Light source control method for projectors, projectors and storage media

Abstract

This invention discloses a light source control method for a projector, a projector, and a storage medium. The light source control method includes: acquiring a first tilt angle of the projector relative to a target projection surface; extracting a corresponding preset brightness value group based on the first tilt angle, the preset brightness value group including multiple ideal brightness values ​​corresponding to different light-emitting units; and controlling the luminous brightness of the corresponding light-emitting unit based on the ideal brightness value of each light-emitting unit in the preset brightness value group. This invention can solve the problem of uneven brightness in LCD projector images.

Description

Technical Field

[0001] This invention relates to the field of projector technology, and more particularly to a light source control method for a projector, a projector, and a storage medium. Background Technology

[0002] Currently, most LCD projector light sources are matrix-type white LED light sources. This type of light source typically arranges individual LEDs in a matrix on a circuit board substrate, and then connects them in parallel or series with wires to form a whole component. Under this light source design concept, the whole lamp component can achieve a large light power output at a relatively low cost, but the brightness of the lamp component can only be adjusted as a whole, and the brightness of individual LEDs cannot be adjusted independently.

[0003] Accordingly, the light emitted from the LCD LEDs illuminates an LCD panel with an RGB filter film on its surface. Each liquid crystal cell on the LCD panel corresponds to a color filter film. By controlling the light transmittance of each liquid crystal cell on the LCD panel, the brightness of the light passing through each liquid crystal cell can be controlled. This solution has advantages such as low cost, high brightness, compatibility with the lighting market, and large production volume; however, this light source also suffers from poor brightness uniformity, mainly manifested as high brightness in the center and low brightness around the edges.

[0004] Therefore, projectors using the above solutions all suffer from uneven brightness in the projected image, mainly manifested as a bright center and dark edges. For example, Figure 1 The image shows a cross-sectional view of the matrix light panel of the projector. b1, b2, b3, b4, b5, and b6 represent LED beads. After being lit, the LED beads emit light at a certain angle. It can be seen that among the regions a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, and a11, region a6 is the brightest because the brightness of the superimposed LED beads is the most concentrated. Regions a1 and a11 each have only one LED bead, so they are the darkest.

[0005] In addition, during the use of projectors, there will be scenarios where side projection is used (that is, the projection direction of the projector is tilted relative to the wall / screen, which will cause the originally rectangular projection image to become trapezoidal). When the projector is used for side projection, the image is corrected by software. This makes the image at the far end dark and the image at the near end bright after the projector is side projected.

[0006] The above background information is provided only to aid in understanding the concept and technical solution of this invention. It does not necessarily belong to the prior art of this patent application. In the absence of clear evidence that the above information was disclosed on the filing date of this patent application, the above background information should not be used to evaluate the novelty and inventiveness of this application. Summary of the Invention

[0007] To address the issue of uneven brightness in LCD projectors, this invention proposes a light source control method for projectors, a projector, and a storage medium.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] In a first aspect, the present invention discloses a light source control method for a projector, used to control multiple light-emitting units arranged in an array, comprising:

[0010] Obtain the first tilt angle of the projector relative to the target projection surface;

[0011] Based on the first tilt angle, a corresponding preset brightness value group is extracted, and the preset brightness value group includes multiple ideal brightness values ​​corresponding to different light-emitting units;

[0012] The luminance of the corresponding light-emitting unit is controlled according to the ideal luminance value of each light-emitting unit in the preset luminance value group.

[0013] Preferably, the step of controlling the luminous brightness of the corresponding light-emitting unit according to the ideal luminous value of each light-emitting unit in the preset luminous value group specifically includes: generating a duty cycle of a PWM signal for controlling each light-emitting unit according to the ideal luminous value of each light-emitting unit in the preset luminous value group, and controlling the luminous brightness of the corresponding light-emitting unit according to the duty cycle of the PWM signal.

[0014] Preferably, before the step of extracting the corresponding preset brightness value group according to the first tilt angle, the method further includes obtaining the preset brightness value group, wherein the step of obtaining the preset brightness value group includes:

[0015] Obtain the second tilt angle of the current projector relative to the target projection surface;

[0016] A second captured image is acquired, and brightness values ​​at multiple feature locations are obtained based on the second captured image. The feature locations correspond to the ideal brightness values ​​of the light-emitting units.

[0017] The brightness difference at each of the aforementioned feature locations is determined based on the brightness value at each of the aforementioned feature locations;

[0018] Based on the brightness difference at each feature location, the ideal brightness value of the light-emitting unit corresponding to each feature location is determined, and the ideal brightness value of the light-emitting unit corresponding to each feature location is used as a preset brightness value group corresponding to the second tilt angle.

[0019] Preferably, the step of acquiring the second captured image and obtaining brightness values ​​at multiple feature locations based on the second captured image specifically includes:

[0020] A brightness calibration image is projected onto the target projection surface, and a second captured image containing the brightness calibration image is obtained;

[0021] Obtain the coordinates of multiple feature locations in the second captured image;

[0022] Obtain the brightness values ​​at the coordinates of multiple feature locations in the second captured image.

[0023] Preferably, before the step of acquiring the second captured image and obtaining the brightness values ​​at each feature location based on the second captured image, the method further includes:

[0024] A coordinate calibration image is projected onto the target projection surface. The coordinate calibration image includes multiple feature maps, and the arrangement of the multiple feature maps corresponds to the array arrangement of the multiple light-emitting units.

[0025] A first captured image containing the coordinate calibration screen is obtained, and the feature position is obtained based on the feature map in the first captured image.

[0026] Preferably, the step of determining the brightness difference at each of the feature locations based on the brightness values ​​at each of the feature locations specifically includes:

[0027] Obtain the brightness value at an edge position in the second captured image, and subtract the brightness value at the edge position from the brightness value at each of the feature positions to obtain the corrected brightness value at each of the feature positions.

[0028] The brightness difference at each of the aforementioned feature locations is determined based on the corrected brightness value at each of the aforementioned feature locations.

[0029] Preferably, the step of determining the brightness difference at each of the feature locations based on the brightness values ​​at each of the feature locations specifically includes:

[0030] Using any one of the feature positions as a reference feature position and the brightness value at the reference feature position as a reference brightness value, calculate the brightness difference between the brightness value at each of the feature positions and the reference brightness value.

[0031] The step of determining the ideal brightness value of the light-emitting unit corresponding to each of the feature locations based on the brightness difference at each feature location specifically includes:

[0032] Based on the brightness difference between the brightness value at each of the aforementioned feature positions and the reference brightness value, the ideal brightness value of the light-emitting unit corresponding to each of the aforementioned feature positions is calculated as follows: Pi = Li + ki * Lk, where Pi is the ideal brightness value of the light-emitting unit corresponding to the i-th feature position, Li is the current brightness value of the light-emitting unit corresponding to the i-th feature position, ki is the brightness difference between the brightness value at the i-th feature position and the reference brightness value, and Lk is the current brightness value of the light-emitting unit corresponding to the reference feature position.

[0033] Preferably, the step of extracting the corresponding preset brightness value group according to the first tilt angle specifically includes: obtaining the calibration tilt angle range corresponding to the first tilt angle in the calibration model according to the first tilt angle, and extracting the calibration brightness value group corresponding to the calibration tilt angle range as the preset brightness value group corresponding to the first tilt angle, wherein the calibration model includes multiple calibration tilt angle ranges and multiple calibration brightness value groups, and there is a one-to-one mapping relationship between each calibration tilt angle range and each calibration brightness value group.

[0034] In a second aspect, the present invention discloses a projector including a processor and a memory, wherein the memory stores a computer program that can be read by the processor to execute in order to implement the light source control method as described in the first aspect.

[0035] Thirdly, the present invention discloses a storage medium storing a computer program, wherein the computer program is configured to be run by a processor to perform the light source control method described in the first aspect.

[0036] Compared with existing technologies, the beneficial effects of this invention are as follows: The light source control method, projector, and storage medium disclosed in this invention control the brightness of each light-emitting unit independently, enabling each unit to emit light according to the ideal brightness value in a preset brightness value group, thereby achieving a balanced screen brightness and solving the common problem of uneven brightness in LCD projectors when projecting from the front or side. Furthermore, this method allows for the reduction of brightness in brighter light-emitting units, balancing the brightness of the corresponding area of ​​the originally brighter light-emitting unit with the surrounding area in the projected image, thus reducing heat loss and energy consumption.

[0037] In a further solution, the brightness of the light-emitting unit is controlled by the duty cycle of the PWM signal. This not only better solves the problem of uneven brightness in the image, but also further reduces the heat loss of the light source.

[0038] In a further improved solution, a calibration model can be built into the projector before the device leaves the factory to enable real-time adjustment of the brightness of each light-emitting unit based on the tilt angle; alternatively, the preset brightness value set corresponding to the tilt angle can be acquired or updated after the device leaves the factory to obtain a more accurate preset brightness value set or to eliminate errors in the calibration model caused by the multiple influences of projection distance, angle, and usage environment on brightness. Attached Figure Description

[0039] Figure 1 This is a cross-sectional schematic diagram of a rectangular light panel in the prior art;

[0040] Figure 2 This is a flowchart of a light source control method for a projector according to Embodiment 1 of the present invention;

[0041] Figure 3 This is a schematic diagram of the projected image when the projector is projecting data.

[0042] Figure 4 This is a schematic diagram of the trapezoidal projection image when the projector projects to the left.

[0043] Figure 5 This is a flowchart of a method for obtaining or updating the preset brightness value group mentioned above in a further embodiment of the present invention;

[0044] Figure 6 This is a schematic diagram showing the formation of feature maps in multiple sub-regions of the projected image.

[0045] Figure 7 This is a schematic diagram of the projection light source assembly in one embodiment. Detailed Implementation

[0046] The embodiments of the present invention will be described in detail below. It should be emphasized that the following description is merely exemplary and not intended to limit the scope and application of the present invention.

[0047] It should be noted that when a component is referred to as "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as "connected to" another component, it can be directly connected to or indirectly connected to that other component. Furthermore, a connection can be used for both fixing and circuit / signal connectivity.

[0048] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of embodiments of the present invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0049] like Figure 2 As shown, Embodiment 1 of the present invention discloses a light source control method for a projector, comprising the following steps:

[0050] S1: Obtain the first tilt angle of the projector relative to the target projection surface;

[0051] This step can obtain the first tilt angle of the projector relative to the target projection surface using a depth sensor such as TOF or other methods.

[0052] S2: Based on the first tilt angle, extract the corresponding preset brightness value group, which includes multiple ideal brightness values ​​corresponding to different light-emitting units;

[0053] In a specific embodiment, based on the first tilt angle, a calibration tilt angle range corresponding to the first tilt angle is obtained in the calibration model, and a calibration brightness value set corresponding to the calibration tilt angle range is extracted as a preset brightness value set corresponding to the first tilt angle. The calibration model includes multiple calibration tilt angle ranges and multiple calibration brightness value sets, and there is a one-to-one mapping relationship between each calibration tilt angle range and each calibration brightness value set. Each calibration brightness value set contains the ideal brightness value corresponding to each light-emitting unit, where the ideal brightness value can be a grayscale value, current value, or duty cycle, etc. The light source driving module of the projection device can control the light emission brightness of the corresponding light-emitting unit according to each ideal brightness value.

[0054] The calibration tilt angle range can be in 10° increments, such as -5° to +5°, +5° to +15°, etc. When the first tilt angle of the projector relative to the target projection surface is within a certain range, the calibration brightness value set corresponding to that calibration tilt angle range is retrieved. For example, if the current projection tilt angle is detected to be +10°, the calibration brightness value set corresponding to the +5° to +15° calibration tilt angle range is retrieved as the preset brightness value set to control the brightness of each light-emitting unit, and so on. The specific calibration tilt angle range can be adjusted according to the actual hardware conditions of the device; this is just an example.

[0055] S3: Control the brightness of the corresponding light-emitting unit according to the ideal brightness value of each light-emitting unit in the preset brightness value group.

[0056] In a specific embodiment, the light-emitting unit is an LED lamp bead, or it can be a common projector light source such as a laser lamp bead.

[0057] In a specific embodiment, the duty cycle of the PWM signal controlling each light-emitting unit is generated according to the ideal brightness value of each light-emitting unit in the preset brightness value group, and the light-emitting brightness of the corresponding light-emitting unit is controlled according to the duty cycle of the PWM signal.

[0058] The brightness of the light-emitting unit is controlled using PWM (Pulse Width Modulation). Its working principle is to maintain a constant voltage or current while varying the on / off time of the current supplied to the light-emitting unit within a certain cycle. Controlling the blinking of the light-emitting unit using frequency is equivalent to connecting a switch in series.

[0059] For example, if the light is on for 0.5 seconds and off for 0.5 seconds within a 1-second timeframe, the light appears to be flickering. However, if the frequency is increased, changing 1 second to 1 millisecond, with the light on for 0.5 milliseconds and off for 0.5 milliseconds, the flickering frequency appears much higher. The duty cycle controls the brightness of the light-emitting unit based on the fact that when the flickering frequency exceeds a certain threshold, the human eye can no longer perceive it. For example, if the light is off for 0.9 milliseconds and on for 0.1 milliseconds within a 1-ms timeframe, the human eye will perceive the light brightness as only one-tenth of its original level. In this embodiment, brightness is adjusted by changing the duration of the light-emitting unit's power-on time; a longer power-on time results in higher brightness.

[0060] Based on the above working principle, in this embodiment, the duty cycle of the PWM signal corresponding to each light-emitting unit can be generated according to the ideal brightness value of each light-emitting unit. After the duty cycle of the PWM signal is generated in the chip, it is directly sent to the light-emitting unit, and then each light-emitting unit can emit light according to the corresponding ideal brightness value.

[0061] In a specific embodiment, if the first tilt angle in step S1 is not 0, it can be known that the projector is currently in side projection mode. When the main controller of the projector receives the user's side projection request, it first performs keystone correction on the image, and then, based on the first tilt angle, it uses a control command to make the microcontroller extract the set of calibrated brightness values ​​corresponding to the calibrated tilt angle range corresponding to the first tilt angle as a preset brightness value set, thereby further adjusting the brightness of the corresponding light-emitting unit according to the preset brightness value set, so that the brightness of each area of ​​the projected image tends to be uniform.

[0062] The calibration model involved in step S2 of the above embodiments can be preset in the memory of the projector, and its preset process steps can be executed before the device leaves the factory. The calibration brightness value group in the calibration model can be read by software program as the corresponding preset brightness value group to control the brightness of the corresponding light-emitting unit. Each element in the calibration brightness value group corresponds to the duty cycle of the PWM of a light-emitting unit, and the elements are used to characterize the ideal brightness value. The calibration brightness value group can be in the following form:

[0063] {255, 255, 255, 255}

[0064] {255, 255, 255, 255}

[0065] {255, 255, 255, 255}

[0066] {255, 255, 255, 255}

[0067] Each element corresponds to a light-emitting unit, and the value of the element corresponds to the brightness of the light-emitting unit. The above-mentioned set of calibrated brightness values ​​indicates that the brightness of each light-emitting unit is consistent. The value range of the elements in the set of calibrated brightness values ​​is 0 to 255, corresponding to a PWM duty cycle of 0 to 100%. For example, when an element is 127, it corresponds to a 50% PWM duty cycle.

[0068] In some embodiments, a calibration model can be pre-set before the device leaves the factory. This calibration model includes pre-set brightness data for orthographic projection and pre-set brightness data for side projection. Further, in some embodiments, the method for obtaining this calibration model is as follows:

[0069] (1) Preset brightness data for orthographic projection

[0070] Taking a light source consisting of 4x4 arranged light-emitting units as an example, the projector is placed at a fixed distance (e.g., 1 meter) relative to a wall. Theoretically, the projected image can be divided into a 4x4 screen area (the specific division method and number of areas depend on the arrangement and number of light-emitting units). In some embodiments, one screen area can correspond to one or more light-emitting units, and the one or more light-emitting units corresponding to the same screen area always share an ideal brightness value. Figure 3As shown, in one embodiment, the projector is placed directly facing the wall. The projected image can be divided into 16 equal areas, A to P. A lux meter (or camera) measures the brightness value at the center of each of these 16 areas. Then, the brightness value (e.g., PWM value) of the corresponding light-emitting unit for each area is modified in the projector's program array until the measured brightness of each area becomes consistent, with the difference within the allowable error range. In one embodiment, the projector is placed directly facing the wall. In this case, the corresponding luminous brightness value of each light-emitting unit can be obtained by adjusting the above method, as shown below:

[0071] {255, 255, 255, 255}

[0072] {255, 220, 220, 255}

[0073] {255, 220, 220, 255}

[0074] {255, 255, 255, 255}

[0075] F, G, J, and K represent the areas corresponding to the four central light-emitting units. These areas are generally brighter than the surrounding areas. Therefore, to balance the brightness of the entire projected image, the brightness of these four central light-emitting units is made relatively dimmer than the surrounding areas. Since the projector is directly facing the wall under these conditions, there is a symmetry in the brightness of the different areas of the projected image; therefore, the brightness of each light-emitting unit also exhibits a corresponding symmetry.

[0076] (2) Preset brightness data for side projection

[0077] Side projection refers to the situation where the projector is tilted relative to the wall. The brightness data preset is similar to that of front projection; select a fixed side. For example, to project to the left, refer to... Figure 4 As shown, when the projector is at angles of 10 degrees, 20 degrees, and 30 degrees relative to the wall / screen (target projection surface), the brightness values ​​of the corresponding light-emitting units in each image area are obtained after manual or automatic brightness equalization. In this embodiment, each image area corresponds to one light-emitting unit. However, it should be noted that the brightness of a projected image area is not solely provided by its corresponding light-emitting unit, but also depends on adjacent and even more distant light-emitting units. However, the overall trend is that the brightness of the projected image area is most significantly affected by the brightness of its corresponding light-emitting unit. The element values ​​in the following matrix represent the ideal brightness values ​​of each light-emitting unit at 10°:

[0078] {255, 250, 230, 200}

[0079] {255, 240, 220, 200}

[0080] {255, 240, 220, 200}

[0081] {255, 250, 230, 200}

[0082] like Figure 4 As shown, this is a trapezoidal projection image produced when the projector projects to the left. The image is farther away on the left and closer on the right. Before the brightness of each light-emitting unit is adjusted, the image area farther away from the projector is larger and darker, while the area closer is relatively brighter. At the same time, the outer area of ​​the projected image is darker than the middle area.

[0083] During the process of obtaining the calibration model, since there is a mirror relationship between the left and right side projections of the projector, after obtaining the brightness table data of the left side projection mentioned above, the data of the right side projection can be directly horizontally mirrored from the corresponding angle data of the left side projection. This reduces the workload of obtaining the brightness data table corresponding to each projection angle. For example, the table below shows the calibration brightness value group corresponding to the projector tilted relative to the wall at -10° (a positive angle indicates that the projector is projecting from the left side relative to the wall, and a negative angle indicates that the projector is projecting from the right side relative to the wall):

[0084] {200, 230, 250, 255}

[0085] {200, 220, 240, 255}

[0086] {200, 220, 240, 255}

[0087] {200, 230, 250, 255}

[0088] The aforementioned calibration model includes multiple calibration tilt angle ranges and multiple sets of calibration brightness values ​​corresponding one-to-one with each calibration tilt angle range. These calibration tilt angle ranges are obtained based on a measured calibration tilt angle ±5°. For example, during orthogonal projection (calibrated tilt angle of 0°), the calibration tilt angle range is -5° to 5°; or during side projection, the ideal brightness value of each light-emitting unit at 10° can be used as the corresponding calibration brightness value set for a calibration tilt angle range of 5° to 15°. The calibration model is measured and preset before normal user use. During user use, when the projector's left-side projection angle relative to the wall / screen (target projection surface) is detected to be any angle value between 5° and 15°, the calibration brightness value set corresponding to that calibration tilt angle range can be used as the corresponding preset brightness value set to control the brightness of each light-emitting unit, and so on.

[0089] Through the above steps S1 to S3, the luminous brightness of each light-emitting unit can be adjusted in real time based on the first tilt angle. In a further embodiment, before executing step S2, the preset brightness value group mentioned above can be obtained, or the preset brightness data group extracted in the calibration model can be updated.

[0090] Because brightness is affected by multiple factors such as projection distance, angle, and usage environment, the calibration model measured before the projector leaves the factory may not be able to fully simulate the actual usage scenarios of all users. This may lead to some errors in the brightness adjustment of the light-emitting unit based on the pre-set calibration model in some projectors. These errors can be eliminated by obtaining or updating the preset brightness value set mentioned above before executing step S2. Therefore, in some embodiments, the user can manually operate the projector to obtain or update the preset brightness value set after the projector leaves the factory, or even obtain the preset brightness value set without pre-shipment testing. Therefore, the preset brightness value set obtained in this further embodiment can both replace the calibration model and update the calibration model.

[0091] The following provides further explanation on how to obtain or update the preset brightness value set mentioned above.

[0092] Specifically, such as Figure 5 As shown, the method for obtaining or updating a preset brightness value group includes the following steps:

[0093] A1: Obtain the second tilt angle of the current projector relative to the target projection surface;

[0094] Specifically, the second tilt angle of the projector relative to the target projection surface (such as the projection wall) can be calculated using a depth detection module (such as a TOF module) on the projector.

[0095] A2: Acquire the second captured image, and obtain the brightness values ​​at multiple feature locations based on the second captured image. There is a correspondence between the feature locations and the ideal brightness values ​​of the light-emitting units.

[0096] Step A2 specifically includes:

[0097] A21: Project a brightness calibration image onto the target projection surface and acquire a second captured image containing the brightness calibration image;

[0098] The brightness calibration image can be a solid color image, as long as the entire image is the same color and the luminous brightness of the light-emitting units is the same.

[0099] A22: Obtain the coordinates of multiple feature locations in the second captured image;

[0100] The coordinates can be obtained by projecting a coordinate calibration image onto the target projection surface. For example, before step A2, the method further includes: projecting a coordinate calibration image onto the target projection surface, the coordinate calibration image including multiple feature maps, and the arrangement of the multiple feature maps corresponding to the array arrangement of multiple light-emitting units; acquiring a first captured image containing the coordinate calibration image, and obtaining the feature position based on the feature maps in the first captured image. In one specific embodiment, the first captured image and the second captured image are images captured at the same angle, and the two images have the same spatial coordinate system. The coordinates of the feature position in the first captured image are the coordinates of the feature position in the second captured image.

[0101] Specifically, a projector can divide the projected image into sub-regions with corresponding numbers and shapes of projections based on the number and arrangement of the light-emitting units, for example... Figure 6 Taking a 3x3 rectangular arrangement of light-emitting units as an example, the projector projects a coordinate calibration screen 20. Specifically, a feature map 10, such as a QR code, is formed at the center of each sub-region (i.e., the feature position) and can be recognized by a visual algorithm. The QR code does not exceed the sub-region. The feature map containing the QR codes of each sub-region is projected out. Any two QR codes can be distinguished by the algorithm. The coordinate calibration screen 20 is captured by the camera on the projector or mobile terminal to obtain the first captured image. The algorithm identifies each QR code in the first captured image and then determines the marker coordinates of each QR code in the first captured image.

[0102] A23: Obtain the brightness values ​​at the coordinates of multiple feature locations in the second captured image.

[0103] The brightness values ​​at the coordinates of multiple feature locations in the second captured image can be obtained from the image grayscale values ​​at the corresponding coordinates of multiple feature locations in the second captured image.

[0104] A3: Determine the brightness difference at each feature location based on the brightness value at each feature location;

[0105] Specifically, this step includes: acquiring a brightness value (characterizing ambient brightness) at an edge location in the second captured image; subtracting the brightness value at the edge location from the brightness value at each feature location to obtain a corrected brightness value at each feature location; and determining the brightness difference at each feature location based on the corrected brightness value. By acquiring the corrected brightness value and determining the brightness difference based on it, the problem of inaccurate calculation results caused by the influence of ambient brightness on projection brightness in some usage scenarios can be overcome.

[0106] A4: Based on the brightness difference at each feature position, determine the ideal brightness value of the light-emitting unit corresponding to each feature position, and use the ideal brightness value of the light-emitting unit corresponding to each feature position as a preset brightness value group corresponding to the second tilt angle.

[0107] In a further embodiment:

[0108] Step A3 specifically includes: taking any one of the feature locations as a reference feature location, and taking the brightness value at that reference feature location as a reference brightness value, calculating the brightness difference between the brightness value at each feature location and the reference brightness value; for example, based on Figure 6 The coordinate c5 in the middle is used as the reference calibration coordinate. The brightness difference between c1 and c5 is defined as k1 = (Lc5 - Lc1) / Lc5; the brightness difference between c2 and c5 is k2 = (Lc5 - Lc2) / Lc5. In the formula, Lc1, Lc2, and Lc5 correspond to the current brightness value (or the corrected current brightness value) at the coordinates c1, c2, and c5, respectively. The brightness difference at the coordinates of other sub-regions is calculated in the same way, thus obtaining the brightness difference values ​​from k1 to k9.

[0109] Correspondingly, step A4 specifically includes: calculating the ideal brightness value of the light-emitting unit corresponding to each feature position based on the brightness difference between the brightness value at each feature position and the reference brightness value: Pi = Li + ki * Lk, where Pi is the ideal brightness value of the light-emitting unit corresponding to the i-th feature position, Li is the current brightness value of the light-emitting unit corresponding to the i-th feature position, ki is the brightness difference between the brightness value at the i-th feature position and the reference brightness value, and Lk is the current brightness value of the light-emitting unit corresponding to the reference feature position.

[0110] After calculating the ideal brightness value of the light-emitting unit corresponding to each feature position, the second tilt angle obtained in step A1 is then matched with the ideal brightness value of the light-emitting unit corresponding to each feature position calculated at the moment. The ideal brightness value of the light-emitting unit corresponding to each feature position calculated at the moment is then used as a preset brightness value group corresponding to the second tilt angle.

[0111] Steps A1 to A4 should then be repeated to obtain different sets of preset brightness values ​​for different tilt angles. The ideal brightness value Pi of each light-emitting unit at each tilt angle should be saved to obtain a mapping table of multiple different tilt angles and multiple different sets of preset brightness values. Subsequently, when the projector's depth detection module detects that the projector is within the trigger range corresponding to the tilt angle (e.g., within ±5° of a certain tilt angle), the preset brightness value set corresponding to that tilt angle is called, and the light-emitting units corresponding to each feature position emit the corresponding brightness according to the ideal brightness value in the preset brightness value set.

[0112] The light source control method for projectors described in the above embodiments of the present invention is applicable not only to the automatic brightness adjustment of white light sources, but also to DLP schemes with RGB three-color light sources. That is, the brightness of each monochrome LED (corresponding to the light-emitting unit mentioned above) is automatically adjusted accordingly, which can also solve the problems of uneven brightness and uniformity of side projection brightness.

[0113] Embodiment 2 of the present invention also discloses a projector, including a processor and a memory. The memory stores a computer program, which can be read by the processor to execute in order to implement the light source control method as described in Embodiment 1 above.

[0114] refer to Figure 7 The projector includes a projection light source assembly, which provides the light required for projecting the image. The projection light source assembly includes a drive control module 10 and a light source module 20. The drive control module 10 includes a control unit 11 and multiple switching transistors 12. The light source module 20 includes multiple light-emitting units 21 arranged in an array. The control unit 11 includes multiple first output ports connected to the switching transistors 12. Each first output port is connected to the control port of at least one switching transistor 12. Each second output port of the switching transistor 12 is connected to at least one light-emitting unit 21. Each first output port of the control unit 11 is used to output a pulse-width adjustable level signal to control the conduction state of the multiple switching transistors 12. The projection light source assembly includes a power supply terminal Vcc. Each switching transistor 12 has an input port connected to the power supply terminal Vcc. The drive control module 10 also includes multiple first current-limiting resistors 13 and multiple second current-limiting resistors 14. The first current-limiting resistors 13 are connected between the first output port of the control unit 11 and the control port of the switching transistor 12, and the second current-limiting resistors 14 are connected between the input port of the switching transistor 12 and the power supply terminal Vcc.

[0115] In one embodiment, the projection light source assembly includes a ground terminal, and the light-emitting unit 21 includes LED beads. The positive terminals of the LED beads are connected to the second output port of the switching transistor 12, and the negative terminals of multiple LED beads are connected in parallel and then connected to the ground terminal. In other embodiments, the light-emitting unit 21 may also be a laser bead or other common projector beads. Additionally, in some embodiments, the control unit 11 may be a microcontroller or a programmable gate array device, and the switching transistor 12 may be a transistor (e.g., an NPN transistor or a PNP transistor) or a MOSFET.

[0116] Embodiment 3 of the present invention discloses a storage medium storing a computer program, wherein the computer program is configured to be run by a processor to perform the steps of the light source control method in Embodiment 1 above.

[0117] Optionally, the aforementioned storage media may include, but are not limited to, USB flash drives, read-only memory (ROM), random access memory (RAM), portable hard drives, magnetic disks, or optical disks, and other media capable of storing computer programs.

[0118] The present invention discloses a light source control method, a projector, and a storage medium for a projector. By independently controlling the brightness of each light-emitting unit, each unit emits light according to an ideal brightness value within a preset brightness value group, achieving a balanced screen brightness and solving the common problem of uneven brightness in LCD projectors when projecting from the front or side. Furthermore, this method allows for the reduction of brightness in brighter light-emitting units, balancing the brightness of the corresponding area of ​​a previously brighter unit with its surrounding area, thereby reducing heat loss and energy consumption.

[0119] The background section of this invention may include background information about the problems or circumstances surrounding the invention, rather than a description of prior art by others. Therefore, the content included in the background section is not an admission of prior art by the applicant.

[0120] The above description provides a further detailed explanation of the present invention in conjunction with specific / preferred embodiments, and it should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various substitutions or modifications can be made to these described embodiments without departing from the concept of the present invention, and all such substitutions or modifications should be considered within the scope of protection of the present invention. In the description of this specification, the reference to terms such as "an embodiment," "some embodiments," "preferred embodiment," "example," "specific example," or "some examples," etc., indicates that the specific features, structures, materials, or characteristics described in connection with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any suitable manner in one or more embodiments or examples. Furthermore, those skilled in the art can combine and integrate different embodiments or examples and features of different embodiments or examples described in this specification without contradiction. Although the embodiments of the present invention and their advantages have been described in detail, it should be understood that various changes, substitutions, and modifications can be made herein without departing from the scope defined by the appended claims.

Claims

1. A light source control method for a projector, characterized in that, Used to control multiple light-emitting units arranged in an array, including: Obtain the first tilt angle of the projector relative to the target projection surface; Based on the first tilt angle, a corresponding preset brightness value group is extracted, and the preset brightness value group includes multiple ideal brightness values ​​corresponding to different light-emitting units; The luminance of the corresponding light-emitting unit is controlled according to the ideal luminance value of each light-emitting unit in the preset luminance value group. Prior to the step of extracting the corresponding preset brightness value group based on the first tilt angle, the method further includes obtaining the preset brightness value group, wherein the step of obtaining the preset brightness value group includes: Obtain the second tilt angle of the current projector relative to the target projection surface; A second captured image is acquired, and brightness values ​​at multiple feature locations are obtained based on the second captured image. The feature locations correspond to the ideal brightness values ​​of the light-emitting units. The brightness difference at each of the aforementioned feature locations is determined based on the brightness value at each of the aforementioned feature locations; Based on the brightness difference at each feature position, the ideal brightness value of the light-emitting unit corresponding to each feature position is determined, and the ideal brightness value of the light-emitting unit corresponding to each feature position is used as a preset brightness value group corresponding to the second tilt angle. The step of acquiring the second captured image and obtaining brightness values ​​at multiple feature locations based on the second captured image specifically includes: A brightness calibration image is projected onto the target projection surface, and a second captured image containing the brightness calibration image is obtained; Obtain the coordinates of multiple feature locations in the second captured image; Obtain the brightness values ​​at the coordinates of multiple feature locations in the second captured image; The method further includes, before the step of acquiring the second captured image and obtaining the brightness values ​​at each feature location based on the second captured image: A coordinate calibration image is projected onto the target projection surface. The coordinate calibration image includes multiple feature maps, and the arrangement of the multiple feature maps corresponds to the array arrangement of the multiple light-emitting units. A first captured image containing the coordinate calibration screen is obtained, and the feature position is obtained based on the feature map in the first captured image.

2. The light source control method according to claim 1, characterized in that, The step of controlling the luminous brightness of the corresponding luminous unit according to the ideal luminous value of each luminous unit in the preset luminous value group specifically includes: Based on the ideal brightness value of each of the light-emitting units in the preset brightness value group, a duty cycle of the PWM signal controlling each of the light-emitting units is generated, and the light-emitting brightness of the corresponding light-emitting unit is controlled according to the duty cycle of the PWM signal.

3. The light source control method according to claim 1, characterized in that, The step of determining the brightness difference at each of the feature locations based on the brightness values ​​at each of the feature locations specifically includes: Obtain the brightness value at an edge position in the second captured image, and subtract the brightness value at the edge position from the brightness value at each of the feature positions to obtain the corrected brightness value at each of the feature positions. The brightness difference at each of the aforementioned feature locations is determined based on the corrected brightness value at each of the aforementioned feature locations.

4. The light source control method according to claim 1, characterized in that, The step of determining the brightness difference at each of the feature locations based on the brightness values ​​at each of the feature locations specifically includes: Using any one of the feature positions as a reference feature position and the brightness value at the reference feature position as a reference brightness value, calculate the brightness difference between the brightness value at each of the feature positions and the reference brightness value. The step of determining the ideal brightness value of the light-emitting unit corresponding to each of the feature locations based on the brightness difference at each feature location specifically includes: Based on the brightness difference between the brightness value at each of the aforementioned feature positions and the reference brightness value, the ideal brightness value of the light-emitting unit corresponding to each of the aforementioned feature positions is calculated as follows: Pi = Li + ki * Lk, where Pi is the ideal brightness value of the light-emitting unit corresponding to the i-th feature position, Li is the current brightness value of the light-emitting unit corresponding to the i-th feature position, ki is the brightness difference between the brightness value at the i-th feature position and the reference brightness value, and Lk is the current brightness value of the light-emitting unit corresponding to the reference feature position.

5. The light source control method according to claim 1, characterized in that, The step of extracting the corresponding preset brightness value group based on the first tilt angle specifically includes: Based on the first tilt angle, a calibration tilt angle range corresponding to the first tilt angle is obtained in the calibration model, and a calibration brightness value group corresponding to the calibration tilt angle range is extracted as a preset brightness value group corresponding to the first tilt angle. The calibration model includes multiple calibration tilt angle ranges and multiple calibration brightness value groups, and there is a one-to-one mapping relationship between each calibration tilt angle range and each calibration brightness value group.

6. A projector, characterized in that, It includes a processor and a memory, wherein the memory stores a computer program that can be read by the processor to execute in order to implement the light source control method as described in any one of claims 1 to 5.

7. A storage medium, characterized in that, The storage medium stores a computer program, wherein the computer program is configured to be run by a processor to perform the light source control method according to any one of claims 1 to 5.

Images