving the Problems]
In order to solve the above problems, the invention according to claim 1 is a liquid crystal display device, comprising: (a) a liquid crystal display panel having a memory function and performing display using selective reflection of a cholesteric liquid crystal phase; A) a driving circuit for driving the liquid crystal display panel; (c) temperature detecting means for detecting an environmental temperature around the liquid crystal display panel; and (d) the environmental temperature detected by the temperature detecting means is equal to or higher than a predetermined temperature. And a control unit for activating the drive circuit and updating the screen of the liquid crystal display panel to an image for preventing burn-in.
[0010]
Further, according to a second aspect of the present invention, in the liquid crystal display device according to the first aspect of the present invention, the control means includes: (d-1) the environmental temperature detected by the temperature detection means is equal to or higher than a predetermined temperature; When a predetermined time has elapsed without updating the display on the liquid crystal display panel, there is provided means for activating the drive circuit and updating the screen of the liquid crystal display panel with the image for preventing burn-in.
[0011]
A third aspect of the present invention is a liquid crystal display device, comprising: (a) a liquid crystal display panel having a memory property and performing display using selective reflection of a cholesteric liquid crystal phase; and (b) the liquid crystal display panel. A driving circuit for driving; (c) temperature detecting means for detecting an environmental temperature around the liquid crystal display panel; and (d) when the environmental temperature detected by the temperature detecting means is equal to or higher than a first temperature. First control means for activating the drive circuit to update the screen of the liquid crystal display panel with the image for preventing burn-in; and (e) controlling the environmental temperature detected by the temperature detection means to the first temperature. A second control unit that immediately activates the drive circuit when the second temperature is higher than the temperature and updates the screen of the liquid crystal display panel with the image for preventing burn-in.
[0012]
The invention according to claim 4 is a liquid crystal display device, wherein (a) a liquid crystal display panel having a memory function and performing display using selective reflection of a cholesteric liquid crystal phase, and (b) the liquid crystal display panel. A drive circuit for transitioning to a rest state after writing an image, (c) a timer for measuring the time elapsed from the screen update on the liquid crystal display panel, and (d) a predetermined time elapsed from the screen update. And control means for activating the drive circuit in the halt state when the time has elapsed to display an image for preventing burn-in on the liquid crystal display panel.
[0013]
The invention according to claim 5 is a liquid crystal display device, comprising: (a) a liquid crystal display panel having a memory function and performing display using selective reflection of a cholesteric liquid crystal phase; (C) a lid member that can shift to a first position that covers the liquid crystal display panel and a second position that opens the liquid crystal display panel after writing the image, d) when the lid member is at the first position, the control circuit activates the drive circuit in the rest state to display an image for preventing burn-in on the screen of the liquid crystal display panel. .
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
<First embodiment>
<Main configuration of liquid crystal display device>
FIG. 1 is a perspective view showing a liquid crystal display device 10 according to the first embodiment of the present invention.
[0015]
The liquid crystal display device 10 is an electronic book type liquid crystal display device having two screens that can be turned into a two-page spread state.
[0016]
The liquid crystal display device 10 includes a liquid crystal display panel 11R forming a right page and a liquid crystal display panel 11L forming a left page. Each panel 11 (11R, 11L) has a full-color liquid crystal display element 100R, 100L described later. The housings 12 (12R, 12L) are connected by a hinge 13 at the center, and can be opened and closed between a closed state where two screens overlap and an open state where two screens are arranged. That is, the housing 12 functions as a lid member that can shift to a first position that covers the liquid crystal display panel and a second position that opens the liquid crystal display panel.
[0017]
The lower part of the housing 12 is configured as operation panels 20R and 20L. The operation panel 20R includes a power key 21 for turning on / off a main power, a menu key 22 for executing a menu display, a decision key 23 for instructing a decision of a command, and a cursor movement key 24R. Is provided. The operation panel 20L has a key 25 for selecting a mode for updating only the right side, a key 26 for selecting a mode for updating only the left side, and a key for selecting a mode for simultaneously updating both sides. 27 and a cursor movement key 24L.
[0018]
The housing 12 is provided with a display window 41 configured as a display device using, for example, a slide member in a central portion around the hinge 13. The display window 41 includes a display window TEMP for indicating the operation state of the burn-in prevention processing and a display window PRCT for displaying the screen update prohibition / permission.
[0019]
The housing 12 has built-in temperature sensors 31R and 31L and speakers 32R and 32L for measuring the environmental temperature around the liquid crystal display elements 100R and 100L. The housing 12R is provided with an antenna 33 for transmitting and receiving communication radio waves. Further, a slot 34 for mounting a recording medium 35 is provided in the housing 12L. The recording medium 35 stores book data to be displayed on the display panel 11, and uses a semiconductor memory, an optical disk, a removable hard disk, or the like. The data to be displayed can be input to the liquid crystal display device 10 via the antenna 33.
[0020]
A drive circuit for driving the liquid crystal display elements 100R and 100L and a control unit 50 (described later) are housed inside the housings 12R and 12L.
[0021]
FIG. 2 is a cross-sectional view illustrating a main configuration of the liquid crystal display elements 100R and 100L.
[0022]
The liquid crystal display elements 100R and 100L are reflection type full-color liquid crystal display elements based on a simple matrix driving method in which display layers 111R, 111G and 111B containing liquid crystals exhibiting a cholesteric phase are stacked.
[0023]
In the liquid crystal display elements 100R and 100L, a red display layer 111R for performing display by switching between a red selective reflection and a transparent state is disposed on the light absorbing layer 121, and a green selective reflection and a transparent state are switched thereon. , And a blue display layer 111B for displaying by switching between blue selective reflection and a transparent state.
[0024]
Each of the display layers 11R, 111G, and 111B has a liquid crystal 116 and a spacer 117 interposed between a transparent substrate 112 made of resin, glass, or the like on which transparent electrodes 113 and 114 are formed. It is what was adhered with. An insulating film 118 and an orientation control film 119 are provided on the transparent electrodes 113 and 114 as needed. Further, a sealant 120 for sealing the liquid crystal 116 is provided on an outer peripheral portion (outside the display area) of the substrate 112.
[0025]
The transparent electrodes 113 and 114 are connected to scanning drive ICs 131R and 131L and signal drive ICs 132R and 132L (see FIG. 3), respectively, and a predetermined pulse voltage is applied to the transparent electrodes 113 and 114, respectively. In response to the applied voltage, the display is switched between a transparent state in which the liquid crystal 116 transmits visible light and a selective reflection state in which visible light of a specific wavelength is selectively reflected.
[0026]
The transparent electrodes 113 and 114 provided on each of the display layers 111R, 111G and 111B are each composed of a plurality of strip electrodes arranged in parallel with a fine interval, and the orientation of the strip electrodes is viewed from a plane. They are opposed to each other so as to be perpendicular to each other. Current is sequentially applied to these upper and lower strip electrodes. That is, display is performed by sequentially applying a voltage to each liquid crystal 116 in a matrix. This is referred to as matrix driving, and a portion where the electrodes 113 and 114 intersect constitutes each pixel. By performing such matrix driving for each display layer, a full-color image is displayed on the liquid crystal display element 100.
[0027]
Specifically, in a liquid crystal display element in which liquid crystal exhibiting a cholesteric phase is sandwiched between two substrates, display is performed by switching the state of the liquid crystal between a planar state and a focal conic state. When the liquid crystal is in the planar state, assuming that the helical pitch of the cholesteric liquid crystal is P and the average refractive index of the liquid crystal is n, light of (wavelength) = P · n is selectively reflected. In the focal conic state, when the selective reflection wavelength of the cholesteric liquid crystal is in the infrared light range, the incident light is scattered, and when it is shorter than that, the scattering is weak and the visible light is substantially transmitted. Therefore, by setting the selective reflection wavelength to the visible light region and providing the light absorbing layer on the side opposite to the observation side of the element, it is possible to display the selective reflection color in the planar state and to display black in the focal conic state. . In addition, by setting the selective reflection wavelength in the infrared light region and providing a light absorbing layer on the side opposite to the observation side of the element, light in the infrared light region is reflected in the planar state, but the wavelength in the visible light region is reflected. Is transmitted, so that a black display can be performed, and a white display due to scattering in the focal conic state can be realized.
[0028]
In the liquid crystal display elements 100R and 100L in which the respective display layers 111R, 111G and 111B are stacked, the blue display layer 111B and the green display layer 111G are in a transparent state in which liquid crystals are in a focal conic arrangement, and the red display layer 111R is in a planar arrangement of liquid crystals. By performing the selective reflection state as described above, red display can be performed. Further, yellow display is performed by setting the blue display layer 111B in a transparent state in which liquid crystals are in a focal conic arrangement, and setting the green display layer 111G and the red display layer 111R in a selective reflection state in which liquid crystals are in a planar arrangement. Can be. Similarly, red, green, blue, white, cyan, magenta, yellow, and black can be displayed by appropriately selecting the state of each display layer between a transparent state and a selective reflection state. Furthermore, by selecting an intermediate selective reflection state as the state of each of the display layers 111R, 111G, and 111B, display of an intermediate color becomes possible, and it can be used as a full-color display element.
[0029]
The liquid crystal 116 preferably exhibits a cholesteric liquid crystal phase at room temperature. In particular, a chiral nematic liquid crystal obtained by adding a sufficient amount of a chiral material to exhibit a cholesteric liquid crystal phase to a nematic liquid crystal is preferable.
[0030]
A chiral material is an additive that has the effect of twisting the molecules of a nematic liquid crystal when added to the nematic liquid crystal. By adding a chiral material to a nematic liquid crystal, a helical structure of liquid crystal molecules having a predetermined twist interval is generated, thereby exhibiting a cholesteric liquid crystal phase.
[0031]
Further, by using this kind of chiral nematic liquid crystal as a display medium, it is possible to obtain a liquid crystal display panel having a so-called memory property that can maintain a display state semipermanently in a state where no voltage is applied. Therefore, the image can be continuously displayed while the CPU of the control unit 50 (described later) is in the sleep mode.
[0032]
Note that the liquid crystal display layer is not necessarily limited to this configuration, and may be a resin structure having a weir shape or a structure in which the resin structure is omitted. Also, a liquid crystal display is formed as a so-called polymer-dispersed liquid crystal composite film in which liquid crystal is dispersed in a conventionally known polymer three-dimensional network structure or a polymer three-dimensional network structure is formed in liquid crystal. It is also possible to configure the layers.
[0033]
FIG. 3 is a diagram illustrating functional blocks of the liquid crystal display device 10.
[0034]
The pixel configuration of the liquid crystal display elements 100R and 100L is represented by a matrix of a plurality of scanning electrodes R1, R2 to Rm and signal electrodes C1, C2 to Cn (m and n are natural numbers). These scan electrodes R1, R2 to Rm are connected to output terminals of the scan drive ICs 131R, 131L, and the signal electrodes C1, C2 to Cn are connected to output terminals of the signal drive ICs 132R, 132L.
[0035]
The scan driving ICs 131R and 131L output a selection signal to predetermined ones of the scanning electrodes R1 and R2 to Rm to be in a selected state, and output a non-selection signal to other electrodes to be in a non-selected state. The scan drive ICs 131R and 131L sequentially apply a selection signal to each of the scan electrodes R1, R2 to Rm while switching the electrodes at predetermined time intervals. On the other hand, the signal driving ICs 132R and 132L simultaneously output signals corresponding to image data to the signal electrodes C1, C2 to Cn in order to rewrite the pixels on the selected scanning electrodes R1, R2 to Rm. For example, when the scanning electrode Ra is selected (a is a natural number satisfying a ≦ m), the pixels LRa-C1 to LRa-Cn at the intersections of the scanning electrode Ra and the signal electrodes C1, C2 to Cn are simultaneously rewritten. It is. Thereby, the voltage difference between the scanning electrode and the signal electrode in each pixel becomes the rewrite voltage of the pixel, and each pixel is rewritten according to the rewrite voltage.
[0036]
Image rewriting is performed by sequentially selecting all scanning lines. In the case of partially rewriting, only a specific scanning line may be sequentially selected so as to include a portion to be rewritten. As a result, only necessary portions can be rewritten in a short time.
[0037]
The control unit 50 includes a central processing unit (CPU) 51 for performing overall control, an LCD controller 52 for controlling the above-described scanning drive IC and signal drive IC, an image processing unit 53 for performing various processes on image data, and It comprises an image memory 54 for storing, a ROM 55 for storing a control program and various data, and a RAM 56 for storing various data.
[0038]
The CPU 51 includes operation panels 20R and 20L, temperature sensors 31R and 31L, speakers 32R and 32L, a communication unit 61, a reader / writer 62 of the recording medium 35, a touch panel 63, and front lights 64R and 64L. It is connected. These devices transmit and receive necessary signals to and from the CPU 51 and are controlled by the CPU 51.
[0039]
The display window 41 and the timer 42 described above are connected to the CPU 51.
[0040]
The timer 42 counts the elapse of a predetermined time from a predetermined timing, and stops the operation by counting up. In addition, the timer 42 has five timers tm1 to tm5 (detailed later) which operate independently.
[0041]
Power is supplied from the power supply unit 70 to the drive ICs 131R, 131L, 132R, and 132L. The power supply unit 70 includes a main battery 71 and a spare battery 72 for performing necessary processing when the capacity of the main battery 71 runs out. The main battery 71 uses a battery such as a lithium secondary battery or a dry battery, and is detachable by an operator by opening a battery cover (not shown) of the housing 12.
[0042]
The power supply section 70 is connected to a power supply switching circuit 73 for selecting a battery (main battery 71, spare battery 72) to be used in accordance with an instruction from the CPU 51. The battery checker 43 for measuring the remaining capacity of the battery of the power supply unit 70 is connected to the CPU 51.
[0043]
The LCD controller 52 controls the driving ICs 131R, 131L, 132R, and 132L based on the image data stored in the image memory 54, and sequentially applies a voltage between the scanning electrodes and the signal electrodes of the liquid crystal display elements 100R and 100L. Write the image.
[0044]
The CPU 51 acquires the environmental temperature information from the temperature sensors 31R and 31L and temporarily stores the information in the RAM 56. Further, the CPU 51 has a sleep mode, and shifts to the sleep mode when necessary processing such as updating of the screen, communication with the outside, access to the recording medium 35, and the like is completed. In the sleep mode, only the minimum necessary functions such as operation detection of the operation panels 20R and 20L are executed, and other functions are stopped to reduce energy consumption.
[0045]
FIG. 4 is a diagram for explaining a connection relationship between a liquid crystal display element and a drive IC (drive circuit).
[0046]
The scanning drive ICs 131R and 131L are provided in common for the display layers 111R, 111G and 111B, and the signal drive ICs 132R and 132L are provided for each display layer. Here, if the drive voltages of the respective display layers are substantially equal, it is preferable to use the scan drive ICs 131R and 131L in common for cost reduction. Of course, the scanning drive ICs 131R and 131L may be provided for each display layer, and the signal drive ICs 132R and 132L may be provided commonly for each display layer.
[0047]
<Operation of liquid crystal display device 10>
FIG. 5 is a flowchart illustrating a basic operation of the liquid crystal display device 10. This flowchart is a main routine showing a control procedure of the liquid crystal display device 10 executed by the CPU 51.
[0048]
When the apparatus is started by mounting a battery, connecting to a commercial power supply, or the like, initialization such as initialization of the RAM 56, setting of default values to registers / flags, and resetting of the timer 42 is performed (step S1). Then, the processing of steps S2 to S10 is sequentially performed. When waking up from the sleep state, the process starts from step S2.
[0049]
In step S2, an input process is performed. In this input process, the operation status of the operation panels 20R and 20L and the touch panel 63 is grasped.
[0050]
In step S3, a temperature detection process is performed. In this temperature detection process, the environmental temperature around the liquid crystal display panel 11 is detected by the temperature sensors 31R and 31L.
[0051]
In steps S4 to S9, a battery check process, an update availability determination process, a burn-in prevention process, a screen update process, a timer correction process, and a redisplay process are sequentially performed (described in detail later).
[0052]
In step S10, other processing, for example, communication processing, exchange of information with the storage medium 35, audio processing, and front light control are performed.
[0053]
In step S11, it is determined whether to shift to the sleep mode. Here, for example, when a predetermined time has elapsed without operation of the liquid crystal display device 10, the mode is shifted to the sleep mode for power saving. Here, when shifting to the sleep mode, the process proceeds to step S12, and when not shifting to the sleep mode, the process returns to step S2.
[0054]
In step S12, the wake-up timer of the timer 42 is reset and started.
[0055]
In step S13, a sleep process is performed. During this sleep, the CPU 51 is set to the power saving mode by operating only the minimum necessary parts of the CPU 51 and turning off other parts, or by lowering the operation clock. The power to each unit is turned off immediately after the execution of the processing except for the necessary ones. During the sleep, the timer 42 is operable and continues to count necessary items.
[0056]
Even during sleep, the liquid crystal display device 10 wakes up periodically or in response to an event, and executes necessary processing, triggered by count-up of the wake-up timer started in step S12, operation by the operator, or the like. Then, by periodically waking up, the temperature sensor detects the environmental temperature around the liquid crystal display panel 11. Thus, the environmental temperature is monitored substantially constantly.
[0057]
In the operation of the liquid crystal display device 10 described above, the drive circuit is turned off when one frame draws a screen, and immediately goes into a halt state to save power. Even when the drive circuit is in a halt state, the display is maintained because the liquid crystal display panel 11 has a memory property capable of maintaining a display without applying a voltage.
[0058]
FIG. 6 is a flowchart illustrating a battery check process corresponding to step S4 described above.
[0059]
In step S11, it is determined whether or not the battery is mounted on the housing 12. Here, when the battery is mounted, the process proceeds to step S12, and when the battery is not mounted, the process proceeds to step S16.
[0060]
In step S12, the remaining capacity of the battery is measured by the battery checker 43.
[0061]
In step S13, it is determined whether the battery capacity measured in step S12 is sufficient. Here, if the battery capacity is sufficient, the process proceeds to step S14, and if not, the process proceeds to step S16.
[0062]
In step S14, it is determined whether the timer tm5 is operating. The timer tm5 counts the elapsed time from the time when the remaining capacity of the main battery 71 reaches the lower limit (battery exhausted) or when the battery case is opened and the battery is removed from the housing 12. In the burn-in prevention process described later, when the count-up of the timer tm5 is detected, the screen is updated to the burn-in prevention image.
[0063]
In this step S14, when the timer tm5 is operating, the process proceeds to step S15, and when it is not operating (count up), the process proceeds to step S4.
[0064]
In step S15, the timer tm5 is stopped and reset.
[0065]
In step S16, similarly to step S14, it is determined whether the timer tm5 is operating. Here, if the timer tm5 is operating, the process proceeds to step S4, and if not, the process proceeds to step S17.
[0066]
In step S17, the timer tm5 is started.
[0067]
In step S18, a warning is issued, for example, by issuing a warning sound from the speakers 32R and 32L.
[0068]
In the above-described battery check process, a warning sound is generated when the battery cover is opened and the main battery is removed from the housing 12, or when the remaining battery capacity falls below the lower limit value at which the screen can be updated. In addition to notifying the operator of the battery exhaustion / disconnection, the timer tm5 counts the elapsed time from that time. Thus, it is possible to prevent the screen of the liquid crystal display panel 11 from being updated to the screen for preventing burn-in due to running out of the battery.
[0069]
FIG. 7 is a flowchart illustrating the update availability determination processing corresponding to step S5 described above.
[0070]
In step S21, it is determined whether the battery in the power supply unit 70 is OK. With this determination, it is possible to prevent the liquid crystal display device 10 from going down without updating the screen when the main battery 71 has been removed or the battery has run out of capacity.
[0071]
If the battery is OK in step S21, the process proceeds to step S22, and if not, the process proceeds to step S23.
[0072]
In step S22, it is determined whether the environmental temperature detected by the temperature sensors 31R and 31L is equal to or higher than the threshold temperature TM. By this determination, when the temperature reaches a threshold temperature TM (for example, 60 degrees) in a high temperature range in which irreversible image sticking occurs even in a short time display, a screen for an image sticking prevention image in image sticking prevention processing described later. Normal screen update operations other than update can be prohibited.
[0073]
If the environmental temperature is equal to or higher than the threshold temperature TM in step S22, the process proceeds to step S23. If the environmental temperature is lower than the threshold temperature TM, the process proceeds to step S25.
[0074]
In step S23, the display window PRCT is turned on.
[0075]
In step S24, normal updating of the screen on the liquid crystal display panel 11 is prohibited. In other words, as long as the environmental temperature is equal to or higher than the threshold temperature TM, a new normal screen update operation (for example, page feed by the user) other than the screen update to the image sticking prevention image in the image sticking prevention processing described later is prohibited.
[0076]
In step S25, it is determined whether the environmental temperature detected by the temperature sensors 31R and 31L has changed below the threshold temperature TM. Here, if the temperature has changed below the threshold temperature TM, the process proceeds to step 26; otherwise, the process proceeds to step S27.
[0077]
In step S26, the timer tm4 is reset and started. This timer tm4 counts the elapsed time from the time when the environmental temperature becomes lower than the threshold temperature TM.
[0078]
In step S27, it is determined whether the housings 12R and 12L are open. By this determination, it is possible to prohibit unnecessary normal screen updating when the housing is closed.
[0079]
If the case is open in step S27, the process proceeds to step S28; otherwise, the process proceeds to step S24.
[0080]
In step S28, it is determined whether a sufficient time has elapsed since the environmental temperature detected by the temperature sensors 31R and 31L has become lower than the threshold temperature TM. This elapsed time is detected by the timer tm4 started in step S26.
[0081]
In step S28, when the environmental temperature is lower than TM for a sufficient time with the housing 12 opened, the display of the display window PRCT is turned off (step S29), and the image update to the liquid crystal display panel 11 is prohibited. Is released and the normal update operation is permitted (step S30).
[0082]
Hereinafter, four types of image sticking prevention processes 1 to 4 corresponding to the above step S6 will be described. For easy understanding, FIG. 8A shows the magnitude relationship between the temperatures TC, TL, and TM used in the following description, and FIG. 8B shows the magnitude relationship between the times t1 to t4.
[0083]
FIG. 9 is a flowchart illustrating the burn-in prevention process 1.
[0084]
In step S31, it is determined whether the flag is 0. Here, when the flag is 0, the process proceeds to step S32, and when the flag is not 0, the process proceeds to step S7.
[0085]
In step S32, it is determined whether or not the environmental temperature around the liquid crystal display panels 11R and 11L monitored by the temperature sensors 31R and 31L is equal to or higher than a predetermined temperature TC (for example, 30 degrees) slightly higher than room temperature. Here, when the temperature is higher than the predetermined temperature TC, the process proceeds to step S33, and when it is lower, the process proceeds to step S7.
[0086]
In step S33, a temperature change per unit time is measured based on the information on the environmental temperature detected by the temperature sensors 31R and 31L, and it is determined whether a temperature rise of a certain value or more (for example, 5 degrees / min or more) is detected. . Here, when a temperature rise equal to or more than a certain value is detected, the process proceeds to step S40, and when not detected, the process proceeds to step S34.
[0087]
In step S34, it is determined whether or not the environmental temperature detected by the temperature sensors 31R and 31L is equal to or higher than a threshold temperature (second temperature) TM. According to this determination, when the environmental temperature has reached the threshold temperature TM, the drive IC (drive circuit) is activated, and the screen can be immediately updated to the image for preventing burn-in in step S40. This can prevent irreversible seizure from occurring when the panel is exposed to a severe high-temperature environment (for example, when the panel is left in a car in the middle of summer).
[0088]
If the environmental temperature is equal to or higher than the threshold temperature TM in step S34, the process proceeds to step S40; otherwise, the process proceeds to step S35.
[0089]
In step S35, it is determined whether the environmental temperature detected by the temperature sensors 31R and 31L is equal to or higher than a threshold temperature (first temperature) TL. According to this determination, if the environmental temperature is lower than the threshold temperature TM for a short period of time, no image sticking occurs, or even if image sticking occurs temporarily, the image is erased and left for a certain period of time. When the temperature is equal to or higher than the threshold temperature TL (for example, 40 degrees) within a temperature range in which image sticking can be eliminated, the image can be updated to an image sticking prevention by a stepwise procedure.
[0090]
If the environmental temperature is equal to or higher than the threshold temperature TL in step S35, the process proceeds to step S36; otherwise, the process proceeds to step S37.
[0091]
In step S36, it is determined whether the timer tm1 is operating. The timer tm1 cumulatively counts the time when the environmental temperature measured by the temperature sensor 31 is between the threshold temperatures TL to TM. The timer tm1 prevents the count value from being reset when the environmental temperature temporarily drops to a temperature lower than the threshold temperature TL, and can more reliably prevent image sticking.
[0092]
In step S36, if the timer tm1 is operating, the process proceeds to step S39. On the other hand, if not in operation, the process proceeds to step S38, and the timer tm1 is started.
[0093]
In step S37, the timer tm1 is stopped.
[0094]
In step S39, it is determined whether a predetermined time t2 (for example, 20 minutes) has elapsed by the timer tm1. According to this determination, when the environment temperature T is in the range of TL ≦ T <TM and the irreversible burn-in does not occur and the predetermined period t2 has elapsed, and the screen display is not updated, the driving circuit is determined in step S40. Is activated, and the screen can be updated to the image for preventing burn-in.
[0095]
If the predetermined time t2 has elapsed in step S39, the process proceeds to step S40, and if not, the process proceeds to step S44.
[0096]
In step S40, the screen is automatically updated to an image for preventing burn-in (for example, a uniform black in the entire surface, that is, a focal conic state).
[0097]
In step S41, the display of the display window TEMP is turned on. That is, a mark indicating that the image for burn-in prevention has been displayed is displayed.
[0098]
In step S42, 1 is substituted for the flag.
[0099]
In step S43, the timer tm1 is reset.
[0100]
In step S44, it is determined by the timer tm1 whether a fixed period tl (for example, 10 minutes) shorter than the time t2 has elapsed. With this determination, when the environmental temperature is equal to or higher than the threshold temperature TL and the predetermined period t1 has elapsed, a warning can be issued when the screen is not updated.
[0101]
In step S45, a warning such as a warning sound is issued from the speakers 32R and 32L. Thus, the operator can be notified in advance before the burn-in prevention function is activated, and the image can be prevented from being erased against the operator's intention.
[0102]
By the above-described image sticking prevention processing 1, image display in a temperature range where irreversible image sticking occurs can be avoided beforehand, and image sticking can be effectively prevented.
[0103]
FIG. 10 is a flowchart illustrating the burn-in prevention process 2.
[0104]
In step S51, it is determined whether the flag is 0. Here, if the flag is 0, the process proceeds to step S52; otherwise, the process proceeds to step S7.
[0105]
In step S52, it is determined whether the housing 12 has been closed. Here, if the case 12 is closed, that is, if the position is to cover the liquid crystal display panel 11, the process proceeds to step S52. If not, the process proceeds to step S7.
[0106]
In step S53, 2 is substituted for the flag.
[0107]
In step S54, as in step S40, the drive circuit is activated to update the screen of the liquid crystal display panel 11 to a burn-in prevention image. Thus, regardless of the environmental temperature, if the screen is updated to the image for preventing burn-in when the necessity of display becomes low, the occurrence of burn-in can be prevented beforehand.
[0108]
In step S55, the timer tm1 is stopped and reset.
[0109]
FIG. 11 is a flowchart illustrating the burn-in prevention process 3.
[0110]
In step S61, it is determined whether the flag is 0. Here, when the flag is 0, the process proceeds to step S62, and when the flag is not 0, the process proceeds to step S7.
[0111]
In step S62, it is determined whether a predetermined time t3 (for example, one hour) has elapsed since the previous image display on the liquid crystal display panel 11. This elapsed time is counted by a timer tm3 that counts the time since the previous image update. Here, if the predetermined time t3 has elapsed, the process proceeds to step S63, and if not, the process proceeds to step S7.
[0112]
In the step S63, 3 is substituted for the flag.
[0113]
In step S64, the screen of the liquid crystal display panel 11 is updated to the image for preventing burn-in, as in step S40. That is, when the elapsed time from the screen update measured by the timer tm3 (time measuring means) reaches the predetermined time t3, the drive circuit in the pause state is activated, and the image for preventing image sticking is displayed on the liquid crystal display panel 11. Write. Thus, regardless of the environmental temperature, if the screen is updated to the image for preventing burn-in when the necessity of display becomes low, the occurrence of burn-in can be prevented beforehand.
[0114]
In step S65, the timer tm1 is stopped and reset.
[0115]
FIG. 12 is a flowchart illustrating the burn-in prevention processing 4.
[0116]
In step S71, it is determined whether the flag is 0. Here, if the flag is 0, the process proceeds to step S72; otherwise, the process proceeds to step S7.
[0117]
In step S72, it is determined whether or not the above-described timer tm5 has counted up. Here, if the timer tm5 has counted up, the process proceeds to step S73; otherwise, the process proceeds to step S7.
[0118]
In step S73, 4 is substituted for the flag.
[0119]
In step S74, the image is updated to the image for preventing image sticking on the liquid crystal display panels 11R and 11L as in step S40.
[0120]
In step S75, the timer tm5 is stopped and reset.
[0121]
When the liquid crystal display device is portable as in this embodiment, a battery is usually used as a power source. Therefore, when the battery is removed from the liquid crystal display device 10 or when the remaining capacity of the battery is lower than the lower limit at which the screen can be updated, updating to the image for preventing burn-in becomes impossible. Therefore, by executing the above-described burn-in prevention processing 4, in these cases, the screen is automatically updated to the burn-in prevention image to prevent the occurrence of burn-in.
[0122]
In the above-mentioned burn-in prevention process 4, in consideration of a temporary battery voltage drop due to battery replacement by the operator or taking the battery outdoors, etc., the burn-in is performed under the condition that the timer tm5 detects the elapse of a predetermined time. Although the update to the prevention image is executed, the update to the burn-in prevention image may be executed immediately when the battery is detached or the battery runs out according to the application.
[0123]
FIG. 13 is a flowchart illustrating a screen update process corresponding to step S7 described above.
[0124]
In step S81, it is determined whether or not there is a screen update request due to an operation of the page feed key by the operator or the like. Here, when there is an update request, the process proceeds to step S82, and when there is no update request, the process proceeds to step S8.
[0125]
In step S82, it is determined whether screen updating is permitted. Here, if the screen update is permitted, the process proceeds to step S83, and if not, the process proceeds to step S8.
[0126]
In step S83, it is determined whether the environmental temperature detected by the temperature sensors 31R and 31L is equal to or higher than the threshold temperature TL. If the temperature is equal to or higher than the threshold temperature TL, the process proceeds to step S84. If the temperature is lower than the threshold temperature TL, the process proceeds to step S86.
[0127]
Next, a correction value relating to display on the liquid crystal display panel 11 is calculated (step S84), and correction is performed so that the liquid crystal display panel 11 has low contrast (step S85). In the contrast adjustment, the image data itself may be corrected, or the driving conditions such as the voltage value and the pulse width of the driving voltage pulse may be corrected.
[0128]
In step S86, the screen is updated on the liquid crystal display panel 11. In this case, if the environmental temperature exceeds the threshold temperature TL, the display is performed with the contrast lowered according to the environmental temperature. Thereby, the influence of image sticking due to drawing in an environment where image sticking is relatively likely to occur can be reduced.
[0129]
In step S87, the timer tm3 for determining execution of the burn-in prevention process 3 is reset and restarted.
[0130]
FIG. 14 is a flowchart illustrating a timer correction process corresponding to step S8 described above.
[0131]
In step S91, the current environmental temperature detected by the temperature sensors 31R and 31L is compared with the previous environmental temperature.
[0132]
In step S92, as a result of the comparison in step S91, it is determined whether or not there is a temperature rise. Here, when there is a temperature rise, the process proceeds to step S93, and when there is no temperature rise, the process proceeds to step S9.
[0133]
In step S93, each addition / subtraction value for the timers tm1 to tm5 is calculated. As for the timer tm1, a correction value for subtracting the count value according to the temperature rise is obtained. As a result, the time required for updating the screen of the liquid crystal display panel to the image for preventing burn-in can be reduced, and the effect of burn-in can be reduced. For the timers tm2 to tm5, a correction value for adding the count value according to the temperature rise is obtained.
[0134]
In step S94, each of the timers tm1 to tm5 is corrected based on the correction value (addition / subtraction value) calculated in step S93.
[0135]
FIG. 15 is a flowchart illustrating the redisplay processing corresponding to step S9 described above.
[0136]
In step S101, it is determined whether the housing 12 is open. Here, if the case 12 is open, the process proceeds to step S12; otherwise, the process proceeds to step S10.
[0137]
In step S102, it is determined whether the flag is 1. If the flag is 1, the process proceeds to step S103. If the flag is not 1, the process proceeds to step S108.
[0138]
In step S103, it is determined whether the environmental temperature detected by the temperature sensors 31R and 31L is lower than the threshold temperature TL. If the temperature is lower than the threshold temperature TL, the process proceeds to step S104, and if the temperature is higher, the process proceeds to step S10.
[0139]
In step S104, it is determined whether the timer tm2 is operating. Here, if the timer tm2 is operating, the process proceeds to step S105, and if not, the process proceeds to step S106.
[0140]
In step S105, the timer tm2 is reset and restarted.
[0141]
In step S106, it is determined whether or not time t4 has elapsed from the start of measurement by the timer tm2. Here, if the time t4 has elapsed, the process proceeds to step S107, and if not, the process proceeds to step S10.
[0142]
In step S107, the display of the display window TEMP is turned off.
[0143]
In step S108, it is determined whether the flag is 2. Here, when the flag is 2, the process proceeds to step S109, and when the flag is not 2, the process proceeds to step S10.
[0144]
In step S109, it is determined whether or not the screen update is permitted. Here, when the screen update is permitted, the process proceeds to step S110, and when the screen update is not permitted, the process proceeds to step S10.
[0145]
In step S110, the image displayed on the liquid crystal display panel 11 is updated to the previous image. That is, the image displayed before updating to the image for preventing burn-in is displayed again on the liquid crystal display panel 11.
[0146]
It may be inconvenient if the image is automatically updated to the burn-in prevention image against the intention of the user. Therefore, if the increase in the environmental temperature is temporary, the temperature is returned to the temperature range where image sticking does not occur, and then the display image is automatically returned to the original display image in step S110. Thereby, for example, even if there is a temporary rise in temperature when the user is absent, seizure is avoided, and no inconvenience occurs when the user returns.
[0147]
When the housing 12 is closed, an image for preventing burn-in is displayed in the burn-in prevention processing 2 described above. However, when the housing 12 is opened, the update permission state is set. In step S110, the display image is automatically returned to the original display image. Thereby, seizure can be prevented, and convenience for the user is improved.
[0148]
In step S111, 0 is substituted for the flag.
[0149]
In step S112, the timer tm3 is reset and restarted.
[0150]
According to the operation of the image display device 10 described above, when there is a risk of burn-in, the screen of the liquid crystal display panel 11 is updated to the image for preventing burn-in, so that burn-in of the liquid crystal panel can be suppressed.
[0151]
Examples of the image for preventing image sticking include the following examples.
[0152]
{Circle around (1)} All pixels are in a focal conic state (transparent state). If the background is black, the display is black. As a result, image sticking does not occur even when exposed to a high temperature environment, and the contrast of the screen is not easily reduced.
[0153]
{Circle around (2)} All pixels are in a planar state (selective reflection state). As a result, image sticking does not occur even when exposed to a high-temperature environment, and the brightness of the screen is not easily reduced.
[0154]
{Circle around (3)} A halftone display state in which all pixels have the same reflectance. As a result, even when exposed to a high-temperature environment, image sticking does not occur, and the contrast and brightness of the screen are relatively low.
[0155]
{Circle around (4)} Based on the data of the original image displayed up to that point, an image having a lower contrast than the original image is displayed. As a result, the display is not erased, so that it is difficult to give the operator any inconvenience.
[0156]
(5) When the liquid crystal display panel is of a laminated type, display is performed on at least one liquid crystal display layer in which image sticking is less likely to occur than in other layers, and the other layers are set to a low contrast state. Burning is also suppressed by setting all pixels to be uniform. For example, in the case of a liquid crystal display panel in which three liquid crystal layers of a blue display layer, a green display layer, and a red display layer are stacked, the red display layer is generally burnt in compared with the blue display layer and the green display layer according to the study of the present inventor. Has been found to be less likely to occur. Therefore, the blue and green display layers are preferably set to have the same reflectance (for example, in a focal conic state) for all pixels, and the red display layer may continue to display. Thereby, since the display is performed on at least one display layer, the observer can grasp the display content.
[0157]
In addition, the liquid crystal display device 10 opens and closes a double-faced housing provided with a plurality of screens, but opens and closes a lid member as a protective cover having no liquid crystal display panel with respect to one screen. It may be something. In this case, when the lid member is closed, the screen is updated to the image for preventing burn-in.
[0158]
In the liquid crystal display device 10, the image may be updated to a burn-in prevention image after a predetermined time elapses after the housing is closed. Thus, even if the housing is opened again immediately after closing the housing, no inconvenience occurs.
[0159]
When the image is updated to the burn-in prevention image after the lapse of the predetermined time, the elapsed time from the time when the threshold temperature is exceeded may be calculated to simplify the control. Alternatively, it may be calculated by a value obtained by integrating only during the period of the operation. This increases accuracy.
[0160]
Further, the warning in the liquid crystal display device 10 is not limited to the sound emitted from the speaker, but may be a message display on the liquid crystal display panel, a warning lamp provided to turn on the device, or a vibration member provided to vibrate the device. For example, a method such as the following may be used.
[0161]
Further, in the liquid crystal display device 10, a recovery process such as voltage application may be performed, and then the image may be updated to a burn-in prevention image. Thereby, the occurrence of seizure can be further suppressed.
[0162]
Further, in the liquid crystal display device 10, an execution mode in which the image is updated to the burn-in prevention image and a non-execution mode in which the image is not executed may be selectable.
[0163]
Further, in the liquid crystal display device 10, the elapsed time from the final operation is counted, and if the burn-in is within a predetermined time in which the burn-in is not a problem, the time until the image is updated to the burn-in prevention image may be delayed. good.
[0164]
<Second embodiment>
<Main configuration of liquid crystal display device>
FIG. 16 is a front view illustrating an appearance of a liquid crystal display device 80 according to the second embodiment of the present invention.
[0165]
The liquid crystal display device 80 is configured as an advertising board type display device, and has a multi-screen type display unit in which four panels 81 (81a to 81d) are arranged. These panels 81a to 81d are individually independent, can be displayed separately, and can be displayed as a single screen with a plurality of panels.
[0166]
FIG. 17 is a diagram showing functional blocks of the liquid crystal display device 80.
[0167]
Each of the panels 81 includes a liquid crystal display panel 82 (82a to 82d) having a configuration similar to that of the first embodiment, a touch panel 83 (83a to 83d), and a temperature sensor 84.
[0168]
The liquid crystal display device 80 includes a driving circuit 85 for driving each liquid crystal display panel 82 and a controller 86 for controlling each touch panel 83.
[0169]
The liquid crystal display device 80 includes a CPU 90 electrically connected to the drive circuit 85 and the controller 86, and a RAM 91, a ROM 92, a timer 93, and a communication circuit 94 connected to the CPU 90.
[0170]
Since the liquid crystal display device 80 performs display to an unspecified number of observers as compared with the liquid crystal display device 10 of the first embodiment used for personal use, it is required to maintain the display as much as possible. From such a point of view, the liquid crystal display device 80 performs control to gradually reduce the display quality and to continue displaying as much as possible. The operation of the liquid crystal display device 80 will be described below.
[0171]
<Operation of liquid crystal display device 80>
The liquid crystal display device 80 performs various processes according to the environmental temperature measured by the temperature sensor 84. Hereinafter, the operation of the liquid crystal display device 80 for each temperature will be described with reference to FIG.
[0172]
(1) Room temperature
The timer 93 updates the image periodically (for example, at 10 minute intervals). For example, on each panel 81 of the liquid crystal display device 80, the display is switched as shown in FIG. 19 (a) → FIG. 19 (b) → FIG. 19 (c) → FIG. 19 (d).
[0173]
In this case, when there is an operation on the touch panel 83, a display corresponding to the operation content is performed. When a predetermined time has elapsed from the end of the operation, the screen returns to the initial screen. This initial screen will be updated periodically.
[0174]
Note that a human detection sensor may be provided so that the display is continued while a human is present. In addition, from the viewpoint of reducing image sticking as much as possible, the image that was displayed with high density by updating the display was reduced to low density, and the image that was displayed with low density was set to high density. Data may be used.
[0175]
(2) TL1
When the environmental temperature detected by the temperature sensor 84 reaches the temperature TL1 higher than the normal temperature, the update frequency is increased (for example, at intervals of 9 minutes). Here, the update interval may be shortened according to the temperature rise.
[0176]
(3) TL2
If the update frequency is too short, it may cause inconvenience to the observer. Therefore, when the environmental temperature reaches TL2, the screen of the liquid crystal display panel 82 is rewritten based on the same data as the currently displayed image data. Execute The execution of this rewriting resets the screen once, which is effective in reducing burn-in.
[0177]
(4) TL3
When the environmental temperature exceeds TL3, the same image is rewritten by shifting pixels. For example, rewriting is performed such that the display state G2 is shifted by one dot to the right from the display state G1 shown in FIG. Thereby, the effect of preventing seizure can be further enhanced.
[0178]
When rewriting is performed by shifting the pixels, it is preferable to simply shift the image by a predetermined number of dots vertically, horizontally, diagonally, or the like, or change the display magnification of the entire image (reduce or enlarge) to redisplay. Alternatively, the image may be reduced and then repositioned at predetermined time intervals to be displayed again.
[0179]
(5) TL4
When the environmental temperature reaches TL4, the frequency of rewriting to the liquid crystal display panel 82 is increased (for example, every two minutes → one minute). Thereby, seizure is further alleviated.
[0180]
(6) TL5
If the environmental temperature reaches a temperature TL5 at which the occurrence of image sticking cannot be sufficiently suppressed by merely updating or rewriting another image, the display of some panels is erased (that is, the image is updated to an image for preventing image sticking). The display is continued only on the remaining panels.
[0181]
For example, as shown in FIG. 21 (a), when an image is displayed on all the panels 81a to 81d and the environmental temperature reaches the temperature TL5, the panel 81a shown in FIG. ), And the screen is partially stopped in the order of the panel 81d shown in FIG. 21D and the panel 81b shown in FIG. This alleviates the burn-in of the pause panel.
[0182]
(7) TL6
When the environmental temperature further rises and reaches the temperature TL6, the pause screen area is enlarged. For example, from the state in which one panel 81a shown in FIG. 22A is suspended, the state in which two panels 81c and 81d shown in FIG. 22B are suspended, and the state shown in FIG. The state shifts to a state where the panels 81a, 81b, 81d are stopped.
[0183]
By eliminating the display on the plurality of panels as described above, the effect of alleviating image sticking can be enhanced.
[0184]
(8) TL7
If the rest screen area is too large, the viewer may be inconvenienced. Therefore, when the environmental temperature reaches the temperature TL7, the display itself is set to have a low contrast. That is, the display of the liquid crystal display panel 81 is updated with a low contrast by adjusting the contrast in the drive circuit 85. For example, the state is shifted from the state shown in FIG. 23A to the low contrast state shown in FIG. Thereby, seizure can be further reduced.
[0185]
(9) TL8
When the environmental temperature further rises to reach the temperature TL8, the degree of decrease in contrast is increased.
[0186]
(10) TL9
If the contrast is too low, the viewer may be inconvenienced. Therefore, when the ambient temperature reaches the temperature TL9, the display is temporarily erased. For example, the state shown in FIG. 24A is temporarily shifted to a state in which all the panels 81a to 81d are stopped as shown in FIG. Such intermittent driving can further reduce seizure.
[0187]
(11) TL10
When the environmental temperature further rises and reaches the temperature TL10, the time for temporarily erasing the display is lengthened, and the pause period is extended.
[0188]
(12) TM
When the environmental temperature exceeds the temperature TM, the display on the entire screen is erased to protect the liquid crystal display panel 82.
[0189]
The above-described operation of the liquid crystal display device 80 controls the liquid crystal display panel 82 to prevent image sticking stepwise according to the environmental temperature. Therefore, the image sticking of the liquid crystal display panel 82 is effectively suppressed while maintaining the display as much as possible. it can.
[0190]
In the liquid crystal display device 80, (1) display update frequency, (2) rewriting and its frequency, (3) pixel shift display, (4) partial screen pause, (5) low contrast display, (6) Although burn-in prevention is performed stepwise in the order of temporary suspension of the screen, the order of these items may be changed as appropriate, or a plurality of items may be executed in parallel. In addition, any of these items may not be performed.
[0191]
Further, in order to more effectively prevent image sticking, a sensor for detecting a human body in front of the display panel is provided in the liquid crystal display device 80, and when the sensor stops detecting a human body, the screen is converted to an image for image sticking prevention. It may be updated.
[0192]
As for the partial pause of the screen in the liquid crystal display panel 82, a partial pause area may be provided in one liquid crystal display panel 82 by processing image data or the like.
[0193]
When the liquid crystal display panel 82 is of a laminated type, display is performed on at least one liquid crystal display layer in which image sticking is unlikely to occur, and the other layers are set in a low contrast state or in a state where all pixels are uniform. Or a mode of sequentially switching between a liquid crystal display layer for setting a low contrast state or a uniform state for all pixels and a liquid crystal display layer for performing display is added to the above items (1) to (6). Is also good.
[0194]
<Modification>
The specific embodiments described above include inventions having the following configurations.
[0195]
(1) In the liquid crystal display device according to claim 2, the control unit prohibits a new update of the screen of the liquid crystal display panel as long as the environmental temperature detected by the temperature detection unit is equal to or higher than a predetermined temperature. A liquid crystal display device having means for controlling the driving circuit so as to perform the operation.
[0196]
As a result, image sticking of the liquid crystal panel can be effectively suppressed.
[0197]
(2) The liquid crystal display device according to claim 1, further comprising a warning unit for giving a warning before updating the image for preventing burn-in on the liquid crystal display panel.
[0198]
Thus, the user can be alerted to the burn-in of the liquid crystal panel.
[0199]
(3) In the liquid crystal display device according to (2), the temperature detecting means continues to detect the environmental temperature even after the environmental temperature becomes equal to or higher than a predetermined temperature, and the control means performs the temperature detection. A liquid crystal display device comprising: a timer correction unit configured to reduce a time required for updating a screen of the liquid crystal display panel to the image for preventing burn-in according to an increase in the environmental temperature detected by the unit.
[0200]
As a result, image sticking of the liquid crystal panel can be effectively suppressed.
[0201]
(4) In the liquid crystal display device according to claim 1, the temperature detecting means continues to detect the environmental temperature even after the environmental temperature becomes equal to or higher than a predetermined temperature, and the control means performs the temperature detection. When the environmental temperature detected by the means is equal to or lower than a predetermined temperature, the driving circuit is activated to re-display the image displayed before updating to the image for preventing burn-in on the liquid crystal display panel. A liquid crystal display device comprising means for displaying.
[0202]
As a result, user convenience is improved.
[0203]
(5) In the liquid crystal display device according to any one of claims 1 to 5, when the screen of the liquid crystal display panel is updated to the image for preventing burn-in, the image for preventing burn-in is displayed. A liquid crystal display device further comprising: means for displaying a mark indicating the effect.
[0204]
Thus, the user can be alerted to the burn-in of the liquid crystal panel.
[0205]
(6) In the liquid crystal display device according to (5), the control unit may be configured to perform the operation when the lid member is at the first position and the image for preventing image sticking is displayed on a screen of the liquid crystal display panel. When the lid member is opened, the liquid crystal display panel further includes means for activating the drive circuit to redisplay an image displayed before updating to the image for preventing burn-in on the liquid crystal display panel. Liquid crystal display device.
[0206]
As a result, user convenience is improved.
[0207]
(7) A liquid crystal display device, which has a memory function and performs display using selective reflection of a cholesteric liquid crystal phase, a driving circuit for driving the liquid crystal display panel, and a periphery of the liquid crystal display panel Temperature detecting means for detecting an environmental temperature in the liquid crystal display device, and when the environmental temperature detected by the temperature detecting means is equal to or higher than a predetermined temperature, the contrast of the liquid crystal display panel is reduced by adjusting the contrast in the drive circuit. A liquid crystal display device comprising: an adjusting unit that updates the display in the step (a).
[0208]
Thereby, the seizure of the liquid crystal panel can be suppressed.
[0209]
【The invention's effect】
As described above, according to the first and second aspects of the invention, when the environmental temperature detected by the temperature detecting means is equal to or higher than the predetermined temperature, the driving circuit is activated to activate the screen of the liquid crystal display panel. Is updated to the image for preventing image sticking, image sticking of the liquid crystal display panel can be suppressed.
[0210]
In particular, according to the invention of claim 2, when the environmental temperature is equal to or higher than the predetermined temperature and a predetermined time has elapsed without updating the display on the liquid crystal display panel, the image of the image on the liquid crystal display panel is prevented from burning. Therefore, image sticking of the liquid crystal display panel can be appropriately suppressed.
[0211]
According to the third aspect of the present invention, when the environmental temperature detected by the temperature detecting means is equal to or higher than the first temperature, the screen of the liquid crystal display panel is updated to the image for preventing burn-in and the environmental temperature is reduced. When the second temperature is higher than the first temperature, the screen of the liquid crystal display panel is immediately updated to the image for preventing burn-in. As a result, image sticking of the liquid crystal display panel can be suppressed step by step.
[0212]
Further, according to the invention of claim 4, when the elapsed time from the screen update in the liquid crystal display panel reaches a predetermined time, the drive circuit in the halt state is activated to burn into the liquid crystal display panel. Since the prevention image is displayed, image sticking of the liquid crystal display panel can be suppressed.
[0213]
According to the fifth aspect of the present invention, when the lid member is at the first position covering the liquid crystal display panel, the drive circuit in the idle state is activated to prevent image sticking on the screen of the liquid crystal display panel. Since an image is displayed, image sticking of the liquid crystal display panel can be suppressed.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a liquid crystal display device 10 according to a first embodiment of the present invention.
FIG. 2 is a cross-sectional view illustrating a main configuration of the liquid crystal display elements 100R and 100L.
FIG. 3 is a diagram showing functional blocks of the liquid crystal display device 10.
FIG. 4 is a diagram for explaining a connection relationship between a liquid crystal display element and a driving IC.
FIG. 5 is a flowchart illustrating a basic operation of the liquid crystal display device 10.
FIG. 6 is a flowchart illustrating a battery check process.
FIG. 7 is a flowchart illustrating an update availability determination process;
FIG. 8 is a diagram for explaining a relationship between temperatures TC, TL, and TM and a relationship between times t1 to t4.
FIG. 9 is a flowchart illustrating a burn-in prevention process 1;
FIG. 10 is a flowchart illustrating an image sticking prevention process 2;
FIG. 11 is a flowchart illustrating an image sticking prevention process 3;
FIG. 12 is a flowchart illustrating an image sticking prevention process 4;
FIG. 13 is a flowchart illustrating a screen update process.
FIG. 14 is a flowchart illustrating a timer correction process.
FIG. 15 is a flowchart illustrating a re-display process.
FIG. 16 is a front view illustrating an appearance of a liquid crystal display device 80 according to a second embodiment of the present invention.
FIG. 17 is a diagram showing functional blocks of the liquid crystal display device 80.
FIG. 18 is a diagram for explaining the operation of the liquid crystal display device 80 at each temperature.
FIG. 19 is a diagram for explaining periodic updating in the liquid crystal display device 80.
FIG. 20 is a diagram for explaining pixel shifting in the liquid crystal display device 80.
FIG. 21 is a diagram for explaining a partial pause in the liquid crystal display device 80.
FIG. 22 is a diagram for explaining enlargement of a rest area in the liquid crystal display device 80.
FIG. 23 is a diagram for explaining a low contrast display in the liquid crystal display device 80.
24 is a diagram for explaining intermittent display in the liquid crystal display device 80. FIG.
[Explanation of symbols]
10,80 liquid crystal display device
11, 11L, 11R, 82, 82a to 82d Liquid crystal display panel
31R, 31L temperature sensor
32R, 32L speaker
41 Display window
42, 93 timer
43 Battery Checker
51, 90 CPU
70 Power supply section
85 Drive circuit
100R, 100L liquid crystal display device
131R, 131L scanning drive IC
132R, 132L signal drive IC
tm1-5 timer

Claims (5)

A liquid crystal display device,
(A) a liquid crystal display panel having a memory property and performing display using selective reflection of a cholesteric liquid crystal phase;
(B) a driving circuit for driving the liquid crystal display panel;
(C) temperature detecting means for detecting an environmental temperature around the liquid crystal display panel;
(D) control means for activating the drive circuit and updating the screen of the liquid crystal display panel to an image for preventing burn-in when the environmental temperature detected by the temperature detection means is equal to or higher than a predetermined temperature. When,
A liquid crystal display device comprising: The liquid crystal display device according to claim 1,
The control means,
(D-1) If the environmental temperature detected by the temperature detecting means is equal to or higher than a predetermined temperature and a predetermined time has elapsed without updating the display on the liquid crystal display panel, the drive circuit is activated. Means for updating the screen of the liquid crystal display panel to the image for preventing burn-in,
A liquid crystal display device comprising: A liquid crystal display device,
(A) a liquid crystal display panel having a memory property and performing display using selective reflection of a cholesteric liquid crystal phase;
(B) a driving circuit for driving the liquid crystal display panel;
(C) temperature detecting means for detecting an environmental temperature around the liquid crystal display panel;
(D) when the environmental temperature detected by the temperature detecting means is equal to or higher than a first temperature, the driving circuit is activated to update the screen of the liquid crystal display panel to the image for preventing image sticking. First control means;
(E) when the environmental temperature detected by the temperature detecting means becomes the second temperature higher than the first temperature, the drive circuit is immediately activated to cause the screen of the liquid crystal display panel to burn in. Second control means for updating to a prevention image,
A liquid crystal display device comprising: A liquid crystal display device,
(A) a liquid crystal display panel having a memory property and performing display using selective reflection of a cholesteric liquid crystal phase;
(B) a driving circuit which shifts to a rest state after writing an image on the liquid crystal display panel;
(C) timing means for measuring a time elapsed from a screen update on the liquid crystal display panel;
(D) control means for activating the drive circuit in the halt state and displaying an image for preventing image sticking on the liquid crystal display panel when the time elapsed from the screen update reaches a predetermined time. When,
A liquid crystal display device comprising: A liquid crystal display device,
(A) a liquid crystal display panel having a memory property and performing display using selective reflection of a cholesteric liquid crystal phase;
(B) a driving circuit which shifts to a rest state after writing an image on the liquid crystal display panel;
(C) a lid member capable of shifting to a first position for covering the liquid crystal display panel and a second position for opening the liquid crystal display panel;
(D) when the lid member is at the first position, a control unit that activates the drive circuit in the pause state to display an image for preventing burn-in on the screen of the liquid crystal display panel;
A liquid crystal display device comprising:

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