Patent Description:
Current display devices can be used in projection system display devices. The projection system display devices need to cooperate with the screen for display. How to achieve a better user experience with lower power consumption is one of the research topics in the industry.

<CIT> discloses a display device according to the preamble of claim <NUM> and <NUM>, respectively, and a corresponding control method for operating such a display device, wherein a voltage is applied across confronting electrodes of a screen to subject the liquid crystal to an electric field so as to change the liquid crystal layer from the light transmissive state to the scattering state, and wherein an image is projected on the screen by the image projecting unit in synchronization with the change to the light scattering state. Then, the voltage across the confronting electrodes of the screen is stopped to eliminate the electric field from the liquid crystal layer so as to change the liquid layer from the light scattering state to the light transmissive state, and the projection of the image by the image projecting unit is turned off in synchronization with the change to the light transmissive state. By repeating this operation, only when the liquid crystal layer of the screen exhibits the light scattering state, an image is projected, and the viewer can see a scattered image on the screen. However, it is not disclosed that the liquid crystal layer of the screen exhibits the light scattering state when the projection of the image by the image projecting unit is turned off.

<CIT> discloses another display device, wherein a synchronous controller controls the image projected screen in a scattering and transmitting state of the projected image light, and controls the non-image projected screen in a transparent and transmitting state. The scattering and transmitting state is the visual state. The transparent and transmitting state is the nonvisual state. When the image light is not projected, each of the segmented regions is controlled in the nonvisual state, that is, in the transparent and transmitting state. Moreover, the synchronous controller controls the optical state of the segmented regions in the visual state where the image light is projected thereon. However, the optical state of the segmented regions in the scattering and transmitting state when the image light is not projected is not disclosed.

It is an object of the present invention to provide a display device and a corresponding control method, implementing driving schemes for the image generator and photo-switchable screen which may provide an additional power saving advantage.

This problem is solved by a display device as claimed in claim <NUM> and <NUM>, respectively, and by a corresponding control method for operating such a display device as claimed in claim <NUM> and <NUM>, respectively.

The disclosure can be more fully understood by referring to the following detailed description and examples with references made to the accompanying drawings, wherein:.

In order to make the purpose, characteristics and advantages of the disclosure more obvious and understandable, embodiments are given in the following paragraphs and detailed explanations are made in accordance with the attached drawings. The specification of the disclosure provides different embodiments to illustrate the technical characteristics of different embodiments of the disclosure. The configuration of the components in embodiments is for illustrative purposes and is not intended to limit the present disclosure. In addition, the partial repetition of the appended drawing labels in the embodiments is for simplification and does not imply a correlation between the different embodiments.

Throughout the specification of the disclosure and the attached claims, certain terms are used to refer to specific components. Technicians in this field should understand that electronic device manufacturers may refer to the same component by different names, and it is not intended to distinguish between components that perform the same function but have different names. In the specification of the disclosure and the attached claims, the terms "include" and "comprise" are used in an open-ended fashion, and thus should be interpreted to mean "include, but not limited to.

The directions mentioned in the following embodiments, such as: up, down, left, right, forward or rear, etc., are the directions referred to in the attached drawing. Therefore, the directional terms used are intended to illustrate and not to limit the present disclosure. It is important to understand that components with specific descriptions or icons can exist in a variety of forms familiar to the technical person. In addition, when a component or film is referred to as being "on", or "connected to" another component or film, it can be directly on, or connected to the other component or film or intervening components or films may be present (indirectly). In contrast, when a component or film is referred to as be "directly on", "directly connected to" another component or film, there are no intervening components or films present.

The ordinal numbers used in the specifications and claims, such as the terms "first", "second", etc. to refer to the claimed components do not in themselves imply any prior ordinal number of the claimed components, nor the order in which one claimed component relates to another claimed component, or the order in the method of manufacture. The ordinal number is used to distinguish one element from another.

<FIG> is a schematic diagram of an exemplary embodiment of a display device according to various aspects of the present disclosure. In this embodiment, the display device <NUM> is applied to a vehicle, but the disclosure is not limited thereto. In one embodiment, the display device <NUM> is applied in an augmented reality system, smart glass, smart window or a projection system. In other embodiments, the display device <NUM> may be applied to an aircraft or another means of transport. In one embodiment, the display device <NUM> is a head-up display (HUD). In this case, the display device <NUM> provides information related to driving directly to the user. Therefore, the user does not need to look down to get information about driving. In this embodiment, the display device <NUM> comprises an image generator <NUM> and a photo-switchable screen <NUM>.

The image generator <NUM> outputs an output image <NUM>. For example, in a light-emitting period, the image generator <NUM> outputs the output image <NUM>. In a non-light-emitting period, the image generator <NUM> stops outputting the output image <NUM>. The disclosure does not limit how image generator <NUM> may output the output image <NUM> by projection or by optical fiber or waveguide. In one embodiment, the image generator <NUM> may utilize a periodicity method to output the output image <NUM>. In one embodiment, in the light-emitting period, a light source or a plurality of light sources (not shown) in the image generator <NUM> is / are turned on. At this time, the image generator <NUM> outputs the output image <NUM>. In the non-light-emitting period, a light source or many light sources in the image generator <NUM> is / are turned off. At this time, the image generator <NUM> stops outputting the output image <NUM>. In this embodiment, since the image generator <NUM> does not continuously output the output image <NUM>, the power consumption of the image generator <NUM> can be reduced.

The kind of image generator <NUM> is not limited in the present disclosure. In one embodiment, the image generator <NUM> is a projector. In other embodiments, the image generator <NUM> may comprise a liquid-crystal display, or light-emitting diode (LED), wherein the light-emitting diode may comprise an organic light-emitting diode (OLED), a mini LED, a micro LED, a quantum dot (QD) (such as QLED or QDOLED), fluorescence, phosphors, another suitable material, or a combination thereof, but the disclosure is not limited thereto. A splicing device may be, for example, a display splicing device, but disclosure is not limited thereto. It should be noted that an electronic device can be any combination of the foregoing, but disclosure is not limited thereto. Hereinafter, a display device will be used as an electronic device or a splicing device to illustrate the content of the present disclosure, but the present disclosure is not limited thereto.

The photo-switchable screen <NUM> is configured to operate in a first operation mode or a second operation mode. In the first operation mode, the photo-switchable screen <NUM> has a first light-transmittance. At this time, if the image generator <NUM> outputs the output image <NUM>, the photo-switchable screen <NUM> generates image information <NUM> according to the output image <NUM>. Therefore, users can directly obtain driving related information, such as speed or navigation information, according to the image information <NUM> displayed on the photo-switchable screen <NUM>.

In some embodiments, when a light-source or a plurality of light-sources (not shown) in the image generator <NUM> is / are turned off, the photo-switchable screen <NUM> is not activated. The period when the light-sources in the image generator <NUM> are turned off is referred to as a non-light-emitting period. In such cases, when a light-source or a plurality of light-sources in the image generator <NUM> is / are turned on, the photo-switchable screen <NUM> may be activated or not activated. The period when the light-sources in the image generator <NUM> are turned on is referred to as a light-emitting period.

The disclosure does not limit how the photo-switchable screen <NUM> generates the image information <NUM>. In one embodiment, the photo-switchable screen <NUM> intermittently generates the image information <NUM>. For example, when the vehicle having the photo-switchable screen <NUM> is stopped in a traffic jam or at a red light, the photo-switchable screen <NUM> stops providing the image information <NUM>. In this case, when the vehicle is moving, the photo-switchable screen <NUM> provides the image information <NUM>. In one embodiment, the photo-switchable screen <NUM> may reflect the output image <NUM> and serve the reflected image as the image information <NUM>. In other embodiments, the photo-switchable screen <NUM> may utilize a projection method or a scattering method, or reduce light transmittance to block the ambient light so that the reflected image information <NUM> has better contrast. The photo-switchable screen <NUM> may increase reflectivity so that the reflected image information <NUM> has a higher brightness. The material of photo-switchable screen <NUM> is not limited in the present disclosure. In one embodiment, the photo-switchable screen <NUM> comprises dye-doped liquid crystal, polymer-dispersed liquid-crystal (PDLC), polymer network liquid-crystal (PNLC), cholesteric liquid-crystal (CLC), electrochromic (EC) material, suspended particle device (SPD), liquid-crystal lens, photonic crystal, or a holographic optical element (HOE).

However, when the photo-switchable screen <NUM> operates in the second operation mode, the photo-switchable screen <NUM> has a second light-transmittance. In this embodiment, the first light-transmittance is less than the second light-transmittance. In some embodiments, the photo-switchable screen <NUM> determines whether to operate in the first operation mode according to a control signal (not shown). For example, when the level of the control signal is a specific level (such as a high level), the photo-switchable screen <NUM> operates in the first operation mode. When the level of the control signal is not the specific level, the photo-switchable screen <NUM> operates in the second operation mode. In some embodiments, the second light-transmittance is approximately <NUM>% to <NUM>%.

In other embodiment, when the control signal at a first level, the photo-switchable screen <NUM> operates in a first operation mode. In the first operation mode, the photo-switchable screen <NUM> has a first light-transmittance. In such case, when the control signal at a second level, the photo-switchable screen <NUM> operates in a second operation mode. In the second operation mode, the photo-switchable screen <NUM> has a second light-transmittance. When the control signal is at a third level, the photo-switchable screen <NUM> operates in a third operation mode. In the third operation mode, the photo-switchable screen <NUM> has a third light-transmittance. The first light-transmittance is less than the second light-transmittance, and the second light-transmittance is less than the third light-transmittance.

In some embodiments, the photo-switchable screen <NUM> comprises a windshield <NUM> or is disposed inside the windshield <NUM>, outside of the windshield <NUM> or on the windshield <NUM>, but the disclosure is not limited thereto. Since the photo-switchable screen <NUM> provides the low light-transmittance, the power consumption of the photo-switchable screen <NUM> can be reduced. In addition, the high transparency of the windshield <NUM> can be maintained when the photo-switchable screen <NUM> provides high light-transmittance. In some embodiments, the light-transmittance (or referred to as penetration rate) depends on the ratio of the intensity of penetration light to the intensity of reference light. The measurements of the intensity of penetration light and the intensity of reference light may be the integration of multiple light-emitting angles, or the intensity of a specific light-emitting angle, for example, the vertical angle perpendicular to the light-emitting surface is taken as the specific light-emitting angle. The penetration rate may be an equivalent penetration rate. The equivalent penetration rate is the integral sum of multiple penetration rates in a certain integration time and divided by the integration time. The location of the photo-switchable screen <NUM> is not limited in the present disclosure. In one embodiment, the photo-switchable screen <NUM> is disposed on the windshield <NUM> of the vehicle. In this case, users can directly obtain speed or navigation information according to the image information <NUM> provided by the photo-switchable screen <NUM>.

<FIG> is an operation schematic diagram of an exemplary embodiment of the image generator <NUM> and the photo-switchable screen <NUM> that is to serve for a better understanding of the present disclosure. To brevity, assume that the image generator <NUM> has a light-source or a plurality of light-sources. In this case, when the light-sources are turned on, the image generator <NUM> outputs the output image <NUM>. When the light-source are turned off, the image generator <NUM> stops outputting the output image <NUM>. Additionally, assume that the photo-switchable screen <NUM> is a cholesteric liquid-crystal display. In this case, when the cholesteric liquid-crystal display has a high reflection rate RH, it means that the light-transmittance of the cholesteric liquid-crystal display is low. When the cholesteric liquid-crystal display has a low reflection rate RL, it means that the light-transmittance of the cholesteric liquid-crystal display is high. In this case, the high reflection rate RH is larger than the low reflection rate RL.

In <FIG>, in the light-emitting periods <NUM>, <NUM>, <NUM>, and <NUM>, the light-sources of the image generator <NUM> are turned on. Therefore, the brightness of the light-source is the high brightness value LH. At this time, the image generator <NUM> outputs the output image <NUM>. However, in the non-light-emitting periods <NUM>, <NUM>, and <NUM>, the light-sources of the image generator <NUM> are turned off. Therefore, the brightness of the light-source is the low brightness value LL. The high brightness value LH is larger than the low brightness value LL (LH>LL). At this time, the image generator <NUM> stops outputting the output image <NUM>. In this embodiment, since the brightness of the light-sources of the image generator <NUM> does not need to be continuously maintained at the high brightness value LH, the power consumption of the image generator <NUM> can be reduced.

In this embodiment, in the light-emitting periods <NUM>, <NUM>, <NUM>, and <NUM>, the photo-switchable screen <NUM> operates in the first operation mode. In the first operation mode, the photo-switchable screen <NUM> has a high reflection rate RH (i.e., a low light-transmittance). At this time, since the image generator <NUM> outputs the output image <NUM> such that the photo-switchable screen <NUM> can generate the image information <NUM>. In the non-light-emitting periods <NUM>, <NUM>, and <NUM>, the photo-switchable screen <NUM> operates in the second operation mode. Therefore, the photo-switchable screen <NUM> has a low reflection rate RL (i.e., a high light-transmittance). Since the photo-switchable screen <NUM> does not need to continually provide the high reflection rate RH (i.e., the low light-transmittance), the power consumption of the photo-switchable screen <NUM> can be reduced.

In one embodiment, the duration of the light-emitting period <NUM>, the duration of the light-emitting period <NUM>, the duration of the light-emitting period <NUM>, and the duration of the light-emitting period <NUM> are the same. In other embodiment, at least one of the duration of the light-emitting period <NUM>, the duration of the light-emitting period <NUM>, the duration of the light-emitting period <NUM>, and the duration of the light-emitting period <NUM> is different from another of the duration of the light-emitting period <NUM>, the duration of the light-emitting period <NUM>, the duration of the light-emitting period <NUM>, and the duration of the light-emitting period <NUM>. Furthermore, the duration of the non-light-emitting period <NUM>, the duration of the non-light-emitting period <NUM>, and the duration of the non-light-emitting period <NUM> are the same, but the disclosure is not limited thereto. In other embodiments, one of the duration of the non-light-emitting period <NUM>, the duration of the non-light-emitting period <NUM>, and the duration of the light-emitting period <NUM> is different from another of the duration of the non-light-emitting period <NUM>, the duration of the non-light-emitting period <NUM>, and the duration of the light-emitting period <NUM>. In some embodiment, the light-emitting period may be <NUM> milliseconds (ms), <NUM>, <NUM> second (sec), <NUM> minute (min), <NUM>, or <NUM> hour(hr), but the disclosure is not limited thereto.

In other embodiments, the duration of the light-emitting period <NUM> and the duration of the non-light-emitting period <NUM> constitute frame time <NUM>. Additionally, the duration of the light-emitting period <NUM> and the duration of the non-light-emitting period <NUM> constitute frame time <NUM>. The duration of the light-emitting period <NUM> and the duration of the non-light-emitting period <NUM> constitute frame time <NUM>. In one embodiment, the frame time <NUM>, <NUM> and <NUM> is about <NUM>.

In another embodiment, the duration of the light-emitting period <NUM> is <NUM>% to <NUM>% of the frame time <NUM>. In this case, the duration of the light-emitting period <NUM> is about <NUM> to <NUM>. In some embodiments, the reflection rate of the photo-switchable screen <NUM> is changed between the high reflection rate RH and the low reflection rate RL so that an equivalent reflection rate of the photo-switchable screen <NUM> is an average of the high reflection rate RH and the low reflection rate RL. In another embodiment, the frequency at which the reflection rate of the photo-switchable screen <NUM> changes between the high reflection rate RH and the low reflection rate RL may be higher than the speed at which the human eye can see (e.g., the frequency of changing the reflection rate of the photo-switchable screen <NUM> may be higher than <NUM>). Furthermore, since the brightness of the light-source of the image generator <NUM> is changed between the high brightness value LH and the low brightness value LL, an equivalent brightness of the image generator <NUM> is an average of the high brightness value LH and the low brightness value LL.

<FIG> is an operation schematic diagram of another exemplary embodiment of the image generator <NUM> and the photo-switchable screen <NUM> according to various aspects of the present disclosure. In the light-emitting periods <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>, the light-sources of the image generator <NUM> are turned on so that the brightness value of the light-source is the high brightness value LH. At this time, the image generator <NUM> outputs the output image <NUM>. However, in the non-light-emitting periods <NUM>, <NUM>, <NUM>, and <NUM>, the light-sources of the image generator <NUM> are turned off so that the brightness value of the light-source is the low brightness value LL. At this time, the image generator <NUM> stops outputting the output image <NUM>. In this case, the durations of the light-emitting periods <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> are the same as each other, and the durations of the non-light-emitting periods <NUM>, <NUM>, <NUM>, and <NUM> are the same as each other.

In this embodiment, in the light-emitting period <NUM>, the non-light-emitting period <NUM>, and the light-emitting period <NUM>, the photo-switchable screen <NUM> operates in the first operation mode. In the first operation mode, the photo-switchable screen <NUM> has the high reflection rate RH. At this time, since the light-transmittance of the photo-switchable screen <NUM> is low, the photo-switchable screen <NUM> is capable of reflecting the output image <NUM> to generate the image information <NUM>. In this case, although the image generator <NUM> stops outputting the output image <NUM> in the non-light-emitting period <NUM>, the users can continually observe the image information <NUM> because the persistence-of-vision phenomenon occurs and the image generator <NUM> outputs the output image <NUM> again in the light-emitting period <NUM>.

In the non-light-emitting period <NUM>, the light-emitting period <NUM>, and the non-light-emitting period <NUM>, the photo-switchable screen <NUM> operates in the second operation mode. At this time, the photo-switchable screen <NUM> has the low light-transmittance RL. Therefore, the photo-switchable screen <NUM> provisionally stops reflecting the output image <NUM>.

In the light-emitting period <NUM>, the non-light-emitting period <NUM>, and the light-emitting period <NUM>, the photo-switchable screen <NUM> operates in the first operation mode again. Therefore, the photo-switchable screen <NUM> has the high reflection rate RH. At this time, since the light-transmittance of the photo-switchable screen <NUM> is low, the photo-switchable screen <NUM> may re-reflect the output image <NUM>. In this case, although the image generator <NUM> stops outputting the output image <NUM> in the non-light-emitting period <NUM>, the users still continually observe the image information <NUM> due to the persistence-of-vision phenomenon.

In one embodiment, the frequency at which the image generator <NUM> outputs the output image <NUM> is a first frequency, and the frequency at which the photo-switchable screen <NUM> generates the image information is a second frequency. In this case, there is a multiple relationship between the first frequency and the second frequency. For example, the first frequency is <NUM>, and the second frequency is <NUM>.

<FIG> is an operation schematic diagram of another exemplary embodiment of the image generator <NUM> and the photo-switchable screen <NUM> according to various aspects of the present disclosure. When the photo-switchable screen <NUM> operates in the second operation mode (i.e., the non-light-emitting period <NUM>), the light-sources of the image generator <NUM> are turned off. At this time, the brightness value of the light-source of the image generator <NUM> is the low brightness value LL.

In this embodiment, in the light-emitting periods <NUM>, <NUM>, <NUM>, and <NUM>, the light-sources of the image generator <NUM> are turned on. Therefore, the image generator <NUM> outputs the output image <NUM>. In the non-light-emitting periods <NUM>, <NUM>, and <NUM>, the light-sources of the image generator <NUM> are turned off. Since the brightness value of the light-sources of the image generator <NUM> is the low brightness value LL, the output image <NUM> cannot be output from the image generator <NUM>. In one embodiment, the durations of the light-emitting periods <NUM>, <NUM>, <NUM>, and <NUM> are the same as each other. Additionally, the durations of the non-light-emitting periods <NUM> and <NUM> may be the same as each other, but the duration of the non-light-emitting period <NUM> or <NUM> may be less than the duration of the non-light-emitting period <NUM>.

In the light-emitting period <NUM>, the non-light-emitting period <NUM>, and the light-emitting period <NUM>, the photo-switchable screen <NUM> operates in the first operation mode. In the first operation mode, the photo-switchable screen <NUM> has the high reflection rate RH. At this time, since the photo-switchable screen <NUM> has the low light-transmittance, the photo-switchable screen <NUM> is capable of reflecting the output image <NUM> to generate a reflection image and provides the reflection image as the image information <NUM>.

In the non-light-emitting period <NUM>, the photo-switchable screen <NUM> operates in the second operation mode. At this time, the photo-switchable screen <NUM> has the low reflection rate RL. Since the photo-switchable screen <NUM> has the high light-transmittance, the photo-switchable screen <NUM> cannot reflect the output image <NUM>. Therefore, in the non-light-emitting period <NUM>, the photo-switchable screen <NUM> stops providing the image information <NUM>. However, the user does not discover the flickering image information <NUM> due to the persistence-of-vision phenomenon.

In the light-emitting period <NUM>, the non-light-emitting period <NUM>, and the light-emitting period <NUM>, the photo-switchable screen <NUM> operates in the first operation mode again. At this time, the photo-switchable screen <NUM> has the high reflection rate RH. Since the light-transmittance of the photo-switchable screen <NUM> is low, the photo-switchable screen <NUM> can reflect the output image <NUM> to generate the image information <NUM>.

<FIG> is an operation schematic diagram of another exemplary embodiment of the actual brightness of the image generator <NUM> and the light-transmittance of the photo-switchable screen according to various aspects of the present disclosure. The image generator <NUM> and the photo-switchable screen <NUM> may not match at all time points due to delays caused by various factors (such as RC delay and response time of a material). Therefore, the image generator <NUM> and the photo-switchable screen <NUM> cannot maintain the corresponding target values (e.g., the high brightness value RH, or the low brightness value LH) for a long time. However, it is required that the time point when the brightness of the light-source of the image generator <NUM> arrives a first target value (e.g., the high brightness value LH) corresponds to the time point when the reflection rate of the photo-switchable screen <NUM> arrives a second target value (e.g., the high reflection rate RH). For example, in the time points <NUM>, <NUM>, and <NUM>, the brightness of the image generator <NUM> arrives the high brightness value LH, and the reflection rate of the photo-switchable screen <NUM> arrives the high reflection rate RH so that the image information <NUM> can be generated.

<FIG> is a schematic diagram of another exemplary embodiment of the brightness of the image generator <NUM> and the light-transmittance of the photo-switchable screen <NUM> according to various aspects of the present disclosure. In one embodiment, when the photo-switchable screen <NUM> on the windshield <NUM> is a component (e.g., a dye-doped liquid-crystal or an electrochromic material) which has a variable light-transmittance, the photo-switchable screen <NUM> at least has the high light-transmittance TH and the low light-transmittance TL. When the brightness of the light-source of the image generator <NUM> is equal to the high brightness value LH, the photo-switchable screen <NUM> provides the low light-transmittance TL. When the brightness of the light-source of the image generator <NUM> is equal to the low brightness value LL, the photo-switchable screen <NUM> provides the high light-transmittance TH.

<FIG> is a schematic diagram of an exemplary embodiment of the light-transmittance and reflection rate of the photo-switchable screen <NUM> according to various aspects of the present disclosure. <FIG> is similar to <FIG> exception that <FIG> shows the reflection rate of the photo-switchable screen <NUM>. As shown in <FIG>, although the light-transmittance of the photo-switchable screen <NUM> is changed between the high light-transmittance TH and the low light-transmittance TL, the reflection rate of the photo-switchable screen <NUM> is maintained at a fixed value MV.

<FIG> is a schematic diagram of another exemplary embodiment of the brightness of the image generator <NUM> and the light-transmittance of the photo-switchable screen <NUM> according to various aspects of the present disclosure. In this embodiment, the light-transmittance of the photo-switchable screen <NUM> is changed between the high light-transmittance TH and the low light-transmittance TL, for example, the photo-switchable screen <NUM> is switched between on (activated) and off (not activated). At this time, if the brightness of the light-source of the image generator <NUM> is maintained at the high brightness value LH and outputs a static image (e.g., in a first light-emitting period), the photo-switchable screen <NUM> displays the static image. In some embodiments, when the brightness of the light-source of the image generator <NUM> is not maintained at the high brightness value LH (e.g., in a first non-light-emitting period), the light-transmittance of the photo-switchable screen <NUM> is the low light-transmittance TL (e.g., the photo-switchable screen <NUM> is not activated or does not output any image). At this time, the photo-switchable screen <NUM> does not display any image.

<FIG> is an operation schematic diagram of another exemplary embodiment of the image generator <NUM> and the photo-switchable screen <NUM> according to various aspects of the present disclosure. When the image generator <NUM> outputs the output image <NUM>-<NUM> to the area <NUM> of the photo-switchable screen <NUM> and outputs the output image <NUM>-<NUM> to the area <NUM> of the photo-switchable screen <NUM>, the photo-switchable screen <NUM> receives the output images from the areas <NUM> and <NUM>. In this embodiment, the areas <NUM> and <NUM> of the photo-switchable screen <NUM> may have the low light-transmittance. Therefore, the area <NUM> is capable of reflecting the output image <NUM>-<NUM>, and the area <NUM> is capable of reflecting the output image <NUM>-<NUM>. In this embodiment, since the image generator <NUM> does not output the output image to the area <NUM>, the photo-switchable screen <NUM> sets the area <NUM> to provide the high light-transmittance. In this case, the area <NUM> is the area outside of the areas <NUM> and <NUM>.

In some embodiments, the photo-switchable screen <NUM> comprises many sensors (not shown) to detect which areas receive the output image. For example, when the image generator <NUM> outputs the output image <NUM>-<NUM> to the area <NUM>, the sensor in the area <NUM> outputs a high level. However, when the image generator <NUM> stops outputting the output image <NUM>-<NUM>, the sensor in the area <NUM> outputs a low level. In such cases, the output of the sensor is utilized to determine whether the area <NUM> receives the output image <NUM>-<NUM>. In another embodiment, before the image generator <NUM> outputs the output images <NUM>-<NUM> and <NUM>-<NUM>, the image generator <NUM> notifies the photo-switchable screen <NUM>. In this case, the photo-switchable screen <NUM> sets the light-transmittance of the corresponding area (e.g., <NUM> and <NUM>) to the low light-transmittance according to the information provided by the image generator <NUM>.

<FIG> is a control schematic diagram of an exemplary embodiment of the display device according to various aspects of the present disclosure. As shown in <FIG>, the display device <NUM> comprises a photo-switchable screen <NUM> and an image generator <NUM>. The image generator <NUM> generates an output image IMO according to external information IME. In this embodiment, the image generator <NUM> generates a trigger signal ST. After receiving the trigger signal ST, the photo-switchable screen <NUM> determines whether to operate in the first operation mode according to a control signal SC.

Taking a cholesteric liquid-crystal (CLC) are an example, when the control signal SC is at a high level (e.g., 5V), the photo-switchable screen <NUM> operates in the first operation mode. At this time, the photo-switchable screen <NUM> has a low light-transmittance (i.e., a high reflection rate). Therefore, the photo-switchable screen <NUM> can reflect the output image IMO to generate image information II. However, when the control signal SC is at a low level (e.g., 0V), the photo-switchable screen <NUM> operates in the second operation mode. At this time, the photo-switchable screen <NUM> has a high light-transmittance (i.e., a low reflection rate). Therefore, the output image IMO cannot be reflected toward human-eye via the photo-switchable screen <NUM>.

<FIG> is a control schematic diagram of another exemplary embodiment of the display device according to various aspects of the present disclosure. In this embodiment, the display device <NUM> comprises a photo-switchable screen <NUM>, an image generator <NUM>, and a timing controller (TCON) <NUM>. The TCON <NUM> provides a synchronizing signal CLK to the photo-switchable screen <NUM> and the image generator <NUM> so that the photo-switchable screen <NUM> operates with image generator <NUM>.

The image generator <NUM> receives and provides external information IME according to the synchronizing signal CLK to generate and output the output image IMO. The photo-switchable screen <NUM> receives a control signal SC according to the synchronizing signal CLK and determines whether to operate in the first operation mode according to the control signal SC. In one embodiment, the photo-switchable screen <NUM> adjusts the count value according to the synchronizing signal CLK. When the count value is equal to a predetermined value, if the control signal SC is at a first level, the photo-switchable screen <NUM> operates in the first operation mode. However, if the control signal is at a second level, the photo-switchable screen <NUM> operates in the second operation mode. The photo-switchable screen <NUM> and image generator <NUM> operate according to the synchronizing signal CLK to prevent the operation of the photo-switchable screen <NUM> from mismatching the operation of the image generator <NUM>.

<FIG> is a flowchart of an exemplary embodiment of a control method according to various aspects of the present disclosure. The control method is applied in a display device. In one embodiment, the display device comprises an image generator and a photo-switchable screen configured to display image information. First, the image generator is directed to output an output image (step S601). In one embodiment, step S601 is to turn on a light-source or a plurality of light-sources in the image generator. In another embodiment, the image generator may utilize a periodicity method to turn on all of the light-sources in the image generator. In this case, when the light-sources are turned on, the image generator outputs the output image. When the light-sources are turned off, the image generator stops outputting the output image.

Next, the photo-switchable screen is directed to operate in a first operation mode or a second operation mode (step S602). In this embodiment, when the photo-switchable screen is directed to operate in the first operation mode, the photo-switchable screen has a first light-transmittance. In the first operation mode, the photo-switchable screen generates the image information according to the output image. However, when the photo-switchable screen is directed to operate in the second operation mode, the photo-switchable screen has a second light-transmittance. In one embodiment, the first light-transmittance is less than the second light-transmittance. In another embodiment, the photo-switchable screen may periodically operate in the first operation mode (step S602). In some embodiment, the second light-transmittance is about <NUM>% to <NUM>%.

<FIG> is a flowchart of another exemplary embodiment of step S601 in the control method according to various aspects of the present disclosure. First, in a light-emitting period, a light-source or a plurality of light-sources in the image generator is turned on to output the output image (step S701). In one embodiment, when the light-sources in the image generator are turned on, the photo-switchable screen is activated or is not activated. Then, in a non-light-emitting period, the light-sources are turned off to stop outputting the output image (step S702). In one embodiment, when the light-sources in the image generator are turned off, the photo-switchable screen operates in the second operation mode. At this time, since the light-transmittance of the photo-switchable screen is high, the photo-switchable screen provisionally stops reflecting the output image. In other embodiments, when the light-sources in the image generator are turned off, the photo-switchable screen is not activated.

In one embodiment, when the light-sources of the image generator are turned on, the photo-switchable screen operates in the first operation mode. In this case, when the light-sources of the image generator are turned off, the photo-switchable screen operates in the second operation mode. Taking <FIG> as an example, in the light-emitting periods <NUM>, <NUM>, <NUM>, and <NUM>, the light-sources of the image generator are turned on. Therefore, the photo-switchable screen operates in the second operation mode. At this time, since the light-transmittance of the photo-switchable screen is low, the photo-switchable screen is capable of reflecting the output image to generate image information. However, in the non-light-emitting periods <NUM>, <NUM>, and <NUM>, the light-sources of the image generator are not turned on. Therefore, the photo-switchable screen operates in the second operation mode. At this time, since the light-transmittance of the photo-switchable screen is high, the photo-switchable screen may stop reflecting the output image.

In other embodiments, when the light-sources of the image generator are turned off, the photo-switchable screen still operates in the first operation mode. Taking <FIG> as an example, in the non-light-emitting periods <NUM> and <NUM>, although the light-sources of the image generator are turned off, the photo-switchable screen still operates in the first operation mode. Similarly, in <FIG>, the light-sources of the image generator are turned off in the non-light-emitting periods <NUM> and <NUM>. At this time, the photo-switchable screen still operates in the first operation mode. In this case, the durations of the non-light-emitting periods <NUM> and <NUM> are less than the duration of the non-light-emitting period <NUM>, and the durations of the light-emitting periods <NUM>, <NUM>, <NUM>, and <NUM> are the same as each other.

In some embodiments, when the light-sources of the image generator are turned on, the photo-switchable screen may operate in the second operation mode. Taking <FIG> as an example, the light-sources of the image generator are turned on in the light-emitting period <NUM>. However, the photo-switchable screen operates in the second operation mode.

In one embodiment, in step S701, when the output image is output to a first area of the photo-switchable screen, the photo-switchable screen sets the light-transmittance of the first area to low and sets the light-transmittance of a second area to high, wherein the second area is outside of the first area. In this case, since the first area has a low light-transmittance, the first area is capable of reflecting the output image.

The present disclosure does not limit when the photo-switchable screen operates in the first operation mode and the second operation mode. In one embodiment, the photo-switchable screen determines whether to operate in the first operation mode according to the level of a control signal. For example, when the level of the control signal is equal to a specific level (e.g., a high level), the photo-switchable screen operates in the first operation mode. However, when the level of the control signal is not equal to the specific level, the photo-switchable screen operates in the second operation mode.

In other embodiments, a timing controller is used to synchronize the operations of the image generator and the photo-switchable screen. The timing controller provides a synchronizing signal to the image generator and the photo-switchable screen. In this case, the image generator receives an external image according to the synchronizing signal to generate the output image. At this time, the photo-switchable screen adjusts the count value according to the synchronizing signal. When the count value is equal to a predetermined value, the photo-switchable screen determines whether to operate in the first operation mode according to the level of the control signal. For example, if the level of the control signal is equal to a specific level, the photo-switchable screen operates in the first operation mode. However, if the level of the control signal is not equal to the specific level, the photo-switchable screen operates in the second operation mode.

Control methods, or certain aspects or portions thereof, may take the form of a program code (i.e., executable instructions) embodied in tangible media, such as floppy diskettes, CD-ROMS, hard drives, or any other machine-readable storage medium, wherein, when the program code is loaded into and executed by a machine such as a computer, the machine thereby becomes a display device for practicing the methods. The methods may also be embodied in the form of a program code transmitted over some transmission medium, such as electrical wiring or cabling, through fiber optics, or via any other form of transmission, wherein, when the program code is received and loaded into and executed by a machine such as a computer, the machine becomes a display device for practicing the disclosed methods. When implemented on a general-purpose processor, the program code combines with the processor to provide a unique apparatus that operates analogously to application-specific logic circuits.

Claim 1:
A display device (<NUM>) for displaying image information (<NUM>) to a user, comprising:
an image generator (<NUM>, <NUM>, <NUM>), configured to output an output image (<NUM>); and
a photo-switchable screen (<NUM>, <NUM>, <NUM>), configured to generate the image information (<NUM>) according to the output image (<NUM>), the photo-switchable screen having a first light-transmittance in a first area (<NUM>) of the photo-switchable screen (<NUM>, <NUM>, <NUM>) in a first operation mode and having a second light-transmittance in the first area (<NUM>) of the photo-switchable screen (<NUM>, <NUM>, <NUM>) in a second operation mode, said first light-transmittance being less than the second light-transmittance;
characterized in that
in a first light-emitting period (<NUM>), the image generator (<NUM>, <NUM>, <NUM>) outputs the output image to the first area and the first area (<NUM>) of the photo-switchable screen (<NUM>, <NUM>, <NUM>) is operated in the first operation mode,
in a first non-light-emitting period (<NUM>), the image generator (<NUM>, <NUM>, <NUM>) stops outputting the output image and the first area (<NUM>) of the photo-switchable screen (<NUM>, <NUM>, <NUM>) is maintained in the first operation mode,
in a second light-emitting period (<NUM>), the image generator (<NUM>, <NUM>, <NUM>) outputs the output image to the first area and the first area (<NUM>) of the photo-switchable screen (<NUM>, <NUM>, <NUM>) is maintained in the first operation mode,
in a second non-light-emitting period (<NUM>), the image generator (<NUM>, <NUM>, <NUM>) stops outputting the output image to the first area and the photo-switchable screen (<NUM>, <NUM>, <NUM>) operates in the second operation mode,
in a third light-emitting period (<NUM>), the image generator (<NUM>, <NUM>, <NUM>) outputs the output image to the first area and the photo-switchable screen (<NUM>, <NUM>, <NUM>) operates in the second operation mode, and
in a third non-light-emitting period (<NUM>), the image generator (<NUM>, <NUM>, <NUM>) stops outputting the output image and the photo-switchable screen (<NUM>, <NUM>, <NUM>) operates in the second operation mode.