Projection equipment

Abstract

An embodiment of the present invention discloses a projection device comprising a light source device, a spatial light modulator, and a control device; the light source device includes at least one laser unit; the control device is configured to obtain brightness distribution information of a current image frame based on an image signal to be displayed, and to control the drive current of the laser unit based on the brightness distribution information of the current image frame and lifetime data of the laser unit, so that the drive current exceeds the rated drive current during at least a portion of the current image frame time; the spatial light modulator is disposed in the optical path of light emitted by the light source device and is configured to modulate the light emitted by the light source device to obtain a modulated image. The above-described projection device can fully utilize the relationship between the lifetime of the laser unit and the drive current, ensuring that the light source device achieves high-brightness display while meeting lifetime requirements.

Description

Technical Field

[0001] The present invention relates to the field of projection display technology, and more particularly, to a projection device. Background Art

[0002] With the development of display technology, projection equipment is increasingly being used in a wide range of applications, including educational projectors, home projectors, and engineering projectors. Projection technology has brought significant changes to people's lives, learning, and work. Demand for display quality in projection equipment continues to increase, as does the demand for high-brightness displays. High dynamic range (HDR) projection systems increase the contrast and peak brightness of projector output, allowing both bright and dark areas of the image to display rich grayscale information, significantly improving the image quality and the audience's viewing experience. HDR technology is becoming a research focus in the projection display field.

[0003] Currently, one solution to achieve HDR projection systems is to use Local Dimming technology of LCD backlight. This technical solution uses a laser array as the light source of the projection device. Each laser is responsible for illuminating an area. During projection display, the luminous intensity of each laser light source is dynamically controlled according to the brightness of each area of ​​the projected image to achieve high-contrast display. However, due to the spatial imbalance of the brightness of the projected image, the lasers irradiating different areas attenuate differently, so after playing the image for a period of time, the remaining life of the lasers in different areas is different. Therefore, how to balance the brightness and life of the light source is an urgent problem to be solved. Summary of the Invention

[0004] An embodiment of the present invention provides a projection device to improve the above-mentioned problem.

[0005] An embodiment of the present invention provides a projection device, including a light source device, a spatial light modulator and a control device; the light source device includes at least one laser unit; the control device is used to obtain brightness distribution information of a current image frame based on an image signal to be displayed, and adjust the driving current of the laser unit based on the brightness distribution information of the current image frame and life data information of the laser unit, so that the adjusted actual driving current is greater than the rated driving current during at least part of the time period within the current image frame; the spatial light modulator is arranged in the optical path of light emitted by the light source device, and is used to modulate the light emitted by the light source device to obtain a modulated image.

[0006] Furthermore, the control device is used to determine the ideal driving current of the laser unit according to the brightness distribution information of the current image frame, and adjust the ideal driving current of the laser unit according to the life data information of the laser unit to obtain the actual driving current.

[0007] Furthermore, the life data information of the laser unit includes the consumed life and usage time of the laser unit. When the consumed life of the laser unit is less than the usage time, the control device adjusts the driving current of the laser unit so that the adjusted actual driving current is greater than the rated driving current during at least part of the time period within the current image frame time.

[0008] Furthermore, the actual driving current of the laser unit during the current image frame time is less than or equal to the maximum cut-off current of the laser unit.

[0009] Furthermore, the maximum cutoff current of the laser unit is determined by the consumed life of the laser unit and the ratio of the consumed life of the laser unit to the used time.

[0010] Furthermore, within the current image frame time, the lifetime decay rate of the laser unit at the actual driving current is less than or equal to the maximum single-frame lifetime decay rate of the laser unit at the maximum cutoff current driving.

[0011] Furthermore, after a preset time of use, the maximum single-frame lifetime decay rate of the laser unit is a certain value.

[0012] Furthermore, the maximum single-frame life decay rate of the laser unit within the current image frame time is determined by the maximum life consumption rate of the laser unit during the current usage time and the maximum life consumption rate when the designed life of the laser unit is reached.

[0013] Furthermore, the maximum single-frame lifetime decay rate of the laser unit within the current image frame time is r D :

[0014]

[0015] Where: L T is the usage time of the laser unit, L d is the design life of the laser unit, a is the usage time of the laser unit L T b is the maximum life decay rate when the laser unit reaches its design life.

[0016] Furthermore, the control device is also used to calculate the life consumption information of the laser unit within the current image frame time to update the life data information of the laser unit.

[0017] Furthermore, the control device is used to calculate the life consumed by the laser unit in the current image frame; and subtract the life consumed by the laser unit in the current image frame from the remaining life of the laser unit before the current image frame is played to obtain updated life data information of the laser unit.

[0018] In the projection device provided by an embodiment of the present invention, the light source device includes at least one laser unit. When displaying each frame of an image, the control device adjusts the driving current of the laser unit based on the brightness distribution information of the current image frame and the life data information of the laser unit, so that the adjusted actual driving current is greater than the rated driving current during at least part of the time period within the current image frame time, so that the laser unit outputs high-brightness light for modulation by the spatial light modulator. This solution determines the driving current of the laser unit based on the brightness of the image to be displayed and the life of the laser unit, fully utilizing the relationship between the life of the laser unit and the driving current. This allows the laser unit to intermittently operate under conditions exceeding its rated driving current to output light with higher peak brightness while not affecting the service life of the system. This ensures that the light source device can achieve high-brightness display while meeting the life requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0020] Figure 1 The figure shows a module block diagram of a projection device proposed in an embodiment of the present invention.

[0021] Figure 2 A schematic diagram of functional modules of a control device for a projection device according to an embodiment of the present invention is shown.

[0022] Figure 3 A flowchart of a working process of a projection device proposed in an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0023] The following will provide a clear and complete description of the technical solutions in the embodiments of the present invention, in conjunction with the accompanying drawings. Obviously, the described embodiments are only a portion of the embodiments of the present invention, and not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention. The following will provide a detailed description of the projection device provided by the present invention, in conjunction with the accompanying drawings and specific embodiments.

[0024] See Figure 1 , Figure 1The following is a block diagram of a projection device 100 provided in an embodiment of the present invention. The projection device 100 may be, but is not limited to, a device with a projection function, such as a laser TV, an educational projector, a micro-projector, or a cinema projector. It may also be a computer system connected to a device with a projection function and utilizing the device's ranging sensor, such as a personal computer, laptop, tablet, or smartphone connected to the projection device. It should be noted that the projection direction of the projection device in the embodiments of the present application is not limited and may be rear projection or front projection.

[0025] The projection device 100 includes a control device 10, a light source device 30, and a spatial light modulator 40. The light source device 30 includes at least one laser unit. The control device 10 is configured to obtain brightness distribution information of the current image frame based on the image signal to be displayed, and to adjust the drive current of the laser unit based on the brightness distribution information of the current image frame and the life data of the laser unit, so that the adjusted actual drive current exceeds the rated drive current for at least part of the current image frame time. The spatial light modulator 40 is disposed in the optical path of the light emitted by the light source device 30 and is configured to modulate the light emitted by the light source device 30 to obtain a modulated image.

[0026] In the above-mentioned projection device 100, the light source device 30 includes at least one laser unit. When displaying each frame of the image, the control device 10 adjusts the driving current of the laser unit according to the brightness distribution information of the current image frame and the life data information of the laser unit, so that the adjusted actual driving current is greater than the rated driving current during at least part of the time period within the current image frame time, so that the laser unit outputs high-brightness light for modulation by the spatial light modulator 40. This scheme determines the driving current of the laser unit according to the brightness of the image to be displayed and the life of the laser unit, and fully utilizes the relationship between the life of the laser unit and the driving current. This allows the laser unit to intermittently work under conditions exceeding its rated driving current to output light with higher peak brightness without affecting the service life of the projection device 100, thereby ensuring that the light source device 30 can achieve high-brightness display while meeting the life requirements.

[0027] In some embodiments, the projection device 100 further includes a light source driver and an imaging element. The light source driver is connected to the control device 10 and the light source device 30, respectively. The control device 10 is configured to receive an image signal to be displayed and generate a control signal based on the image signal to be displayed. The light source driver is configured to receive the control signal sent by the control device 10 and output a driving current to drive the light source device 30 based on the control current output, thereby illuminating the light source device 30. The light source driver adjusts the driving current input to the light source device 30 based on the control signal to drive the light source device 30. For the projection device 100 that incorporates dynamic light source modulation technology, the driving current of the light source device 30 varies with the content of the displayed image. The light source device 30 is configured to emit light source light, and the spatial light modulator 40 is configured to modulate the light source light emitted by the light source device 30 based on the image signal to generate image light having a modulated image. The imaging element is configured to receive the image light generated by the spatial light modulator 40 and project the image light onto a predetermined location or predetermined element (such as a projection screen or wall) to display the projected image.

[0028] The control device 10 of the projection device 100 provided in this application will be introduced in detail below.

[0029] See also Figure 2 The control device 10 may include a signal processing module 11, an adjustment module 12 and a life management module 13, wherein the life management module 13 includes a storage unit for storing the life data information of the laser unit. The signal processing module 11 is used to obtain the brightness distribution information of the current image frame based on the image signal to be displayed, and determine the ideal driving current of the laser unit based on the brightness distribution information of the current image frame. The adjustment module 12 adjusts the ideal driving current of the laser unit according to the life data information of the laser unit to obtain the actual driving current of the adjusted laser unit. The laser unit emits light under the drive of the actual driving current so that the laser unit outputs light of the target brightness. The life management module 13 is used to calculate the life consumption information of the laser unit in the current image frame to update the life data information of the laser unit. The above modules can be program modules running in a computer-readable storage medium. The purpose and work of the above modules are as follows:

[0030] The signal processing module 11 is used to obtain the brightness distribution information of the current image frame based on the image signal to be displayed, and to determine the ideal driving current of the laser unit based on the brightness distribution information of the current image frame. The image signal to be displayed can be stored locally in the projection device, or it can be an image signal received by the projection device based on a data connection (such as a local area network data connection or a wide area network data connection, etc.). Among them, the image signal can come from image content that is stored in advance (for example, the audio and video data to be projected are copied to the projection device for storage in advance) or stored in real time (for example, a mobile hard disk storing the audio and video data to be projected is inserted into the projection device). The specific storage method is not limited; the image content can be the image content in a video file, the image content in a picture file, etc., and the embodiments of the present application do not limit this.

[0031] In an embodiment of the present application, the projection device can count the brightness distribution of the current image frame according to its own type and the image signal to be displayed. As an embodiment, the projection device can be a projection device based on global dimming technology, in which case it is only necessary to count the maximum brightness of the entire screen. For a projection device using local dimming, it is necessary to count the maximum brightness of each area in a region-by-region manner. For a projection device using dynamic color gamut technology, it is necessary to count the maximum brightness of different primary colors in the entire screen. For a projection device using a scanning light source, it is necessary to convert the brightness distribution of the two-dimensional screen into a brightness change curve on the scanning path.

[0032] After acquiring the brightness distribution information of the current image frame, the signal processing module 11 generates an ideal drive current I(t) for the laser unit based on this brightness distribution information. This ideal drive current I(t) represents the ideal brightness of the light output by the corresponding laser unit. The ideal drive current I(t) for the laser unit can be understood as the drive current without considering the actual operating conditions and lifespan data of the laser unit. Based on the brightness distribution (brightness curve) of the current image frame, the signal processing module 11 determines the ideal drive current I(t) for the laser unit required to display the current image frame.

[0033] Adjustment module 12 adjusts the ideal drive current I(t) of the laser unit based on the lifetime data of the laser unit to obtain an actual drive current I'(t). The actual drive current I'(t) of the laser unit represents the actual brightness of the light output by the corresponding laser unit. This actual drive current I'(t) is greater than the rated drive current during at least a portion of the current image frame time. This indicates that the laser unit is in an overcurrent drive state during at least a portion of the current image frame time, resulting in the laser emitting light with higher brightness, thereby meeting the brightness requirements of the light source device for HDR.

[0034] In the embodiment of the present application, the spatial light modulator 40 includes but is not limited to a digital micro-mirror device (DMD), and may also be a liquid crystal display panel (LCD) or liquid crystal on silicon (LCOS). For ease of explanation, the spatial light modulator 40 is exemplified by a digital micro-mirror device, but this is not intended to limit the scope of the present invention. The spatial light modulator 40 includes a plurality of micro-mirror units, each of which corresponds to a pixel of the modulated image. When the micro-mirror unit is in the "on" state, the micro-mirror unit reflects light from the light source to the corresponding pixel area, and the corresponding pixel is in the "bright" state. When the micro-mirror unit is in the "off" state, the micro-mirror unit does not reflect light from the light source to the corresponding pixel area, and the corresponding pixel is in the "dark" state. The light emitted by the light source device 30 is irradiated on the spatial light modulator 40. The spatial light modulator 40 modulates the light emitted by the light source device 30 according to the image signal to be displayed. During the current image frame time, the adjustment module 12 adjusts the ideal driving current I(t) of the laser unit according to the life data information of the laser unit, so that the adjusted actual driving current I'(t) is greater than the rated driving current during at least part of the time period within the current image frame time. Compared with continuous constant current drive, the brightness of the light emitted by the light source device 30 can be improved when it operates in a current overshoot manner.

[0035] Specifically, the current image frame time includes multiple bit-plane modulation periods (e.g., 8 or 10 bits). The adjustment module 12 adjusts the ideal drive current I(t) of the laser unit based on the lifetime data of the laser unit, so that the adjusted actual drive current I'(t) exceeds the rated drive current during at least one bit-plane modulation period within the current image frame time. If the laser unit drive current is at the rated drive current and the laser unit's luminance is L, then during the at least one bit-plane modulation period, the actual drive current I'(t) of the laser unit is greater than the rated drive current. At this time, the luminance of the laser unit can reach ML (M>1), thereby improving the luminance of the light source device 30 during the at least one bit-plane modulation period and ensuring that each pixel of the modulated image reaches a preset grayscale value.

[0036] In the embodiment of the present application, the control device 10 determines a corresponding lifetime management strategy for the laser unit (i.e., the optimization process for the ideal control current provided herein) based on the lifetime data of the laser unit, thereby enabling the laser unit to output light with a higher peak brightness while maintaining the lifetime of the system. Specifically, the lifetime data of the laser unit is used to characterize factors that may affect the actual lifetime of the laser unit. The lifetime data of the laser unit includes the consumed lifetime and the elapsed time of the laser unit.

[0037] Regardless of the type of laser projection device, after a period of use, the laser unit life will inevitably decay, which means that the remaining life of the laser unit will be reduced. The life of the laser unit that has been consumed can be determined by the display principle of the laser projection device and the actual operating conditions of the laser unit. For example, in ordinary laser projection devices, the laser unit operates at a constant current, so the laser unit's life decay rate is a constant value. In laser projection devices that use global dimming technology, the laser unit determines the output of the laser unit based on the maximum brightness of the image. Therefore, the laser unit's life decay rate is a value that changes with the operating conditions. However, since all laser units in global dimming technology change uniformly, the life decay rate of each laser unit is the same. If a laser projection device uses dynamic color gamut technology (HDC technology), laser light units of different primary colors (such as blue lasers that produce fluorescence, red and green lasers for color compensation, etc.) will produce different modulation curves based on the content of the image, so laser units of different primary colors have different life decay rates. For laser projection equipment that uses local dimming technology, due to the spatial imbalance of picture brightness, the laser units in different areas illuminate different primary color light laser units, so after playing the picture for a period of time, the remaining life of the laser units in different areas is different.

[0038] Catastrophic optical damage (COD) is the most important factor affecting the life of the laser unit. The life of the laser unit under high current drive is mainly determined by COD. Taking into account other factors affecting the life of the laser unit, such as COD and normal material attenuation of the laser unit, the life of the laser unit L can be expressed as:

[0039]

[0040] Where: I is the continuous constant driving current of the laser unit, T is the operating temperature of the laser unit, I and T are used to characterize the working conditions of the laser unit during actual operation. When the driving current I of the laser unit is greater than the COD threshold current I at this temperature th (T), COD will occur, so the laser unit life is 0 at this current. When the driving current I of the laser unit is less than the threshold current I th (T), COD will not occur in the laser unit. Under such an environment and working conditions, the life of the laser unit L can be expressed as a function of current and temperature (i.e., the above formula (1)). The value of this function decreases as the driving current increases, which means that the larger the driving current, the shorter the life of the laser unit. The inherent life curve f(I,T) of the laser unit can be understood as the inherent characteristics of the laser unit, which can be preset in the projection device (for example, pre-stored in the memory of the projection device) or obtained through laser unit aging test.

[0041] Assume that the design life of the laser unit is L d , then the life r(I,T) consumed by the laser unit in unit time under the working conditions (driving current I and working temperature T) can be expressed as:

[0042]

[0043] After the laser unit has been used for time t0, its consumed life L(t0) can be expressed as:

[0044]

[0045] Then the over-life utilization rate O(t0) of the laser unit can be defined as:

[0046]

[0047] If O(t0) is greater than 1, it means that the actual operating conditions of the laser unit during the used time t0 have exceeded the operating conditions designed for the design life. If no subsequent changes are made to the laser unit, the actual life of the laser unit will be shorter than the design life. If O(t0) is less than 1, it means that the actual operating conditions of the laser unit during the used time t0 have not exceeded the operating conditions designed for the design life. If no subsequent changes are made, the actual life of the laser unit will be longer than or equal to the design life. Therefore, for laser units with O(t0) less than 1, their drive current is increased so that they operate under overcurrent drive. That is, when the consumed life of the laser unit is less than the used time, the control device 10 adjusts the drive current of the laser unit so that the adjusted actual drive current is greater than the rated drive current for at least part of the current image frame time, thereby achieving a balance between outputting maximum brightness and meeting the design life.

[0048] Since the life of the laser unit under high current driving is mainly determined by COD, for the laser unit driven by overcurrent, in order to prevent COD from occurring in the laser unit, it is necessary to limit the upper limit of its driving current.

[0049] Furthermore, the signal processing module 11 determines the overcurrent drive magnification p of the laser unit based on the ideal control current I(t) and the rated drive current I0 of the laser unit. The overcurrent drive magnification p of the laser unit is represented by the ratio of the ideal control current I(t) of the laser unit to the rated drive current I0 of the laser unit, that is, the overcurrent drive magnification p of the laser unit can be expressed as:

[0050]

[0051] If p is less than 1, the laser unit's drive current is less than the rated drive current I0, resulting in dimmed light. If p is greater than 1, the laser unit is in an overcurrent drive state, resulting in brighter light. If p is too large, meaning the ideal drive current I(t) for the laser unit, obtained by the signal processing module 11 based on the brightness distribution information of the current image frame, is significantly greater than the laser unit's rated drive current I0, then directly driving the laser unit with this ideal drive current I(t) may result in a risk of COD.

[0052] To prevent COD in the laser unit, the control device 10 adjusts the laser unit's drive current so that the adjusted actual drive current satisfies the following condition: During the current image frame, the actual drive current of the laser unit is less than or equal to the laser unit's maximum cutoff current. The maximum cutoff current of the laser unit is determined by the laser unit's consumed lifespan and the ratio of the laser unit's consumed lifespan to its usage time.

[0053] Furthermore, the adjustment module 12 is used to determine the maximum single-frame lifetime decay rate of the laser unit based on the lifetime data information of the laser unit, and calculate the maximum cutoff current of the laser unit based on the obtained maximum single-frame lifetime decay rate, and adjust the ideal control current I(t) of the laser unit based on the maximum cutoff current, so that the actual driving current I'(t) of the laser unit after adjustment is less than or equal to the maximum cutoff current.

[0054] Specifically, the adjustment module 12 is used to calculate the consumed life of the laser unit before the image frame to be displayed is displayed based on the used time of the laser unit, the historical driving current, and the historical life decay rate, and based on the used time of the laser unit, determine the ratio of the consumed life of the laser unit to the used time, that is, the over-life usage rate O(t0) of the laser unit. Regardless of the life management strategy adopted for the laser unit (the optimization process for the ideal control current), the maximum single-frame life decay rate r of the laser unit within the current image frame time is D It is determined by the consumed life of the laser unit and the over-life utilization rate of the laser unit. D Under this condition, there is a maximum cutoff current for the laser unit. Furthermore, the adjustment module 12 is further configured to calculate the maximum cutoff current of the laser unit based on the maximum single-frame lifetime decay rate, and optimize the ideal drive current I(t) based on the maximum cutoff current to obtain the actual drive current I'(t). Thus, the actual drive current of the laser unit is obtained, thereby completing the optimization of the ideal drive current I(). In this embodiment, the actual drive current I'(t) obtained through optimization is used to drive the laser unit, so that the lifetime decay rate of the laser unit at the actual drive current within the current image frame time is less than or equal to the maximum single-frame lifetime decay rate of the laser unit when driven with the maximum cutoff current.

[0055] In an embodiment of the present application, the life management module 13 is used to calculate the life consumption information of the laser unit in the current image frame, including: obtaining the actual driving current and actual operating temperature of the laser unit in the current image frame, determining the life consumed by the laser unit in the current image frame, and updating the life data information of the laser unit. Specifically, the remaining life of the laser unit before the current image frame is played is subtracted from the life consumed by the laser unit in the current image frame to obtain the updated life data information of the laser unit. For example, the life management module 13 calibrates the life of the laser unit as 100% before the laser unit is put into use. The life management module 13 is also used to use the percentage of the life consumed by the laser unit in the current image frame as the life consumed by the laser unit, and subtract the life consumed by the laser unit in the current image frame from the remaining life of the laser unit before the current image frame is played, thereby obtaining the updated life data information of the laser unit.

[0056] In this embodiment of the present application, the updated lifetime data is used to optimize the ideal drive current required by the laser unit when displaying the next image frame, thereby determining the actual drive current required by the laser unit when displaying the next image frame. In this embodiment of the present application, the operating conditions of the laser unit include the drive current value and the operating temperature of the laser unit. When the current image frame is displayed, the projection device can obtain the drive current value based on the actual drive current and obtain the operating temperature of the laser unit using a temperature sensor.

[0057] In some embodiments, when the current image frame is displayed, the control device 10 continues to determine the next image frame to be displayed based on the image signal to be displayed, and determines the ideal driving current of the laser unit required for the next image frame to be displayed, and re-determines the life data information of the laser unit, which is used to optimize the ideal driving current of the laser unit required for the next image frame to be displayed, and then obtain the actual driving current when the next image frame is displayed.

[0058] See also Figure 3 ,The following section will describe in detail the calculation of the ,above-mentioned parameters in conjunction with the flowchart of ,parameter calculation.

[0059] (1) Laser unit life data information

[0060] In the embodiment of the present application, the life data information of the laser unit includes the design life of the laser unit, the consumed life, the used time, the remaining life, and the ratio of the consumed life to the used time (excess life usage rate). A timer can be set inside the projection device to record the used time of the laser unit. The control device 10 calculates the consumed life of the laser unit before the image frame to be displayed based on historical operating conditions such as the used time of the laser unit, the historical driving current, and the historical life decay rate. The remaining life of the laser unit can be calculated based on the design life of the laser unit. The calculation process of the remaining life of the laser unit can be derived from the following analysis.

[0061] As an implementation method, the laser unit life curve f(I, T) can be used to calculate the consumed life of the laser unit based on the historical operating conditions of the laser unit, thereby determining whether the laser unit can meet the design life indicator. According to the above calculation formula (2), after the laser unit has been operating for time t0, its consumed life L(t0) can be expressed as:

[0062]

[0063] In this embodiment, for a projection device that is currently playing image content, the current remaining life of the laser unit can be determined based on the life of the laser unit that has been consumed during its historical operation, the historical remaining life, and the life required to be consumed by the current image frame. Specifically, the life of the laser unit that has been consumed during its historical operation should be understood as the cumulative life of the laser unit consumed before the current image frame was displayed; the historical remaining life should be understood as the remaining life of the laser unit before the current image frame was displayed; and the current remaining life of the laser unit should be understood as the remaining life of the laser unit after the current image frame was displayed. Then we can obtain:

[0064] The current remaining life of the laser unit (referred to as the remaining life for short) = the historical remaining life - the life consumed by the laser unit within the current image frame time.

[0065] The remaining life of the laser unit can be determined based on the design life and the life of the laser unit consumed in the historical operation process. The life of the laser unit consumed in the historical operation process can be calculated according to the above calculation formula (6); the life of the laser unit required to be consumed in the current image frame time L(t0+t f ) can be calculated by the following formula:

[0066]

[0067] Among them, t f Displays the duration of the current frame for the laser unit.

[0068] According to the above calculation formulas (6) and (7), the updated life data information of each laser unit can be obtained, that is, the remaining life of the laser unit:

[0069] L d =L d -L(t0)-L(t0+t f ).

[0070] (2) Maximum cut-off current

[0071] In the embodiment of the present application, the life management strategy determined by the control device 10 limits the actual driving current I'(t) of the laser unit after adjustment to be less than or equal to the maximum cut-off current I max , wherein the maximum cutoff current of the laser unit is determined by the consumed life of the laser unit and the ratio of the consumed life of the laser unit to the used time (excess life usage rate).

[0072] As an embodiment, the life management strategy defines the life management parameter conditions. When the control device 10 optimizes the ideal control current of the laser unit according to the preset life management strategy, the operating parameters of the laser unit should meet the life management parameter conditions (for example, the actual driving current I'(t) of the laser unit in the current image frame time is less than or equal to the maximum cut-off current I max , the maximum single-frame life decay rate of the laser unit should be less than the maximum single-frame life decay rate threshold determined by the preset life management strategy) so that the projection equipment can ensure that the actual life of the laser unit is greater than the design life while improving the display high brightness.

[0073] Furthermore, in some specific embodiments, when the control device optimizes the ideal control current of the laser unit based on the set life management strategy, the maximum single-frame life decay rate r of the laser unit can be determined according to the consumed life L(t0) of the laser unit and the over-life usage rate O(t0) of the laser unit. D , then the maximum single-frame lifetime decay rate of the laser unit r D It can be expressed as:

[0074] r D =r D (L(t0)).

[0075] Based on the above analysis, the ideal driving current I(t) of the laser unit is optimized according to the life data of the laser unit, which can be understood as: the maximum single-frame lifetime decay rate r of the laser unit D There is a maximum cut-off current I max and use the maximum cut-off current I max The ideal driving current I(t) of the laser unit is cut off, so that the actual driving current I′(t) of the laser unit after adjustment is obtained as follows:

[0076]

[0077] To meet the life management parameter condition of "the life decay rate of the laser unit under the actual driving current is less than or equal to the maximum single-frame life decay rate of the laser unit under the maximum cut-off current driving", the maximum cut-off current of the laser unit I max The following inequalities should be satisfied:

[0078]

[0079] Among them, L(t0+t f ) is the ideal control current I(t) of the laser unit during the current image frame time. max Lifespan consumed after truncation, t f is the duration of the current image frame. Then:

[0080]

[0081] Therefore, in the calculation process of the actual driving current I′(t) of the laser unit, there is a maximum cut-off current I max , satisfying the above inequality. According to the maximum cut-off current I max Adjust the ideal driving current I(t) of the laser unit. According to the above formula (8), the actual driving current I′(t) of the laser unit after adjustment can be obtained, and the actual driving current I′(t) is less than or equal to the maximum cut-off current I max Therefore, based on the above equations (8), (9) and (10), the ideal driving current I(t) of the laser unit can be optimized to obtain the actual driving current I′(t) of the laser unit after adjustment.

[0082] (3) Maximum single-frame lifetime decay rate

[0083] The following is an example of the calculation process of the maximum single-frame lifetime decay rate.

[0084] From the above derivation, it can be seen that, as an embodiment, the life management strategy determined by the control device 10 defines the life management parameter conditions (such as the maximum single frame life decay rate r D , Maximum cut-off current I max ), when optimizing the ideal driving current I(t) of the laser unit according to the lifetime management strategy, the operating parameters of the laser unit should meet the lifetime management parameter conditions, that is, the actual driving current I'(t) of the laser unit within the current image frame time is less than or equal to the maximum cut-off current I max2. The maximum single-frame life decay rate of the laser unit should be less than the maximum single-frame life decay rate threshold determined by the preset life management strategy, so that the projection equipment can ensure that the actual life of the laser unit meets the design life requirements while improving the display high brightness.

[0085] In some practical usage scenarios, the display of image signals requires the projection device 100 to always display high brightness. As a life management strategy for the laser unit, the maximum single-frame life decay rate of the laser unit can be set to 0 after the projection device 100 has been used for a preset time. max The control device 10 is set to a certain value so that the maximum brightness displayed by the projection device 100 remains substantially constant. The preset time can be 0, that is, the projection device 100 is a new machine, or it can be after a certain period of use. The control device 10 is based on the constant maximum cut-off current I max To adjust the ideal driving current I(t) of the laser unit, in order to ensure that the actual life of the laser unit meets the design life L d The maximum single-frame lifetime decay rate r of the laser unit is D The following inequalities should be satisfied:

[0086]

[0087] Based on the above inequality (11), the maximum single-frame lifetime decay rate r of the laser unit is determined. D When r D The maximum single-frame lifetime decay rate r of the laser unit can be taken as the limit value. D It can be calculated by the following formula:

[0088]

[0089] For example, in some actual usage scenarios, the display of image signals does not require the projection device to always display high brightness. In this case, the actual driving current value used to drive the laser unit is usually less than its rated driving current I0. At this time, the consumed life of the laser unit is less than its used time. In the subsequent time, when the projection device requires high brightness, the actual driving current of the laser unit can be made greater than its rated driving current I0. In this case, the maximum single-frame life decay rate r of the laser unit should be determined based on the current consumed life of the laser unit, that is, based on the remaining life of the laser unit. Assuming that the laser unit has been running for L T time, in order to ensure that the actual life of the laser unit meets the design life L d The maximum single-frame lifetime decay rate of the laser unit is r D The following inequalities should be satisfied:

[0090]

[0091] Among them, r real For the laser unit that has already run L T The actual life decay rate of the laser unit within a certain period of time.

[0092] Based on inequality (13), the maximum single-frame lifetime decay rate r of the laser unit is determined. D When r D The limit value can be taken to ensure that the actual life of the laser unit meets the design life L d The maximum single-frame lifetime decay rate r of the laser unit is D It can be calculated by the following formula:

[0093]

[0094] For example, in some actual usage scenarios, the actual driving current I'(t) of the laser unit should make the actual life of the laser unit longer than the designed life. If the consumed life of the laser unit is longer than the running time, the maximum single-frame life decay rate of the laser unit can be determined based on the maximum single-frame life decay rate when the running time of the laser unit reaches the designed life and the maximum single-frame life decay rate of the laser unit at the current time. Specifically, assuming that the laser unit has run to the current L T According to the optimized lifetime management strategy, the maximum single-frame lifetime decay rate r of the laser unit is D It can be expressed as:

[0095]

[0096] Where: L T is the usage time of the laser unit, L d is the design life of the laser unit, a is the usage time of the laser unit L T b is the maximum lifetime decay rate when the laser unit reaches its design lifetime. Typically, the maximum lifetime decay rate reaches its minimum when the laser unit reaches its design lifetime, so a > b.

[0097] Substituting the above calculation formula (15) into the above inequality (14), we can get the inequality:

[0098]

[0099] in, is the average value of the historical lifetime decay rate of the laser unit.

[0100] As an embodiment, the greater than or equal to symbol in inequality (16) can be replaced with an equal to symbol to calculate the laser unit running time reaching the current time L TThe maximum value of the maximum life decay rate a when the laser unit runs for a certain time, that is, the laser unit running time reaches the current time L T The maximum value of the maximum life decay rate a can be obtained by the following calculation formula:

[0101]

[0102] From the above derivation, it can be seen that b in inequality (16) represents the maximum output brightness limit of the laser unit when the laser unit operating time reaches the design life. The value of b can be set according to the application requirements and standard restrictions of the actual projection equipment. For example, according to the industry specifications of laser display, under normal circumstances, when the laser unit operating time reaches the design life, the display brightness attenuation of the laser unit should not exceed 50%. Therefore, the value of b can be taken as 0.5. Therefore, when b is known, it can be determined by calculating formula (17) that the entire laser unit operating time reaches the current time L T The maximum lifetime decay rate a at the time of the image is obtained, and then according to the calculation formula (15), the maximum single-frame lifetime decay rate r of the laser unit in the current image frame time can be obtained. D .

[0103] In summary, before the image frame to be displayed is displayed, the historical life decay rate of the laser unit can be calculated based on the historical operating conditions. The projection device can calculate the consumed life of the laser unit before the image frame to be displayed based on the laser unit's usage time, historical driving current, and historical life decay rate. From this, the remaining life of the laser unit can be obtained, and the maximum single-frame life decay rate r can be calculated. D , according to the maximum single-frame lifetime decay rate r D Calculate the maximum cutoff current I of the laser unit max , based on the maximum cut-off current I max By optimizing the ideal control current I(t), the actual control current I′(t) of the laser unit can be obtained. The overcurrent drive magnification p of the laser unit can also be obtained, thereby completing the optimization of the ideal drive current I(t) of the laser unit.

[0104] It should be noted that the embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the purpose of the present invention and the claims, which are all within the protection of the present invention.

Claims

1. A projection device, characterized in that: It includes a light source device, a spatial light modulator and a control device; The light source device includes at least one laser unit; The control device is configured to obtain brightness distribution information of a current image frame based on an image signal to be displayed, and adjust a driving current of the laser unit based on the brightness distribution information of the current image frame and life data information of the laser unit, so that the adjusted actual driving current is greater than the rated driving current during at least a portion of a current image frame time, wherein the life data information of the laser unit includes the consumed life and usage time of the laser unit; The spatial light modulator is arranged on the optical path of the light emitted by the light source device, and is used to modulate the light emitted by the light source device to obtain a modulated image.

2. The projection device according to claim 1, wherein: The control device is used to determine the ideal driving current of the laser unit according to the brightness distribution information of the current image frame, and adjust the ideal driving current of the laser unit according to the life data information of the laser unit to obtain the actual driving current.

3. The projection device according to any one of claims 1 to 2, characterized in that: When the consumed life of the laser unit is less than the used time, the control device adjusts the driving current of the laser unit so that the adjusted actual driving current is greater than the rated driving current during at least a portion of the current image frame time.

4. The projection device according to claim 3, wherein: The actual driving current of the laser unit during the current image frame time is less than or equal to the maximum cut-off current of the laser unit.

5. The projection device according to claim 4, wherein: The maximum cutoff current of the laser unit is determined by the consumed life of the laser unit and the ratio of the consumed life of the laser unit to the used time.

6. The projection device according to claim 4, wherein: The lifetime decay rate of the laser unit at the actual driving current during the current image frame time is less than or equal to the maximum single-frame lifetime decay rate of the laser unit at the maximum cutoff current driving condition.

7. The projection device according to claim 6, wherein: After a preset time of use, the maximum single-frame life decay rate of the laser unit is a certain value.

8. The projection device according to claim 6, wherein: The maximum single-frame life decay rate of the laser unit within the current image frame time is determined by the maximum life consumption rate of the current usage time of the laser unit and the maximum life consumption rate when the designed life of the laser unit is reached.

9. The projection device according to claim 8, wherein: The maximum single-frame lifetime decay rate of the laser unit within the current image frame time is: : ； in: is the usage time of the laser unit, is the design life of the laser unit, The laser unit is used for a period of time of The maximum life decay rate when b It is the maximum life decay rate when the service life of the laser unit reaches the designed life.

10. The projection device according to claim 1, wherein: The control device is further configured to calculate the life consumption information of the laser unit within the current image frame time to update the life data information of the laser unit.

11. The projection device according to claim 10, wherein: The control device is used to calculate the lifespan consumed by the laser unit in the current image frame; and to subtract the lifespan consumed by the laser unit in the current image frame from the remaining lifespan of the laser unit before the current image frame is played, to obtain updated lifespan data information of the laser unit.

Images