Display device, wristwatch-type electronic device equipped with the display device, and instrument panel of a vehicle

Abstract

The present invention provides a display device that can suppress a decrease in display power efficiency in a configuration that enables multiple display modes by stacking two display panels, as well as a wristwatch-type electronic device and a vehicle instrument panel equipped with the display device. [Solution] The display device 1 comprises a backlight 30, a first polarizing plate 12, a first liquid crystal display panel 10, a second liquid crystal display panel 20 that overlaps the first liquid crystal display panel 10 with a gap between them, and a second polarizing plate 22. The backlight 30 has multiple modes in which the emission timing differs for each of the multiple emission colors. The first liquid crystal display panel 10 is provided with a first color filter 13R that transmits first light, a second color filter 13G that transmits second light, and a third color filter 13B that transmits third light. The second liquid crystal display panel 20 is not provided with color filters. There is no polarizing plate between the first liquid crystal display panel 10 and the second liquid crystal display panel 20.

Description

Technical Field

[0001] The present invention relates to a display device, a wristwatch-type electronic device including the display device, and an instrument panel of a vehicle.

Background Art

[0002] In recent years, wristwatch-type electronic devices such as so-called smartwatches are known. In such wristwatch-type electronic devices, a technique for realizing a plurality of display modes by changing the state of two display panels arranged via an air layer has been disclosed (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a configuration in which two display panels are arranged overlapping each other, it is conceivable that the transmittance decreases due to light passing through a plurality of components, and the luminance of the display image decreases. Further, there is a possibility that the display power efficiency decreases in order to suppress the decrease in the luminance of the display image.

[0005] The present disclosure has been made in view of the above problems, and in a configuration in which two display panels are arranged overlapping each other and a plurality of display modes can be realized, a display device capable of suppressing a decrease in display power efficiency, a wristwatch-type electronic device including the display device, and an instrument panel of a vehicle are provided.

Means for Solving the Problems

[0006] It should be noted that there is an incorrect character "缉马" in the original text at line 25 which is retained as is in the translation for the purpose of following the rules. You may want to correct this in the original text for a more accurate translation.A display device according to one aspect of the present disclosure includes a backlight, a first polarizing plate to which direct light from the backlight is incident and which transmits light polarized in a first direction and blocks light polarized in a direction other than the first direction, a first liquid crystal display panel to which the light transmitted from the first polarizing plate is incident, a second liquid crystal display panel overlapping the first liquid crystal display panel with a gap between them and to which the light transmitted from the first liquid crystal display panel is incident, and a second liquid crystal display panel to which the light transmitted from the second liquid crystal display panel is incident and which transmits light polarized in a second direction different from the first direction and blocks light polarized in a direction different from the second direction. The backlight comprises a second polarizing plate that shields the light, and the backlight has multiple modes in which the light emission timing differs for each of the multiple light emission colors, and the first liquid crystal display panel is provided with a first color filter that transmits first light, a second color filter that transmits second light different from the first light, and a third color filter that transmits third light different from the first and second light, the second liquid crystal display panel is not provided with a color filter, and no other polarizing plate is provided between the first liquid crystal display panel and the second liquid crystal display panel.

[0007] A wristwatch-type electronic device according to one aspect of this disclosure includes the above-mentioned display device.

[0008] An instrument panel of a vehicle according to one aspect of this disclosure includes the above-mentioned display device. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a block diagram showing an example of a schematic configuration of a meter device illustrating an application example of the display device according to the embodiment. [Figure 2A] Figure 2A is a schematic diagram showing a first example of the first image displayed on the first liquid crystal display panel. [Figure 2B] Figure 2B is a schematic diagram showing the first example of the second image displayed on the second liquid crystal display panel. [Figure 3A] Figure 3A is a schematic diagram showing a second example of the first image displayed on the first liquid crystal display panel. [Figure 3B]Figure 3B is a schematic diagram showing a second example of the second image displayed on the second liquid crystal display panel. [Figure 4] Figure 4 is a timing chart showing an example of the driving modes for the first liquid crystal display panel, the second liquid crystal display panel, and the backlight in the first mode. [Figure 5] Figure 5 is a timing chart showing an example of the driving modes for the first liquid crystal display panel, the second liquid crystal display panel, and the backlight in the second mode. [Figure 6] Figure 6 is a schematic diagram showing a specific example of the color gamut of the second image in the second mode. [Figure 7] Figure 7 is a timing chart showing an example of the driving modes for the first liquid crystal display panel, the second liquid crystal display panel, and the backlight in the third mode. [Modes for carrying out the invention]

[0010] Embodiments for implementing this disclosure will be described in detail with reference to the drawings. However, this disclosure is not limited to the embodiments described below. Furthermore, the components described below include those that are easily conceivable to a person skilled in the art, and those that are substantially the same. Moreover, the components described below can be combined as appropriate. Also, this disclosure is merely an example, and any modifications that a person skilled in the art can easily conceive while maintaining the spirit of the disclosure are naturally included within the scope of this disclosure. Furthermore, in order to clarify the explanation, the drawings may schematically represent the width, thickness, shape, etc., of each part compared to the actual embodiment, but these are merely examples and do not limit the interpretation of this disclosure. In addition, in this specification and in each drawing, elements similar to those described above in previously shown drawings are denoted by the same reference numerals, and detailed explanations may be omitted as appropriate.

[0011] Figure 1 is a block diagram showing an example of a schematic configuration of a meter device illustrating an application example of a display device according to the embodiment. Examples of the meter device 100 include a wristwatch-type electronic device such as a smartwatch, and an instrument panel installed in front of the driver's seat of a vehicle such as an automobile. The meter device 100 comprises a display device 1 and a control circuit 2 that controls each component constituting the display device 1.

[0012] The display device 1 comprises, as its main components, a first liquid crystal display panel 10 for displaying a first image, a second liquid crystal display panel 20 for displaying a second image, and a backlight 30. The control circuit 2 synchronizes the first liquid crystal display panel 10, the second liquid crystal display panel 20, and the backlight 30 to control the image display.

[0013] The first liquid crystal display panel 10 is illuminated by direct light from the backlight 30.

[0014] The second liquid crystal display panel 20 is positioned with a gap S between it and the first liquid crystal display panel 10. The second liquid crystal display panel 20 is illuminated by light transmitted from the first liquid crystal display panel 10.

[0015] In this disclosure, the first liquid crystal display panel 10 and the second liquid crystal display panel 20 are transmissive liquid crystal display panels. The first liquid crystal display panel 10 and the second liquid crystal display panel 20 overlap in the user's line of sight direction (Z direction) of the meter device 100.

[0016] In the display device 1 according to the embodiment, the first liquid crystal display panel 10 includes a liquid crystal layer 11 and a color filter 13. The color filter 13 is provided between the first polarizing plate 12 and the second liquid crystal display panel 20. The liquid crystal layer 11 is provided between the first polarizing plate 12 and the color filter 13.

[0017] Also, in the display device 1 according to the embodiment, the second liquid crystal display panel 20 includes a liquid crystal layer 21. The second liquid crystal display panel 20 is provided between the second polarizing plate 22 and the first liquid crystal display panel 10. Different from the first liquid crystal display panel 10, a color filter is not provided on the second liquid crystal display panel 20.

[0018] The first polarizing plate 12 and the second polarizing plate 22 are arranged in a state (cross Nicol) where the transmission axes are orthogonal to each other with respect to the incident light. In the display device 1 according to the present disclosure, no polarizing plate is provided between the first liquid crystal display panel 10 and the second liquid crystal display panel 20.

[0019] The first polarizing plate 12 is an optical member that transmits light polarized in the first direction and shields light polarized in a direction different from the first direction. Specifically, the first polarizing plate 12 is, for example, a linear polarizing plate having a transmission axis in the Y direction.

[0020] The second polarizing plate 22 is an optical member that transmits light polarized in a second direction different from the first direction and shields light polarized in a direction different from the second direction. Specifically, the second polarizing plate 22 is, for example, a linear polarizing plate having a transmission axis in the X direction.

[0021] The color filter 13 includes a first color filter 13R that transmits the first light (for example, red light), a second color filter 13G that transmits the second light different from the first light (for example, green light), and a third color filter 13B that transmits the third light different from the first light and the second light (for example, blue light).

[0022] <00001The backlight 30 includes a first light source 30R, a second light source 30G, and a third light source 30B. The first light source 30R, the second light source 30G, and the third light source 30B each emit light under the control of the control circuit 2. The first light source 30R, the second light source 30G, and the third light source 30B are light sources using light-emitting elements such as light-emitting diodes (LEDs), but are not limited to these; any light source whose light emission timing can be controlled is acceptable. In this disclosure, the emission color (first color) of the first light source 30R is red (R), the emission color (second color) of the second light source 30G is green (G), and the emission color (third color) of the third light source 30B is blue (B).

[0023] The first light source 30R irradiates the first liquid crystal display panel 10 with light L1 of the first color. The light L1 emitted from the first light source 30R passes through the liquid crystal layer 11 of the first liquid crystal display panel 10, the first color filter 13R, and the second liquid crystal display panel 20 in that order, and reaches the user's line of sight.

[0024] The second light source 30G irradiates the first liquid crystal display panel 10 with a second color of light L2. The light L2 emitted from the second light source 30G passes through the liquid crystal layer 11 of the first liquid crystal display panel 10, the second color filter 13G, and the second liquid crystal display panel 20 in that order, and reaches the user's line of sight.

[0025] The third light source 30B irradiates the first liquid crystal display panel 10 with a third color of light L3. The light L3 emitted from the third light source 30B passes through the liquid crystal layer 11 of the first liquid crystal display panel 10, the third color filter 13B, and the second liquid crystal display panel 20 in that order, and reaches the user's line of sight.

[0026] The image output area of ​​the first liquid crystal display panel 10 and the image output area of ​​the second liquid crystal display panel 20 overlap in the line of sight direction (Z direction) when viewing the display device 1 from the user's viewpoint. As a result, the first image displayed on the first liquid crystal display panel 10 and the second image displayed on the second liquid crystal display panel 20 are viewed by the observer in an overlapping state.

[0027] Figure 2A is a schematic diagram showing a first example of a first image displayed on the first liquid crystal display panel. Figure 2B is a schematic diagram showing a first example of a second image displayed on the second liquid crystal display panel. The first example shown in Figures 2A and 2B illustrates an application of the display device 1 according to the embodiment to a smartwatch.

[0028] In the first example shown in Figures 2A and 2B, an analog clock face is displayed as the first image shown on the first liquid crystal display panel 10, and the clock hands, including the hour, minute, and second hands of the analog clock, are displayed as the second image shown on the second liquid crystal display panel 20.

[0029] As shown in Figures 2A and 2B, at least when viewed from the line of sight (Z direction) in which the first liquid crystal display panel 10 and the second liquid crystal display panel 20 overlap and are visible to the user, the display area AA1 on the first liquid crystal display panel 10 where the first image is displayed and the non-display area IAA2 on the second liquid crystal display panel 20 where no image is displayed overlap, and the non-display area IAA1 on the first liquid crystal display panel 10 where no image is displayed and the display area AA2 on the second liquid crystal display panel 20 where the second image is displayed overlap.

[0030] Light that has passed through the first image displayed in the display area AA1 of the first liquid crystal display panel 10 passes through the non-display area IAA2 of the second liquid crystal display panel 20 and reaches the user's viewpoint. As a result, the first image displayed in the display area AA1 of the first liquid crystal display panel 10 (in this case, the dial of an analog clock) is visible to the user.

[0031] Light that passes through the non-display area IAA1 of the first liquid crystal display panel 10 passes through the second image displayed in the display area AA2 of the second liquid crystal display panel 20 and reaches the user's viewpoint. As a result, the second image displayed in the display area AA2 of the second liquid crystal display panel 20 (in this case, the hands of an analog clock) is visible to the user.

[0032] Figure 3A is a schematic diagram showing a second example of the first image displayed on the first liquid crystal display panel. Figure 3B is a schematic diagram showing a second example of the second image displayed on the second liquid crystal display panel. The second example shown in Figures 3A and 3B illustrates an application of the display device 1 according to the embodiment to the instrument panel of a vehicle.

[0033] In the second example shown in Figures 3A and 3B, the first image displayed on the first liquid crystal display panel 10 is the dial of a car's speedometer, and the second image displayed on the second liquid crystal display panel 20 is the meter needle of a car's speedometer.

[0034] As shown in Figures 3A and 3B, at least when viewed from the line of sight (Z direction) in which the first liquid crystal display panel 10 and the second liquid crystal display panel 20 overlap and are visible to the user, the display area AA1 on the first liquid crystal display panel 10 where the first image is displayed and the non-display area IAA2 on the second liquid crystal display panel 20 where no image is displayed overlap, and the non-display area IAA1 on the first liquid crystal display panel 10 where no image is displayed and the display area AA2 on the second liquid crystal display panel 20 where the second image is displayed overlap.

[0035] Light that has passed through the first image displayed in the display area AA1 of the first liquid crystal display panel 10 passes through the non-display area IAA2 of the second liquid crystal display panel 20 and reaches the user's line of sight. As a result, the first image displayed in the display area AA1 of the first liquid crystal display panel 10 (in this case, the dial of a car's speedometer) is visible to the user.

[0036] Light that passes through the non-display area IAA1 of the first liquid crystal display panel 10 passes through the second image displayed in the display area AA2 of the second liquid crystal display panel 20 and reaches the user's viewpoint. As a result, the second image displayed in the display area AA2 of the second liquid crystal display panel 20 (in this case, the meter needle of a car's speedometer) is visible to the user.

[0037] In the configuration of the display device 1 according to the above embodiment, a gap S is provided between the first liquid crystal display panel 10 and the second liquid crystal display panel 20, so that a three-dimensional composite image composed of a first image displayed on the first liquid crystal display panel 10 and a second image displayed on the second liquid crystal display panel 20 can be viewed by the user.

[0038] In the display device 1 according to this disclosure, multiple modes can be provided by changing the emission color of the backlight 30 and varying the emission timing of each emission color. Examples of variations in backlight emission color and emission timing will be described below.

[0039] Figure 4 is a timing chart showing an example of the driving modes for the first liquid crystal display panel, the second liquid crystal display panel, and the backlight in the first mode.

[0040] In the first mode shown in Figure 4, one frame period FP1 for displaying the first image on the first liquid crystal display panel 10 includes multiple frame periods FP2 for displaying the second image on the second liquid crystal display panel 20. Figure 4 shows an example in which one frame period FP1 for displaying the first image on the first liquid crystal display panel 10 is time-division into four frame periods FP2 for displaying the second image on the second liquid crystal display panel 20. In Figure 4, the frame frequency of the first liquid crystal display panel 10 is set to 15 Hz, and the frame frequency of the second liquid crystal display panel 20 is set to 60 Hz. One frame period FP1 on the first liquid crystal display panel 10 is set to 66.7 ms, and one frame period FP2 on the second liquid crystal display panel 20 is set to 16.7 ms. Note that the frame frequency of the first liquid crystal display panel 10 is not limited to 15 Hz, and the frame frequency of the second liquid crystal display panel 20 is not limited to 60 Hz.

[0041] Furthermore, in the first mode shown in Figure 4, the frame period FP2 for displaying the second image on the second liquid crystal display panel 20 is time-division into a first subframe period (first period) RF, a second subframe period (second period) GF, and a third subframe period (third period) BF. The first subframe period (first period) RF, the second subframe period (second period) GF, and the third subframe period (third period) BF are each set to 5.6 ms.

[0042] During the first subframe period (first period) RF, the control circuit 2 writes image data corresponding to the first color (red (R)) of the second image of the second liquid crystal display panel 20, and during the emission period RON of the first subframe period (first period) RF, the first light source 30R of the backlight 30 is made to emit light.

[0043] During the second subframe period (second period) GF, the control circuit 2 writes image data corresponding to the second color (green (G)) of the second image of the second liquid crystal display panel 20, and during the light emission period GON of the second subframe period (second period) GF, the second light source 30G of the backlight 30 is made to emit light.

[0044] During the third subframe period (third period) BF, the control circuit 2 writes image data corresponding to the third color (blue (B)) of the second image of the second liquid crystal display panel 20, and during the illumination period BON of the third subframe period (third period) BF, the third light source 30B of the backlight 30 is illuminated.

[0045] As a result, one frame of the second image is displayed on the second liquid crystal display panel 20.

[0046] Throughout the FP1 frame period, the control circuit 2 writes image data corresponding to each color of the first image on the first liquid crystal display panel 10. As a result, the first image for one frame is displayed on the first liquid crystal display panel 10.

[0047] In the first mode described above, both the first image displayed on the first liquid crystal display panel 10 and the second image displayed on the second liquid crystal display panel 20 can be displayed in full color (16.77 million colors in the case of 256 gradations).

[0048] Figure 5 is a timing chart showing an example of the driving modes for the first liquid crystal display panel, the second liquid crystal display panel, and the backlight in the second mode.

[0049] In the second mode shown in Figure 5, the frame period FP1 for displaying the first image on the first liquid crystal display panel 10 includes multiple frame periods FP2 for displaying the second image on the second liquid crystal display panel 20. Figure 5 shows an example in which the frame period FP1 for displaying the first image on the first liquid crystal display panel 10 is time-division into four frame periods FP2 for displaying the second image on the second liquid crystal display panel 20. In Figure 5, the frame frequency of the first liquid crystal display panel 10 is set to 15 Hz, and the frame frequency of the second liquid crystal display panel 20 is set to 60 Hz. The frame period FP1 on the first liquid crystal display panel 10 is set to 66.7 ms, and the frame period FP2 on the second liquid crystal display panel 20 is set to 16.7 ms. Note that the frame frequency of the first liquid crystal display panel 10 is not limited to 15 Hz, nor is the frame frequency of the second liquid crystal display panel 20 limited to 60 Hz.

[0050] Furthermore, in the second mode shown in Figure 5, the frame period FP2 for displaying the second image on the second liquid crystal display panel 20 is time-divided into a first subframe period (first period) YF and a second subframe period (second period) BF. The first subframe period (first period) YF and the second subframe period (second period) BF are each set to 8.3 ms.

[0051] During the first subframe period (first period) YF, the control circuit 2 writes image data corresponding to the composite color (yellow (Y)) of the first color (red (R)) and second color (green (G)) of the second image of the second liquid crystal display panel 20, and during the light emission periods RON,GON of the first subframe period (first period) YF, the first light source 30R and the second light source 30G of the backlight 30 are simultaneously illuminated.

[0052] During the second subframe period (second period) BF, the control circuit 2 writes image data corresponding to the third color (blue (B)) of the second image of the second liquid crystal display panel 20, and during the illumination period BON of the second subframe period (second period) BF, the third light source 30B of the backlight 30 is illuminated.

[0053] As a result, one frame of the second image is displayed on the second liquid crystal display panel 20.

[0054] Throughout the FP1 frame period, the control circuit 2 writes image data corresponding to each color of the first image on the first liquid crystal display panel 10. As a result, the first image for one frame is displayed on the first liquid crystal display panel 10.

[0055] In addition, the light emission color of the backlight 30 during the first subframe period (first period) and the second subframe period (second period) of the second mode may be any of the first color (red (R)), second color (green (G)), or third color (blue (B)), or it may be a composite color of multiple colors from the first color (red (R)), second color (green (G)), and third color (blue (B)).

[0056] In the example shown in Figure 5, the combined color of the backlight 30's emission color during the first subframe period (first period) and the backlight 30's emission color during the second subframe period (second period) is white, so the first image displayed on the first liquid crystal display panel 10 can be displayed in full color (16.77 million colors in the case of 256 gradations). Note that the emission color of the backlight 30 during the first subframe period (first period) and the second subframe period (second period) in the second mode is not limited to the example shown in Figure 5. Figure 6 is a schematic diagram showing a specific example of the color reproduction range of the second image in the second mode.

[0057] As shown in Figure 5, if the emission color of the backlight 30 during the first subframe period (first period) is yellow (Y) and the emission color of the backlight 30 during the second subframe period (second period) is blue (B), then, as shown in Figure 6, the second image displayed on the second liquid crystal display panel 20 can be represented within a color gamut that connects yellow (Y) and blue (B) through white (W).

[0058] Alternatively, for example, if the emission color of the backlight 30 during the first subframe period (first period) is red (R), and the emission color of the backlight 30 during the second subframe period (second period) is cyan (CY), which is a composite color of blue (B) and green (G), then, as shown in Figure 6, the second image displayed on the second liquid crystal display panel 20 can be represented within a color gamut that spans a linear range connecting red (R) and cyan (CY) through white (W).

[0059] Furthermore, for example, if the emission color of the backlight 30 during the first subframe period (first period) is set to green (G), and the emission color of the backlight 30 during the second subframe period (second period) is set to magenta (MG), which is a composite color of red (R) and blue (B), then, as shown in Figure 6, the second image displayed on the second liquid crystal display panel 20 can be represented within a color gamut that spans a linear range connecting green (G) and magenta (MG) through white (W).

[0060] Furthermore, for example, by changing the ratio of the light emission amounts of the light sources emitted during the first subframe period (first period) and the second subframe period (second period), the color gamut of the second image displayed on the second liquid crystal display panel 20 can be arbitrarily set. In this case, by setting the ratio of the light emission amounts of the light sources emitted during the first subframe period (first period) and the second subframe period (second period) so that the composite color of the light emission color of the backlight 30 during the first subframe period (first period) and the light emission color of the backlight 30 during the second subframe period (second period) is white (W), the first image displayed on the first liquid crystal display panel 10 can be displayed in full color (16.77 million colors in the case of 256 gradations). In addition, the color gamut of the second image displayed on the second liquid crystal display panel 20 can be represented by a color gamut in a linear range connecting the light emission color of the backlight 30 during the first subframe period (first period) and the light emission color of the backlight 30 during the second subframe period (second period), passing through white (W).

[0061] Figure 7 is a timing chart showing an example of the driving modes for the first liquid crystal display panel, the second liquid crystal display panel, and the backlight in the third mode.

[0062] In the third mode shown in Figure 7, the frame period FP1 for displaying the first image on the first liquid crystal display panel 10 includes the frame period FP2 for displaying the second image on the second liquid crystal display panel 20. In Figure 7, the frame period FP1 for displaying the first image on the first liquid crystal display panel 10 and the frame period FP2 for displaying the second image on the second liquid crystal display panel 20 are the same, and the frame frequency of both the first liquid crystal display panel 10 and the second liquid crystal display panel 20 is set to 15 Hz. The frame period FP1 for the first liquid crystal display panel 10 and the frame period FP2 for the second liquid crystal display panel 20 are both set to 66.7 ms. Note that the frame frequency of the first liquid crystal display panel 10 and the frame frequency of the second liquid crystal display panel 20 are not limited to 15 Hz.

[0063] Furthermore, in the third mode shown in Figure 7, the backlight 30 continuously emits a constant light color during one frame period FP1 of the first liquid crystal display panel 1 (one frame period FP2 of the second liquid crystal display panel 20).

[0064] Throughout the FP1 frame period, the control circuit 2 writes the corresponding image data for the first image to the first liquid crystal display panel 10. Similarly, through the FP2 frame period, the control circuit 2 writes the corresponding image data for the second image to the second liquid crystal display panel 20. As a result, one frame of the first image is displayed on the first liquid crystal display panel 10, and one frame of the second image is displayed on the second liquid crystal display panel 20.

[0065] Figure 7 illustrates a configuration in which, during one frame period FP1 of the first liquid crystal display panel 10 (one frame period FP2 of the second liquid crystal display panel 20), the first light source 30R, the second light source 30G, and the third light source 30B are simultaneously emitted, and white light, which is a composite color of the first color (red (R)), the second color (green (G)), and the third color (blue (B)), is incident on the first liquid crystal display panel 10. This allows the first image displayed on the first liquid crystal display panel 10 to be displayed in full color (16.77 million colors in the case of 256 gradations), and the second image displayed on the second liquid crystal display panel 20 to be displayed in monochrome.

[0066] In addition, the light color of the backlight 30 when it is constantly illuminated in the third mode is not limited to white. The light color of the backlight 30 in the third mode may be any of the first color (red (R)), second color (green (G)), or third color (blue (B)), or it may be a composite color of multiple colors from the first color (red (R)), second color (green (G)), and third color (blue (B)).

[0067] The display device 1 according to this embodiment is provided with a first light source 30R that emits a first color (red (R)), a second light source 30G that emits a second color (green (G)), and a third light source 30B that emits a third color (blue (B)). In the frame period FP2 in which the second image is displayed on the second liquid crystal display panel 20, the display is time-divided into a first subframe period (first period) RF in which the first light source 30R emits light, a second subframe period (second period) GF in which the second light source 30G emits light, and a third subframe period (third period) BF in which the third light source 30B emits light. This allows the second image to be displayed in full color (16.77 million colors in the case of 256 gradations) without providing a color filter on the second liquid crystal display panel 20 (first mode). This makes it possible to suppress the decrease in brightness of the displayed image caused by a decrease in transmittance. It also makes it possible to suppress the decrease in display power efficiency associated with the decrease in brightness of the displayed image.

[0068] Furthermore, as mentioned above, by changing the emission color of the backlight 30 and varying the emission timing of each emission color, it is possible to create multiple modes.

[0069] Specifically, for example, by dividing the FP2 frame period 2 in which the second image is displayed on the second liquid crystal display panel 20 into a first subframe period (first period) and a second subframe period (second period) in which the backlight 30 emits different colors, the panel drive frequency of the second liquid crystal display panel 20 can be reduced compared to the first mode (second mode). Furthermore, the effect of suppressing the decrease in display power efficiency can be enhanced as the panel drive frequency of the second liquid crystal display panel 20 decreases.

[0070] Furthermore, by making the frame period FP1 for displaying the first image in the first liquid crystal display panel 10 and the frame period FP2 for displaying the second image in the second liquid crystal display panel 20 the same, and by keeping the backlight 30 constantly emitting light in a constant color, the panel drive frequency of the second liquid crystal display panel 20 can be further reduced than in the second mode (third mode).

[0071] In this way, by making it possible to switch between multiple modes that combine variations in the emission color of the backlight 30 and variations in the emission timing of each emission color, it becomes possible to set the mode according to the function and usage situation.

[0072] In addition to the first, second, and third modes described above, the system may also include a fourth mode in which the second liquid crystal display panel 20 is turned off to further enhance the power consumption reduction effect. When the second liquid crystal display panel 20 is turned off, the system may either continue driving the second liquid crystal display panel 20 with a frame frequency of, for example, 1 Hz or less, or it may stop driving the second liquid crystal display panel 20.

[0073] Furthermore, while examples of applications for the display device 1 have been described, such as a smartwatch or a meter device 100 installed on an instrument panel in front of the driver's seat of a vehicle such as an automobile, the applications of the display device 1 are not limited to these. Specifically, for example, the display device 1 according to this embodiment may be applied to a head-up display (HUD).

[0074] While preferred embodiments of this disclosure have been described above, this disclosure is not limited to such embodiments. The contents disclosed in the embodiments are merely examples, and various modifications are possible without departing from the spirit of this disclosure. For example, any appropriate modifications made without departing from the spirit of this disclosure naturally fall within the technical scope of the present invention. [Explanation of symbols]

[0075] 1 Display device 2 Control circuits 10. First LCD display panel 11 Liquid crystal layer 12. First polarizing plate 13 Color Filters 20. Second LCD display panel 21 Liquid crystal layer 22. Second polarizing plate 30 Backlight 100 meter device S gap

Claims

1. Backlight and, A first polarizing plate receives direct light from the backlight, transmits light polarized in a first direction, and blocks light polarized in a direction other than the first direction, The first liquid crystal display panel into which the transmitted light from the first polarizing plate is incident, A second liquid crystal display panel overlaps the first liquid crystal display panel with a gap between them, and into which transmitted light from the first liquid crystal display panel is incident. A second polarizing plate is provided, which receives transmitted light from the second liquid crystal display panel, transmits light polarized in a second direction different from the first direction, and blocks light polarized in a direction different from the second direction. Equipped with, The backlight has multiple modes, each with a different emission timing for each of the multiple emission colors. The first liquid crystal display panel is provided with a first color filter that transmits first light, a second color filter that transmits second light different from the first light, and a third color filter that transmits third light different from the first and second light. The second liquid crystal display panel does not have a color filter. No other polarizing plate is provided between the first liquid crystal display panel and the second liquid crystal display panel. Display device.

2. The backlight has a first mode that includes, within one frame period of the second liquid crystal display panel, a period during which a first color is emitted, a period during which a second color different from the first color is emitted, and a period during which a third color different from the first and second colors is emitted. The display device according to claim 1.

3. The first color is red, The second color is green, The third color is blue. The display device according to claim 2.

4. The backlight has a second mode that includes a first period and a second period in which the emitted light color differs within one frame period of the second liquid crystal display panel. The display device according to claim 1.

5. The composite color of the emitted color during the first period and the emitted color during the second period is white. The display device according to claim 4.

6. The backlight has a third mode in which it continuously emits a predetermined light color during one frame period of the first liquid crystal display panel. The display device according to claim 1.

7. Viewed from at least one direction in which the first liquid crystal display panel and the second liquid crystal display panel overlap, In the first liquid crystal display panel, the display area for displaying an image and the non-display area in the second liquid crystal display panel where no image is displayed overlap. In the first liquid crystal display panel, the non-display area where no image is displayed and the display area where an image is displayed in the second liquid crystal display panel overlap. The display device according to any one of claims 1 to 6.

8. Light that has passed through the non-display area of ​​the first liquid crystal display panel is incident on the display area of ​​the second liquid crystal display panel. The display device according to claim 7.

9. The length of one frame period of the second liquid crystal display panel is less than or equal to the length of one frame period of the first liquid crystal display panel. The display device according to any one of claims 1 to 6.

10. The backlight switches between modes during a first display period and a second display period, each displaying a different image. The display device according to claim 1.

11. A display device according to any one of claims 1 to 6, A wristwatch-type electronic device.

12. A display device according to any one of claims 1 to 6, The instrument panel of a vehicle.

Images