Backlight source, head-up display device and vehicle

Abstract

The utility model provides a backlight used in a head-up display device, the backlight comprises at least one lamp string, the lamp string comprises a plurality of lamp banks connected in series, and each lamp bank comprises a backlight or a plurality of backlights connected in series; the output end of each current source is electrically connected with the first end of one lamp string; the controller is configured to generate a corresponding backlight control signal according to image information to be displayed; the driving circuit comprises a logic control unit and a plurality of switch units, and the input end and the output end of each switch unit are electrically connected with the two ends of the corresponding lamp set respectively; the logic control unit is configured to provide a pulse width modulation signal with a corresponding duty ratio for each switch unit according to a backlight control signal; the switch unit is configured to control on-off between the input end and the output end of the switch unit according to the pulse width adjusting signal. The utility model also provides a head-up display device and a vehicle. The loss of the driving circuit can be reduced, and the driving efficiency is improved.

Description

Technical Field

[0001] This disclosure relates to the field of head-up display technology, and more specifically to a backlight, a head-up display device, and a vehicle. Background Technology

[0002] Head-up display (HUD) technology uses optical reflection to project light emitted from an image source onto an imaging window (image panel, windshield, etc.), which then reflects the light into the viewing box to form a virtual image. This virtual image can display desired information, such as vehicle speed and other driving-related information, preventing driver distraction caused by looking down at the instrument panel while driving, thus improving driving safety and providing a better driving experience. In the image source, a backlight provides backlighting to the display panel, which converts this backlighting into image light.

[0003] Head-up displays (HUDs) have two backlight control methods: global backlight control and local dimming. Global backlight control cannot control the backlight of a specific area based on the displayed content, while local dimming has lower driving efficiency and generates more heat. Utility Model Content

[0004] This disclosure aims to address at least one of the technical problems existing in the prior art, and proposes a backlight, a head-up display device, and a vehicle.

[0005] To achieve the above objectives, this disclosure provides a backlight source for use in a head-up display device. The backlight source includes: at least one light string, the light string including multiple light groups connected in series, each light group including one backlight or multiple backlights connected in series; at least one current source, the output terminal of each current source electrically connected to a first terminal of one of the light strings, and the second terminal of the light string electrically connected to a reference voltage terminal; a controller configured to generate a corresponding backlight control signal based on image information to be displayed; and a driving circuit including a logic control unit and multiple switching units, each switching unit corresponding to one light group, the input terminal and output terminal of the switching unit being electrically connected to the two ends of the corresponding light group, respectively; the logic control unit is configured to provide a pulse width modulation signal with a corresponding duty cycle to each of the switching units according to the backlight control signal; and the switching units are configured to control the on / off state between the input terminal and the output terminal of the switching unit according to the pulse width modulation signal, thereby controlling the luminous brightness of the light group.

[0006] In some embodiments, the switching unit includes: a switch driver electrically connected to the logic control unit and configured to output a drive signal switching between a first level potential and a second level potential according to the pulse width modulation signal, wherein the frequency and duty cycle of the drive signal are the same as those of the pulse width modulation signal; and a switching device, wherein the control terminal of the switching device is electrically connected to the switch driver, a first terminal of the switching device serves as the input terminal of the switching unit, and a second terminal of the switching device serves as the output terminal of the switching unit; the switching device is configured to turn on the first terminal and the second terminal of the switching device in response to the first level potential of the drive signal, and to turn off the first terminal and the second terminal of the switching device in response to the second level potential of the drive signal.

[0007] In some embodiments, the switching device includes: a field-effect transistor, wherein the gate of the field-effect transistor serves as the control terminal of the switching device, one of the source and drain of the field-effect transistor serves as a first terminal of the switching device, and the other of the source and drain serves as a second terminal of the switching device.

[0008] In some embodiments, the backlight includes a plurality of light strings and a plurality of current sources, wherein the light strings and the current sources are connected in a one-to-one correspondence.

[0009] In some embodiments, the driving circuit and the light string are mounted on the same driving circuit board.

[0010] In some embodiments, the backlight includes multiple driving circuits connected to the same controller; different driving circuits are connected to different light strings; each driving circuit and the corresponding multiple light strings are disposed on the same driving circuit board, and different driving circuits are located on different driving circuit boards.

[0011] In some embodiments, the driving circuit further includes a fault diagnosis unit, which is configured to acquire the on / off state of the switching unit and feed back the on / off state of the switching unit to the controller; the controller is further configured to determine whether the switching unit has malfunctioned based on the on / off state of each of the switching units.

[0012] In some embodiments, the plurality of backlights in the backlight source are arranged in an array.

[0013] Secondly, this disclosure also provides a head-up display device, comprising: a backlight as described above, the backlight comprising a plurality of backlight zones, each of the backlight zones comprising at least one of the lamp groups; a display panel disposed on the light-emitting side of the backlight, the display panel being used to convert the light from the backlight into image light and output it to the eye box area; the display panel comprising display zones corresponding one-to-one with the backlight zones.

[0014] Thirdly, this disclosure also provides a vehicle, including: the head-up display device described above; and a reflective imaging element, the reflective imaging element being used to reflect image light emitted from the head-up display device to the eye box area.

[0015] In this embodiment, the controller can generate a backlight control signal based on image information. The logic control unit in the drive circuit can provide pulse width modulation signals with corresponding duty cycles to each switching unit based on the backlight control signal. Under the control of the pulse width modulation signal, the switching unit turns on or off its input and output terminals, thereby controlling the brightness of the corresponding lamp group. Therefore, in this embodiment, the brightness of each lamp group can be controlled based on image information, achieving local backlight control. Furthermore, compared to a scheme using multiple parallel channels, in this embodiment, multiple backlight lamps driven by the current source are connected in series to form a lamp string. The current source only needs to adjust the output voltage based on the forward voltage of the entire lamp string. Theoretically, there is no headroom voltage. The overall power loss of the drive structure composed of the current source and the drive circuit mainly lies in the losses of the switching units. Since the losses generated by the switching units are low, the overall loss of the drive structure can be reduced, thereby improving drive efficiency and reducing the heat generated by the backlight. Attached Figure Description

[0016] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings:

[0017] Figure 1 This is a schematic diagram illustrating the application of head-up display devices provided in some examples.

[0018] Figure 2 The circuit schematics for global backlight control are provided in some examples.

[0019] Figure 3 The circuit schematics for local backlight control are provided in some examples.

[0020] Figure 4 The circuit schematics are shown for some embodiments of the backlight provided in this disclosure.

[0021] Figure 5This is a schematic diagram of the partitioning of the backlight provided in some embodiments of this disclosure.

[0022] Figure 6 The circuit schematics are for backlights provided in other embodiments of this disclosure.

[0023] Figure 7 The circuit schematic of the backlight provided in some embodiments of this disclosure is shown below.

[0024] Figure 8 This is a schematic diagram of a head-up display device provided in some embodiments of this disclosure.

[0025] Figure 9 This is a schematic diagram of a backlight and display panel provided in some embodiments of this disclosure.

[0026] Figure 10 This is a schematic diagram illustrating the application of a head-up display device provided in some embodiments of this disclosure to a vehicle. Detailed Implementation

[0027] The specific embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this disclosure.

[0028] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this disclosure. All other embodiments obtained by those skilled in the art based on the described embodiments of this disclosure without creative effort are within the scope of protection of this disclosure.

[0029] Unless otherwise defined, the technical or scientific terms used in the embodiments of this disclosure should be understood in their ordinary sense by one of ordinary skill in the art to which this disclosure pertains. The terms "first," "second," and similar terms used in this disclosure do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, but does not exclude other elements or objects.

[0030] As used herein, “parallel” and “perpendicular” include the described situation and situations that are similar to the described situation, within an acceptable range of deviation, which is determined by those skilled in the art taking into account the measurement under discussion and the error associated with the measurement of a particular quantity (i.e., the limitations of the measurement system). For example, “parallel” includes absolute parallelism and approximate parallelism, where an acceptable range of deviation for approximate parallelism may be, for example, within 5°; “perpendicular” includes absolute perpendicularity and approximate perpendicularity, where an acceptable range of deviation for approximate perpendicularity may also be, for example, within 5°.

[0031] In the description of this disclosure, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this disclosure and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this disclosure.

[0032] Unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this disclosure according to the specific circumstances.

[0033] Figure 1 These are illustrations of head-up display (HUD) applications, shown in some examples. The HUD can be installed on vehicles or other modes of transportation. For example... Figure 1 As shown, the head-up display device includes an image source 100 for outputting image light. The image source 100 includes a backlight unit and a display panel 20 disposed on the light-emitting side of the backlight unit. The backlight unit provides backlight to the display panel 20. The backlight unit may include a backlight 10 and a dimming element disposed on the light-emitting side of the backlight 10. For example, the backlight 10 may include a plurality of backlight lamps 11, and the dimming element includes a plurality of lenses, each lens corresponding to a backlight lamp 11, for adjusting the emission direction of the corresponding backlight lamp 11.

[0034] The display panel 20 is a liquid crystal display panel, which includes multiple pixel units, each pixel unit including multiple pixels, for example, each pixel unit including red pixels, green pixels, and blue pixels; or, for example, each pixel unit including red pixels, green pixels, blue pixels, and white pixels. The display panel 20 is used to convert the backlight provided by the backlight unit into image light. The windshield 200 of the vehicle is used to reflect the image light onto a preset area 300, so that when the observer's eyes are within the preset area 300, they can see the image formed by the image light. At this time, the image seen by the observer is a virtual image 400 formed by the windshield 200 through reflection imaging. The observer can be a driver or a passenger, and the observer can obtain the required vehicle information from the virtual image 400 in front of their line of sight, such as driving speed, fuel consumption, etc., or other information, such as images from virtual rearview mirrors or audio-visual entertainment images.

[0035] The aforementioned preset area 300 is the eyebox area of ​​the head-up display device, specifically the area where the observer's eyes are located and where they can see the image output by the head-up display device. The preset area 300 has a certain size, so even if the observer's eyes are deviated from the center of the preset area 300 by a certain distance, such as a certain distance in the vertical or horizontal direction, as long as they are still within the preset area 300, they can see the image output by the head-up display device.

[0036] In some embodiments, a global backlight control method is used to adjust the brightness of the backlight 11. Specifically, such as... Figure 2 As shown, multiple backlights 11 of the backlight 10 are connected in series and electrically connected to the output of the driver chip 12. The driver chip 12 provides drive current to the backlights 11 to control the brightness of all backlights 11. In the global backlight control method, since all backlights 11 are connected in series to form a current channel, the drive current flowing through each backlight 11 is relatively large; however, the global backlight control method cannot perform local backlight control based on the content displayed on the head-up display.

[0037] In other embodiments, a local backlight control method is used to adjust the brightness of the backlight 11. Specifically, such as... Figure 3 As shown, all the backlights 11 of the backlight 10 form multiple current channels connected in parallel, and each current channel includes multiple backlights 11 connected in series. Each output terminal of the driver chip 12 corresponds to one current channel, and each output terminal is electrically connected to one end of the corresponding current channel. The other end of the current channel is electrically connected to the first voltage terminal V1. The driver chip 12 uses a current sink to provide driving current to the backlights 11 on the current channel. Figure 3In this system, the brightness of the backlight 11 on each current channel can be controlled according to the image content. For example, when the brightness of a certain area of ​​the image is low, the brightness of the backlight 11 corresponding to that area can be reduced, thereby reducing the power consumption of the backlight 10 and improving the contrast of the image.

[0038] and Figure 2 compared to, Figure 3 The increased overall power loss and heat generation of the driver chip 12 are due to the following reasons: The driver chip 12 uses a current trap for driving, which has a headroom voltage (i.e., voltage margin, which is the voltage drop consumed internally by the circuit). The larger the current in the current trap, the higher the headroom voltage will be. Furthermore, each current channel has a headroom voltage, where Vheadroom = Vled - Vfs, where Vled is the constant voltage drive voltage for each current channel, and Vfs is the serial voltage of the current channel. Since the forward voltages of each backlight lamp differ, the serial voltages of each current channel also differ, leading to differences in the headroom voltages of each channel. To ensure normal operation, Vled needs to be increased to ensure that the headroom voltage of each channel meets the requirements, thus increasing the overall power loss of the driver chip 12, which in turn reduces driving efficiency and increases heat generation. In addition, in actual design, one design scheme is to set the driver chip 12 on the driver board (PCB board) and the backlight 11 on another lamp board, and then interconnect the driver board and the lamp board, which increases the design difficulty and cost; another design scheme is to design the driver chip 12 and the backlight 11 on the same driver board. In this case, in order to meet the wiring requirements of the driver chip 12, the number of layers of the driver board needs to be increased, which will be more expensive.

[0039] To at least solve one of the aforementioned technical problems, this disclosure provides a backlight 10 for use in a head-up display device. For example... Figure 4 As shown, the backlight 10 includes: at least one LED string 110, at least one current source 13, a controller 14, and a drive circuit 15.

[0040] The light string 110 includes multiple light groups 11a connected in series. Each light group 11a includes a backlight 11, or may include multiple backlights 11 connected in series. Figure 4 The following explanation uses each lamp group 11a as an example, which includes multiple backlights 11 connected in series.

[0041] For example, the current source 13 can be a constant current source, and the output terminal of each current source 13 is electrically connected to the first terminal of a lamp string 110, and the second terminal of the lamp string 110 is electrically connected to the reference voltage terminal Vref. The reference voltage terminal Vref can be a low-level signal terminal, such as a ground terminal.

[0042] The controller 14 is configured to generate corresponding backlight control signals based on the image information to be displayed. These backlight control signals are used to indicate whether each lamp group 11a emits light and its brightness level. For example, ... Figure 5 As shown, the backlight 10 includes multiple backlight zones 10a, each of which is equipped with one or more lamp groups 11a; the display panel of the head-up display device includes display zones that correspond one-to-one with the backlight zones 10a. The controller 14 determines the target brightness of each backlight zone 10a based on the image information corresponding to each display zone, and generates a corresponding backlight control signal, so that the drive circuit 15 can control the brightness of the lamp groups 11a in each backlight zone 10a according to the backlight control signal, thereby realizing local backlight control.

[0043] The driving circuit 15 includes a logic control unit 151 and multiple switching units 152. Each switching unit 152 corresponds to a lamp group 11a, and the input and output terminals of the switching unit 152 are electrically connected to the two ends of the corresponding lamp group 11a, respectively. The logic control unit 151 is configured to provide pulse width modulation signals with corresponding duty cycles to each switching unit 152 according to the backlight control signal. The switching units 152 are configured to control the on / off state between their input and output terminals according to the pulse width modulation signal, thereby controlling the brightness of the lamp group 11a.

[0044] The pulse width modulation (PWM) signal switches between high and low potentials. Switching unit 152 can turn on its input and output terminals when the PWM signal is at either a high or low potential, thus short-circuiting the corresponding lamp group 11a. When the PWM signal is at either a high or low potential, it can disconnect the input and output terminals, allowing the current supplied by current source 13 to flow through lamp group 11a, causing it to emit light. It should be understood that due to the persistence of vision, when the frequency of the PWM signal is high, the human eye will not perceive the flickering of the backlight 11. Furthermore, given a fixed current supplied by current source 13, the longer the light emission duration of lamp group 11a within each cycle of the PWM signal, the higher the perceived brightness; conversely, the shorter the light emission duration of lamp group 11a within each cycle of the PWM signal, the lower the perceived brightness. Therefore, by controlling the duty cycle of the PWM signal, the brightness of lamp group 11a can be controlled.

[0045] In this embodiment, the controller 14 can generate a backlight control signal based on image information; the logic control unit 151 in the drive circuit 15 can provide pulse width modulation signals with corresponding duty cycles to each switching unit 152 based on the backlight control signal. Under the control of the pulse width modulation signal, the switching unit 152 turns its input and output terminals on or off, thereby controlling the brightness of the corresponding lamp group 11a. Therefore, in this embodiment, the brightness of each lamp group 11a can be controlled based on image information to achieve local backlight control. Furthermore, with... Figure 3 In contrast, in this embodiment of the present disclosure, the multiple backlights 11 driven by the current source 13 are connected in series to form a light string 110. The current source 13 only needs to adjust the output voltage according to the forward voltage of the entire light string 110. Theoretically, there is no headroom voltage. The overall power loss of the driving structure composed of the current source 13 and the driving circuit 15 is mainly due to the loss of the switching unit 152. Since the loss generated by the switching unit 152 is low, the overall loss of the driving structure can be reduced, thereby improving the driving efficiency and reducing the heat generated by the backlight 10.

[0046] In some embodiments, such as Figure 4 As shown, the switching unit 152 includes a switch driver 152a and a switching device 152b.

[0047] The switch driver 152a is electrically connected to the logic control unit 151 and is configured to output a drive signal that switches between a first level potential and a second level potential according to the pulse width modulation signal. The frequency of the drive signal is the same as the frequency of the pulse width modulation signal, and the duty cycle of the drive signal is the same as the duty cycle of the pulse width modulation signal.

[0048] The control terminal of the switching device 152b is electrically connected to the switch driver 152a. The first terminal of the switching device 152b serves as the input terminal of the switching unit 152, and the second terminal of the switching device 152b serves as the output terminal of the switching unit 152. The switching device 152b is configured to turn on its first and second terminals in response to a first level potential of the drive signal, and to turn off its first and second terminals in response to a second level potential of the drive signal.

[0049] In this circuit, the frequency and duty cycle of the driving signal and the pulse width modulation signal are the same, but the amplitude of the driving signal and the amplitude of the pulse width modulation signal can be different. The switch driver 152a is equivalent to adjusting the amplitude of the pulse width modulation signal to ensure that when the switch device 152b is turned on, the driving signal can reach the turn-on threshold of the switch device 152b, so as to better control the turn-on and turn-off of the switch device 152b.

[0050] In some embodiments, the control terminal of the switching device 152b is electrically connected to the switch driver 152a. The first terminal of the switching device 152b serves as the input terminal of the switching unit 152, and the second terminal of the switching device 152b serves as the output terminal of the switching unit 152. The switching device 152b is configured to turn on its first and second terminals in response to a first level potential of the drive signal, and to turn off its first and second terminals in response to a second level potential of the drive signal.

[0051] In some embodiments, the switching device 152b can be a field-effect transistor, with the gate of the field-effect transistor serving as the control terminal of the switching device 152b, one of the source and drain of the field-effect transistor serving as the first terminal of the switching device 152b, and the other of the source and drain serving as the second terminal of the switching device 152b.

[0052] For example, if the first voltage level is high and the second voltage level is low, then the field-effect transistor can be an N-type transistor; or, for another example, if the first voltage level is low and the second voltage level is high, then the field-effect transistor can be a P-type transistor.

[0053] Because the internal resistance of the field-effect transistor is low, approximately tens of mΩ, when the field-effect transistor is turned on and the corresponding lamp group 11a is short-circuited, the power loss on the field-effect transistor is approximately in the mW range, which is negligible compared to the overall power of the drive circuit 15. Therefore, the power loss generated by the drive circuit is small, thereby reducing the heat generated. Furthermore, because the internal resistance of the field-effect transistor is low, a higher current can flow when the field-effect transistor is turned on, thereby allowing a higher current to flow through the entire current path and achieving high-power drive of the backlight 11.

[0054] Furthermore, since the driving circuit 15 generates relatively little heat in this embodiment, in some embodiments, the driving circuit 15 and the corresponding light string 110 can be mounted on the same circuit board, together with... Figure 3 In contrast, since one driving circuit 15 in this embodiment is connected to one light string 110, when the driving circuit 15 and the light string 110 are set on the same circuit board, there is no need to make complex wiring between the driving circuit 15 and the light string 110, thereby eliminating the need to increase the number of circuit board layers and reducing the complexity of peripheral auxiliary circuits, thus effectively reducing the complexity and cost of the design.

[0055] In some embodiments, such as Figure 4As shown, the drive circuit 15 may further include a fault diagnosis unit 153, wherein the fault diagnosis unit 153 is configured to acquire the on / off state of the switch unit 152 and feed back the on / off state of the switch unit 152 to the controller 14. The controller 14 is further configured to determine whether the switch unit 152 has malfunctioned based on the on / off state of each switch unit 152, thereby facilitating fault detection and maintenance of the drive circuit 15.

[0056] In some embodiments, such as Figure 4 As shown, the backlight 10 includes a string of lights 110 and a current source 13. The multiple backlights 11 in the string of lights 110 can be arranged in an array.

[0057] In some embodiments, the driving circuit 15 can be integrated into a driving chip, which has a communication interface 154 for communicating with the controller 14. This communication interface 154 can be an I2C, SPI, UART, CAN, or other interface. Alternatively, in practical applications, whether to include an interface chip or transceiver 16 can be determined based on actual needs.

[0058] In some embodiments, such as Figure 4 As shown, the controller 14 can also be electrically connected to the current source 13 for power-on and power-off control of the current source 13.

[0059] Figure 6 This is a circuit schematic diagram of the backlight 10 provided in some other embodiments of this disclosure. Figure 6 The backlight 10 shown is Figure 4 The backlight 10 shown is similar, the only difference being that... Figure 6 In the backlight 10, there are multiple light strings 110 and multiple current sources 13, with each light string 110 and current source 13 connected in a one-to-one correspondence.

[0060] The driving currents of the multiple current sources 13 can be the same or different, and can be set according to the optical brightness requirements.

[0061] When the backlight 10 includes multiple light strings 110, the multiple backlights 11 in the backlight 10 can also be arranged in an array. The form of the array arrangement (e.g., the number of rows, the number of columns, and the spacing between adjacent rows and adjacent columns) is not limited.

[0062] Figure 7 This is a circuit schematic diagram of the backlight 10 provided in some embodiments of the present disclosure. Figure 7 The backlight 10 shown is Figure 6 The backlight 10 shown is similar, the only difference being that... Figure 7In this backlight 10, there are multiple driving circuits 15, each of which is electrically connected to a light string 110. Different driving circuits 15 are connected to different light strings 110. Multiple driving circuits 15 are connected to the same controller 14.

[0063] When the backlight 10 includes multiple driving circuits 15 and multiple light strings 110, the multiple backlights 11 in the backlight 10 are also arranged in an array, and the form of the array arrangement (e.g., the number of rows, the number of columns, the spacing between two adjacent rows and two adjacent columns) is not limited.

[0064] By setting up multiple drive circuits 15, the arrangement of the backlight 11 and the brightness control of different light strings 110 can be made more flexible.

[0065] In some examples, when the backlight 10 includes multiple driving circuits 15 and multiple light strings 110, each driving circuit 15 and the corresponding controlled light string 110 can be integrated on the same driving board, thereby simplifying the structure of the backlight 10, while different driving circuits 15 are located on different driving circuit boards.

[0066] This disclosure also provides a head-up display device, such as... Figure 8 and Figure 9 As shown, the head-up display device includes a display panel 20 and a backlight 10 as described in any of the above embodiments, wherein, as Figure 9 As shown, the backlight 10 includes multiple backlight zones 10a, each of which includes at least one lamp group 11a. A display panel 20 is disposed on the light-emitting side of the backlight 10. The display panel 20 converts the light from the backlight 10 into image light and outputs it to the eye-box area. The display panel 20 includes display zones 20a corresponding one-to-one with the backlight zones 10a. The controller 14 generates corresponding backlight control signals based on the information of the image to be displayed in each display zone 20a.

[0067] like Figure 8 As shown, the head-up display device may also include an output element 700, which is used to receive image light output from the display panel and output the image light to the eye box area 300.

[0068] In some embodiments, such as Figure 8 As shown, the head-up display device may also include a housing 600, within which the backlight 10, display panel 20, backlight control device 500, and output element 700 are all located. The housing 600 has an opening 601 so that image light can be emitted from the opening 601.

[0069] In some embodiments, such as Figure 8As shown, the output element 700 may include an amplification element 701, which enables the head-up display device to have a greater imaging distance and a larger imaging size. For example, the imaging distance and imaging size can be changed by altering the magnification of the amplification element 701. The magnification can be changed by adjusting parameters such as the curvature of the amplification element 701.

[0070] In some embodiments, the magnifying element 701 can be a curved reflector, optionally a concave reflector, that is, a reflector with a concave curved reflective surface. When the curved reflector is a concave reflector, if the optical distance between the display panel 20 and the concave reflector is less than the focal length of the concave reflector, the concave reflector forms an upright, magnified virtual image based on the image output from the display panel. For example, according to the imaging properties of a concave reflector, when the optical distance between the display panel 20 and the concave reflector is less than the focal length of the concave reflector (i.e., the display panel 20 is within one focal length of the concave reflector), the image distance of the concave reflector increases as the optical distance between the display panel 20 and the concave reflector increases. In other words, the greater the optical distance between the display panel 20 and the concave reflector, the greater the distance between the observer and the virtual image they see.

[0071] Optionally, the curved mirror is a free-form mirror, that is, a mirror with a free-form surface, or a surface that does not have rotational symmetry, in order to improve the imaging quality of the head-up display device.

[0072] In some alternative embodiments, the amplification element 701 may be an optical waveguide or a holographic optical element.

[0073] like Figure 8 As shown, the output element 700 is not limited to only including the amplification element 701, but may also include a plane mirror 702, which adjusts the optical path of the image light propagation, thereby reducing the size of the head-up display device.

[0074] This disclosure also provides a vehicle that includes the head-up display device and reflective imaging element described in the above embodiments. For example, such as Figure 10As shown, the reflective imaging element is a windshield 200, which reflects the image light emitted from the head-up display device to the eye-box region 300. The windshield 200 has a semi-transparent, semi-reflective characteristic, allowing the image light emitted from the head-up display device to be reflected to the eye-box region 300. Simultaneously, light from outside the vehicle can also pass through the windshield 200 to reach the eye-box region 300, enabling the observer's eyes to simultaneously see both the image formed by the head-up display device and the external scenery when positioned in the eye-box region 300. In this embodiment, "semi-transparent, semi-reflective" means that the windshield 200 can both transmit and reflect light, and is not limited to transmitting 50% and reflecting 50%. For example, the transmittance of visible light may be greater than or equal to 70%.

[0075] It is understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of this disclosure, and this disclosure is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and substance of this disclosure, and these modifications and improvements are also considered to be within the scope of protection of this disclosure.

Claims

1. A backlight source for use in a head-up display device, characterized in that, The backlight includes: At least one light string, the light string comprising multiple light groups connected in series, each light group comprising a backlight or multiple backlights connected in series; At least one current source, the output of each current source being electrically connected to a first end of one of the light strings, and the second end of the light string being electrically connected to a reference voltage terminal; The controller is configured to generate corresponding backlight control signals based on the image information to be displayed; The driving circuit includes a logic control unit and multiple switching units, each switching unit corresponding to a lamp group. The input and output terminals of the switching unit are electrically connected to the two ends of the corresponding lamp group, respectively. The logic control unit is configured to provide a pulse width modulation signal with a corresponding duty cycle to each switching unit according to the backlight control signal. The switching units are configured to control the on / off state between their input and output terminals according to the pulse width modulation signal, thereby controlling the brightness of the lamp group.

2. The backlight according to claim 1, characterized in that, The switching unit includes: A switch driver, electrically connected to the logic control unit, and configured to output a drive signal that switches between a first level potential and a second level potential according to the pulse width modulation signal, wherein the frequency and duty cycle of the drive signal are the same as those of the pulse width modulation signal. A switching device, wherein the control terminal of the switching device is electrically connected to the switch driver, the first terminal of the switching device serves as the input terminal of the switching unit, and the second terminal of the switching device serves as the output terminal of the switching unit; the switching device is configured to turn on the first terminal and the second terminal of the switching device in response to a first level potential of the drive signal, and to turn off the first terminal and the second terminal of the switching device in response to a second level potential of the drive signal.

3. The backlight according to claim 2, characterized in that, The switching device includes: A field-effect transistor (FET), wherein the gate of the FET serves as the control terminal of the switching device, one of the source and drain of the FET serves as the first terminal of the switching device, and the other of the source and drain serves as the second terminal of the switching device.

4. The backlight according to any one of claims 1 to 3, characterized in that, The backlight includes multiple light strings and multiple current sources, with each light string and current source connected in a one-to-one correspondence.

5. The backlight according to claim 4, characterized in that, The driving circuit and the light string are mounted on the same driving circuit board.

6. The backlight according to any one of claims 1 to 3, characterized in that, The backlight includes multiple driving circuits connected to the same controller; different driving circuits are connected to different light strings; each driving circuit and the corresponding multiple light strings are arranged on the same driving circuit board, and different driving circuits are located on different driving circuit boards.

7. The backlight according to any one of claims 1 to 3, characterized in that, The driving circuit further includes a fault diagnosis unit, which is configured to acquire the on / off state of the switch unit and feed back the on / off state of the switch unit to the controller. The controller is also configured to determine whether a switch unit has malfunctioned based on the on / off state of each switch unit.

8. The backlight according to any one of claims 1 to 3, characterized in that, The backlights in the backlight source are arranged in an array.

9. A head-up display device, characterized in that, include: The backlight source as described in any one of claims 1 to 8, the backlight source comprising a plurality of backlight zones, each of the backlight zones comprising at least one of the lamp groups; The display panel is disposed on the light-emitting side of the backlight and is used to convert the light from the backlight into image light and output it to the eye box area. The display panel includes display zones that correspond one-to-one with the backlight zones.

10. A vehicle, characterized in that, include: The head-up display device as claimed in claim 9; A reflective imaging element is used to reflect image light emitted from the head-up display device onto the eye box area.

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