CN114173100A - Projection device - Google Patents

Projection device Download PDF

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Publication number
CN114173100A
CN114173100A CN202010955040.7A CN202010955040A CN114173100A CN 114173100 A CN114173100 A CN 114173100A CN 202010955040 A CN202010955040 A CN 202010955040A CN 114173100 A CN114173100 A CN 114173100A
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China
Prior art keywords
laser unit
current
lifetime
image frame
driving current
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CN202010955040.7A
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Chinese (zh)
Inventor
余新
胡飞
李屹
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Shenzhen Appotronics Corp Ltd
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Appotronics Corp Ltd
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Priority to CN202010955040.7A priority Critical patent/CN114173100A/en
Priority to PCT/CN2021/116379 priority patent/WO2022052867A1/en
Publication of CN114173100A publication Critical patent/CN114173100A/en
Pending legal-status Critical Current

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N9/00—Details of colour television systems
    • H04N9/12—Picture reproducers
    • H04N9/31—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM]
    • H04N9/3141—Constructional details thereof
    • H04N9/315—Modulator illumination systems
    • H04N9/3161—Modulator illumination systems using laser light sources
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B21/00—Projectors or projection-type viewers; Accessories therefor
    • G03B21/14—Details
    • G03B21/20—Lamp housings
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B21/00—Projectors or projection-type viewers; Accessories therefor
    • G03B21/14—Details
    • G03B21/20—Lamp housings
    • G03B21/2006—Lamp housings characterised by the light source
    • G03B21/2033—LED or laser light sources
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B21/00—Projectors or projection-type viewers; Accessories therefor
    • G03B21/14—Details
    • G03B21/20—Lamp housings
    • G03B21/206—Control of light source other than position or intensity
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N9/00—Details of colour television systems
    • H04N9/12—Picture reproducers
    • H04N9/31—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N9/00—Details of colour television systems
    • H04N9/12—Picture reproducers
    • H04N9/31—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM]
    • H04N9/3141—Constructional details thereof
    • H04N9/315—Modulator illumination systems
    • H04N9/3155—Modulator illumination systems for controlling the light source
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N9/00—Details of colour television systems
    • H04N9/12—Picture reproducers
    • H04N9/31—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM]
    • H04N9/3179—Video signal processing therefor

Abstract

The embodiment of the invention discloses projection equipment, which comprises a light source device, a spatial light modulator and a control device, wherein the light source device comprises a light source, a spatial light modulator and a light source; the light source device comprises at least one laser unit; the control device is used for acquiring the brightness distribution information of the current image frame according to the image signal to be displayed, and controlling the driving current of the laser unit according to the brightness distribution information of the current image frame and the service life data information of the laser unit, so that the driving current is larger than the rated driving current in at least part of the time period within the current image frame; the spatial light modulator is arranged on a light path of light emitted by the light source device and is used for modulating the light emitted by the light source device to obtain a modulated image. The projection equipment can make full use of the relationship between the service life of the laser unit and the driving current, and can ensure that the light source device can realize high-brightness display under the condition of meeting the service life requirement.

Description

Projection device
Technical Field
The invention relates to the technical field of projection display, in particular to a projection device.
Background
With the development of display technology, the application of projection equipment is more and more extensive, including education projectors, home projectors, engineering projectors and the like, and the projection technology brings great changes to the lives, the study and the work of people. The demand for high brightness display is increasing as well as the demand for high quality display of projection devices is increasing. The High Dynamic Range (HDR) projection system can increase the contrast and peak brightness output by the projector, so that the bright field and dark field parts in the picture can display rich gray scale information, thereby greatly improving the picture effect and audience viewing experience, and the HDR technology is becoming the focus of research in the field of projection display.
Currently, one solution for implementing HDR projection systems is to use Local Dimming (Local Dimming) technology for LCD backlights. According to the technical scheme, the laser array is used as a light source of the projection equipment, each laser is responsible for illumination of one area, and the luminous intensity of each laser light source is dynamically controlled according to the brightness of each area of a projection picture during projection display so as to realize high-contrast display. However, due to the spatial imbalance of the brightness of the projected picture, the attenuation of the laser irradiating different areas is different, and thus the remaining life of the laser in different areas after the picture is played for a period of time is different. Therefore, how to balance the brightness and the lifetime of the light source is an urgent problem to be solved.
Disclosure of Invention
Embodiments of the present invention provide a projection apparatus to improve the above problem.
The embodiment of the invention provides projection equipment, which comprises a light source device, a spatial light modulator and a control device; the light source device comprises at least one laser unit; the control device is used for acquiring the brightness distribution information of the current image frame according to the image signal to be displayed, and adjusting the driving current of the laser unit according to the brightness distribution information of the current image frame and the service life data information of the laser unit, so that the adjusted actual driving current is greater than the rated driving current in at least part of the time period within the current image frame time; the spatial light modulator is arranged on a light path of light emitted by the light source device and is used for modulating the light emitted by the light source device to obtain a modulated image.
Further, the control device is used for determining an ideal driving current of the laser unit according to the brightness distribution information of the current image frame, and adjusting the ideal driving current of the laser unit according to the service life data information of the laser unit to obtain an actual driving current.
Further, the life data information of the laser unit comprises the consumed life and the used time of the laser unit, and when the consumed life of the laser unit is smaller than the used time, the control device adjusts the driving current of the laser unit so that the adjusted actual driving current is larger than the rated driving current in at least part of the period within the current image frame time.
Further, the actual driving current of the laser unit is less than or equal to the maximum off-current of the laser unit during the current image frame time.
Further, the maximum off-current of the laser unit is determined by a consumed lifetime of the laser unit, a ratio of the consumed lifetime of the laser unit to a used time.
Further, the lifetime decay rate of the laser unit under the actual driving current in the current image frame time is less than or equal to the maximum single-frame lifetime decay rate of the laser unit under the maximum cut-off current driving.
Further, the maximum single frame lifetime decay rate of the laser unit is a certain value after the preset time of use.
Further, the maximum single frame lifetime decay rate of the laser unit within the current image frame time is determined by the maximum lifetime consumption rate of the current usage time of the laser unit and the maximum lifetime consumption rate at the time the laser unit design lifetime arrives.
Further, the maximum single-frame lifetime decay rate of the laser unit in the current image frame time is rD：
Figure BDA0002678309290000021
Wherein: l isTIs the used time of the laser unit, LdFor the design life of the laser unit, a is the service life of the laser unit LTB is the maximum lifetime decay rate at which the service time of the laser unit reaches the design lifetime.
Further, the control device is also used for calculating the service life consumption information of the laser unit in the current image frame time so as to update the service life data information of the laser unit.
Further, the control device is used for calculating the service life consumed by the laser unit in the current image frame; and subtracting the service life consumed by the laser unit in the current image frame from the residual service life of the laser unit before the current image frame is played to obtain the service life data information after the laser unit is updated.
In the projection apparatus provided by the embodiment of the invention, the light source device comprises at least one laser unit, and when each frame of image picture is displayed, the control device adjusts the driving current of the laser unit according to the brightness distribution information of the current image frame and the service life data information of the laser unit, so that the adjusted actual driving current is larger than the rated driving current in at least part of the time period within the current image frame time, so that the laser unit outputs high-brightness light for the spatial light modulator to modulate, the proposal determines the drive current of the laser unit according to the brightness of the picture to be displayed and the service life of the laser unit, makes full use of the relationship between the service life of the laser unit and the drive current, the laser unit intermittently works under the working condition of exceeding the rated driving current of the laser unit, so that the service life of the system is not influenced while the light with higher peak brightness is output, and the high-brightness display of the light source device can be realized under the condition of meeting the service life requirement.
Drawings
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Fig. 1 shows a block diagram of a projection apparatus according to an embodiment of the present invention.
Fig. 2 is a functional block diagram of a control device of a projection apparatus according to an embodiment of the present invention.
Fig. 3 shows a flowchart of a work flow of a projection apparatus according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention. The projection device provided by the invention will be described in detail with reference to the accompanying drawings and specific embodiments.
Referring to fig. 1, fig. 1 shows a block diagram of a projection apparatus 100 according to an embodiment of the present invention, where the projection apparatus 100 may be, but is not limited to, an apparatus with a projection function, such as a laser television, an educational projector, a micro-projector, a cinema projector, or a computer system, such as a personal computer, a notebook computer, a tablet, a smart phone, etc., connected to the projection apparatus, and using a distance measuring sensor of the apparatus connected to the apparatus with the projection function. It should be noted that the projection direction of the projection apparatus in the embodiment of the present application is not limited, and it may be rear projection or front projection.
The projection apparatus 100 comprises control means 10, light source means 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 a current image frame according to an image signal to be displayed, and adjust a driving current of the laser unit according to 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 a rated driving current for at least a part of a time period within a current image frame time; the spatial light modulator 40 is disposed on the optical path of the light emitted from the light source device 30, and modulates the light emitted from the light source device 30 to obtain a modulated image.
In the projection apparatus 100, the light source device 30 comprises at least one laser unit, and when displaying each frame of image picture, 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 for at least part of the time period within the current image frame time, so that the laser unit outputs high-brightness light for the spatial light modulator 40 to modulate, the proposal determines the drive current of the laser unit according to the brightness of the picture to be displayed and the service life of the laser unit, makes full use of the relationship between the service life of the laser unit and the drive current, the laser unit intermittently operates under the condition that the rated driving current of the laser unit is exceeded, so that the service life of the projection equipment 100 is not influenced while the laser unit outputs light with higher peak brightness, and the light source device 30 can be ensured to realize high-brightness display under the condition that the service life requirement is met.
In some embodiments, projection device 100 also 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 according to the image signal to be displayed, and the light source driver is configured to receive the control signal sent by the control device 10 and output a driving current for driving the light source device 30 according to the control current to light the light source device 30, wherein the light source driver adjusts the driving current input to the light source device 30 according to the control signal to drive the light source device 30. For the projection apparatus 100 incorporating the light source dynamic modulation technique, the driving current of the light source device 30 is varied according to the content of the display screen. 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 from the light source device 30 according to an image signal to generate image light having a modulated image. The imaging element is configured to receive image light generated by the spatial light modulator 40 and project the image light to a predetermined position or a predetermined element (e.g., a projection screen or a wall, etc.) to display a projected image.
The control device 10 of the projection apparatus 100 provided in the present application will be described in detail below.
Referring to fig. 2, the control device 10 may include a signal processing module 11, an adjusting module 12, and a lifetime management module 13, wherein the lifetime management module 13 includes a storage unit for storing lifetime data information of the laser unit. The signal processing module 11 is configured to obtain brightness distribution information of a current image frame according to an image signal to be displayed, determine an ideal driving current of the laser unit according to the brightness distribution information of the current image frame, adjust the ideal driving current of the laser unit according to life data information of the laser unit by the adjustment module 12, obtain an adjusted actual driving current of the laser unit, and enable the laser unit to emit light at a target brightness under the driving of the actual driving current. The life management module 13 is configured to calculate life consumption information of the laser unit in the current image frame to update life data information of the laser unit. The modules may be program modules running in a computer-readable storage medium, and the purpose and operation of the modules are as follows:
the signal processing module 11 is configured to obtain brightness distribution information of a current image frame according to an image signal to be displayed, and determine an ideal driving current of the laser unit according to the brightness distribution information of the current image frame. The image signal to be displayed may be stored locally in the projection device, or may be an image signal received by the projection device based on a data connection (e.g., a local area network data connection or a wide area network data connection). The image signal may be from image content that is stored first (for example, audio/video data that needs to be projected is copied to the projection device in advance for storage) or stored immediately (for example, a mobile hard disk that stores the audio/video data that needs to be projected is inserted into the projection device), and the specific storage manner is not limited; the image content may be image content in a video file, image content in a picture file, and the like, which is not limited in this application.
In the embodiment of the application, the projection device may count the brightness distribution of the current image frame picture according to the type of the projection device and the image signal to be displayed. As an embodiment, the projection device may be a projection device based on global dimming technology, and only the maximum brightness value of the whole picture needs to be counted. The projection device using local dimming requires to count the maximum brightness of each region in regions. The projection device using the dynamic color gamut technology needs to count the maximum brightness values of different primary colors in the whole picture. A projection apparatus using a scanning light source needs to change the luminance distribution of a two-dimensional picture into a luminance variation curve on a scanning path.
After acquiring the brightness distribution information of the current image frame, the signal processing module 11 generates an ideal driving current i (t) of the laser unit based on the brightness distribution information of the current image frame, where the ideal driving current i (t) represents an ideal brightness of output light of the corresponding laser unit. The ideal driving current i (t) of the laser unit may be understood as a driving current without considering the actual working condition and the life data information of the laser unit. The signal processing module 11 determines an ideal driving current i (t) of the laser unit required for displaying the current image frame based on the brightness distribution (brightness curve) of the current image frame.
The adjusting module 12 adjusts the ideal driving current I (t) of the laser unit according to the life data information of the laser unit to obtain an actual driving current I '(t), where the actual driving current I' (t) of the laser unit represents the actual brightness of the output light of the corresponding laser unit. The actual driving current I' (t) is greater than the rated driving current for at least a part of the period within the current image frame time, that is, the laser unit is in an over-current driving state for at least a part of the period within the current image frame time, so that the laser emits light with higher brightness, thereby meeting the brightness requirement of HDR on the light source device.
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 (LCD) or a Liquid Crystal On Silicon (LCOS). For convenience of illustration, the spatial light modulator 40 is exemplified by a digital micromirror device, but this is not intended to limit the scope of the invention. The spatial light modulator 40 includes a plurality of micro mirror units, each micro mirror unit corresponds to a pixel of the modulated image, when the micro mirror unit is in an "on" state, the micro mirror unit reflects the light source light to the corresponding pixel region, and the corresponding pixel is in a "bright" state, when the micro mirror unit is in an "off" state, the micro mirror unit does not reflect the light source light to the corresponding pixel region, and the corresponding pixel is in a "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, and in the current image frame time, the adjusting module 12 adjusts the ideal driving current I (t) of the laser unit according to the service life data information of the laser unit, so that the adjusted actual driving current I' (t) is greater than the rated driving current in at least part of the time period in the current image frame time, and compared with the continuous constant current driving, the brightness of the light emitted by the light source device 30 when the light source device operates in a current overshoot mode can be improved.
Specifically, the current image frame time includes a plurality of bit plane modulation periods (e.g. 8 bits or 10 bits), and the adjusting module 12 adjusts the ideal driving current I (t) of the laser unit according to the lifetime data information of the laser unit, so that the adjusted actual driving current I' (t) is greater than the rated driving current for at least one bit plane modulation period within the current image frame time. If the driving current of the laser unit is the rated driving current and the light-emitting brightness of the laser unit is L, the actual driving current I' (t) of the laser unit is greater than the rated driving current in the at least one bit-plane modulation period, and the light-emitting brightness of the laser unit can reach ML (M >1) at this time, so that the light-emitting brightness of the light source device 30 in the at least one bit-plane modulation period is increased, and each pixel of the modulated image reaches the preset gray level value.
In the embodiment of the present application, the control device 10 determines a lifetime management strategy corresponding to the laser unit (that is, an optimization process for the ideal control current provided in the present application) according to lifetime data information of the laser unit, so that the laser unit outputs light with higher peak brightness without affecting the service life of the system. Specifically, the life data information of the laser unit is used for characterizing factors capable of influencing the actual life of the laser unit, and the life data information of the laser unit comprises the consumed life and the used time of the laser unit.
Whatever the laser projection apparatus, after a period of use, it necessarily results in a decay of the lifetime of the laser unit, i.e. a reduction of the remaining lifetime of the laser unit. The consumed service life of the laser unit can be determined by the display principle of the laser projection equipment and the actual working condition of the laser unit. For example, in a general laser projection apparatus, a laser unit is operated at a constant current, and thus, a lifetime decay rate of the laser unit is a constant value. In the laser projection device adopting the global dimming technology, the laser unit determines the output of the laser unit according to the maximum brightness in the picture, so that the life decay rate of the laser unit is a value which changes along with the working condition, but the life decay rate of each laser unit is the same because all the laser units in the global dimming technology are uniformly changed. If a laser projection device using a dynamic color gamut (HDC) technique is used, laser light units of different primary colors (e.g., blue laser for generating fluorescence, red and green laser for color compensation, etc.) will generate different modulation curves according to the content of the picture, so that the laser light units of different primary colors have different life decay rates. In the laser projection device adopting the Local dimming technology, because the brightness of the picture is unbalanced in space, the laser units with different primary colors irradiating different areas are different, so that the residual life of the laser units in different areas is different after the picture is played for a period of time.
Optical catastrophic damage (COD) is the most important factor affecting the lifetime of a laser unit, and the lifetime of a laser unit under high current drive is mainly determined by COD. The lifetime L of the laser unit, taking into account other lifetime influencing factors such as COD and normal material attenuation of the laser unit, can be expressed as:
Figure BDA0002678309290000071
wherein: i is the continuous constant driving current of the laser unit, T is the working temperature of the laser unit, and I, T is used for representing the working condition of the laser unit in actual operation. When the driving current I of the laser unit is larger than the COD threshold current I at the temperatureth(T), COD occurs, and thus the laser unit life is 0 at this current. When the driving current I of the laser unit is smaller than the threshold current Ith(T), COD does not occur in the laser unit. Under such circumstances and conditions, the lifetime L of the laser unit can be expressed as current and temperatureIs a function of (i.e., equation (1) above). The value of this function decreases with increasing drive current, meaning that the longer the drive current, the shorter the lifetime of the laser unit. The inherent lifetime curve f (I, T) of the laser unit may be understood as an inherent characteristic of the laser unit, which may be pre-set in the projection device (e.g. pre-stored in a memory of the projection device) or may be derived from a laser unit aging test.
Assuming that the design lifetime of the laser unit is LdThe lifetime r (I, T) consumed by the laser unit under the operating conditions (driving current I and operating temperature T) per unit time can be expressed as:
Figure BDA0002678309290000081
laser unit in use time t0Thereafter, its consumed life L (t)0) Can be expressed as:
Figure BDA0002678309290000082
the laser unit's super-life usage O (t) can be defined0) Comprises the following steps:
Figure BDA0002678309290000083
O(t0) Greater than 1 indicates that the laser unit is in use for a time t0The actual working condition in the process exceeds the designed working condition when the design service life is prolonged, and the actual service life of the laser unit is shorter than the design service life if the actual service life of the laser unit is not changed subsequently. And O (t)0) Less than 1 indicates that the laser unit is in use for a time t0The actual working condition in the process does not exceed the designed working condition when the design life is prolonged, and if the actual life of the laser unit is not changed subsequently, the actual life of the laser unit is longer than or equal to the design life. Thus, for O (t)0) The laser unit with the service life less than 1 is driven by overcurrent to work, namely when the consumed service life of the laser unit is less than the used time, the control device10 adjusting the driving current of the laser unit to make the adjusted actual driving current greater than the rated driving current in at least part of the period of the current image frame time, thereby realizing the balance between outputting the maximum brightness and meeting the design life.
Since the lifetime of a laser unit under high current driving is mainly determined by COD, for an over-current driven laser unit, in order to prevent the laser unit from generating COD, it is necessary to limit the upper limit of its driving current.
Further, the signal processing module 11 is based on the ideal control current I (t) and the rated driving current I of the laser unit0And determining the overcurrent driving multiplying power p of the laser unit. The over-current drive multiplying power p of the laser unit is determined by the ideal control current I (t) of the laser unit and the rated drive current I of the laser unit0The ratio of (a) to (b), i.e. the over-current driving magnification p of the laser unit can be expressed as:
Figure BDA0002678309290000091
p less than 1 means that the drive current of the laser unit is less than the rated drive current I0The light emission is reduced, and the p is more than 1, which indicates that the laser unit is in an overcurrent driving state and the light emission is bright. If p is too large, the ideal driving current I (t) of the laser unit obtained by the signal processing module 11 according to the brightness distribution information of the current image frame is much larger than the rated driving current I of the laser unit0If the laser unit is directly driven with the ideal drive current i (t), there is a risk of COD occurring.
In order to avoid the generation of COD in the laser unit, the control device 10 adjusts the driving current of the laser unit so that the adjusted actual driving current satisfies the following conditions: the actual driving current of the laser unit is less than or equal to the maximum cut-off current of the laser unit during the current image frame time. Wherein the maximum cut-off current of the laser unit is determined by the consumed life of the laser unit, and the ratio of the consumed life to the used time of the laser unit.
Further, the adjusting module 12 is configured to determine a maximum single-frame lifetime attenuation rate of the laser unit according to the lifetime data information of the laser unit, calculate a maximum cut-off current of the laser unit according to the obtained maximum single-frame lifetime attenuation rate, and adjust the ideal control current I (t) of the laser unit based on the maximum cut-off current, so that the adjusted actual driving current I' (t) of the laser unit is less than or equal to the maximum cut-off current.
Specifically, the adjusting module 12 is configured to calculate a consumed lifetime of the laser unit before the image frame to be displayed is displayed according to the used time of the laser unit, the historical driving current and the historical lifetime decay rate, and determine a ratio of the consumed lifetime to the used time of the laser unit, i.e. an over-lifetime usage rate O (t) of the laser unit based on the used time of the laser unit0). Regardless of the lifetime management strategy (optimization procedure for ideal control current) applied to the laser unit, the maximum single-frame lifetime decay rate r of the laser unit during the current image frame timeDIs determined by the consumed lifetime of the laser unit and the over-lifetime usage of the laser unit, at which maximum single frame lifetime decay rate rDNext, there is a maximum off current of one laser unit. Further, the adjusting module 12 is further configured to calculate a maximum cut-off current of the laser unit according to the maximum single frame lifetime decay rate, and optimize the ideal driving current I (t) based on the maximum cut-off current to obtain an actual driving current I' (t), so as to obtain an actual driving current of the laser unit, and then complete the optimization of the ideal driving current I (). In the embodiment, the optimized actual driving current I' (t) is used for driving the laser unit, so that the lifetime decay rate of the laser unit under the actual driving current in the current image frame time can be smaller than or equal to the maximum single-frame lifetime decay rate of the laser unit under the maximum cut-off current driving.
In the embodiment of the present application, the lifetime management module 13 is configured to calculate lifetime consumption information of the laser unit in the current image frame, and includes: and acquiring the actual driving current and the actual working temperature of the laser unit in the current image frame, and determining the service life consumed by the laser unit in the current image frame so as to update the service life data information of the laser unit. Specifically, the remaining life of the laser unit before the current image frame is played is subtracted by the life consumed by the laser unit in the current image frame, so as 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 to be 100% before the laser unit is put into use, and the life management module 13 is further configured 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 remaining life of the laser unit before the current image frame is played from the life consumed by the laser unit in the current image frame, so as to obtain the updated life data information of the laser unit.
In the embodiment of the application, the updated life data information is used for optimizing an ideal driving current required by the laser unit when the next image frame is displayed, so as to obtain an actual driving current of the laser unit when the next image frame is displayed. In the embodiment of the present application, the working condition of the laser unit includes a driving current value and an operating temperature of the laser unit. When the current image frame is displayed, the projection device may obtain a driving current value according to the actual driving current, and obtain the operating temperature of the laser unit according to the temperature sensor.
In some embodiments, when the current image frame is displayed completely, the control device 10 continues to determine the image frame to be displayed in the next frame according to the image signal to be displayed, and determines the ideal driving current of the laser unit in the next frame required in the display of the next image frame, 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 in the display of the next image frame, so as to obtain the actual driving current in the display of the next image frame.
Referring to fig. 3, the calculation of each parameter will be described in detail with reference to a flow chart of parameter calculation.
Life data information of laser unit
In the embodiment of the present application, the lifetime data information of the laser unit includes a design lifetime, a consumed lifetime, a used time, a remaining lifetime, a ratio of the consumed lifetime to the used time (an ultra lifetime usage rate), and the like of the laser unit. The inside of the projection device may be provided with a timer for recording the used time of the laser unit, and the control device 10 may calculate the consumed lifetime of the laser unit before the image frame to be displayed is displayed according to the used time of the laser unit, the historical driving current, the historical lifetime decay rate, and other historical operating conditions, and may calculate the remaining lifetime of the laser unit based on the designed lifetime of the laser unit. The calculation of the remaining lifetime of the laser unit can be derived from the following analysis.
As an embodiment, the lifetime curve f (I, T) of the laser unit may be used to calculate the consumed lifetime of the laser unit according to the historical operating condition of the laser unit, so as to determine whether the laser unit can reach the design lifetime index. According to the above formula (2), the laser unit is operated at t0After time, it has consumed life L (t)0) Can be expressed as:
Figure BDA0002678309290000111
in this embodiment, for a projection device that is running playing image content, the current remaining life of the laser unit may be determined based on the lifetime that the laser unit has consumed during the historical run, the historical remaining lifetime, and the lifetime that needs to be consumed for the current image frame. In particular, the lifetime that the laser unit has consumed during the historical operation is understood to be the cumulative lifetime consumed by the laser unit before the current image frame is displayed; historical remaining life, which is understood to be the remaining life of the laser unit before the current image frame is displayed; the current remaining lifetime of the laser unit is understood to be the remaining lifetime of the laser unit after the current image frame is displayed. Then it is obtained:
the current remaining life of a laser unit (abbreviated as "remaining life") is the historical remaining life — the life consumed by the laser unit during the current image frame time.
The historical remaining life may be determined based on the design life and the consumed life of the laser unit during historical operation of the laser unitThe consumed life in the process can be calculated according to the calculation formula (6); the life L (t) of the laser unit required to be consumed in the current image frame time0+tf) Can be calculated from the following equation:
Figure BDA0002678309290000112
wherein, tfThe duration of the current frame is displayed for the laser unit.
From the above-mentioned calculation expressions (6) and (7), the lifetime data information after each laser unit update, that is, the remaining lifetime of the laser unit, can be obtained:
Ld＝Ld-L(t0)-L(t0+tf)。
(II) maximum cut-off current
In the embodiment of the present application, the lifetime management strategy determined by the control device 10 defines that the adjusted actual drive current I' (t) of the laser unit is less than or equal to the maximum cut-off current ImaxWherein the maximum cut-off current of the laser unit is determined by the consumed life of the laser unit, and the ratio of the consumed life to the used time of the laser unit (over-life usage rate).
As an embodiment, the life management policy defines a life management parameter condition that the operating parameter of the laser unit should satisfy when the control device 10 optimizes the ideal control current of the laser unit according to a preset life management policy (e.g., the actual driving current I '(t) of the laser unit is less than or equal to the maximum off-current I' during the current image frame time)maxThe maximum single-frame life attenuation rate of the laser unit is smaller than the maximum single-frame life attenuation rate threshold determined by a preset life management strategy), so that the actual life of the laser unit is ensured to be longer than the designed life on the premise that the display high brightness of the projection equipment is improved.
Further, in some embodiments, the control device may optimize the desired control current of the laser unit based on a set lifetime management strategy according to the laser unitConsumed lifetime L (t)0) And the super life usage rate O (t) of the laser unit0) Determining a maximum single frame lifetime decay rate r of a laser unitDThe maximum single frame lifetime decay rate r of the laser unitDCan be expressed as:
rD＝rD(L(t0))。
based on the above analysis, the ideal driving current i (t) of the laser unit is optimized according to the life data information of the laser unit, which can be understood as: maximum single frame lifetime decay rate r at the laser unitDThere may be a maximum cut-off current ImaxAnd using the maximum cut-off current ImaxCutting off the ideal driving current I (t) of the laser unit, so as to obtain the adjusted actual driving current I' (t) of the laser unit as follows:
Figure BDA0002678309290000121
if the service life management parameter condition that the service life attenuation rate of the laser unit under the actual driving current is less than or equal to the maximum single-frame service life attenuation rate of the laser unit under the maximum cut-off current drive is to be met, the maximum cut-off current I of the laser unitmaxThe following inequalities should be satisfied:
Figure BDA0002678309290000122
wherein, L (t)0+tf) I (t) is made for the ideal control current I (t) of the laser unit in the current image frame timemaxLife consumed after cutting, tfThe duration of the current image frame. Then there are:
Figure BDA0002678309290000131
therefore, during the calculation of the actual drive current I '(t) of the laser unit, there is a maximum off-current I' (t)maxSatisfy the following requirementsThe inequality above. According to the maximum cut-off current ImaxAdjusting the ideal driving current I (t) of the laser unit, obtaining the adjusted actual driving current I '(t) of the laser unit according to the formula (8), and making the actual driving current I' (t) less than or equal to the maximum cut-off current ImaxTherefore, based on the above equations (8), (9) and (10), the adjusted actual drive current I' (t) of the laser unit can be obtained by optimizing the ideal drive current I (t) of the laser unit.
(III) maximum Single frame Life decay Rate
The calculation of the maximum single frame lifetime decay rate will be illustrated below.
From the above derivation, as an embodiment, the lifetime management policy determined by the control device 10 defines a lifetime management parameter condition (e.g., a maximum single-frame lifetime decay rate r)DMaximum off current Imax) When the ideal driving current I (t) of the laser unit is optimized according to the lifetime management strategy, the operating parameters of the laser unit should satisfy the lifetime management parameter condition, i.e., the actual driving current I '(t) of the laser unit is less than or equal to the maximum cut-off current I' during the current image frame timemaxAnd the maximum single-frame life attenuation rate of the laser unit is smaller than the maximum single-frame life attenuation rate threshold determined by a preset life management strategy, so that the actual life of the laser unit is ensured to meet the requirement of the design life on the premise of improving the display high brightness of the projection equipment.
In some practical usage scenarios, the display of the image signal requires that the projection apparatus 100 always display a higher brightness, and as a life management strategy for the laser unit, the maximum single-frame life decay rate I of the laser unit may be set after the projection apparatus 100 is used for a preset timemaxSet to a value such that the maximum brightness displayed by the projection device 100 remains substantially constant. The preset time may be 0, that is, the projection apparatus 100 is a new machine, or may be after a certain time of use. The control device 10 is based on this constant maximum cut-off current ImaxTo adjust the ideal driving current I (t) of the laser unit to ensure the actual life of the laser unit to meet the design life LdOf the laser unit, maximum single frame lifetime decay rate rDThe following inequalities should be satisfied:
Figure BDA0002678309290000132
based on the above inequality (11), the maximum single-frame lifetime decay rate r of the laser unit is determinedDWhen r isDCan be taken as a limit value, the maximum single-frame lifetime decay rate r of the laser unitDCan be calculated from the following equation:
Figure BDA0002678309290000141
for another example, in some practical usage scenarios, the display of the image signal does not require the projection device to always display a high brightness, and the actual driving current value actually used to drive the laser unit is usually smaller than its rated driving current I0At this time, the consumed service life of the laser unit is less than the used time of the laser unit, and when the projection equipment needs high brightness in the subsequent time, the actual driving current of the laser unit can be made to be greater than the rated driving current flowing current I of the laser unit0The maximum single frame lifetime decay rate r of the laser unit should be determined based on the currently consumed lifetime of the laser unit, i.e. based on the remaining lifetime of the laser unit. Suppose the laser unit has been operating LTTo ensure that the actual life of the laser unit meets the design life LdThe maximum single frame lifetime decay rate r of the laser unitDThe following inequalities should be satisfied:
Figure BDA0002678309290000142
wherein r isrealTo operate the laser unit alreadyTThe actual lifetime decay rate of the laser unit.
Based on inequality (13), determining the maximum single-frame lifetime decay rate of the laser unitRate rDWhen r isDA limit value can be taken, and the design life L is ensured to meet the actual life of the laser unitdOf the laser unit, maximum single frame lifetime decay rate rDCan be calculated from the following equation:
Figure BDA0002678309290000143
for another example, in some practical usage scenarios, the actual driving current I' (t) of the laser unit should make the actual lifetime of the laser unit longer than the designed lifetime, and if the consumed lifetime of the laser unit is longer than the operated lifetime, the maximum single frame lifetime decay rate of the laser unit may be determined according to the maximum single frame lifetime decay rate when the operated lifetime of the laser unit reaches the designed lifetime and the maximum single frame lifetime decay rate of the current time of the laser unit. In particular, assume that the laser unit has been operated to reach the current LTAccording to the optimized lifetime management strategy, the maximum single-frame lifetime decay rate r of the laser unitDCan be expressed as:
Figure BDA0002678309290000144
wherein: l isTIs the used time of the laser unit, LdFor the design life of the laser unit, a is the service life of the laser unit LTB is the maximum lifetime decay rate at which the service time of the laser unit reaches the design lifetime. Typically, the maximum lifetime decay rate of a laser unit has a minimum value when the laser unit is used for the design lifetime, and therefore, a is typically>b。
By substituting the above calculation equation (15) into the above inequality equation (14), an inequality can be obtained:
Figure BDA0002678309290000151
wherein the content of the first and second substances,
Figure BDA0002678309290000152
is the average of the historical lifetime decay rates of the laser unit.
As an example, the symbol equal to or greater than the symbol in the inequality (16) may be replaced with the symbol equal to calculate the laser unit operation time to the current time LTMaximum value of the maximum lifetime decay rate a of time, i.e. the laser unit operation time reaches the current time LTThe maximum value of the temporal maximum lifetime decay rate a can be obtained by the following calculation formula:
Figure BDA0002678309290000153
as can be derived from the above, b in the inequality (16) represents the maximum brightness limitation condition of the output of the laser unit when the operating time of the laser unit reaches the design life, and the value of b can be set according to the application requirement and the standard limitation of the actual projection device. For example, according to the industry specification of laser display, in general, when the operating time of the laser unit reaches the design life, the display brightness attenuation of the laser unit should not exceed 50%, and therefore, the value of b may be 0.5. Therefore, when b is known, the calculation formula (17) can determine that the entire laser unit operation time reaches the current time LTThe maximum lifetime decay rate a of the time, and then the maximum single-frame lifetime decay rate r of the laser unit in the current image frame time can be obtained according to the calculation formula (15)D。
In summary, before the image frame to be displayed is displayed, the historical lifetime decay rate of the laser unit can be calculated according to the historical working condition, the projection device can calculate the consumed lifetime of the laser unit before the image frame to be displayed is displayed according to the used time, the historical driving current and the historical lifetime decay rate of the laser unit, so as to obtain the remaining lifetime of the laser unit, and calculate the maximum single-frame lifetime decay rate rDAccording to the maximum single frame lifetime decay rate rDCalculating the maximum cut-off current I of the laser unitmaxBased on the maximum cut-off current ImaxThe ideal control current I (t) is optimized, so that the actual control current I' (t) of the laser unit is obtained, and the overcurrent driving multiplying power p of the laser unit can also be obtained, so that the optimization of the ideal driving current I (t) of the laser unit is completed.
It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to make many alternative embodiments without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (11)

1. A projection device, characterized by: comprises a light source device, a spatial light modulator and a control device;
the light source device comprises at least one laser unit;
the control device is used for acquiring the brightness distribution information of the current image frame according to the image signal to be displayed, and adjusting the driving current of the laser unit according to the brightness distribution information of the current image frame and the service life data information of the laser unit, so that the adjusted actual driving current is greater than the rated driving current in at least part of the time period within the current image frame time;
the spatial light modulator is arranged on a light path of light emitted by the light source device and used for modulating the light emitted by the light source device to obtain a modulated image.
2. The projection apparatus as claimed in claim 1, wherein the control means is configured to determine an 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 apparatus according to any of claims 1 to 2, wherein the lifetime data information of the laser unit includes a consumed lifetime and a used time of the laser unit, and when the consumed lifetime of the laser unit is less than the used time, the control means adjusts the driving current of the laser unit such that the adjusted actual driving current is greater than the rated driving current for at least a part of the period within the current image frame time.
4. The projection device of claim 3, wherein an actual drive current of the laser unit during a current image frame time is less than or equal to a maximum cutoff current of the laser unit.
5. The projection device of claim 4, wherein a maximum off-current of the laser unit is determined by a ratio of a consumed lifetime of the laser unit, the consumed lifetime of the laser unit, and a used time.
6. The projection device of claim 4, wherein a lifetime decay rate of the laser unit at an actual drive current during a current image frame time is less than or equal to a maximum single frame lifetime decay rate of the laser unit at a maximum cutoff current drive.
7. The projection device of claim 6, wherein a maximum single frame lifetime decay rate of the laser unit after a preset time of use is a certain value.
8. The projection device of claim 6, wherein a maximum single frame lifetime decay rate of the laser unit within a current image frame time is determined by a maximum lifetime consumption rate for a current time of use of the laser unit and a maximum lifetime consumption rate at which the laser unit design lifetime has arrived.
9. The projection device of claim 8, wherein at the current imageThe maximum single-frame lifetime decay rate of the laser unit within a frame time is rD：
Figure FDA0002678309280000021
Wherein: l isTFor the used time of the laser unit, LdFor the design life of the laser unit, a is the service life of the laser unit is LTB is the maximum lifetime decay rate when the service time of the laser unit reaches the design lifetime.
10. The projection device of claim 1, wherein the control means is further configured to calculate lifetime consumption information of the laser unit during a current image frame time to update lifetime data information of the laser unit.
11. The projection device of claim 10, wherein the control means is configured to calculate a lifetime consumed by the laser unit within a current image frame; and subtracting the service life consumed by the laser unit in the current image frame from the residual service life of the laser unit before the current image frame is played to obtain the updated service life data information of the laser unit.
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