TWI849951B - Head up display device - Google Patents

Abstract

The head up display device of the present invention uses a bias element and a polarization control element with a backlight to achieve the local dimming function, wherein the bias element and the polarization control element have a high transmittance, so that the overall transmittance of the head up display device can be improved, using a low-power backlight. The head up display device further uses a dual-axis compensation film or two single-axis compensation films to improve the contrast of the head up display device.

Description

Heads-up display

The present invention relates to a head-up display device, and in particular to a head-up display device with improved transmittance and contrast.

The head-up display device allows the information provided by the in-vehicle information system to be displayed in the driver's line of sight while driving, so the driver can obtain information without lowering his head, avoiding the driver's inability to pay attention to the external road conditions for a short period of time and causing danger when lowering his head to view the display information system. For example, the information can be the speed of the car, so the driver can know the speed of the car without lowering his head to look at the dashboard, thereby improving safety.

FIG1 shows a schematic diagram of a conventional head-up display device applied to a car. The head-up display device 10 of FIG1 includes a picture generation unit (PGU) 12, a free-form surface mirror (FFM) 14, and a free-form surface mirror 16. The image generation unit 12 is used to display and project an image P1. The free-form surface mirror 14 and the free-form surface mirror 16 are arranged on the optical path of the image P1 to reflect the image P1 to the front windshield 18 of the car. Finally, the image P1 is reflected to the driver's eyes 20 through the front windshield 18, so that the driver sees a virtual image 22, wherein the content displayed by the virtual image 22 is consistent with the image P1.

The conventional image generation unit 12 includes a display panel and a backlight panel. The backlight panel provides a light to the display panel. The display panel displays the image P1 and generates a transmission light including the image P1 according to the light. The backlight panel may have a local dimming function to control the light intensity distribution of the transmission light.

FIG. 2 shows a backlight panel 122 with a regional dimming function, and a virtual image 22 when all regions of the backlight panel 122 are lit. FIG. 3 shows a backlight panel 122 with a regional dimming function, and a virtual image 22 when a portion of the backlight panel 122 is lit. As shown in FIG. 2 and FIG. 3, the backlight panel 122 has a plurality of regions 1222, and the brightness of the plurality of regions 1222 can be controlled individually. When all regions 1222 of the backlight panel 122 are lit, the virtual image 22 can display a complete image P1, as shown in FIG. 2. When only a portion of the regions 1222 of the backlight panel 122 are lit, the virtual image 22 only displays a portion of the image P1, as shown in FIG. 3. As shown in FIG. 2 and FIG. 3, when only a portion of the display panel displays the image P1, the backlight panel 122 can only light up the area 1222 corresponding to the image P1 to reduce power consumption.

FIG4 shows a cross-sectional schematic diagram of a conventional head-up display device with a regional dimming function. The head-up display device 30 of FIG4 includes a backlight panel 32, a display panel 34 and a mirror assembly 36. The backlight panel 32 and the display panel 34 constitute the image generation unit 12 of FIG1. The mirror assembly 36 includes at least one of the free-form mirrors 14 and 16 of FIG1. The display panel 34 includes a first polarizer 342, a thin film transistor liquid crystal display 344 and a second polarizer 346. The first polarizer 342 and the second polarizer 346 are respectively arranged on the first side and the second side of the thin film transistor liquid crystal display 344, wherein the first side is opposite to the second side. The backlight panel 32 has a plurality of regions 322, and each region 322 can be independently brightness controlled. However, in the head-up display device 30 of FIG. 4 , in order to avoid mutual influence of light between regions 322 , the luminous angle θ of each region 322 is smaller, so it is easier to generate stray light, as shown by light 40 and 42 in FIG. 5 .

FIG6 shows a cross-sectional schematic diagram of a conventional head-up display device for improving the stray light problem. The head-up display device 50 of FIG6 includes a display panel 34 and a lens assembly 36 in the same manner as the head-up display device 30 of FIG4. In addition, the head-up display device 50 further includes a backlight source 52, a third polarizer 54, and a thin film transistor liquid crystal display 56. The backlight source 52 is a single light source, so the stray light problem can be reduced, as shown in FIG7. The head-up display device 50 uses the third polarizer 54 and the thin film transistor liquid crystal display 56 to achieve a regional dimming function. Specifically, the thin film transistor liquid crystal display 56 has a plurality of regions (not shown in the figure), and the thin film transistor liquid crystal display 56 controls the twisting of the liquid crystal molecules in each region to control the transmittance of each region, thereby achieving a regional dimming function. However, the light emitted by the backlight source 52 must additionally pass through the third polarizer 54 and the thin film transistor liquid crystal display 56, so the overall transmittance of the head-up display device 50 is relatively low, so the head-up display device 50 requires a higher power backlight source 52, resulting in reduced efficiency of the head-up display device 50.

One of the purposes of the present invention is to provide a head-up display device with improved transmittance.

One of the purposes of the present invention is to provide a head-up display device with improved contrast.

The head-up display device of the present invention comprises: a backlight source for providing a first light, wherein the first light is non-polarized light; a display panel for displaying and projecting an image; a polarizing element between the backlight source and the display panel for generating a second light according to the first light, wherein the second light is linearly polarized light; a polarization control element between the polarizing element and the display panel, having a plurality of regions for generating a third light to the display panel according to the second light, wherein the polarization control element controls the transmittance of the plurality of regions.

In one embodiment, the head-up display device of the present invention further includes a mirror set disposed on the optical path of the image to reflect the image to the outside of the head-up display device.

In one embodiment, the head-up display device of the present invention further includes a dual-axis compensation film on the surface of the plurality of regions close to the display panel, and generates a fourth light to the display panel based on the third light, wherein the dual-axis compensation film is used to convert the elliptical polarized light in the third light into linear polarized light.

In one embodiment, the head-up display device of the present invention further includes a dual-axis compensation film on the surface of the display panel close to the polarization control element, and generates a fourth light to the display panel based on the third light, wherein the dual-axis compensation film is used to convert the elliptical polarized light in the third light into linear polarized light.

In one embodiment, the head-up display device of the present invention further includes: a first uniaxial compensation film, which is on the surface of the display panel in the multiple regions and generates a fourth light to the display panel according to the third light, wherein the first uniaxial compensation film is used to convert the elliptical polarized light in the third light into linear polarized light; and a second uniaxial compensation film, which is on the surface of the display panel and close to the polarization control element, and generates a fifth light to the display panel according to the fourth light, wherein the second uniaxial compensation film is used to convert the elliptical polarized light in the fourth light into linear polarized light; wherein the optical axis direction of the first uniaxial compensation film is perpendicular to the direction of the second uniaxial compensation film.

In one embodiment, the display panel includes: a thin film transistor liquid crystal display for displaying the image; a first polarizer disposed on a first side of the thin film transistor liquid crystal display; and a second polarizer disposed on a second side of the thin film transistor liquid crystal display opposite to the first side.

In one embodiment, the polarizing element includes a reflective polarizer.

In one embodiment, the polarizing element includes a reflective polarizing brightness enhancement film.

In one embodiment, the polarization control element includes a twisted liquid crystal display.

In one embodiment, the polarization control element includes a super twist liquid crystal display.

10: Heads-up display device

12: Image generation unit

122: Backlight panel

1222: Area

14: Free-form mirror

16: Free-form mirror

20: Driver's eyes

22: Virtual Image

30: Heads-up display device

32: Backlight panel

322: Area

34: Display panel

342: First polarizer

344: Thin Film Transistor Liquid Crystal Display

346: Second polarizer

36: Lens set

40: Light

42: Light

50: Heads-up display device

52: Backlight

54: Third polarizer

56: Thin Film Transistor Liquid Crystal Display

60: Heads-up display device

62: Backlight

64: Polarizing element

66: Polarization control element

68: Display panel

682: First polarizer

684: Thin Film Transistor Liquid Crystal Display

686: Second polarizer

70: Lens set

72: Double-axis compensation film

74: Double-axis compensation film

80: Heads-up display device

90: Heads-up display device

L1: First Light

L2: Second ray

L3: The third ray

L3_E: elliptically polarized light

L3_L: linearly polarized light

L4: The fourth ray

L5: Fifth Ray

P1: Image

Figure 1 shows a schematic diagram of a traditional head-up display device applied to a car.

Figure 2 shows a backlight with local dimming function and the virtual image when all areas of the backlight are lit.

Figure 3 shows a backlight with local dimming function and the virtual image when part of the backlight is lit.

FIG4 shows a cross-sectional schematic diagram of a conventional head-up display device with a local dimming function.

Figure 5 shows the stray light problem of the head-up display device in Figure 4.

FIG6 is a cross-sectional schematic diagram of a conventional head-up display device for improving stray light problems.

FIG7 shows that the head-up display device of FIG6 can improve the stray light problem.

FIG8 shows a first embodiment of the head-up display device of the present invention.

FIG9 shows a second embodiment of the head-up display device of the present invention.

FIG10 shows a third embodiment of the head-up display device of the present invention.

FIG11 shows a fourth embodiment of the head-up display device of the present invention.

Figure 8 shows the first embodiment of the head-up display device of the present invention. The head-up display device 60 of FIG. 8 includes a backlight 62 , a polarizing element 64 , a polarization control element 66 , a display panel 68 and a lens assembly 70 . The backlight 62 is a single light source, so the problem of stray light can be reduced. The backlight 62 is used to provide a first light L1, where the first light L1 is unpolarized light. The polarizing element 64 is between the backlight 62 and the display panel 68 and generates a second light L2 according to the first light L1, where the second light L2 is linearly polarized light. In one embodiment, the polarizing element 64 may be, but is not limited to, a reflective polarizer (RP) or a reflective polarization enhancement film (Dual Brightness Enhancement Film; DBEF). The polarization control element 66 has a plurality of regions (not shown) between the polarizing element 64 and the display panel 68 . The polarization control element 66 generates a third light L3 to the display panel 68 according to the second light L2. The polarization control element 66 controls the transmittance of the multiple areas, thereby achieving a local dimming function. In one embodiment, the polarization control element 66 may be, but is not limited to, a twisted liquid crystal display (Twist Nematic; TN) or a super twisted liquid crystal display (Super Twist Nematic; STN). The display panel 68 is used to display and project an image P1. The display panel 68 includes a first polarizing plate 682 , a thin film transistor liquid crystal display 684 and a second polarizing plate 686 . The first polarizing plate 682 and the second polarizing plate 686 are respectively disposed on the first side and the second side of the thin film transistor liquid crystal display 684, where the first side is opposite to the second side. The backlight source 62, the polarizing element 64, the polarization control element 66 and the display panel 68 of FIG. 8 constitute the image generating unit 12 of FIG. 1. The mirror assembly 70 is arranged on the optical path of the image P1 to reflect the image P1 to the head-up display device. 60. The mirror assembly 70 includes at least one of the free-form mirrors 14 and 16 of FIG. 1.

The head-up display device 60 of the present invention uses a polarizing element 64 (such as RP or DBEF) and a polarization control element 66 (such as TN or STN) with higher transmittance, so the head-up display device 60 has a higher overall transmittance, so the head-up display device 60 can use a lower power backlight source 62 to improve efficiency.

As shown in FIG8 , when the incident angle of the second light ray L2 from the polarizing element 64 is greater than a preset value, the third light ray L3 output by the polarization control element 66 may appear as elliptically polarized light L3_E. In other words, the third light ray L3 may include part of the elliptically polarized light L3_E in addition to the linearly polarized light L3_L. The elliptically polarized light L3_E may cause the contrast of the head-up display device 60 to decrease. FIG9 shows a second embodiment of the head-up display device of the present invention. The head-up display device 60 of FIG9 includes a backlight source 62, a polarizing element 64, a polarization control element 66, a display panel 68, a lens assembly 70 and a dual-axis compensation film 72. The backlight source 62 is a single light source, so the stray light problem can be reduced. The backlight source 62 is used to provide a first light ray L1, wherein the first light ray L1 is non-polarized light. The polarizing element 64 is between the backlight source 62 and the display panel 68, and generates a second light ray L2 according to the first light ray L1, wherein the second light ray L2 is linearly polarized light. The polarization control element 66 has multiple regions (not shown) between the polarizing element 64 and the display panel 68. The polarization control element 66 generates a third light ray L3 according to the second light ray L2. The polarization control element 66 controls the transmittance of the multiple regions, thereby achieving a regional dimming function. The biaxial compensation film 72 is on the surface of the multiple regions of the polarization control element 66 close to the display panel 68. The biaxial compensation film 72 generates a fourth light ray L4 to the display panel 68 according to the third light ray L3. The two-axis compensation film 72 is used to convert the elliptical polarized light L3_E (as shown in FIG8 ) in the third light L3 into linear polarized light L4_L. The display panel 68 is used to display and project an image P1. The display panel 68 includes a first polarizer 682, a thin film transistor liquid crystal display 684, and a second polarizer 686. The first polarizer 682 and the second polarizer 686 are respectively disposed on the first side and the second side of the thin film transistor liquid crystal display 684, wherein the first side is opposite to the second side. The backlight source 62, the polarizing element 64, the polarization control element 66, the display panel 68, and the two-axis compensation film 72 of FIG9 constitute the image generation unit 12 of FIG1 . The mirror assembly 70 is arranged on the optical path of the image P1 to reflect the image P1 to the outside of the head-up display device 60. The mirror assembly 70 includes at least one of the free-form mirrors 14 and 16 of FIG. 1 .

The head-up display device 80 of the present invention uses a polarizing element 64 (such as RP or DBEF) and a polarization control element 66 (such as TN or STN) with high transmittance, so the head-up display device 80 has a higher overall transmittance, so the head-up display device 80 can use a lower power backlight source 62 to improve efficiency. The head-up display device 80 of the present invention uses a dual-axis compensation film 72 to eliminate or reduce the elliptical polarized light L3_E, thereby improving the contrast of the head-up display device 80.

FIG10 shows a third embodiment of the head-up display device of the present invention. The head-up display device 90 of FIG10 includes a backlight source 62, a polarizing element 64, a polarization control element 66, a display panel 68, a lens group 70 and a biaxial compensation film 74. The backlight source 62 is a single light source, so the stray light problem can be reduced. The backlight source 62 is used to provide a first light ray L1, wherein the first light ray L1 is non-polarized light. The polarizing element 64 is between the backlight source 62 and the display panel 68, and generates a second light ray L2 according to the first light ray L1, wherein the second light ray L2 is linearly polarized light. The polarization control element 66 has a plurality of regions (not shown) between the polarizing element 64 and the display panel 68. The polarization control element 66 generates a third light ray L3 according to the second light ray L2. The polarization control element 66 controls the transmittance of the multiple regions, thereby achieving a regional dimming function. The two-axis compensation film 74 is on the surface of the display panel 68 close to the polarization control element 66, and the two-axis compensation film 74 generates a fourth light L4 for the display panel 68 according to the third light L3. The two-axis compensation film 74 is used to convert the elliptical polarized light L3_E in the third light L3 into linear polarized light. The display panel 68 is used to display and project an image P1. The display panel 68 includes a first polarizer 682, a thin film transistor liquid crystal display 684 and a second polarizer 686. The first polarizer 682 and the second polarizer 686 are respectively arranged on the first side and the second side of the thin film transistor liquid crystal display 684, wherein the first side is opposite to the second side. The backlight source 62, polarizing element 64, polarization control element 66, display panel 68 and two-axis compensation film 74 of FIG. 10 constitute the image generation unit 12 of FIG. 1. The mirror group 70 is arranged on the optical path of the image P1 to reflect the image P1 to the outside of the head-up display device 60. The mirror group 70 includes at least one of the free-form surface mirrors 14 and 16 of FIG. 1.

The head-up display device 90 of the present invention uses a polarizing element 64 (such as RP or DBEF) and a polarization control element 66 (such as TN or STN) with high transmittance, so the head-up display device 90 has a high overall transmittance, so the head-up display device 90 can use a lower power backlight source 62 to improve efficiency. The head-up display device 90 of the present invention uses a dual-axis compensation film 74 to eliminate or reduce elliptical polarized light L3_E, thereby improving the contrast of the head-up display device 90.

FIG11 shows a fourth embodiment of the head-up display device of the present invention. The head-up display device 100 of FIG11 includes a backlight source 62, a polarizing element 64, a polarization control element 66, a display panel 68, a lens assembly 70, a first uniaxial compensation film 76, and a second uniaxial compensation film 78. The backlight source 62 is a single light source, so the stray light problem can be reduced. The backlight source 62 is used to provide a first light ray L1, wherein the first light ray L1 is non-polarized light. The polarizing element 64 is between the backlight source 62 and the display panel 68, and generates a second light ray L2 according to the first light ray L1, wherein the second light ray L2 is linearly polarized light. The polarization control element 66 is between the polarizing element 64 and the display panel 68, and has a plurality of regions (not shown in the figure). The polarization control element 66 generates a third light ray L3 according to the second light ray L2. The polarization control element 66 controls the transmittance of the multiple regions, thereby achieving a regional dimming function. The first uniaxial compensation film 76 is on the surface of the multiple regions of the polarization control element 66 close to the display panel 68. The first uniaxial compensation film 76 generates a fourth light ray L4 according to the third light ray L3. The first uniaxial compensation film 76 is used to convert the elliptical polarized light in the third light ray L3 into linear polarized light. The second uniaxial compensation film 78 is on the surface of the display panel 68 close to the polarization control element 66, and the second uniaxial compensation film 78 generates a fifth light ray L5 to the display panel 68 according to the fourth light ray L4. The fourth light L4 outputted by the first uniaxial compensation film 76 may still contain elliptically polarized light, so the second uniaxial compensation film 78 is used to convert the elliptically polarized light in the fourth light L4 into linearly polarized light. The display panel 68 is used to display and project an image P1. The display panel 68 includes a first polarizer 682, a thin film transistor liquid crystal display 684 and a second polarizer 686. The first polarizer 682 and the second polarizer 686 are respectively arranged on the first side and the second side of the thin film transistor liquid crystal display 684, wherein the first side is opposite to the second side. The backlight source 62, the polarizing element 64, the polarization control element 66, the display panel 68 and the two-axis compensation film 74 of FIG. 10 constitute the image generation unit 12 of FIG. 1. The mirror assembly 70 is arranged on the optical path of the image P1 to reflect the image P1 to the outside of the head-up display device 60. The mirror assembly 70 includes at least one of the free-form mirrors 14 and 16 of FIG. 1 .

The head-up display device 100 of the present invention uses a polarizing element 64 (such as RP or DBEF) and a polarization control element 66 (such as TN or STN) with high transmittance, so the head-up display device 100 has a higher overall transmittance, so the head-up display device 100 can use a lower power backlight source 62 to improve efficiency. The head-up display device 100 of the present invention uses a first uniaxial compensation film 76 and a second uniaxial compensation film 78 to eliminate or reduce elliptical polarized light L3_E, thereby improving the contrast of the head-up display device 100.

The above is only an embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as above by the embodiment, it is not used to limit the present invention. Any person with ordinary knowledge in the relevant technical field can make some changes or modifications to the technical contents disclosed above as equivalent embodiments within the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of the technical solution of the present invention.

20: Driver's eyes

60: Heads-up display device

62: Backlight

64: Polarizing element

66: Polarization control element

68: Display panel

682: First polarizer

684: Thin Film Transistor Liquid Crystal Display

686: Second polarizer

70: Lens set

L1: First Light

L2: Second ray

L3: The third ray

L3_E: elliptically polarized light

L3_L: linearly polarized light

P1: Image

Claims (9)

A head-up display device includes: a backlight source for providing a first light, wherein the first light is non-polarized light; a display panel for displaying and projecting an image; a polarizing element between the backlight source and the display panel, for generating a second light according to the first light, wherein the second light is linearly polarized light; a polarization control element between the polarizing element and the display panel, having a plurality of regions for generating a third light to the display panel according to the second light, wherein the polarization control element controls the transmittance of the plurality of regions; the head-up display device further includes a biaxial compensation film on the surface of the plurality of regions close to the display panel, and generating a fourth light to the display panel according to the third light, wherein the biaxial compensation film is used to convert the elliptical polarized light in the third light into linearly polarized light. The head-up display device of claim 1 further includes a mirror set disposed on the optical path of the image to reflect the image to the outside of the head-up display device. The head-up display device of claim 1 further includes a dual-axis compensation film on the surface of the display panel close to the polarization control element, and generates a fourth light to the display panel based on the third light, wherein the dual-axis compensation film is used to convert the elliptical polarized light in the third light into linear polarized light. The head-up display device of claim 1 further comprises: a first uniaxial compensation film, which is on the surface of the display panel in the plurality of regions and generates a fourth light to the display panel according to the third light, wherein the first uniaxial compensation film is used to convert the elliptical polarized light in the third light into linear polarized light; and a second uniaxial compensation film, which is on the surface of the display panel and close to the polarization control element, and generates a fifth light to the display panel according to the fourth light, wherein the second uniaxial compensation film is used to convert the elliptical polarized light in the fourth light into linear polarized light; wherein the optical axis direction of the first uniaxial compensation film is perpendicular to the direction of the second uniaxial compensation film. A head-up display device as claimed in claim 1, wherein the display panel comprises: a thin film transistor liquid crystal display for displaying the image; a first polarizer disposed on a first side of the thin film transistor liquid crystal display; and a second polarizer disposed on a second side of the thin film transistor liquid crystal display opposite to the first side. A head-up display device as claimed in claim 1, wherein the polarizing element comprises a reflective polarizer. A head-up display device as claimed in claim 1, wherein the polarizing element includes a reflective polarizing brightness enhancement film. A head-up display device as claimed in claim 1, wherein the polarization control element includes a twisted liquid crystal display. A head-up display device as claimed in claim 1, wherein the polarization control element includes a super-twisted liquid crystal display.