CN111223427B - Projection device and method for operating the same - Google Patents

Projection device and method for operating the same Download PDF

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Publication number
CN111223427B
CN111223427B CN201811582405.5A CN201811582405A CN111223427B CN 111223427 B CN111223427 B CN 111223427B CN 201811582405 A CN201811582405 A CN 201811582405A CN 111223427 B CN111223427 B CN 111223427B
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China
Prior art keywords
light emitting
switch
emitting diode
voltage
mode
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CN201811582405.5A
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CN111223427A (en
Inventor
苏韦志
邱胜裕
吴伯彦
陈荣基
王志琳
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Coretronic Corp
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Coretronic Corp
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Priority to US16/690,101 priority Critical patent/US11070777B2/en
Priority to JP2019210094A priority patent/JP7385441B2/en
Priority to EP19210804.1A priority patent/EP3668090B1/en
Publication of CN111223427A publication Critical patent/CN111223427A/en
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    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/001—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes using specific devices not provided for in groups G09G3/02 - G09G3/36, e.g. using an intermediate record carrier such as a film slide; Projection systems; Display of non-alphanumerical information, solely or in combination with alphanumerical information, e.g. digital display on projected diapositive as background
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/22—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources
    • G09G3/30—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels
    • G09G3/32—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED]

Abstract

The invention provides a projection device and an operation method thereof. The projection device includes a light emitting element, a driving circuit, and a control circuit. The driving circuit is coupled to the light emitting element. The driving circuit drives the light emitting element to generate projection light according to at least one control signal. The control circuit receives at least one video frame and analyzes color content of the at least one video frame. The control circuit selects one of the highlight mode and the normal mode as a selected mode according to the color content, and correspondingly sets at least one control signal to the driving circuit according to the selected mode. Wherein the brightness of the projected light of the light emitting element in the highlight mode is greater than the brightness of the projected light of the light emitting element in the normal mode. The projection device and the operation method thereof can dynamically increase the brightness of the projection light of the light-emitting element according to the color content of the video frame.

Description

Projection device and method for operating the same
Technical Field
The present invention relates to a light emitting device, and more particularly, to a projection device and an operating method thereof.
Background
The known projection lamps are all configured to emit projection light with a fixed brightness solely from the light-emitting element. The brightness of the projection light cannot be adjusted according to different situations. For example, since the projected light brightness of the known projection lamp is fixed, the effect of the projected light cannot be enhanced for a particular object (or situation).
The background section is only for the purpose of aiding in the understanding of the present invention and thus the disclosure of the background section may include some of the known art that does not form part of the understanding of those skilled in the art. The disclosure of the "background" section is not intended to represent the subject matter disclosed as one or more embodiments of the present invention, which may be known or appreciated by those skilled in the art prior to the application of the present invention.
Disclosure of Invention
The invention provides a projection device and an operation method thereof, which can dynamically increase the brightness of projection light of a light emitting element according to the color content of a video frame.
Other objects and advantages of the present invention will be further appreciated from the technical features disclosed in the present invention.
To achieve one or a part or all of the above or other objects, an embodiment of the present invention provides a projection apparatus. The projection device includes a light emitting element, a driving circuit, and a control circuit. The driving circuit is coupled to the light emitting element. The driving circuit is used for driving the light emitting element to generate projection light according to at least one control signal. The control circuit is used for receiving at least one video frame and analyzing the color content of the at least one video frame. The control circuit selects one of a highlight mode and a normal mode as a selected mode (selected mode) according to the color content, and correspondingly sets at least one control signal to the driving circuit according to the selected mode. Wherein the brightness of the projected light of the light emitting element in the highlight mode is greater than the brightness of the projected light of the light emitting element in the normal mode.
To achieve one or a part or all of the above or other objects, an embodiment of the present invention provides a method for operating a projection device. The operation method comprises the following steps: driving the light emitting element by the driving circuit according to at least one control signal to generate projection light; analyzing, by the control circuit, color content of at least one video frame; and selecting one of the highlight mode and the normal mode as a selected mode by the control circuit according to the color content, and correspondingly setting at least one control signal to the driving circuit according to the selected mode. Wherein the brightness of the projected light of the light emitting element in the highlight mode is greater than the brightness of the projected light of the light emitting element in the normal mode.
Based on the foregoing, embodiments of the present invention have at least one of the following advantages or effects. The projection device and its method of operation may analyze the color content of a video frame. The projection device may switch the operation mode to one of a highlight mode and a normal mode according to the color content of the video frame. Therefore, the projection device can dynamically increase the brightness of the projection light of the light-emitting element according to the situation.
In order to make the above features and advantages of the present invention more comprehensible, embodiments accompanied with figures are described in detail below.
Drawings
Fig. 1 is a schematic circuit block diagram of a projection apparatus according to an embodiment of the invention.
Fig. 2 is a flow chart illustrating an operation method of a projection device according to an embodiment of the invention.
Fig. 3 is a histogram of a video frame according to an embodiment of the present invention.
Fig. 4 is a schematic diagram of a human-machine interface according to an embodiment of the invention.
Fig. 5 is a schematic diagram illustrating an operation period of the red light emitting diode, the green light emitting diode, and the blue light emitting diode in a highlight mode according to an embodiment of the present invention.
Fig. 6 is a schematic diagram illustrating an operation period of the red light emitting diode, the green light emitting diode, and the blue light emitting diode in a normal mode according to an embodiment of the present invention.
Fig. 7 is a schematic diagram illustrating an operation period of the red light emitting diode, the green light emitting diode, and the blue light emitting diode in a normal mode according to another embodiment of the present invention.
Fig. 8 is a circuit block diagram illustrating the control circuit, the driving circuit and the light emitting device shown in fig. 1 according to an embodiment of the present invention.
Fig. 9 is a circuit block diagram illustrating the control circuit, the driving circuit and the light emitting device shown in fig. 1 according to another embodiment of the present invention.
Fig. 10 is a circuit block diagram illustrating the control circuit, the driving circuit and the light emitting device shown in fig. 1 according to another embodiment of the present invention.
Fig. 11 is a flowchart illustrating an operation method of a projection device according to another embodiment of the invention.
Detailed Description
The foregoing and other features, aspects and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiment, which proceeds with reference to the accompanying drawings. The directional terms mentioned in the following embodiments are, for example: upper, lower, left, right, front or rear, etc., are merely references to the directions of the drawings. Thus, the directional terminology is used for purposes of illustration and is not intended to be limiting of the invention.
Fig. 1 is a schematic circuit block diagram of a projection apparatus 100 according to an embodiment of the invention. The projection device 100 may be implemented as a projector, and/or other optical projection device, depending on design requirements. In the embodiment shown in fig. 1, the projection device 100 includes a control circuit 110, at least one driving circuit 120, and at least one light emitting element 130. For simplicity of the drawing, other components of the projection device 100 (e.g., display panel, keyboard panel, etc.) are not depicted in fig. 1.
The control circuit 110 may receive at least one video frame (or a stream of video frames). The control circuit 110 may analyze the color content of the video frame and select one of the highlight mode and the normal mode as a selected mode (selected mode) according to the color content of the video frame, i.e., the selected mode refers to the selected mode. The control circuit 110 correspondingly sets at least one control signal Sc to the driving circuit 120 according to the selected mode.
The input end of the driving circuit 120 is coupled to the control circuit 110 to receive the control signal Sc. The output terminal of the driving circuit 120 is coupled to the light emitting element 130. The control circuit 110 correspondingly sets the control signal Sc according to the selected mode, and the driving circuit 120 can drive the light emitting element 130 to generate the projection light according to the control signal Sc. The projection light generated by the light emitting element 130 may be projected to the outside of the projection device 100 via an optical element (or an optical element group, not shown). Depending on design requirements, the optical element (or group of optical elements) may include a light valve, a lens (or group of lenses), a mirror, and/or other optical elements.
The control circuit 110 correspondingly sets the control signal Sc according to the selected mode, and the driving circuit 120 can drive the light emitting element 130 to generate the projection light according to the control signal Sc. Therefore, the control circuit 110 can adjust the brightness of the projected light of the light emitting element 130 according to the selected mode. Wherein the brightness of the projected light of the light emitting element 130 in the highlight mode is greater than the brightness of the projected light of the light emitting element 130 in the normal mode. In the normal mode, the control circuit 110 may reduce the driving current of the light emitting element 130 to save power consumption. In the highlighting mode, the control circuit 110 may increase the driving current of the light emitting element 130 (e.g., set the driving current to be the rated current/the maximum current of the light emitting element 130) to achieve the purpose of outputting the super-bright.
The control circuit 110 can analyze the color content of the video frame in any manner according to the design requirements, and the conditions for determining the selected mode can also be determined according to the design requirements. For example, fig. 2 is a flow chart illustrating an operation method of a projection device according to an embodiment of the invention. In step S210, the video frames (or video frame streams) are input to the control circuit 110. In step S220, the control circuit 110 may analyze the color content of the video frame. In step S230, the control circuit 110 may determine whether the video frame is a white frame (e.g. a full white frame).
When the color content of the video frame indicates that the video frame is a white video frame (i.e. yes in step S230), the control circuit 110 selects the highlight mode as the selected mode (step S240), and correspondingly sets the control signal Sc according to the highlight mode. The driving circuit 120 may adjust/set a driving current for driving the light emitting element 130 according to the control signal Sc. In the highlighting mode, the drive current provided by the drive circuit 120 to the light emitting element 130 may be fixed (the drive current is independent of the application context or other application conditions). The driving current supplied to the light emitting element 130 in the highlight mode is greater than the driving current supplied to the light emitting element 130 in the normal mode.
When the color content of the video frame indicates that the video frame is not a white video frame (i.e., no in step S230), the control circuit 110 selects the normal mode as the selected mode (step S250), and correspondingly sets the control signal Sc according to the normal mode. In the normal mode, the driving circuit 120 can dynamically adjust/vary the driving current of the light emitting element 130 according to the application situation or other application conditions based on the control of the control circuit 110. The driving current supplied to the light emitting element 130 in the normal mode is smaller than the driving current supplied to the light emitting element 130 in the highlight mode.
In no way should the operation of the control circuit 110 be limited to the embodiment shown in fig. 2. For example, in another embodiment, when the color content of the video frame indicates that the video frame is a white image frame (e.g. a full white picture), the operation mode of the control circuit 110 may be switched from the normal mode to the highlight mode, and the control circuit 110 correspondingly sets the control signal Sc according to the highlight mode; when a non-white object appears in the white image frame or the color content of the video frame indicates that the video frame is not the white image frame, the operation mode of the control circuit 110 is switched back to the normal mode from the highlight mode, and the control circuit 110 correspondingly sets the control signal Sc according to the normal mode. For example, when one mouse cursor (mouse cursor) moves into a white image frame, the operation mode of the control circuit 110 switches back from the highlight mode to the normal mode in real time.
In yet another embodiment, the control circuit 110 may determine the color content of the video frame according to a histogram (histogram) of the video frame (e.g., determine whether a majority of the video frame is white). For example, fig. 3 is a histogram of a video frame according to an embodiment of the present invention. Please refer to fig. 1 and 3. The control circuit 110 may analyze red sub-pixels in a video frame to obtain a histogram R of red sub-pixels, analyze green sub-pixels in a video frame to obtain a histogram G of green sub-pixels, and analyze blue sub-pixels in a video frame to obtain a histogram B of blue sub-pixels. In general, the horizontal axis of the histogram represents gray scale, while the vertical axis of the histogram represents the number of sub-pixels, wherein the histograms of different pixels are represented by different bar patterns, the histogram R of red pixels is represented by a blank, the histogram G of green pixels is represented by a dot matrix, and the histogram B of blue pixels is represented by a diagonal line. For convenience of explanation, a ratio of the number of red sub-pixels in the video frame satisfying the condition of "the gray level of the red sub-pixel is greater than the red threshold value" to the number of all the red sub-pixels in the video frame may be referred to as a first ratio value, a ratio of the number of green sub-pixels in the video frame satisfying the condition of "the gray level of the green sub-pixel is greater than the green threshold value" to the number of all the green sub-pixels in the video frame may be referred to as a second ratio value, and a ratio of the number of blue sub-pixels in the video frame satisfying the condition of "the gray level of the blue sub-pixel is greater than the blue threshold value" to the number of all the blue sub-pixels in the video frame may be referred to as a third ratio value. The red threshold, the green threshold and the blue threshold may be determined according to design requirements.
When the first ratio value is greater than the first ratio threshold, the second ratio value is greater than the second ratio threshold, and the third ratio value is greater than the third ratio threshold, the control circuit 110 selects the highlight mode as the selected mode, and the control circuit 110 correspondingly sets the control signal Sc according to the highlight mode. When the first ratio value is smaller than the first ratio threshold, or the second ratio value is smaller than the second ratio threshold, or the third ratio value is smaller than the third ratio threshold, the control circuit 110 selects the normal mode as the selected mode, and the control circuit 110 correspondingly sets the control signal Sc according to the normal mode. The first, second and third ratio thresholds may be determined according to design requirements. The first, second, and third ratio thresholds may be any value that is different (or the same) from each other. For example, when the first ratio value is greater than 95%, and the second ratio value is greater than 95%, and the third ratio value is greater than 95%, the control circuit 110 selects the highlight mode as the selected mode.
In the embodiment shown in fig. 1, the projection device 100 further comprises a user interface circuit 140. The user interface circuitry 140 may provide a human-machine interface for receiving user instructions. When a user inputs instructions via a human-machine interface, the user interface circuitry 140 may transmit the user instructions to the control circuitry 110. At this time, the control circuit 110 may select one of the highlight mode and the normal mode as the selected mode according to the user instruction, and correspondingly set the control signal Sc according to the selected mode. In some embodiments, the user interface circuitry 140 may be omitted, depending on design requirements.
Fig. 4 is a schematic diagram of a human-machine interface according to an embodiment of the invention. The user interface circuit 140 may provide a screen, i.e., an on-screen display (OSD) menu, of the human machine interface shown in fig. 4. The user may select disable (enable) "general projection illumination mode" and/or "special display illumination mode". The user may communicate user instructions to the user interface circuit 140 via an input mechanism (not shown), such as keys, a touch pad, a mouse, and/or other input means. The user interface circuit 140 may transmit user instructions to the control circuit 110. At this time, the control circuit 110 may select one of the highlight mode and the normal mode as the selected mode according to the user instruction, and correspondingly set the control signal Sc according to the selected mode. For example, when the user "special display illumination mode" is enabled (set to "On"), the control circuit 110 may perform the flow shown in fig. 2.
In another embodiment, the user interface circuit 140 may receive an Infrared (IR) signal. The user may transmit a user instruction to the user interface circuit 140 via the infrared IR remote controller to set the operation mode of the control circuit 110 to the highlight mode or the normal mode.
In yet another embodiment, a personal computer may be connected to the user interface circuit 140 via an RS-232 port (computer serial port). The personal computer may transmit a user instruction to the user interface circuit 140 to set the operation mode of the control circuit 110 to the highlight mode or the normal mode.
The implementation of the light emitting device 130 shown in fig. 1 may be determined according to design requirements. For example, the light emitting element 130 may include a laser light source (Laser light source), a light-emitting diode (LED), a bulb, or other light emitting means. The light emitting element 130 may include one light emitting member or a plurality of light emitting members. In the case where the light emitting element 130 includes a plurality of light emitting members, the number of the driving circuits 120 may be plural so as to drive the plurality of light emitting members, respectively. In the case where the light emitting element 130 includes a single light emitting member, the number of the driving circuits 120 may be single.
The color of the projected light of the light emitting element 130 can be determined according to design requirements. For example, the light emitting element 130 may include a white light emitting diode so as to emit white projection light. In some embodiments, the light emitting element 130 may include a red light emitting diode, a green light emitting diode, and a blue light emitting diode. The driving circuit 120 may drive the red light emitting diode, the green light emitting diode and the blue light emitting diode of the light emitting element 130 according to the control signal Sc to generate the projection light. In the normal mode, the light emission period of the blue light emitting diode is not overlapped with the light emission period of the red light emitting diode, and the light emission period of the blue light emitting diode is not overlapped with the light emission period of the green light emitting diode. That is, the light emitting element 130 emits white or other color projection light by using red, green, and blue light emitting diodes according to the time-domain color mixing method. In the highlighting mode, the light emitting period of the red light emitting diode, the light emitting period of the green light emitting diode, and the light emitting period of the blue light emitting diode are completely overlapped to emit white projection light having high brightness. In some embodiments, the light emitting element 130 may include a white light emitting diode to be turned on in the high light mode, so that the light emitting period of the white light emitting diode, the light emitting period of the red light emitting diode, the light emitting period of the green light emitting diode, and the light emitting period of the blue light emitting diode are completely overlapped to generate white projection light.
In some embodiments, the control signal Sc includes a first switching signal associated with a red light emitting diode, a second switching signal associated with a green light emitting diode, and a third switching signal associated with a blue light emitting diode. The driving circuit 120 can drive the red light emitting diode, the green light emitting diode and the blue light emitting diode of the light emitting element 130 according to the first switch signal, the second switch signal and the third switch signal, respectively, so as to generate the projection light. For example, the red light emitting diode emits light when the first switching signal is at the first logic level, and the red light emitting diode does not emit light when the first switching signal is at the second logic level. In the highlight mode, the duty ratio (duty cycle) of the first switch signal, the second switch signal and the third switch signal is 100%. Accordingly, the light emitting element 130 can continuously emit white projection light having high brightness. In the normal mode, a duty ratio of at least one of the first switching signal, the second switching signal, and the third switching signal is less than 100%.
In other embodiments, the duty cycles of the first, second, and third switching signals may be fixed values near 100% in the highlight mode. The duty ratios of the first, second and third switching signals may be dynamic values far from 100%, for example, between 0% and 50% in the normal mode, but the present invention is not limited thereto.
Fig. 5 is a schematic diagram illustrating an operation period (duty period) of the red light emitting diode, the green light emitting diode, and the blue light emitting diode in a highlight mode according to an embodiment of the present invention. The horizontal axis in fig. 5 represents time, and the vertical axis represents the state of the light emitting diode. "On" shown in fig. 5 indicates that the state of the light emitting diode is "turn On", and "Off" indicates that the state of the light emitting diode is "turn Off". The "operating period" means a period in which the state of the light emitting diode is "on continuously" (i.e., a period in which light emission is continuously performed). The curve 501 shown in fig. 5 represents the state of a red light emitting diode, the curve 502 represents the state of a green light emitting diode, and the curve 503 represents the state of a blue light emitting diode.
In the highlight mode, the duty cycles of the red, green, and blue light emitting diodes may be fixed values close to 100%, even 100%. Thus, in the embodiment shown in fig. 5, the three periods of operation of the red light emitting diode, the green light emitting diode, and the blue light emitting diode are completely overlapped with each other. That is, the ratio of the operation period of the curve 501 to the operation period of the curve 502 shown in fig. 5 is 100%, and the ratio of the operation period of the curve 502 to the operation period of the curve 503 is 100%. In one embodiment, the duty cycle of the red led, the green led and the blue led may be 100%, that is, the On states of the curves 501 to 503 are completely overlapped in one period, that is, the overlapping ratio of the three is 100% during operation, so that the light emitting element 130 can continuously emit the positive white projection light with high brightness.
In other embodiments, the user interface circuit 140 may transmit overlay adjustment information (user instructions) to the control circuit 110 to set/adjust the ratio of the three overlapping each other during operation of the red light emitting diode, during operation of the green light emitting diode, and during operation of the blue light emitting diode in the highlight mode.
Fig. 6 is a schematic diagram illustrating an operation period of the red light emitting diode, the green light emitting diode, and the blue light emitting diode in a normal mode according to an embodiment of the present invention. The horizontal axis in fig. 6 represents time, and the vertical axis represents the state of the light emitting diode. "On" shown in fig. 6 indicates that the state of the light emitting diode is "On", and "Off" indicates that the state of the light emitting diode is "Off". A curve 601 shown in fig. 6 represents the state of the red light emitting diode, a curve 602 represents the state of the green light emitting diode, and a curve 603 represents the state of the blue light emitting diode.
In the normal mode, the duty cycles of the red, green and blue leds may be dynamic values far from 100%, for example between 0% and 90%. In addition, in the embodiment shown in fig. 6, the operating periods of the red light emitting diode, the green light emitting diode and the blue light emitting diode do not overlap each other at all. That is, the ratio of the operating period of the red light emitting diode of the curve 601 to the operating period of the green light emitting diode of the curve 602 shown in fig. 6 is 0%, and the ratio of the operating period of the green light emitting diode of the curve 602 to the operating period of the blue light emitting diode of the curve 603 is also 0%.
Fig. 7 is a schematic diagram illustrating an operation period of the red light emitting diode, the green light emitting diode, and the blue light emitting diode in a normal mode according to another embodiment of the present invention. The horizontal axis in fig. 7 represents time, and the vertical axis represents the state of the light emitting diode. "On" shown in fig. 7 indicates that the state of the light emitting diode is "On", and "Off" indicates that the state of the light emitting diode is "Off". The curve 701 shown in fig. 7 represents the state of the red light emitting diode, the curve 702 represents the state of the green light emitting diode, and the curve 703 represents the state of the blue light emitting diode.
In the embodiment shown in fig. 7, the operating periods of the red light emitting diodes, the green light emitting diodes and the blue light emitting diodes partially overlap each other. The "PW" shown in fig. 7 represents an operation period of the light emitting diode ("on-continuously" period), and the "OL" represents an overlapping period in which the operation periods of the two light emitting diodes partially overlap each other. The ratio of the overlap period OL to the operation period PW may be any value. For example, in the normal mode, the ratio of two of the operation period of the red light emitting diode, the operation period of the green light emitting diode, and the operation period of the blue light emitting diode to overlap each other is 0 to 40%. In detail, the ratio of the operating period of the red led of the curve 701 to the operating period of the green led of the curve 702 (i.e., the ratio of OL to PW) in fig. 7 may be 0-40%, and the ratio of the operating period of the green led of the curve 702 to the operating period of the blue led of the curve 703 (i.e., the ratio of OL to PW) may be 0-40%.
In the highlight mode, the driving current of the light emitting element 130 may be a fixed large current. In the normal mode, the driving current of the light emitting element 130 may be a dynamically adjusted and varied smaller current. In the normal mode, the control circuit 110 may reduce the driving current of the light emitting element 130 to save power consumption. In the highlighting mode, the control circuit 110 may increase the driving current of the light emitting element 130 to achieve the purpose of outputting ultra-high brightness.
In some embodiments, the driving circuit 120 may include a first current source (not shown), a second current source (not shown), and a third current source (not shown), and the control signal Sc includes a first bias voltage, a second bias voltage, and a third bias voltage. The first bias voltage may control a first current source associated with a red light emitting diode of light emitting element 130, the second bias voltage may control a second current source associated with a green light emitting diode of light emitting element 130, and the third bias voltage may control a third current source associated with a blue light emitting diode of light emitting element 130. For example, when the current of the first current source is increased by changing the first bias voltage, the projected brightness of the red led of the light emitting device 130 can be increased. In the highlight mode, the first bias voltage is a first fixed voltage, the second bias voltage is a second fixed voltage, and the third bias voltage is a third fixed voltage. The level of the first fixed voltage, the level of the second fixed voltage and the level of the third fixed voltage can be determined according to design requirements, for example, a designer can design the level of the fixed voltage according to the electrical condition of the light emitting element and the matching of the current source. In the normal mode, the first bias voltage is a first dynamic voltage less than the first fixed voltage, the second bias voltage is a second dynamic voltage less than the second fixed voltage, and the third bias voltage is a third dynamic voltage less than the third fixed voltage. Therefore, the luminance of the projection light of the light emitting element 130 in the highlight mode is greater than that of the projection light of the light emitting element 130 in the normal mode.
Fig. 8 is a circuit block diagram illustrating the control circuit 110, the driving circuit 120 and the light emitting device 130 shown in fig. 1 according to an embodiment of the present invention. The driving circuit 120 shown in fig. 8 includes a current source 121. The current source 121 correspondingly provides a driving current to the light emitting element 130 according to the bias voltage Vbias to generate the projection light. The light emitting element 130 shown in fig. 8 includes a light emitting diode 131. The light emitting diode 131 may be a white light emitting diode, a red light emitting diode, a green light emitting diode, or a blue light emitting diode, which have been mentioned in the above embodiments, according to design requirements. A first terminal (e.g., anode) of the light emitting diode 131 is coupled to the current supply terminal of the current source 121 to receive the driving current. A second terminal (e.g., cathode) of the led 131 is coupled to a reference voltage VSSA (e.g., ground voltage or other fixed voltage).
In any event, the implementation of the driving circuit 120 and the light emitting element 130 should not be limited to the example shown in fig. 8. For example, in another embodiment, a first terminal (e.g., cathode) of the light emitting diode 131 is coupled to the current drawing terminal of the current source 121, and a second terminal (e.g., anode) of the light emitting diode 131 is coupled to the power voltage VDDA. The current supply terminal of the current source 121 is coupled to the reference voltage VSSA. The invention is not limited to terminating at the power voltage VDDA and the reference voltage VSSA, which may be changed to other bias points according to design requirements.
Referring to fig. 8, the control circuit 110 includes a voltage generating circuit 111, a bias circuit 112, a switch 113, and a controller 114. The voltage generation circuit 111 is used for generating a fixed voltage V1. The present embodiment does not limit the implementation of the voltage generation circuit 111. For example, the voltage generating circuit 111 may include a resistor R1 and a resistor R2. The first end of the resistor R1 is coupled to the power voltage VDDA. The second terminal of the resistor R1 is coupled to the first selection terminal of the switch 113 to provide a fixed voltage V1. The first terminal of the resistor R2 is coupled to the second terminal of the resistor R1. The second terminal of the resistor R2 is coupled to the reference voltage VSSA.
The bias circuit 112 is used to generate a dynamic voltage V2 smaller than the fixed voltage V1. The implementation of the bias circuit 112 is not limited in this embodiment. For example, in some embodiments, the bias circuit 112 may be a known bias circuit that provides a bias voltage to the light emitting element driving circuit in a known projector. The bias circuit can generate a dynamic voltage V2 to the light emitting device driving circuit to determine/adjust the current of the light emitting device (i.e. to determine/adjust the brightness of the light emitting device). The implementation details of the bias circuit are not described herein.
The first selection terminal of the switch 113 is coupled to the voltage generation circuit 111 to receive the fixed voltage V1. A second selection terminal of the switch 113 is coupled to the bias circuit 112 to receive the dynamic voltage V2. The common terminal of the switch 113 is coupled to the current source 121 to provide the bias voltage Vbias. The controller 114 may analyze the color content of the video frame to select one of the highlight mode and the normal mode as the selected mode. In the highlight mode, the controller 114 controls the switch 113 to transmit the fixed voltage V1 to the current source 121 as the bias voltage Vbias, and the current source 121 correspondingly provides the driving current to the light emitting element 130 according to the bias voltage Vbias (i.e. the fixed voltage V1) to generate the projection light. In the normal mode, the controller 114 controls the switch 113 to transmit the dynamic voltage V2 to the current source 121 as the bias voltage Vbias, and the current source 121 correspondingly provides the driving current to the light emitting element 130 according to the bias voltage Vbias (i.e. the fixed voltage V2) to generate the projection light. Since the fixed voltage V1 is greater than the dynamic voltage V2, the brightness of the projected light of the light emitting diode 131 in the highlight mode is greater than the brightness of the projected light of the light emitting diode 131 in the normal mode.
Fig. 9 is a circuit block diagram illustrating the control circuit 110, the driving circuit 120, and the light emitting device 130 shown in fig. 1 according to another embodiment of the present invention. The drive circuit 120 shown in fig. 9 includes a power switch 122. The first terminal of the power switch 122 is coupled to a power voltage VDDA. A second terminal of the power switch 122 is coupled to the light emitting element 130. The power switch 122 determines whether to transmit the power voltage VDDA to the light emitting device 130 according to the switching signal Vsw to generate the projection light.
The light emitting element 130 shown in fig. 9 can refer to the related description of the light emitting element 130 shown in fig. 8, and thus will not be described again. A first terminal (e.g., anode) of the light emitting diode 131 of the light emitting device 130 shown in fig. 9 is coupled to the second terminal of the power switch 122 to receive the power voltage VDDA. A second terminal (e.g., cathode) of the led 131 is coupled to a reference voltage VSSA (e.g., ground voltage or other fixed voltage). In any event, the implementation of the driving circuit 120 and the light emitting element 130 should not be limited to the example shown in fig. 9. For example, in another embodiment, the second terminal (e.g., anode) of the light emitting diode 131 is coupled to the power voltage VDDA, and the first terminal of the power switch 122 is coupled to the reference voltage VSSA.
Referring to fig. 9, the control circuit 110 includes a controller 114, a pulse width modulation (pulse width modulation, PWM) circuit 115, and a switch 116. The pwm circuit 115 is used for generating a pwm signal VPWM. The duty cycle of the pwm signal VPWM is less than 100%. The present embodiment is not limited to the implementation of the pwm circuit 115. For example, in some embodiments, the pulse width modulation circuit 115 may be a known pulse width modulation circuit that provides pulse width modulation signals to the light emitting element driving circuit in a known projector. The known pwm circuit can generate a pwm signal VPWM to the light emitting device driving circuit to determine/adjust the average current of the light emitting device (i.e. to determine/adjust the brightness of the light emitting device). The details of the implementation of the known pwm circuit are not described here.
The first select terminal of the switch 116 shown in fig. 9 is coupled to a fixed voltage. In the case of a "high voltage on" power switch 122, "the fixed voltage may be the power voltage VDDA or other fixed voltage sufficient to turn on the power switch 122. In the case of "low voltage on power switch 122," the fixed voltage may be a reference voltage VSSA or other fixed voltage sufficient to turn on power switch 122. A second selection terminal of the switch 116 is coupled to the pwm circuit 115 to receive the pwm signal VPWM. The common terminal of the switch 116 is coupled to the control terminal of the power switch 122 to provide the switching signal Vsw.
The controller 114 may analyze the color content of the video frame to select one of the highlight mode and the normal mode as the selected mode. In the highlight mode, the controller 114 controls the switch 116 to transmit a fixed voltage (e.g., the power voltage VDDA) to the control terminal of the power switch 122 as the switching signal Vsw. In the normal mode, the controller 114 controls the switch 116 to transmit the pwm signal VPWM to the control terminal of the power switch 122 as the switching signal Vsw. The fixed voltage (e.g., the power voltage VDDA) may be regarded as a pulse width modulation signal having a duty ratio of 100%, and the duty ratio of the pulse width modulation signal VPWM is less than 100%, so that the brightness of the projected light of the light emitting diode 131 in the highlight mode is greater than that of the light emitting diode 131 in the normal mode.
Fig. 10 is a circuit block diagram illustrating the control circuit 110, the driving circuit 120, and the light emitting device 130 shown in fig. 1 according to another embodiment of the present invention. The driving circuit 120 shown in fig. 10 includes a current source 121 and a power switch 122. The current source 121 correspondingly provides a driving current according to the bias voltage Vbias. The first terminal of the power switch 122 is coupled to the current supply terminal of the current source 121 to receive the driving current. A second terminal of the power switch 122 is coupled to the light emitting element 130. The power switch 122 determines whether to transmit the driving current of the current source 121 to the light emitting device 130 according to the switching signal Vsw to generate the projection light.
The light emitting element 130 shown in fig. 10 can refer to the light emitting element 130 shown in fig. 8 or the related description of the light emitting element 130 shown in fig. 9, and thus will not be described again. A first terminal (e.g., anode) of the light emitting diode 131 of the light emitting device 130 shown in fig. 10 is coupled to the second terminal of the power switch 122 to receive the power voltage VDDA. A second terminal (e.g., cathode) of the led 131 is coupled to a reference voltage VSSA (e.g., ground voltage or other fixed voltage). In any event, the implementation of the driving circuit 120 and the light emitting element 130 should not be limited to the example shown in fig. 10. For example, in another embodiment, the second terminal (e.g., anode) of the light emitting diode 131 is coupled to the power voltage VDDA, the current drawing terminal of the current source 121 is coupled to the first terminal of the power switch 122, and the current providing terminal of the current source 121 is coupled to the reference voltage VSSA.
Referring to fig. 10, the control circuit 110 includes a voltage generating circuit 111, a bias circuit 112, a switch 113, a controller 114, a pulse width modulation circuit 115 and a switch 116. The voltage generating circuit 111, the bias circuit 112, the switch 113 and the controller 114 shown in fig. 10 can refer to the related descriptions of the voltage generating circuit 111, the bias circuit 112, the switch 113 and the controller 114 shown in fig. 8, and the controller 114, the pwm circuit 115 and the switch 116 shown in fig. 10 can refer to the related descriptions of the controller 114, the pwm circuit 115 and the switch 116 shown in fig. 9, so that the description is omitted.
The controller 114 is configured to analyze the color content of the video frame to select one of the highlight mode and the normal mode as the selected mode. In the highlight mode, the controller 114 controls the switch 113 to transmit the fixed voltage V1 to the current source 121 as the bias voltage Vbias, and the controller 114 controls the switch 116 to transmit the fixed voltage (e.g., the power voltage VDDA) to the control terminal of the power switch 122 as the switching signal Vsw. In the normal mode, the controller 114 controls the switch 113 to transmit the dynamic voltage V2 to the current source 121 as the bias voltage Vbias, and the controller 114 controls the switch 116 to transmit the pwm signal VPWM to the control terminal of the power switch 122 as the switching signal Vsw. Since the fixed voltage V1 is greater than the dynamic voltage V2, and since the duty ratio of the power voltage VDDA is greater than the duty ratio of the pulse width modulation signal VPWM, the brightness of the projected light of the light emitting diode 131 in the highlight mode is greater than the brightness of the projected light of the light emitting diode 131 in the normal mode.
Fig. 11 is a flowchart illustrating an operation method of a projection device according to another embodiment of the invention. In step S710, the control circuit 110 analyzes the color content of at least one video frame. In step S720, the control circuit 110 selects one of the highlight mode and the normal mode as the selected mode according to the color content of the video frame. In step S730, the control circuit 110 correspondingly sets at least one control signal Sc to the driving circuit 120 according to the selected mode. In step S740, the driving circuit 120 drives the light emitting element 130 according to the control signal Sc to generate the projection light. Wherein the brightness of the projected light of the light emitting element 130 in the highlight mode is greater than the brightness of the projected light of the light emitting element 130 in the normal mode.
In some embodiments, step S720 includes: when the color content of the video frame indicates that the video frame is a white image frame, the control circuit 110 selects a highlight mode as the selected mode; and when the color content of the video frame indicates that the video frame is not a white image frame, the control circuit 110 selects the normal mode as the selected mode.
In some embodiments, step S720 includes: when the color content of the video frame indicates that the video frame is a white image frame, the operation mode of the control circuit 110 is switched from the normal mode to the highlight mode; and when a non-white object appears in the white image frame or the color content of the video frame indicates that the video frame is not already a white image frame, the operation mode of the control circuit 110 is switched back from the highlight mode to the normal mode.
In some embodiments, the ratio of the number of red subpixels in a video frame that meet the condition that the gray level of a "red subpixel is greater than the red threshold" to the number of all red subpixels in the video frame is referred to as a first ratio value, the ratio of the number of green subpixels in the video frame that meet the condition that the gray level of a "green subpixel is greater than the green threshold" to the number of all green subpixels in the video frame is referred to as a second ratio value, and the ratio of the number of blue subpixels in the video frame that meet the condition that the gray level of a "blue subpixel is greater than the blue threshold" to the number of all blue subpixels in the video frame is referred to as a third ratio value. In some embodiments, step S720 includes: when the first ratio value is greater than the first ratio threshold, and the second ratio value is greater than the second ratio threshold, and the third ratio value is greater than the third ratio threshold, the control circuit 110 selects the highlight mode as the selected mode; and when the first ratio value is smaller than the first ratio threshold, or the second ratio value is smaller than the second ratio threshold, or the third ratio value is smaller than the third ratio threshold, the control circuit 110 selects the normal mode as the selected mode.
In some embodiments, the light emitting element 130 includes a red light emitting diode, a green light emitting diode, and a blue light emitting diode. In other embodiments, the light emitting element 130 further comprises a white light emitting diode.
In some embodiments, the light emitting period of the red light emitting diode, the light emitting period of the green light emitting diode, and the light emitting period of the blue light emitting diode are completely overlapped in the highlight mode. In the normal mode, the light emission period of the blue light emitting diode is not overlapped with the light emission period of the red light emitting diode, and the light emission period of the blue light emitting diode is not overlapped with the light emission period of the green light emitting diode. In other embodiments, in the highlight mode, the light emitting period of the white light emitting diode, the light emitting period of the red light emitting diode, the light emitting period of the green light emitting diode, and the light emitting period of the blue light emitting diode are completely overlapped.
In some embodiments, the control signal Sc includes a first switching signal associated with a red light emitting diode, a second switching signal associated with a green light emitting diode, and a third switching signal associated with a blue light emitting diode. In the highlight mode, the duty ratio of the first switch signal, the second switch signal and the third switch signal is 100%. In the normal mode, a duty ratio of at least one of the first switching signal, the second switching signal, and the third switching signal is less than 100%.
In some embodiments, the control signal Sc includes a first bias voltage, a second bias voltage, and a third bias voltage. The first bias voltage controls a first current source associated with the red light emitting diode, the second bias voltage controls a second current source associated with the green light emitting diode, and the third bias voltage controls a third current source associated with the blue light emitting diode. In the highlight mode, the first bias voltage is a first fixed voltage, the second bias voltage is a second fixed voltage, and the third bias voltage is a third fixed voltage. In the normal mode, the first bias voltage is a first dynamic voltage less than the first fixed voltage, the second bias voltage is a second dynamic voltage less than the second fixed voltage, and the third bias voltage is a third dynamic voltage less than the third fixed voltage.
In some embodiments, the drive circuit 120 includes a current source 121. The current source 121 correspondingly provides a driving current to the light emitting element 130 according to the bias voltage Vbais to generate the projection light. In some embodiments, step S730 includes: generating a dynamic voltage V2 less than the fixed voltage V1 by the bias circuit 112; the controller 114 controls the switch 113, wherein a first selection terminal of the switch 113 is coupled to the fixed voltage V1, a second selection terminal of the switch 113 is coupled to the bias circuit 112 to receive the dynamic voltage V2, a common terminal of the switch 113 is coupled to the current source 121 to provide the bias voltage Vbias, and the controller 114 analyzes the color content of the video frame to select one of the highlight mode and the normal mode as a selected mode; in the highlight mode, the fixed voltage V1 is transmitted to the current source 121 via the switch 113 as the bias voltage Vbias; and in the normal mode, the dynamic voltage V2 is transmitted to the current source 121 via the switch 113 as the bias voltage Vbias.
In some embodiments, the drive circuit 120 includes a power switch 122. The first and second terminals of the power switch 122 are coupled to the power voltage VDDA and the light emitting device 130, respectively. The power switch 122 determines whether to transmit the power voltage VDDA to the light emitting device 130 according to the switching signal Vsw to generate the projection light. In some embodiments, step S730 includes: generating a pwm signal VPWM by the pwm circuit 115, wherein a duty cycle of the pwm signal VPWM is less than 100%; the controller 114 controls the switch 116, wherein a first selection terminal of the switch 116 is coupled to a fixed voltage (e.g., a power voltage VDDA), a second selection terminal of the switch 116 is coupled to the pulse width modulation circuit 115 to receive the pulse width modulation signal VPWM, a common terminal of the switch 116 is coupled to a control terminal of the power switch 122 to provide a switch signal Vsw, and the controller 114 analyzes the color content of the video frame to select one of a highlight mode and a normal mode as a selected mode; in the highlight mode, a fixed voltage (e.g., power voltage VDDA) is transmitted to the control terminal of the power switch 122 as a switch signal Vsw via the switch 116; and in the normal mode, the pwm signal VPWM is transmitted to the control terminal of the power switch 122 as the switching signal Vsw via the switch 116.
In some embodiments, the driving circuit 120 includes a current source 121 and a power switch 122. The current source 121 correspondingly provides a driving current according to the bias voltage Vbias. A first terminal of the power switch 122 is coupled to the current source 121 to receive the driving current. A second terminal of the power switch 122 is coupled to the light emitting element 130. The power switch 122 determines whether to transmit the driving current of the current source 121 to the light emitting device 130 according to the switching signal Vsw to generate the projection light. In some embodiments, step S730 includes: the bias circuit 112 generates a dynamic voltage V2 smaller than the fixed voltage V1; the controller 114 controls the switch 113, wherein a first selection terminal of the switch 113 is coupled to the fixed voltage V1, a second selection terminal of the switch 113 is coupled to the bias circuit 112 to receive the dynamic voltage V2, a common terminal of the switch 113 is coupled to the current source 121 to provide the bias voltage Vbias, and the controller 114 analyzes the color content of the video frame to select one of the highlight mode and the normal mode as a selected mode; the pwm circuit 115 generates a pwm signal VPWM, wherein a duty cycle of the pwm signal VPWM is less than 100%; the controller controls the switch 116, wherein a first selection terminal of the switch 116 is coupled to a fixed voltage (e.g., a power voltage VDDA), a second selection terminal of the switch 116 is coupled to the PWM circuit 115 to receive the PWM signal VPWM, and a common terminal of the switch 116 is coupled to a control terminal of the power switch 122 to provide a switch signal Vsw; in the highlight mode, the fixed voltage V1 is transmitted to the current source 121 as the bias voltage Vbias via the switch 113, and the fixed voltage (e.g., the power voltage VDDA) is transmitted to the control terminal of the power switch 122 as the switching signal Vsw via the switch 116; and in the normal mode, the dynamic voltage V2 is transmitted to the current source 121 as the bias voltage Vbias via the switch 113, and the pwm signal VPWM is transmitted to the control terminal of the power switch 122 as the switching signal Vsw via the switch 116.
In some embodiments, the method of operation further comprises: receiving, by the user interface circuit, a user instruction; transmitting a user instruction to the control circuit; and the control circuit selects one of the highlight mode and the normal mode as a selected mode according to a user instruction.
The blocks of the control circuit 110 and/or the controller 114 may be implemented in hardware (hardware), firmware (firmware), software (software) or a combination of any three according to various design requirements. In hardware, the blocks of the control circuit 110 and/or the controller 114 may be implemented as logic circuits on an integrated circuit (integrated circuit). The above-described control circuitry 110 and/or associated functions of controller 114 may be implemented as hardware using a hardware description language (hardware description languages, such as Verilog HDL or VHDL) or other suitable programming language. For example, the above-described control circuit 110 and/or related functions of the controller 114 may be implemented in various logic blocks, modules, and circuits in one or more controllers, microcontrollers, microprocessors, application-specific integrated circuits (ASICs), digital signal processors (digital signal processor, DSPs), field programmable gate arrays (Field Programmable Gate Array, FPGAs), and/or other processing units.
In view of the foregoing, embodiments of the present invention have at least one of the following advantages or effects. The projection device 100 and the operation method thereof according to the embodiments of the present invention can analyze the color content of a video frame. Depending on the color content of the video frame, the projection device 100 may switch the operation mode to one of a highlight mode and a normal mode. Therefore, the projection device 100 can dynamically increase the brightness of the projection light of the light emitting element according to the situation.
The foregoing description is only illustrative of the preferred embodiments of the present invention and is not intended to limit the scope of the invention, i.e., all simple and equivalent changes and modifications that come within the meaning and range of equivalency of the claims and the summary of the invention are to be embraced by the invention. Not all of the objects, advantages, or features of the present disclosure are required to be achieved by any one embodiment or claim of the present disclosure. Furthermore, the abstract and the title of the invention are provided solely for the purpose of assisting patent document retrieval and are not intended to limit the scope of the claims. Furthermore, references to "first," "second," etc. in this specification or in the claims are only intended to name an element or distinguish between different embodiments or ranges, and are not intended to limit the upper or lower limit on the number of elements.
Reference numerals illustrate:
100: projection device
110: control circuit
111: voltage generating circuit
112: bias circuit
113: switch
114: controller for controlling a power supply
115: pulse width modulation circuit
116: switch
120: driving circuit
121: current source
122: power switch
130: light-emitting element
131: light emitting diode
140: user interface circuit
501 to 503, 601 to 603, 701 to 703: curve of curve
B: histogram of blue sub-pixels
G: histogram of green sub-pixels
R: histogram of red sub-pixels
R1 and R2: resistor
S210 to S250, S710 to S740: step (a)
Sc: control signal
V1: fixed voltage
V2: dynamic voltage
Vbias: bias voltage
VDDA: power voltage
VPWM: pulse width modulation signal
VSSA: reference voltage
Vsw: and (3) a switching signal.

Claims (21)

1. A projection device, comprising a light emitting element, a driving circuit, and a control circuit, wherein:
the light emitting element comprises a red light emitting diode, a green light emitting diode and a blue light emitting diode;
the driving circuit is coupled to the light emitting element and used for driving the light emitting element to generate projection light according to at least one control signal; and
the control circuit is used for receiving at least one video frame and analyzing the color content of the at least one video frame, wherein the control circuit selects one of a highlight mode and a normal mode as a selected mode according to the color content, and correspondingly sets the at least one control signal to the driving circuit according to the selected mode,
Wherein the brightness of the projected light of the light emitting element in the highlight mode is greater than the brightness of the projected light of the light emitting element in the normal mode, wherein a ratio of the number of red sub-pixels in the at least one video frame satisfying a condition that the gray scale of the red sub-pixel is greater than a red threshold to the number of all red sub-pixels in the at least one video frame is a first ratio value;
the ratio of the number of green sub-pixels in the at least one video frame, which meets the condition that the gray scale of the green sub-pixels is larger than the green threshold value, to the number of all green sub-pixels in the at least one video frame is a second ratio value;
the ratio of the number of blue sub-pixels in the at least one video frame, which meets the condition that the gray scale of the blue sub-pixels is larger than the blue threshold value, to the number of all blue sub-pixels in the at least one video frame is a third ratio value;
when the first ratio value is greater than a first ratio threshold, and the second ratio value is greater than a second ratio threshold, and the third ratio value is greater than a third ratio threshold, the control circuit selects the highlight mode as the selected mode; and
When the first ratio value is smaller than a first ratio threshold, or the second ratio value is smaller than a second ratio threshold, or the third ratio value is smaller than a third ratio threshold, the control circuit selects the normal mode as the selected mode.
2. Projection device according to claim 1, characterized in that,
in the highlight mode, the light emission period of the red light emitting diode, the light emission period of the green light emitting diode, and the light emission period of the blue light emitting diode are completely overlapped.
3. Projection device according to claim 1, characterized in that,
the light emitting element further includes a white light emitting diode, and in the highlight mode, a light emitting period of the white light emitting diode, a light emitting period of the red light emitting diode, a light emitting period of the green light emitting diode, and a light emitting period of the blue light emitting diode are completely overlapped.
4. Projection device according to claim 1, characterized in that,
the at least one control signal comprises a first switch signal related to the red light emitting diode, a second switch signal related to the green light emitting diode and a third switch signal related to the blue light emitting diode;
In the highlight mode, the duty ratio of the first switching signal, the second switching signal, and the third switching signal is 100%.
5. Projection device according to claim 1, characterized in that,
the ratio of two of the operation period of the red light emitting diode, the operation period of the green light emitting diode, and the operation period of the blue light emitting diode to overlap each other in the normal mode is 0 to 40%.
6. Projection device according to claim 1, characterized in that,
the at least one control signal includes a first bias voltage, a second bias voltage, and a third bias voltage, wherein the first bias voltage controls a first current source associated with the red light emitting diode, the second bias voltage controls a second current source associated with the green light emitting diode, and the third bias voltage controls a third current source associated with the blue light emitting diode;
in the highlight mode, the first bias voltage is a first fixed voltage, the second bias voltage is a second fixed voltage, and the third bias voltage is a third fixed voltage; and
In the normal mode, the first bias voltage is a first dynamic voltage that is less than the first fixed voltage, the second bias voltage is a second dynamic voltage that is less than the second fixed voltage, and the third bias voltage is a third dynamic voltage that is less than the third fixed voltage.
7. The projection device of claim 1, wherein the driving circuit includes a current source that correspondingly provides a driving current to the light emitting element to generate the projection light according to a bias voltage, and the control circuit includes a bias circuit, a switch, and a controller, wherein:
the bias circuit is used for generating a dynamic voltage smaller than a fixed voltage;
the switch has a first selection terminal, a second selection terminal and a common terminal, wherein the first selection terminal is coupled to the fixed voltage, the second selection terminal is coupled to the bias circuit to receive the dynamic voltage, and the common terminal is coupled to the current source to provide the bias voltage; and
the controller is to analyze the color content of the at least one video frame to select one of the highlight mode and the normal mode as the selected mode;
Wherein, in the highlight mode, the controller controls the switch to transmit the fixed voltage to the current source as the bias voltage;
wherein the controller controls the switch to transmit the dynamic voltage to the current source as the bias voltage in the normal mode.
8. The projection device of claim 1, wherein the driving circuit comprises a power switch having a first end and a second end coupled to a power voltage and the light emitting element, respectively, the power switch determining whether to transmit the power voltage to the light emitting element to generate the projection light according to a switching signal, and the control circuit comprises a pulse width modulation circuit, a switch, and a controller, wherein:
the pulse width modulation circuit is used for generating a pulse width modulation signal, wherein the duty ratio of the pulse width modulation signal is less than 100%;
the switch is provided with a first selection end, a second selection end and a common end, wherein the first selection end is coupled to a fixed voltage, the second selection end is coupled to the pulse width modulation circuit to receive the pulse width modulation signal, and the common end is coupled to a control end of the power switch to provide the switching signal; and
The controller is to analyze the color content of the at least one video frame to select one of the highlight mode and the normal mode as the selected mode, wherein in the highlight mode the controller controls the switch to transmit the fixed voltage to the control terminal of the power switch as the switch signal, and in the normal mode the controller controls the switch to transmit the pulse width modulated signal to the control terminal of the power switch as the switch signal.
9. The projection device of claim 1, wherein the driving circuit comprises a current source and a power switch, the current source provides a driving current according to a bias voltage, a first terminal of the power switch is coupled to the current source to receive the driving current, a second terminal of the power switch is coupled to the light emitting element, the power switch determines whether to transmit the driving current to the light emitting element to generate the projection light according to a switching signal, and the control circuit comprises a bias circuit, a first switch, a pulse width modulation circuit, a second switch, and a controller, wherein:
The bias circuit is used for generating a dynamic voltage smaller than a first fixed voltage;
the first switch has a first selection end, a second selection end and a common end, wherein the first selection end of the first switch is coupled to the first fixed voltage, the second selection end of the first switch is coupled to the bias circuit to receive the dynamic voltage, and the common end of the first switch is coupled to the current source to provide the bias voltage;
the pulse width modulation circuit is used for generating a pulse width modulation signal, wherein the duty ratio of the pulse width modulation signal is less than 100%;
the second switch has a first selection end, a second selection end and a common end, wherein the first selection end of the second switch is coupled to a second fixed voltage, the second selection end of the second switch is coupled to the pulse width modulation circuit to receive the pulse width modulation signal, and the common end of the second switch is coupled to a control end of the power switch to provide the switching signal; and
the controller is to analyze the color content of the at least one video frame to select one of the highlight mode and the usual mode as the selected mode,
Wherein, in the highlight mode, the controller controls the first switch to transmit the first fixed voltage to the current source as the bias voltage, and the controller controls the second switch to transmit the second fixed voltage to the control terminal of the power switch as the switching signal;
wherein in the normal mode, the controller controls the first switch to transmit the dynamic voltage to the current source as the bias voltage, and the controller controls the second switch to transmit the pulse width modulation signal to the control terminal of the power switch as the switching signal.
10. The projection device of claim 1, further comprising:
the user interface circuit is used for receiving a user instruction and transmitting the user instruction to the control circuit;
wherein the control circuit selects one of the highlight mode and the normal mode as the selected mode in accordance with the user instruction.
11. A method of operating a projection device, the method comprising:
Driving the light emitting element by the driving circuit according to at least one control signal to generate projection light;
analyzing, by the control circuit, color content of at least one video frame; and
selecting one of a highlight mode and a normal mode as a selected mode by the control circuit according to the color content, and correspondingly setting the at least one control signal to the driving circuit according to the selected mode;
wherein the brightness of the projected light of the light emitting element in the highlight mode is greater than the brightness of the projected light of the light emitting element in the normal mode, wherein the step of selecting one of the highlight mode and the normal mode as the selected mode further comprises:
the ratio of the number of red sub-pixels in the at least one video frame meeting the condition that the gray scale of the red sub-pixels is greater than the red threshold value to the number of all red sub-pixels in the at least one video frame is a first ratio value;
the ratio of the number of green sub-pixels in the at least one video frame, which meets the condition that the gray scale of the green sub-pixels is larger than the green threshold value, to the number of all green sub-pixels in the at least one video frame is a second ratio value;
The ratio of the number of blue sub-pixels in the at least one video frame, which meets the condition that the gray scale of the blue sub-pixels is larger than the blue threshold value, to the number of all blue sub-pixels in the at least one video frame is a third ratio value;
selecting, by the control circuit, the highlight mode as the selected mode when the first scale value is greater than a first scale threshold, and the second scale value is greater than a second scale threshold, and the third scale value is greater than a third scale threshold; and
and when the first proportion value is smaller than a first proportion threshold value, or the second proportion value is smaller than a second proportion threshold value, or the third proportion value is smaller than a third proportion threshold value, the control circuit selects the normal mode as the selected mode.
12. The method of operation of claim 11, wherein the light emitting element comprises a red light emitting diode, a green light emitting diode, and a blue light emitting diode.
13. The method of operation of claim 12, wherein,
in the highlight mode, the light emission period of the red light emitting diode, the light emission period of the green light emitting diode, and the light emission period of the blue light emitting diode are completely overlapped.
14. The method of operation of claim 12, wherein,
the light emitting element further includes a white light emitting diode, and in the highlight mode, a light emitting period of the white light emitting diode, a light emitting period of the red light emitting diode, a light emitting period of the green light emitting diode, and a light emitting period of the blue light emitting diode are entirely overlapped.
15. The method of operation of claim 12, wherein,
the at least one control signal comprises a first switch signal related to the red light emitting diode, a second switch signal related to the green light emitting diode and a third switch signal related to the blue light emitting diode;
in the highlight mode, the duty ratio of the first switching signal, the second switching signal, and the third switching signal is 100%.
16. The operation method according to claim 12, wherein a ratio of two of the operation period of the red light emitting diode, the operation period of the green light emitting diode, and the operation period of the blue light emitting diode to overlap each other in the normal mode is 0 to 40%.
17. The method of operation of claim 12, wherein,
the at least one control signal includes a first bias voltage, a second bias voltage, and a third bias voltage, wherein the first bias voltage controls a first current source associated with the red light emitting diode, the second bias voltage controls a second current source associated with the green light emitting diode, and the third bias voltage controls a third current source associated with the blue light emitting diode;
in the highlight mode, the first bias voltage is a first fixed voltage, the second bias voltage is a second fixed voltage, and the third bias voltage is a third fixed voltage; and
in the normal mode, the first bias voltage is a first dynamic voltage that is less than the first fixed voltage, the second bias voltage is a second dynamic voltage that is less than the second fixed voltage, and the third bias voltage is a third dynamic voltage that is less than the third fixed voltage.
18. The method of claim 11, wherein the driving circuit includes a current source that provides a driving current to the light emitting element in response to a bias voltage to generate the projected light, and wherein the step of setting the at least one control signal to the driving circuit includes:
Generating a dynamic voltage less than the fixed voltage by the bias circuit;
controlling, by a controller, a switch, wherein a first select terminal of the switch is coupled to the fixed voltage, a second select terminal of the switch is coupled to the bias circuit to receive the dynamic voltage, a common terminal of the switch is coupled to the current source to provide the bias voltage, and the controller analyzes the color content of the at least one video frame to select one of the highlight mode and the usual mode as the selected mode;
in the highlight mode, transmitting the fixed voltage to the current source via the switch as the bias voltage; and
in the normal mode, the dynamic voltage is transmitted to the current source via the switch as the bias voltage.
19. The method of claim 11, wherein the driving circuit comprises a power switch, a first terminal and a second terminal of the power switch are respectively coupled to a power voltage and the light emitting device, the power switch determines whether to transmit the power voltage to the light emitting device to generate the projection light according to a switching signal, and the step of setting the at least one control signal to the driving circuit comprises:
Generating a pulse width modulation signal by a pulse width modulation circuit, wherein the duty cycle of the pulse width modulation signal is less than 100%;
controlling a switch by a controller, wherein a first select terminal of the switch is coupled to a fixed voltage, a second select terminal of the switch is coupled to the pulse width modulation circuit to receive the pulse width modulation signal, a common terminal of the switch is coupled to a control terminal of the power switch to provide the switch signal, and the controller analyzes the color content of the at least one video frame to select one of the highlight mode and the usual mode as the selected mode;
transmitting the fixed voltage to the control terminal of the power switch as the switching signal via the switch in the highlight mode; and
in the normal mode, the pulse width modulation signal is transmitted to the control terminal of the power switch via the switch as the switching signal.
20. The method of claim 11, wherein the driving circuit comprises a current source and a power switch, the current source provides a driving current according to a bias voltage, a first terminal of the power switch is coupled to the current source to receive the driving current, a second terminal of the power switch is coupled to the light emitting device, the power switch determines whether to transmit the driving current to the light emitting device to generate the projected light according to a switching signal, and the step of setting the at least one control signal to the driving circuit comprises:
Generating a dynamic voltage less than the first fixed voltage by the bias circuit;
controlling, by a controller, a first switch, wherein a first select terminal of the first switch is coupled to the first fixed voltage, a second select terminal of the first switch is coupled to the bias circuit to receive the dynamic voltage, a common terminal of the first switch is coupled to the current source to provide the bias voltage, and the controller analyzes the color content of the at least one video frame to select one of the highlight mode and the usual mode as the selected mode;
generating a pulse width modulation signal by a pulse width modulation circuit, wherein the duty cycle of the pulse width modulation signal is less than 100%;
controlling, by the controller, a second switch, wherein a first select terminal of the second switch is coupled to a second fixed voltage, a second select terminal of the second switch is coupled to the pwm circuit to receive the pwm signal, and a common terminal of the second switch is coupled to a control terminal of the power switch to provide the switching signal;
in the highlight mode, transmitting the first fixed voltage to the current source via the first switch as the bias voltage, and transmitting the second fixed voltage to the control terminal of the power switch via the second switch as the switch signal; and
In the normal mode, the dynamic voltage is transmitted to the current source as the bias voltage via the first switch, and the pulse width modulation signal is transmitted to the control terminal of the power switch as the switching signal via the second switch.
21. The method of operation of claim 11, further comprising:
receiving, by the user interface circuit, a user instruction;
transmitting the user instruction to the control circuit; and
one of the highlight mode and the normal mode is selected as the selected mode by the control circuit in accordance with the user instruction.
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