Display apparatus that controls a length of an emission period or luminance of a display area according to temperature of a liquid crystal panel

A display apparatus including: a liquid crystal panel for displaying left and right images; a liquid crystal driver for writing an image signal into the liquid crystal panel; a backlight source for radiating light to the liquid crystal panel; and a controller for controlling the backlight source so that it emits the light during first emission periods which are set for a left viewing periods while a left image is viewed with a left eye and right viewing periods while a right image is viewed with a right eye, respectively, wherein the controller controls the backlight source so that it emits the light during a second emission period within a non-viewing period, during which no image is viewed, and sets a turn-off period during which the backlight source is turned off between the first and second emission periods.

TECHNICAL FIELD

The present invention is related to a display apparatus for displaying an image, which is stereoscopically perceived, and an image viewing system for allowing a viewer to view the image displayed by the display apparatus.

BACKGROUND OF THE INVENTION

A display apparatus configured to display an image, which is stereoscopically perceived, alternately shows a left image for a left eye and a right image for a right eye in a given cycle (e.g., a field cycle). The displayed left and right images contain different contents from each other by parallax. A viewer views the left and right images by means of an eyeglass device, which has liquid-crystal shutters driven in synchronism with the display cycle of the left and right images (cf., Patent Documents 1 and 2). As a result, the viewer may perceive a stereoscopic object depicted in the left and right images.

FIG. 12is a block diagram of a conventional image viewing system. The image viewing system shown inFIG. 12receives an input of a 60-Hz image signal (left and right image signals).

An image viewing system900comprises an image signal processor901configured to receive an input of a 60-Hz image signal (left and right image signals). The image signal processor901converts the input image signal into 120-Hz left and right image signals. The left and right image signals obtained as a result of the conversion are output to a liquid crystal driver902and a backlight source controller903. The liquid crystal driver902converts the 120-Hz left and right image signals according to a display format of a liquid crystal panel904. The left and right image signals converted by the liquid crystal driver902are output to the liquid crystal panel904. The backlight source controller903outputs an emission control signal to a backlight source905. The backlight source905emits light to the liquid crystal panel904from its back surface in response to the emission control signal. Therefore, left and right images are alternately displayed at 120 Hz on the liquid crystal panel904.

An eyeglass device950has a left shutter951and a right shutter952. A shutter control circuit906for the left shutter951and a shutter control circuit907for the right shutter952synchronously control the left and right shutters951,952in response to the 120-Hz left and right image signals converted by the image signal processor901.

FIG. 13is a control timing chart of the conventional image viewing system900. Section (A) ofFIG. 13shows scan timing for scanning the left and right images on the liquid crystal panel904. Section (B) ofFIG. 13shows timing for brightening the backlight source905. Section (C) ofFIG. 13shows timing for opening/closing the shutters951,952of the eyeglass device950. The conventional image viewing system900is described with reference toFIGS. 12 and 13.

The left and right image signals are sequentially written into the liquid crystal panel904. Meanwhile, the backlight source905is brightened all the time. The shutter control circuits906,907control the shutters951,952. After the right-and-left alternate write-scanning on the liquid crystal panel904, the shutters951,952are opened/closed under the control of the shutter control circuits906,907so that an open period of each shutter becomes half of each image period. The left and right images are viewed with the right and left eyes of the viewer through the shutters951,952. Therefore, the viewer may create a visually stereoscopic image in the brain.

In the image viewing system, which is operated under the control timing shown inFIG. 13, the viewer views only one of the left and right images while one of the shutters951,952are opened (an image viewing period long enough to create a stereoscopic image). On the other hand, the backlight source905is brightened all the times even in another period than the opening periods of the shutters951,952. Therefore, the image viewing system, which is operated under the control timing shown inFIG. 13, is not preferable in terms of saving electricity.

FIG. 14is another control timing chart of the conventional image viewing system900. Section (A) ofFIG. 14shows scan timing for scanning the left and right images on the liquid crystal panel904. Section (B) ofFIG. 14shows timing for brightening the backlight source905. Section (C) ofFIG. 14shows timing for opening/closing the shutters951,952of the eyeglass device950. The conventional image viewing system900is further described with reference toFIGS. 12 to 14.

Patent Document 2 discloses control to turn on the backlight source905only while the left or right image is viewed. Unlike the control shown inFIG. 13, under the control shown inFIG. 14, the backlight source905emits the light only while the left or right image is viewed. Therefore, the control shown inFIG. 14is better than the control shown inFIG. 13in terms of saving electricity.

The image viewing system shown inFIG. 14has the following problems. The fact that the backlight source905is turned on only while the left or right image is viewed means a shortened lighting period to turn on the backlight source905. A temperature of the liquid crystal panel goes down under the shortened lighting period of the backlight source905. The decrease in temperature of the liquid crystal panel904reduces a response speed of the liquid crystal panel904.

If the response speed of the liquid crystal panel904goes down, for example, the left image may be still partially displayed on the liquid crystal panel904even after completion of the right image scanning because of a delayed response of liquid crystal. As a result, image light from the left image travels through the right shutter and reaches the right eye of the viewer. Likewise, the image light from a part of the right image, which is still displayed after completion of the left image scanning, travels through the left shutter and reaches the left eye of the viewer. The left image viewed with the right eye and/or the right image viewed with the left eye are obstruction images called “crosstalk”, which interferes with the creation of the visually stereoscopic image in the brain of the viewer.

Patent Document 1: JP 62-133891 A

Patent Document 2: JP 2009-25436 A

DISCLOSURE OF THE INVENTION

An object of the present invention is to provide a display apparatus and an image viewing system, which may moderate the crosstalk between left and right images.

A display apparatus according to one aspect of the present invention includes: a liquid crystal panel configured to temporally and alternately switch over and display a left image which is viewed with a left eye and a right image which is viewed with a right eye; a liquid crystal driver configured to write an image signal into the liquid crystal panel, the image signal including a left image signal to create the left image and a right image signal to create the right image; a backlight source configured to radiate light to the liquid crystal panel; and a controller configured to control the backlight source so that the backlight source emits the light during first emission periods which are set for a left viewing period while the left image is viewed with the left eye and a right viewing period while the right image is viewed with the right eye, respectively, wherein the controller controls the backlight source so that the backlight source emits the light during a second emission period within a non-viewing period, during which none of the left and right images is viewed, and sets a turn-off period during which the backlight source is turned off between the first and second emission periods.

An image viewing system according to another aspect of the present invention includes: a display apparatus configured to temporally switch over and display a left image and a right image; and an eyeglass device which includes a left filter configured to adjust a light amount reaching the left eye and a right filter configured to adjust a light amount reaching the right eye, wherein the display apparatus includes: a liquid crystal panel configured to temporally and alternately switch over and display the left and right images; a liquid crystal driver configured to write an image signal into the liquid crystal panel, the image signal including a left image signal to create the left image and a right image signal to create the right image; a backlight source configured to radiate light to the liquid crystal panel; and a controller configured to control the backlight source so that the backlight source emits the light during first emission periods which are set for a left viewing period while the left image is viewed with the left eye and a right viewing period while the right image is viewed with the right eye, respectively; and wherein the left filter increases the light amount reaching the left eye in the left viewing period under control of the controller, the right filter increases the light amount reaching the right eye in the right viewing period under the control of the controller, and the controller controls the backlight source so that the backlight source emits the light during a second emission period within a non-viewing period, during which none of the left and right images is viewed, and sets a turn-off period during which the backlight source is turned off between the first and second emission periods.

DETAILED DESCRIPTION OF THE INVENTION

A display apparatus and image viewing system according to various embodiments are described hereinafter with reference to the accompanying drawings. The same reference numerals are used for describing the same components in the following embodiments. Redundant descriptions thereof are omitted for the purpose of clarification. The purpose of configurations, arrangements or shapes shown in the drawings as well as the descriptions related to the drawings, are simply for facilitating to make principles of the embodiments understood, and the principles of the embodiments are not limited thereto.

(Configuration of Image Viewing System)

FIG. 1is a block diagram schematically showing a configuration of an image viewing system according to the first embodiment.FIG. 2is a schematic view of the image viewing system shown inFIG. 1. The configuration of the image viewing system is described with reference toFIGS. 1 and 2.

An image viewing system100comprises a display apparatus200configured to display a left image in response to a left image signal viewed with the left eye (referred to as “L signal” hereinafter), and a right image in response to a right image signal viewed with a right eye (referred to as “R signal” hereinafter), and an eyeglass device300which assists in viewing the images displayed by the display apparatus200. A viewer uses the eyeglass device300to stereoscopically perceive the images displayed by the display apparatus200.

The eyeglass device300, which looks like visual correction eyeglasses, has an optical filter portion310which includes a left filter311in front of the left eye of the viewer and a right filter312in front of the right eye of the viewer. The left and right filters311,312include optical elements for adjusting a light amount reaching the left eye of the viewer (referred to as “left light amount” hereinafter) and a light amount reaching the right eye of the viewer (referred to as “right light amount” hereinafter), from the images displayed by the display apparatus200. Shutter elements (e.g., liquid crystal shutters) for opening/closing optical paths which travels to the left and right eyes of the viewer, deflection elements (e.g., liquid crystal filters) for deflecting light which travels to the left and right eyes of the viewer, or other optical elements configured to adjust the light amount, are suitably used as the left and right filters311,312. The left filter311is controlled so as to increase the left light amount in synchronization with display of the left image, and to also reduce the left light amount in synchronization with display of the right image. Likewise, the right filter312is controlled so as to increase the right light amount in synchronism with display of the right image, and to also reduce the right light amount in synchronism with display of the left image.

The display apparatus200comprises an image signal processor210, a liquid crystal driver220, a display portion230, a first controller250, and a second controller240.

The image signal processor210receives an input of an image signal (the left and right image signals) which has a vertical synchronization frequency to be used as a base to control the image viewing system. The image signal processor210divides the input image signal into an L signal and an R signal at a frequency, which is N times as high as the control-basis vertical synchronization frequency (N is a natural number). In the present embodiment, the input 60-Hz image signal is converted to 120-Hz L and R signals. The L and R signals obtained by the conversion are output to the liquid crystal driver220. The image signal processor210outputs a control signal to the first controller250in synchronism with the output of the L and R signals. The first controller250controls a backlight source232of the display portion230in response to the control signal from the image signal processor210. The image signal processor210outputs a control signal to control the second controller240, in synchronism with the output of the L and R signals. The second controller240controls the optical filter portion310in response to the control signal from the image signal processor210. The control signal output to the first and/or second controllers250,240may be the L and/or R signals themselves converted by the image signal processor210. Alternatively, the control signal output to the first and/or second controllers250,240may be a 120-Hz synchronization signal, which synchronizes with the output of the L and/or R signals. In the present embodiment, the first and/or second controllers250,240are exemplified as the controller.

The display portion230comprises a liquid crystal panel231configured to temporally and alternately switch over and display the left and right images, which are viewed with the left and right eyes, respectively, and the backlight source232which radiates light to the liquid crystal panel231. The liquid crystal driver220converts the 120-Hz L and R signals into a display format of the liquid crystal panel231. The liquid crystal driver220writes the converted L and R signals into the liquid crystal panel231.

The liquid crystal panel231modulates the light entering from its back surface, in response to the input L and R signals, and sequentially displays the left and right images, which are viewed with the left and right eyes, respectively. For example, various driving systems such as an IPS (In Plane Switching) system, a VA (Vertical Alignment) system, and a TN (Twisted Nematic) system are suitably applied to the liquid crystal panel231.

The backlight source232radiates the light from the back surface toward a display surface of the liquid crystal panel231. In the present embodiment, several light-emitting diodes (LED) (not shown), which are two-dimensionally arrayed for surface-emission, are used as the backlight source232. Alternatively, several fluorescent tubes which are arrayed for the surface-emission may be used as the backlight source232. The light-emitting diodes or the fluorescent tubes used as the backlight source232may be disposed at an edge of the liquid crystal panel231for the surface emission (edge type).

The first controller250outputs an emission control signal in response to the 120-Hz control signal, which is output from the image signal processor210. The backlight source232blinks in response to the emission control signal.

The second controller240controls the optical filter portion310of the eyeglass device300in accordance with the display cycle of the left and right images. The second controller240includes a left filter controller241(referred to as “L filter controller241” hereinafter) configured to control the left filter311, and a right filter controller242(referred to as “R filter controller242” hereinafter) configured to control the right filter312. For example, if the liquid crystal panel231displays the left and right images at 120 Hz, the L filter controller241controls the eyeglass device300so that the left filter311adjusts (increases and reduces) the left light amount with a cycle of 60 Hz. Likewise, the R filter controller242controls the eyeglass device300so that the right filter312adjusts (increases and reduces) the right light amount with a cycle of 60 Hz.

As shown inFIG. 2, in the present embodiment, the display apparatus200comprises a first transmitter243which transmits a first synchronization signal in synchronism with the left image display, and a second transmitter244which transmits a second synchronization signal in synchronism with the right image display. In addition, the eyeglass device300comprises a receiver320situated between the left and right filters311,312. The receiver320receives the first and second synchronization signals. The first and second synchronization signals are preferably different in waveform from each other. The receiver320distinguishes between the first and second synchronization signals on the basis of the waveforms of the received synchronization signals. Therefore, the eyeglass device300operates the left filter311in response to the first synchronization signal. The eyeglass device300also operates the right filter312in response to the second synchronization signal. Other known communication technologies and other known signal processing technologies may be used in the wireless communication of the synchronization signals between the display apparatus200and the eyeglass device300and internal processes of the synchronization signals by the eyeglass device300. Alternatively, wired communication of the synchronization signals may be performed between the display apparatus200and the eyeglass device300. The first and second transmitters243,244which transmit the first and second synchronization signals in synchronism with the display of the left and right images, respectively, may be integrated into a single common transmission device. In this case, the left and right images may be alternately displayed in synchronization with rising edges of communalized synchronization signals.

The L and R filter controllers241,242determine a phase of a rise/fall cycle of the left light amount caused by the left filter311and a phase of a rise/fall cycle of the right light amount caused by the right filter312, on the basis of the control signals from the image signal processor210. The L and R filter controllers241,242output the first and second synchronization signals on the basis of the determined phases. The left and right filters311,312increase/decrease the left and right light amounts, respectively, in synchronization with the display of the left and right images, in response to the first and second synchronization signals.

With taking account of response characteristics of the liquid crystal panel231and crosstalk (mutual interference) between the displayed left and right images, the second controller240determines periods during which the left or right filters311,312increases the left or right light amount (referred to as “increased light period” hereinafter), and timing (phase) of the increased light period. In the present embodiment, a length of the increased light period is 25% (duty: 25%) of one cycle period (16.7 msec) in which the 60-Hz left and/or right image is displayed. The L filter controller241controls the length and the timing of the increased light period for the left light amount. The R filter controller242controls the length and the timing of the increased light period for the right light amount. In the present embodiment, the increased light period in correspondence to the left light amount is set at a time period, which is half a left scanning period during which the left image is scanned. The increased light period in correspondence to the right light amount is set at a time period which is half a right scanning period during which the right image is scanned.

The first controller250, which is operated in response to the 120-Hz control signal from the image signal processor210, outputs the emission control signal to emit the light from the backlight source232in synchronization with light amount adjustments performed by the left and right filters311,312. The backlight source232blinks in response to the emission control signal. In the present embodiment, under the control of the first controller250, the backlight source232emits the light during a left viewing period in which the left image is viewed (i.e., a period during which the left light amount is increased by the left filter311operated under the control of the second controller240) and a right viewing period in which the right image is viewed (i.e., a period during which the right light amount is increased by the right filter312operated under the control of the second controller240). The left and right viewing periods during which the backlight source232emits the light are referred to as “first emission period” in the following descriptions. In the present embodiment, the backlight source232also emits the light under the control of the first controller250, during other periods than the left and right viewing periods (i.e., a non-viewing period in which none of the left and right images is viewed). The other periods than the left and right viewing periods, during which the backlight source232emits the light, are referred to as “second emission period” in the following descriptions. The first controller250sets the first and second emission periods intermittently.

FIG. 3is a schematic control timing chart showing control of the image viewing system100. Section (A) ofFIG. 3schematically shows scan timing for scanning the images on the liquid crystal panel231. Section (B) ofFIG. 3shows lighting of the backlight source232. Section (C) ofFIG. 3schematically shows changes in left light amount adjusted by the left filter311of the eyeglass device300, and changes in right light amount adjusted by the right filter312. Control of the backlight source232is described with reference toFIGS. 1 and 3.

As shown inFIG. 3, one field period of 16.7 msec is divided into the left scanning period (referred to as “L period” hereinafter) and the right scanning period (referred to as “R period” hereinafter). The left image is scanned in the L period. The right image is scanned in the R period. The left image signal is written into the liquid crystal panel231in the L period of each field. The right image signal is written into the liquid crystal panel231in the R period of each field.

The arrows A shown in section (A) ofFIG. 3indicate directions in which the image signals (L and R signals) are written. The liquid crystal panel231shown in section (A) ofFIG. 3includes an upper display area D1for displaying upper parts of the images, a lower display area D3for displaying lower parts of the images, and an intermediate display area D2between the upper and lower display areas D1, D3. The intermediate display area D2displays an image part between the image parts displayed on the upper and lower display areas D1, D3.

As shown by the arrows A in section (A) ofFIG. 3, the image signals (L and R signals) are sequentially written to the upper display area D1, the intermediate display area D2and the lower display area D3of the liquid crystal panel231. In the present embodiment, it takes approximately ¼ of one field (16.7 msec) to write each of the L and R signals.

A numerical value “150” shown in section (B) ofFIG. 3represents a relative luminance of the backlight source232. For example, the numerical value “150” of the relative luminance of the backlight source232may be understood as a relative luminance based on a numerical value “100” (as shown inFIG. 13, for example), which is provided as an appropriate luminance to the backlight source232which is turned on all the time.

As shown in section (B) ofFIG. 3, the backlight source232emits the light in the first and second emission periods E1, E2. A turn-off period LO, in which the backlight source232is turned off, is set between the first and second emission periods E1, E2which are set intermittently. Timing and length of the first emission period E1are substantially coincident with the timing and length of the increased light period I in which the left or right filter311,312increases the left or right light amount. The second emission period E2is set within a period in which both of the left and right filters311,312reduce the light amount reaching the left and right eyes (i.e., the period other than the increased light period I). The period in which both of the left and right filters311,312reduce the light amount reaching the left and right eyes is the non-viewing period in which none of the left and right images is viewed. As shown inFIG. 3, the light emission by the backlight source232during the first emission period E1is referred to as “main emission” in the following descriptions. The light emission by the backlight source232during the second emission period E2is referred to as “sub emission”.

Functions of the main emission and the sub emission are described. As shown in section (C) ofFIG. 3, the increased light period I starts almost at the same time as the completion of scanning the left image in the L period and the completion of scanning the right image in the R period, and ends once the L and R periods are switched over. As a result, the viewer views the left image with the left eye in the L period and the right image with the right eye in the R period.

With the parallax between the left and right images, the brain of the viewer stereoscopically perceives an object depicted in the left and right images. Therefore, the light emission by the backlight source232during the increased light period I in which the light amount reaching the left or right eye increases, directly impacts the viewing of the image. The light emission by the backlight source232during the first emission period E1is referred to as “main emission” in the following descriptions.

On the other hand, the light emitted from the backlight source232during the period in which the light amount reaching the left and right eyes is reduced (the other period than the increased light period I) (i.e., the light emission by the backlight source232during the second emission period E2) is blocked by the left and right filters311,312, and therefore does not reach the left and right eyes of the viewer. Therefore, the light emission by the backlight source232during the second emission period E2does not have a direct impact on the viewing of the images. In the following descriptions, the light emission by the backlight source232during the second emission period E2is referred to as “sub emission”. In the present embodiment, luminance in the main emission and the sub emission is the relative luminance of “150” (e.g., luminance which is 1.5 times as great as that of the conventional backlight source shown inFIG. 14). The second emission period E2(i.e., the sub emission period) is approximately ⅓ as long as the first emission period E1(i.e., the main emission period).

A relationship between the liquid crystal panel231and crosstalk is described. The liquid crystal panel231comprises a liquid crystal layer (not shown) for displaying images. The liquid crystal driver220writing the L or R signal changes orientations of liquid crystal molecules included in the liquid crystal layer of the liquid crystal panel231to adjust light transmittance of the liquid crystal panel231. If the backlight source232radiates the light to the liquid crystal panel231, the luminance of the liquid crystal panel231changes in response to the change in light transmittance of the liquid crystal panel231, so that the viewer may view the left or right image in response to the L or R signal, which is written by the liquid crystal driver220.

In general, response of the liquid crystal molecules with respect to the writing of the image signal (L and/or R signals) by the liquid crystal driver220become slow under a low temperature of the liquid crystal layer of the liquid crystal panel231, which means that it takes longer to change the light transmittance of the liquid crystal panel231after the image signal is written to the liquid crystal panel231. Unless the change in light transmittance of the liquid crystal panel231(the change in light transmittance in response to the writing of the image signal) is completed before the start of the increased light period I, a part of the image, which is depicted before the image signal is written, passes through the left or right filter311,312and reaches the left or right eye. Consequently, the left image is viewed with the right eye while the right image is viewed with the left eye. Such trouble is referred to as “crosstalk”.

As shown inFIG. 3, the luminance of the backlight source232is set at a high value during the first emission period E1to increase a temperature of the liquid crystal panel231. The second emission period E2is set to moderate a temperature drop of the liquid crystal panel231. Therefore, it becomes less likely that there is a delayed response of the liquid crystal of the liquid crystal panel231. Thus, the image viewing system100according to the present embodiment may show a quality stereoscopic image with less crosstalk.

In general, the luminance of the LEDs used in the backlight source232is adjusted by changing a driving current applied to the LEDs and at least one of the light emission periods (light emission duties). In the present embodiment, the timing and the length of the first emission period E1are set to substantially coincide with the timing and length of the increased light period I, which is defined for displaying each of the left and right images.

In the present embodiment, the luminance of the LEDs in the first emission period E1is adjusted by means of the driving current applied to the LEDs. The applied driving current to the LEDs is preferably adjusted within a less influential range to operation life of the LEDs, a less influential range to display color changes resulting from emission color changes, and/or a range to achieve efficient light emission in terms of saving electricity. As a result, it becomes less likely that there is the shortened operation life, the emission color changes (chromaticity), and/or the inefficient light emission.

Instead of the increase rate of the luminance described in the present embodiment, which is 1.5 times as great as that of the conventional backlight source, the luminance of the backlight source232may be changed to another increase rate in accordance with the type of the LED elements or a combination of a driving current and a light emission duty. For example, the luminance increase rate of the backlight source232is preferably determined on the basis of the life of the LED elements. Pulse width modulation (PWM) driving on the LED elements may be performed, instead of the luminance adjustment of the backlight source232on the basis of the driving current applied to the LED elements, in order to adjust the luminance of the backlight source232. The pulse width modulation (PWM) driving may be performed to control the backlight source232so that the backlight source232reduces the luminance.

In the present embodiment, a high luminance is set for the backlight source232in the first emission period E1, which is directly influential on the viewing of a stereoscopic image. Therefore, a bright stereoscopic image may be displayed so that the viewer may easily view the image.

As described above, the sub emission happened in the second emission period E2is less likely to affect the viewing of the stereoscopic image (because the optical filter portion310reduces the light transmission). Therefore, the sub emission in the second emission period E2increases the temperature of the liquid crystal panel231with little effect on the viewing of the stereoscopic image. As a result of the temperature increase of the liquid crystal panel231due to the sub emission in the second emission period E2, the response speed of the liquid crystal molecules of the liquid crystal panel231goes up. Accordingly, the response of the liquid crystal to display the left and/or right images is completed within a short time to decrease the crosstalk between the left and right images. In the present embodiment, the luminance in the sub emission and the length of the second emission period E2are determined to achieve a sufficiently high response speed of the liquid crystal of the liquid crystal panel231with matching the luminance in the sub emission and the length of the second emission period E2with operation conditions of the optical filter portion310.

As described above, the luminance of the sub emission in the second emission period E2is substantially equal to the luminance of the main emission in the first emission period E1. The second emission period E2is approximately ⅓ times as long as the first emission period E1. Alternatively, another luminance of the sub emission or another second emission period E2, which is determined to match with the characteristics of the liquid crystal panel231and/or operating conditions of the eyeglass device300, may be used. As described above, the luminance of the LEDs in the second emission period E2is preferably determined with taking account of the life and reliability of the LEDs. If the temperature of the liquid crystal panel231is sufficiently increased by the main emission in the first emission period E1, the sub emission in the second emission period E2may be omitted.

(Configuration of Image Viewing System)

FIG. 4is a block diagram schematically showing a configuration of an image viewing system100A according to the second embodiment. Differences between the image viewing systems100A,100according to the second and first embodiments are described.

The image viewing system100A comprises the same eyeglass device300as that of the first embodiment, and a display apparatus200A configured to alternately display the left and right images. The display apparatus200A comprises the image signal processor210, the liquid crystal driver220, a display portion230A, a first controller250A, and the second controller240. In the present embodiment, the display portion230A includes a temperature detector233in addition to the backlight source232and the liquid crystal panel231which are the same as those of the first embodiment.

The temperature detector233detects the temperature of the liquid crystal panel231to output a temperature signal, which corresponds to the detected temperature, to the first controller250A. The first controller250A outputs not only a control signal output from the image signal processor210but also an emission control signal to the backlight source232, in order to adjust the length of each light emission period of the backlight source232and the timing of the light emission period on the basis of the temperature signal from the temperature detector233.

FIG. 5is a control timing chart schematically showing control of the image viewing system100A. The left side ofFIG. 5shows control performed on the backlight source232under a high temperature of the liquid crystal panel231. The right side ofFIG. 5shows control performed on the backlight source232if the temperature of the liquid crystal panel231goes down. Section (A) ofFIG. 5schematically shows scan timing for scanning an image on the liquid crystal panel231. Section (B) ofFIG. 5shows lighting of the backlight source232. Section (C) ofFIG. 5schematically shows changes in left light amount adjusted by the left filter311of the eyeglass device300, and changes in right light amount adjusted by the right filter312. Differences in control of the backlight source232between the first and second embodiments are described with reference toFIGS. 4 and 5.

As shown in section (A) ofFIG. 5, the left and right image signals are written to the liquid crystal panel231by the liquid crystal driver220like the first embodiment. Operations of the optical filter portion310(the left and right filters311,312) under the control of the second controller240are also the same as those of the first embodiment. As shown in section (B) ofFIG. 5, the first controller250A changes the length (light emission duty) of the second emission period E2in response to the detected temperature of the liquid crystal panel231. It should be noted that the length and the timing of the first emission period E1are the same as those described in the first embodiment. Like the first embodiment, the turn-off period LO is set between the first and second emission periods E1, E2. Changes in control performed on the backlight source232by the first controller250A are described hereinafter. It should be noted that the control changes happen if the temperature of the liquid crystal panel231decreases from a high temperature condition of the liquid crystal panel231(the left side ofFIG. 5). For example, the changes in temperature of the liquid crystal panel231are caused by ambient temperature changes or continuous operation time of the display apparatus200A.

The luminance of the backlight source232, which blinks under the control of the first controlling unit250A, is a relative luminance of “150” in both of the first and second emission periods E1, E2. In the present embodiment, the first controller250A keeps the luminance of the backlight source232constant, regardless of the changes in temperature of the liquid crystal panel231.

If the liquid crystal achieves a sufficiently high response speed under a temperature condition (see the left side ofFIG. 5), the first controller250A controls the backlight source232so as to set a short second emission period E2. If the temperature of the liquid crystal panel231becomes less than a predetermined value, the first controller250A controls the backlight source232to increase the length of the second emission period E2(see the right side ofFIG. 5). As a result, the temperature of the liquid crystal panel231is kept so that the response speed of the liquid crystal stays at a level high enough to prevent the crosstalk. Therefore, the crosstalk between the left and right images is preferably less likely to occur.

FIG. 6is a graph showing a relationship between the temperature of the liquid crystal panel231and the second emission period E2(sub emission duty) set according to the temperature of the liquid crystal panel231. The horizontal axis of the graph inFIG. 6represents a temperature of the liquid crystal panel231. The vertical axis of the graph inFIG. 6represents a sub emission duty where a ratio of the second emission period E2is expressed in percentage (%) if one field (60 Hz) cycle is 100%. Adjustment and control of the length of the second emission period E2is further described with reference toFIGS. 4 to 6.

InFIG. 6, an appropriate temperature range for displaying a stereoscopic image is described as “stereoscopic display temperature range”. The upper limit of the stereoscopic display temperature range is expressed by “TH”. The lower limit of the stereoscopic display temperature range is expressed by “TL”. The threshold set for a temperature of the liquid crystal of the liquid crystal panel231is expressed by “TTH”. If the temperature of the liquid crystal panel231is no less than TTHand no more than TH, the liquid crystal of the liquid crystal panel231has a sufficient response speed. Therefore, the liquid crystal panel231may show the viewer images (the left and right images) with sufficiently decreased crosstalk between the left and right images. Meanwhile, the first controller250A controls the backlight source232so as to set the sub emission duty at 0% (i.e., so as not to provide the second emission period E2).

The term “DMAX” shown in the vertical axis of the graph inFIG. 6represents a duty of the sub emission period with respect to the longest second emission period E2. In other words, a value obtained by adding the second emission period E2to the first emission period E1becomes equal to one field if the duty value of the sub emission period is DMAX. If the temperature of the liquid crystal panel231falls below the TTH, the first controller250A controls the backlight source232so as to gradually increase the duty of the sub emission period (i.e., to lengthen the second emission period E2). In the control performed on the duty of the sub emission period as shown inFIG. 6, the first controller250A controls the backlight source232so that the duty value of the sub emission period becomes DMAX if the temperature of the liquid crystal panel231is TL.

According to the control on the duty of the sub emission period shown inFIG. 6, the display apparatus200A may consume less power to prevent the changes in temperature of the liquid crystal panel231from causing the crosstalk between the left and right images. Therefore, the display apparatus200A may show the viewer a quality stereoscopic image with low power consumption, under various environments or operation conditions in which the display apparatus200A is situated.

FIGS. 7A and 7Bshow a method for detecting the temperature of the liquid crystal panel231by means of the temperature detector233.FIGS. 7A and 7Bshow display areas of the liquid crystal panel231. The display area of the liquid crystal panel231shown inFIG. 7Ais conceptually divided in a sub-scanning direction (traverse direction) in which the image signals are written by the liquid crystal driver220. The display area of the liquid crystal panel231shown inFIG. 7Bis conceptually divided into rows and columns. Detection of the temperature of the liquid crystal panel231by the temperature detector233is described with reference toFIGS. 4 to 7B.

The display area of the liquid crystal panel231shown inFIG. 7Ais conceptually divided into areas A1to A5. Each of the areas A1to A5is used for integrally displaying the left and right images, respectively. The backlight source232includes a radiation area (not shown) configured to radiate the light to each of the areas A1to A5. The temperature detector233detects a temperature of each area A1to A5. The first controller250A independently controls the length of the second light emission E2in the corresponding radiation areas to the areas A1to A5. For example, if the temperature detector233detects lower temperature in the area A3than the other areas, the first controller250A controls the backlight source232so as to make the second emission period E2of the corresponding radiation area to the area A3longer than the other areas.

Alternatively, the temperature detector233may measure the temperature in one of the areas A1to A5. The temperature detector233may output an average temperature among the areas A1to A5as the temperature of the liquid crystal panel231. The first controller250A may control the backlight source232so that the second emission period E2of a corresponding radiation area to a lower area (e.g., the area A5or A4) becomes longer than the second emission period E2of a corresponding radiation area to a higher area (e.g., the area A1or A2). For instance, the first controller250A may control the backlight source232so that the duties of the sub emission periods of the corresponding radiation areas to the areas A4and A5are more than the duty of the sub emission period of the radiation area corresponding to the area A3by 5%, and so that the duties of the sub emission periods of the radiation areas corresponding to the areas A1and A2are lower than the same by 5%. Accordingly, the second emission period E2may be adjusted in consideration of effect from thermal convection.

As shown inFIG. 7B, the display area of the liquid crystal panel231may be conceptually divided into rows and columns. As described with reference toFIG. 7A, the backlight source232includes radiation areas corresponding to the conceptual divisional areas (areas A11to A53inFIG. 7B) of the liquid crystal panel231. The temperature detector233detects temperatures of the areas A11to A53, respectively. The first controller250A adjusts the lengths of the second emission periods E2of the corresponding radiation area to the areas A11to A53in response to the detected temperatures, respectively. An increase in number of areas obtained by conceptually dividing the display area and number of the radiation areas which may be controlled independently results in precise control of the backlight source232in accordance with characteristics of the display apparatus200A. For example, if there is an element which causes large heat near the area A42, the temperature detector233detects a temperature rise of the liquid crystal which is caused by the element. As a result, the first controller250A may appropriately control the backlight source232without excessively lengthening the second emission period E2of the area A42and/or the surrounding area, which results in power saving of the display apparatus200A.

The configuration of the image viewing system100A described with reference toFIG. 4is incorporated in the third embodiment. In the third embodiment, the first controller250A adjusts the luminance of the backlight source232in the second emission period E2in response to the temperature of the liquid crystal panel231, instead of the length of the second emission period E2.

FIG. 8is a control timing chart schematically showing control of the image viewing system100A. The left side ofFIG. 8shows control, which is performed on the backlight source232if the temperature of the liquid crystal panel231is high. The right side ofFIG. 8shows control which is performed on the backlight source232if the temperature of the liquid crystal panel231goes down. Section (A) ofFIG. 8schematically shows scan timing for scanning the images on the liquid crystal panel231. Section (B) ofFIG. 8shows lighting of the backlight source232. Section (C) ofFIG. 8schematically shows changes in left light amount adjusted by the left filter311of the eyeglass device300, and changes in right light amount adjusted by the right filter312. Differences in control of the backlight source232between the second and third embodiments are described with reference toFIGS. 4 and 8.

As shown in section (A) ofFIG. 8, the left and right image signals are written to the liquid crystal panel231by the liquid crystal driver220, like the second embodiment. The operations of the optical filter portion310(the left and right filters311,312) under the control of the second controller240are also the same as those of the second embodiment. The length and the timing of the first emission period E1and the luminance of the backlight source232in the first emission period are the same as those described in the second embodiment. Like the second embodiment, the turn-off period LO is set between the first and second emission periods E1, E2.

As shown in section (B) ofFIG. 8, the first controller250A changes the luminance of the backlight source232in the second emission period E2in response to the temperature of the liquid crystal panel231detected by the temperature detector233. Changes in the control performed on the backlight source232by the first controller250A are described hereinafter. It should be noted that the changes of the control happen if the temperature of the liquid crystal panel231goes down from a high temperature condition of the liquid crystal panel231(the left side ofFIG. 8).

In the present embodiment, the first controller250A keeps the lengths and the timings of the first and second emission periods E1, E2constant, regardless of the changes in temperature of the liquid crystal panel231.

The first controller250A turns the backlight source232on at a low luminance (a relative luminance of “50” is shown on the left side ofFIG. 8) in the second emission period E2if the liquid crystal achieves a sufficiently high response speed under the temperature condition. If the temperature of the liquid crystal panel231becomes no more than a predetermined value, the first controller250A increases the luminance of the backlight source232in the second emission period E2(a relative luminance of “150” is shown on the right side ofFIG. 8). As a result, the temperature of the liquid crystal panel231increases to make the response speed of the liquid crystal high. Therefore, the crosstalk between the left and right images is less likely to occur. As described above, the driving current, which is applied to the LEDs of the backlight source232in order to adjust the luminance of the LEDs, is preferably determined in light of the life and reliability of the LEDs.

FIG. 9is a graph showing a relationship between the temperature of the liquid crystal panel231and the relative luminance of the backlight source232obtained during the second emission period E2set in response to the temperature of the liquid crystal panel231. The horizontal axis of the graph inFIG. 9represents the temperature of the liquid crystal panel231. The vertical axis of the graph inFIG. 9represents the relative luminance of the backlight source232obtained during the second emission period E2. Adjustment and control of the luminance of the backlight source232in the second emission period E2is further described with reference toFIGS. 4,8and9.

InFIG. 9, an appropriate temperature range for displaying a stereoscopic image is described as “stereoscopic display temperature range”. The upper limit of the stereoscopic display temperature range is expressed by “TH”. The lower limit value of the stereoscopic display temperature range is expressed by “TL”. The threshold for the temperature of the liquid crystal of the liquid crystal panel231is expressed by “TTH”. If the temperature of the liquid crystal panel231is no less than TTHand no more than TH, the liquid crystal of the liquid crystal panel231achieves a response speed high enough for the liquid crystal panel231to show the viewer images (the left and right images) with sufficiently little crosstalk between the left and right images. Meanwhile, for example, the first controller250A controls the backlight source232so that the relative luminance of the backlight source232in the second emission period E2becomes “50”. The relationship between the relative luminance and the temperature of the liquid crystal panel231shown inFIG. 9does not limit the principles of the present embodiment at all. For example, if the temperature of the liquid crystal panel231is sufficiently high, the first controller250A may turn the backlight source232off. Therefore, like the second embodiment, for example, if the temperature of the liquid crystal panel231is no less than “TTH”, the first controller250A may control the backlight source232so that the relative luminance of the backlight source232becomes “0”.

If the temperature of the liquid crystal panel231falls below the TTH, the first controller250A controls the backlight source232so as to gradually increase the relative luminance of the backlight source232in the second emission period E2. In the control performed on the luminance of the backlight source232during the second emission period E2shown inFIG. 9, the first controller250A controls the backlight source232so that the relative luminance of the backlight source232in the second emission period E2becomes “150” if the temperature of the liquid crystal panel231is TL.

According to the control on the luminance of the backlight source232in the second emission period E2shown inFIG. 9, it becomes less likely under low power consumption that the display apparatus200A causes crosstalk between the left and right images even if there are changes in temperature of the liquid crystal panel231, which may cause the crosstalk. Thus, the display apparatus200A may show the viewer a quality stereoscopic image with low power consumption under various environments or operation conditions in which the display apparatus200A is situated.

As described with reference toFIGS. 7A and 7B, in the present embodiment as well, the temperature detector233may measure the temperatures of the areas A1to A5(seeFIG. 7A) or the areas A11to A53(seeFIG. 7B), which are conceptually defined in the display area of the liquid crystal panel231. The first controller250A may independently adjust the luminance of the radiation areas corresponding to the areas A1to AS (seeFIG. 7A) or the areas A11to A53(seeFIG. 7B), which are conceptually defined in the display area of the liquid crystal panel231. For example, if the area A2shown inFIG. 7Ahas lower luminance than the other areas A1and A3to A5, the first controller250A may make the luminance of the radiation area of the backlight source232, which radiates the light to the area A2, higher than that of the other areas in the second emission period E2. Alternatively, the first controller250A may control the backlight source232in consideration of heat transfer in the display apparatus200A so that the luminance of the radiation areas, which radiates the light to the upper areas of the liquid crystal panel231, becomes higher than the luminance of the radiation areas, which radiate the light to the lower areas of the liquid crystal panel231.

In the second and third embodiments, a temperature sensor used as the temperature detector233measures the temperature of the liquid crystal panel231. Alternatively, a temperature sensor configured to detect a temperature of an environment where the display apparatus200A is situated may be used as the temperature detector233.

In the second embodiment, the length of the second emission period E2is independently adjusted. In the third embodiment, the luminance of the backlight source232in the second emission period E2is adjusted. Alternatively, the first controller250A may adjust both the length of the second emission period E2and the luminance of the backlight source232in the second emission period E2, in response to the temperature of the liquid crystal panel231.

The relationship between the temperature of the liquid crystal panel231and the length of the second emission period E2shown inFIG. 6and the relationship between the temperature of the liquid crystal panel231and the relative luminance of the backlight source232in the second emission period E2shown inFIG. 9, are exemplary. Therefore, other settings about these relationships may be used.

The configuration of the image viewing system100A described with reference toFIG. 4is incorporated in the fourth embodiment. In the fourth embodiment, the first controller250A controls the timing of the first emission period E1for each of the radiation areas of the backlight source232, in response to a control signal from the image signal processor210.

FIG. 10is a control timing chart schematically showing control of the image viewing system100A. Section (A) ofFIG. 10schematically shows scan timing for scanning the images on the liquid crystal panel231. Section (B) ofFIG. 10shows lighting of the backlight source232. Section (C) ofFIG. 10schematically shows changes in left light amount adjusted by the left filter311of the eyeglass device300, and changes in right light amount adjusted by the right filter312. Differences in control of the backlight source232between the first and fourth embodiments are described with reference toFIGS. 4 and 10.

As shown in section (A) ofFIG. 10, the left and right image signals are written to the liquid crystal panel231by the liquid crystal driver220, like the first embodiment. It should be noted that the display area of the liquid crystal panel231is conceptually divided into the area D1(the uppermost display area) to the area D8(the lowermost display area) for convenience of explanation.

The backlight source232shown in section (B) ofFIG. 10includes eight radiation areas L1to L8, which are divided in the sub-scanning direction of the images (the left and right images) by the liquid crystal driver220. Each of the radiation areas L1to L8radiates the light to the areas D1to D8of the liquid crystal panel231. The first controller250A adjusts turn-on timing and length of a turn-on period (the first and second emission periods E1, E2) of the backlight source232in each of the radiation areas L1to L8. In each of the radiation areas L1to L8, the first controller250A sets the first emission period E1, within which the backlight source232performs the main emission that directly affects the viewing of the images, and the second emission period E2within which the backlight source232performs the sub emission that does not directly affect the viewing of the images. In each of the radiation areas L1to L8, the turn-off period LO, during which the backlight source232is turned off, is set between the first and second emission periods E1, E2.

The main emission of the backlight source232in the first emission period E1is described. As shown by the arrows A in section (A) ofFIG. 10, the image signals (the left and right image signals) are written from the area D1situated in an upper portion of the liquid crystal panel231to the area D8situated in a lower portion of the liquid crystal panel231. Thus, the liquid crystal layer of the liquid crystal panel231starts the response from the area D1and ends it at the area D8, so that an upper portion of the liquid crystal panel is subjected to the switching operation from the left image to the right image and vice versa earlier to display the images.

As shown in section (C) ofFIG. 10, the second controller240controls the optical filter portion310of the eyeglass device300so as to increase the light amount passing through the left or right filter311,312from a response completion time of the liquid crystal layer of the liquid crystal panel231in the area D1to a response completion time of the liquid crystal layer in the area D8. Therefore, the increased light period I is set over a switching time between the L and R periods. The increased light period I starts before the switching time between the L and R periods, and ends after the switching time between the L and R periods.

In the area D1of the liquid crystal panel231, if the liquid crystal completes the response to the writing of the image signals, the first controller250A controls the backlight source232to turn the radiation area L1on. Thereafter, the first controller250A controls the backlight source232to turn the radiation area L1off before the subsequent image signal writing is started in the area D1of the liquid crystal panel231. As a result of turning on and off the corresponding radiation area L1of the backlight source232in synchronization with the writing of the image signal to the area D1of the liquid crystal panel231(or the completion of the liquid crystal response in the liquid crystal panel231), the image (the left or right image) displayed on the area D1of the liquid crystal panel231reaches the left or right eye. The descriptions related to the area D1of the liquid crystal panel231and the radiation area L1of the backlight source232are similarly applied to the areas D2to D8and the corresponding radiation areas L2to L8, which are located below the area D1and the radiation area L1, respectively. Therefore, the backlight source232is sequentially turned on and off from the upper portion to the lower portion.

As described above, in each of the areas, each of the radiation areas L1to L8of the backlight source232is turned on after the image signals are written to the liquid crystal panel231and after the liquid crystal completes the response to the writing. Therefore, the viewer may enjoy viewing a stereoscopic image with sufficiently decreased crosstalk between the left and right images. If the timing to turn on/off each of the radiation areas L1to L8is independently controlled, the first emission period E1may be made longer as a whole than those of the first to third embodiments (in which the entire backlight source232emits the light at once). As a result, the viewer may enjoy viewing a brighter stereoscopic image. The method for turning on the backlight source232, which is described with reference toFIG. 10(the method for sequentially turning on/off each of the radiation areas L1to L8), is referred to as “backlight scan” (or “backlight scroll”). The backlight scan controls of the backlight source232, which is performed in response to the writing of the left image signal, may be substantially the same as the backlight scan control of the backlight source232, which is performed in response to the writing of the right image signal. If the liquid crystal panel231displays the left and right images under the backlight scanning, the viewer may view a brighter and quality stereoscopic image with little crosstalk.

It should be noted in section (C) ofFIG. 10that the increased light period I is set so as to cover a period between a starting point of the backlight scan (i.e., a starting time of the first emission period E1in the radiation area L1) and an ending point of the backlight scan (i.e., an ending time of the first emission period E1in the radiation area L8).

The sub emission of the backlight source232, which is performed in the second emission period E2, is described. As shown inFIG. 10, the second emission period E2is set in another period than the increased light period I (i.e., a period in which the left and right filters311,312reduces the transmission light amount from the images displayed on the liquid crystal panel231). Like the first to third embodiments, if there is the second emission period E2, the temperature of the liquid crystal panel231is less likely to go down. As a result, the crosstalk between the left and right images is less likely to occur.

In the present embodiment, the second emission period E2turns the backlight source232on so as to substantially cover other periods than the increased light period I. Alternatively, the length of the second emission period E2(i.e., the sub emission duty) may be determined as a fixed value at which appropriate response characteristics of the liquid crystal may be effected regardless of the temperature around the display apparatus200A. Likewise, the luminance of the backlight source232in the second emission period E2may be determined as a fixed value at which appropriate response characteristics of the liquid crystal may be achieved regardless of the temperature around the display apparatus200A. The temperature detector233may be omitted if the length of the second emission period E2and/or the level of the luminance of the backlight source232in the second emission period E2are determined as a fixed value.

Alternatively, the length of the second emission period E2and/or the luminance of the backlight source232in the second emission period E2may be adjusted in response to the temperature of the liquid crystal panel231detected by the temperature detector233or the temperature around the display apparatus200A. The crosstalk is less likely to occur with low power consumption under the adjustment for the length of the second emission period E2and/or the luminance of the backlight source232in the second emission period E2in response to the temperature of the liquid crystal panel231or the temperature around the display apparatus200A.

The configuration of the image viewing system100A described with reference toFIG. 4is incorporated in the fifth embodiment. In the fifth embodiment, in addition to the timing of the first emission period E1, the first controller250A adjusts the timing and the length of the second emission period E2for each of the radiation areas of the backlight source232in response to a control signal from the image signal processor210.

FIG. 11is a control timing chart schematically showing control of the image viewing system100A. Section (A) ofFIG. 11schematically shows scan timing for scanning the images on the liquid crystal panel231. Section (B) ofFIG. 11shows lighting of the backlight source232. Section (C) ofFIG. 11schematically shows changes in left light amount adjusted by the left filter311of the eyeglass device300, and changes in right light amount adjusted by the right filter312. Differences in control of the backlight source232between the fourth and fifth embodiments are described with reference toFIGS. 4 and 11.

As shown in section (A) ofFIG. 11, the left and right image signals are written to the liquid crystal panel231by the liquid crystal driver220, like the fourth embodiment. Like the fourth embodiment, the display area of the liquid crystal panel231is conceptually divided into the area D1(the uppermost display area) to the area D8(the lowermost display area) for convenience of explanation. A correspondence relationship between the areas D1to D8and the radiation areas L1to L8of the liquid crystal panel231is the same as that of the fourth embodiment. In addition, like the fourth embodiment, the second controller240controls the optical filter portion310of the eyeglass device300so as to increase the light amount passing through the left or right filter311,312from the response completion time of the liquid crystal layer of the liquid crystal panel231in the area D1to the response completion time of the liquid crystal layer in the area D8. Therefore, the increased light period I is set over the switching time between the L and R periods. The increased light period I starts before the switching time between the L and R periods, and ends after the switching time between the L and R periods. The backlight source232is turned on in the first emission period E1in accordance with the backlight scan described in the fourth embodiment.

The display apparatus200A in general stands substantially upright. Therefore, the area D1displaying the upper parts of the images (the left and right images) is usually positioned physically on the upper side. The area D8displaying the lower parts of the images is often positioned physically on the lower side. At this moment, heat generated as a result of operating the liquid crystal panel231and the backlight source232is transmitted upward by convection. Thus, the display area located at a higher position in the liquid crystal panel231becomes higher temperature. On the other hand, the display area located at a lower position in the liquid crystal panel231becomes lower temperature.

As shown in section (C) ofFIG. 11, the first controller250A makes the sub emission duty of the backlight source232(the length of the second emission period E2) greater towards the lower radiation areas (i.e., “the sub emission duty in the radiation area L1”<“the sub emission duty in the radiation area L2”< . . . <“the sub emission duty in the radiation area L8”). As a result, the heat generation of the backlight source232gradually increases toward the lower radiation areas. As a result, a substantially even temperature distribution may appear on the display area of the liquid crystal panel231to achieve little crosstalk in the entire liquid crystal panel231.

As described above, in the present embodiment, the first controller250A adjusts the length of the second emission period E2in each of the radiation areas L1to L8. Alternatively, the first controller250A may adjust the luminance of the backlight source232in the second emission period E2for each of the radiation areas L1to L8. For example, the first controller250A may control the backlight source232so as to obtain a relationship as “the sub luminance in the radiation area L1”<“the sub luminance in the radiation area L2”< . . . <“the sub luminance in the radiation area L8”.

As described above, in the present embodiment, the first controller250A controls the backlight source232to obtain a relationship as “the sub emission duty in the radiation area L1”<“the sub emission duty in the radiation area L2”< . . . <“the sub emission duty in the radiation area L8”. Alternatively, the first controller250A may control the backlight source232in accordance with temperature distribution characteristics of the display area of the liquid crystal panel231, which are defined in accordance with the environment where the display apparatus200A is situated and/or the characteristics of the display apparatus200A. For instance, if the display apparatus200A is characterized in having a middle part in the display area of the liquid crystal panel231that becomes warm easily, the first controller250A may control the backlight source232to warm up areas near the periphery of the liquid crystal panel231.

The temperature detector233may detect a temperature in a part of the liquid crystal panel231. Alternatively, the temperature detector233may detect temperatures in the areas D1to D8of the liquid crystal panel231or a temperature of a part of each area. The first controller250A may adjust the sub emission duties (the lengths of the second light emission period E2) or the luminance of the radiation areas L1to L8in the second light emission period E2in response to the temperatures detected in the areas D1to D8. A preferable uniform temperature distribution may appear on the liquid crystal panel231to cause little local crosstalk under such control.

It is preferred that the first controller250A may adjust one of the parameters such as the length of the second emission period E2of each radiation areas L1to L8or the luminance of the backlight source232in the second emission period E2. Thus, a preferable uniform temperature distribution may appear on the liquid crystal panel231to achieve little local crosstalk.

Various modifications may be made by those skilled in the art as long as these modifications do not depart from the principles described through the aforementioned embodiments. In addition, combinations of the components described in the various embodiments above are contained within the scope of the above descriptions.

The aforementioned embodiments are exemplary rather than restrictive in all aspects. The scope of the above descriptions is illustrated not by the embodiments described in detail but by the appended claims, and is intended to include the meanings equivalent to the appended claims and all modifications made within the scope.

The aforementioned embodiments mainly include the following configurations. A display apparatus and an image viewing system which have the following configurations may cause less crosstalk between the left and right images.

A display apparatus according to one aspect of the aforementioned embodiments includes: a liquid crystal panel configured to temporally and alternately switch over and display a left image which is viewed with a left eye and a right image which is viewed with a right eye; a liquid crystal driver configured to write an image signal into the liquid crystal panel, the image signal including a left image signal to create the left image and a right image signal to create the right image; a backlight source configured to radiate light to the liquid crystal panel; and a controller configured to control the backlight source so that the backlight source emits the light during first emission periods which are set for a left viewing period while the left image is viewed with the left eye and a right viewing period while the right image is viewed with the right eye, respectively, wherein the controller controls the backlight source so that the backlight source emits the light during a second emission period within a non-viewing period, during which none of the left and right images is viewed, and sets a turn-off period during which the backlight source is turned off between the first and second emission periods.

According to the aforementioned configuration, the liquid crystal panel temporally and alternately switches over and displays the left and right images, which are viewed with the left and right eyes, respectively, in response to the image signal written by the liquid crystal driver. The left image is viewed with the left eye in the left viewing period. The right image is viewed with the right eye in the right viewing period. As a result, a viewer may create a visual stereoscopic image in the brain. The backlight source radiates the light to the liquid crystal panel under the control of the controller. The first emission periods in which the backlight source emits the light are set in the left and right viewing periods, during which the left and right images are viewed with the left and right eyes, respectively. Therefore, the viewer may preferably view the left and right images in the left and right viewing periods, respectively. The controller further sets the second emission period, during which the backlight source emits the light, within the non-viewing period in which none of the left and right images is viewed. The turn-off period in which the backlight source is turned off is set between the first and second emission periods, so that the backlight source preferably consumes less power and moderates a temperature drop of the backlight source. The moderation of the temperature drop of the backlight source results in preferable moderation of a decrease in response speed of the liquid crystal panel. Consequently, the crosstalk between the left and right images is less likely to occur.

In the aforementioned configuration, it is preferred that the display apparatus further includes a temperature detector configured to detect a temperature of the liquid crystal panel, wherein the controller adjusts a length of the second emission period in response to the temperature of the liquid crystal panel.

According to the aforementioned configuration, the temperature detector detects the temperature of the liquid crystal panel. The controller adjusts the length of the second emission period in response to the temperature of the liquid crystal panel, so that the temperature of the backlight source is appropriately controlled. Therefore, the crosstalk between the left and right images is less likely to occur.

In the aforementioned configuration, it is preferred that the display apparatus further includes a temperature detector configured to detect a temperature of the liquid crystal panel, wherein the controller adjusts a luminance of the backlight source in the second emission period in response to the temperature of the liquid crystal panel.

According to the aforementioned configuration, the temperature detector detects the temperature of the liquid crystal panel. The controller adjusts the luminance of the backlight source in the second emission period in response to the temperature of the liquid crystal panel, so that the temperature of the backlight source is appropriately controlled. Therefore, the crosstalk between the left and right images is less likely to occur.

In the aforementioned configuration, it is preferred that the backlight source includes a first radiation area and a second radiation area which radiate the light to different areas on the liquid crystal panel from each other, and the controller independently controls a length of the second emission period in the first radiation area and a length of the second emission period in the second radiation area.

According to the aforementioned configuration, the backlight source includes the first and second radiation areas. The first and second radiation areas radiate the light to the different areas on the liquid crystal panel from each other. The controller independently controls the length of the second emission period in the first radiation area and the length of the second emission period in the second radiation area, so that the length of the second emission period are controlled in response to a change in temperature of the liquid crystal panel. Therefore, the crosstalk between the left and right images is less likely to occur.

In the aforementioned configuration, it is preferred that the backlight source includes a first radiation area and a second radiation area which radiate the light to different area on the liquid crystal panel from each other, and the controller independently controls a luminance of the first radiation area and a luminance of the second radiation area.

According to the aforementioned configuration, the backlight source includes the first and second radiation areas. The first and second radiation areas radiate the light to the different areas on the liquid crystal panel from each other. The controller independently controls the luminance of the first and second radiation areas, so that the luminance is controlled in response to a change in temperature of the liquid crystal panel. Therefore, the crosstalk between the left and right images is less likely to occur.

In the aforementioned configuration, it is preferred that the liquid crystal panel includes a first display area to which the first radiation area radiates the light, and a second display area to which the second radiation area radiates the light, the temperature detector detects temperatures of the first and second display areas, the controller makes the second emission period of the first radiation area longer than the second emission period of the second radiation area if the temperature of the first display area is lower than the temperature of the second display area, and the controller makes the second emission period of the second radiation area longer than the second emission period of the first radiation area if the temperature of the second display area is lower than the temperature of the first display area.

According to the aforementioned configuration, the temperature detector detects the temperature of the first display area to which the first radiation area radiates the light, and the temperature of the second display area to which the second radiation area radiates the light. If the temperature of the first display area is lower than the temperature of the second display area, the controller makes the second emission period of the first radiation area longer than the second emission period of the second radiation area. If the temperature of the second display area is lower than the temperature of the first display area, the controller makes the second emission period of the second radiation area longer than the second emission period of the first radiation area. Therefore, if there is a temperature drop of a certain area, the temperature may be appropriately increased. Accordingly, the crosstalk between the left and right images is less likely to occur. The backlight source may consume less power because the second emission period is not unnecessarily elongated.

In the aforementioned configuration, it is preferred that the liquid crystal panel includes the liquid crystal panel includes a first display area to which the first radiation area radiates the light, and a second display area to which the second radiation area radiates the light, the temperature detector detects temperatures of the first and second display areas, the controller makes the luminance of the first radiation area greater than the luminance of the second radiation area if the temperature of the first display area is lower than the temperature of the second display area, and the controller makes the luminance of the second radiation area greater than the luminance of the first radiation area if the temperature of the second display area is lower than the temperature of the first display area.

According to the aforementioned configuration, the temperature detector detects the temperature of the first display area to which the first radiation area radiates the light, and the temperature of the second display area to which the second radiation area radiates the light. If the temperature of the first display area is lower than the temperature of the second display area, the controller makes the luminance of the first radiation area greater than the luminance of the second radiation area. If the temperature of the second display area is lower than the temperature of the first display area, the controller makes the luminance of the second radiation area greater than the luminance of the first radiation area. Accordingly, if there is a temperature drop in a certain area, the temperature may be appropriately increased. Therefore, the crosstalk between the left and right images is less likely to occur. The backlight source may consume less power because the second emission period is not unnecessarily elongated.

In the aforementioned configuration, it is preferred that the first radiation area is situated above the second radiation area, and the controller makes the second emission period of the second radiation area longer than the second emission period of the first radiation area.

According to the aforementioned configuration, the second emission period of the second radiation area, which radiates the light to a lower area, is made longer than the second emission period of the first radiation, which radiates the light to an upper area although the temperature in the lower area generally becomes lower than the temperature in the upper area because of heat convection. Therefore, even if there is a temperature drop in a certain area, the temperature may be appropriately increased. Accordingly, the crosstalk between the left and right images and the right image is less likely to occur. The backlight source may consume less power because the second emission period is not unnecessarily elongated.

In the aforementioned configuration, it is preferred that the first radiation area is situated above the second radiation area, and the controller makes the luminance of the second radiation area greater than the luminance of the first radiation area.

According to the aforementioned configuration, the luminance of the second radiation area, which radiates the light to a lower area, is made greater than the luminance of the first radiation, which radiates the light to an upper area, although the temperature in the lower area generally becomes lower than the temperature in the upper area because of heat convection. Therefore, even if there is a temperature drop in a certain area, the temperature may be appropriately increased. Accordingly, the crosstalk between the left and right images is less likely to occur. The backlight source may consume less power because the second emission period is not unnecessarily elongated.

In the aforementioned configuration, it is preferred that the first and second display areas are divided in a sub-scanning direction in which the image signal is written by the liquid crystal driver, and the controller sets the first emission period so that the first radiation area emits the light in synchronization with writing of the image signal into the first display area and so that the second radiation area emits the light in synchronization with writing of the image signal into the second display area.

According to the aforementioned configuration, the first and second display areas are divided in the sub-scanning direction in which the image signal is written by the liquid crystal driver. Because the controller sets the first emission period so that the first radiation area emits the light in synchronization with writing of the image signal into the first display area and so that the second radiation area emits the light in synchronization with writing of the image signal into the second display area, the first emission period may become long. Therefore, the viewer may view a bright image.

In the aforementioned configuration, it is preferred that the controller controls an eyeglass device which includes a left filter configured to adjust a light amount reaching the left eye and a right filter configured to adjust a light amount reaching the right eye, the left filter increases the light amount reaching the left eye in the left viewing period under control of the controller, and the right filter increases the light amount reaching the right eye in the right viewing period under the control of the controller.

According to the aforementioned configuration, the controller controls the eyeglass device, which includes the left filter configured to adjust the light amount reaching the left eye and the right filter configured to adjust the light amount reaching the right eye. The controller increases the light amount reaching the left eye in the left viewing period and the light amount reaching the right eye in the right viewing period. Therefore, the viewer may view the left image with the left eye in the left viewing period and the right image with the right eye in the right viewing period.

An image viewing system according to another aspect of the aforementioned embodiments includes: a display apparatus configured to temporally switch over and display a left image and a right image; and an eyeglass device which includes a left filter configured to adjust a light amount reaching the left eye and a right filter configured to adjust a light amount reaching the right eye, wherein the display apparatus includes: a liquid crystal panel configured to temporally and alternately switch over and display the left and right images; a liquid crystal driver configured to write an image signal into the liquid crystal panel, the image signal including a left image signal to create the left image and a right image signal to create the right image; a backlight source configured to radiate light to the liquid crystal panel; and a controller configured to control the backlight source so that the backlight source emits the light during first emission periods which are set for a left viewing period while the left image is viewed with the left eye and a right viewing period while the right image is viewed with the right eye, respectively; and wherein the left filter increases the light amount reaching the left eye in the left viewing period under control of the controller, the right filter increases the light amount reaching the right eye in the right viewing period under the control of the controller, and the controller controls the backlight source so that the backlight source emits the light during a second emission period within a non-viewing period, during which none of the left and right images is viewed, and sets a turn-off period during which the backlight source is turned off between the first and second emission periods.

According to the aforementioned configuration, the liquid crystal panel temporally and alternately switches over and displays the left and right images, which are viewed with the left and right eyes, respectively, in response to the image signal written by the liquid crystal driver. The left filter of the eyeglass device increases the light amount reaching the left eye in the left viewing period. Therefore, the viewer may view the left image with the left eye in the left viewing period. The right filter of the eyeglass device increases the light amount reaching the right eye in the right viewing period. Therefore, the viewer may view the right image with the right eye in the right viewing period. As a result, the viewer may create a visual stereoscopic image in the brain. The backlight source radiates the light to the liquid crystal panel under the control of the controller. The first emission period, in which the backlight source emits the light, is set in the left and right viewing periods, respectively, so that the viewer may preferably view the left and right images in the left and right viewing periods, respectively. The controller also sets the second emission period for the backlight source to emit the light within the non-viewing period, during which none of the left and right images is viewed, so as to intermittently arrange the first and second emission periods. Thus, the backlight source consumes less power and moderates a temperature drop of the backlight source. The moderation of the temperature drop of the backlight source results in preferable moderation of a decrease in response speed of the liquid crystal panel. Thus, the crosstalk between the left and right images is less likely to occur.

INDUSTRIAL APPLICABILITY

The principles of the embodiments are preferably applied to a display apparatus and an image viewing system configured to reduce the crosstalk.