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CN116963353A - Display device and display control method - Google Patents

Display device and display control method Download PDF

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Publication number
CN116963353A
CN116963353A CN202210412214.4A CN202210412214A CN116963353A CN 116963353 A CN116963353 A CN 116963353A CN 202210412214 A CN202210412214 A CN 202210412214A CN 116963353 A CN116963353 A CN 116963353A
Authority
CN
China
Prior art keywords
voltage
module
transistor
secondary coil
lamp string
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN202210412214.4A
Other languages
Chinese (zh)
Inventor
庞震华
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hisense Visual Technology Co Ltd
Original Assignee
Hisense Visual Technology Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hisense Visual Technology Co Ltd filed Critical Hisense Visual Technology Co Ltd
Priority to CN202210412214.4A priority Critical patent/CN116963353A/en
Priority to CN202280092484.XA priority patent/CN118786757A/en
Priority to PCT/CN2022/121412 priority patent/WO2023201988A1/en
Publication of CN116963353A publication Critical patent/CN116963353A/en
Priority to US18/895,335 priority patent/US20250016897A1/en
Pending legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/30—Driver circuits
    • H05B45/37—Converter circuits
    • 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
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of DC power input into DC power output
    • H02M3/02—Conversion of DC power input into DC power output without intermediate conversion into AC
    • H02M3/04—Conversion of DC power input into DC power output without intermediate conversion into AC by static converters
    • H02M3/10—Conversion of DC power input into DC power output without intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M3/145—Conversion of DC power input into DC power output without intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M3/155—Conversion of DC power input into DC power output without intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/156—Conversion of DC power input into DC power output without intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of DC power input into DC power output
    • H02M3/22—Conversion of DC power input into DC power output with intermediate conversion into AC
    • H02M3/24—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters
    • H02M3/28—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC
    • H02M3/325—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/33507—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of the output voltage or current, e.g. flyback converters
    • H02M3/33523—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of the output voltage or current, e.g. flyback converters with galvanic isolation between input and output of both the power stage and the feedback loop
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of DC power input into DC power output
    • H02M3/22—Conversion of DC power input into DC power output with intermediate conversion into AC
    • H02M3/24—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters
    • H02M3/28—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC
    • H02M3/325—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/33561—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having more than one ouput with independent control
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of DC power input into DC power output
    • H02M3/22—Conversion of DC power input into DC power output with intermediate conversion into AC
    • H02M3/24—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters
    • H02M3/28—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC
    • H02M3/325—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/33569—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of DC power input into DC power output
    • H02M3/22—Conversion of DC power input into DC power output with intermediate conversion into AC
    • H02M3/24—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters
    • H02M3/28—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC
    • H02M3/325—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/33569—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
    • H02M3/33576—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements having at least one active switching element at the secondary side of an isolation transformer
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of DC power input into DC power output
    • H02M3/22—Conversion of DC power input into DC power output with intermediate conversion into AC
    • H02M3/24—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters
    • H02M3/28—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC
    • H02M3/325—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/33569—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
    • H02M3/33576—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements having at least one active switching element at the secondary side of an isolation transformer
    • H02M3/33592—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements having at least one active switching element at the secondary side of an isolation transformer having a synchronous rectifier circuit or a synchronous freewheeling circuit at the secondary side of an isolation transformer
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2330/00—Aspects of power supply; Aspects of display protection and defect management
    • G09G2330/02—Details of power systems and of start or stop of display operation
    • G09G2330/021—Power management, e.g. power saving

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • General Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Dc-Dc Converters (AREA)

Abstract

The application provides a display device and a display control method. Comprising the following steps: the device comprises a transformer, a voltage conversion module, a feedback module and a lamp string group; the voltage conversion modules are in one-to-one correspondence with the lamp string groups, and the lamp string groups comprise first lamp strings and second lamp strings; the first secondary coil of the transformer outputs a first voltage; the two ends of the second secondary coil of the transformer alternately output a second voltage; the second secondary coils are in one-to-one correspondence with the lamp string groups; the voltage conversion module generates a superposition voltage according to the first voltage, and superimposes the superposition voltage on the second voltage to output a third voltage; the feedback module is used for generating a feedback signal and sending the feedback signal to the voltage conversion module so as to adjust the third voltage; the first light string is connected to one end of the second secondary coil, and the second light string is connected to the other end of the second secondary coil for emitting light based on the third voltage. In the application, two lamp strings share the same power supply coil and voltage conversion module, thus simplifying the circuit; meanwhile, stepped power supply is realized by voltage superposition, and heat loss is reduced.

Description

Display device and display control method
Technical Field
The present application relates to the field of display technologies, and in particular, to a display device and a display control method.
Background
With the development of electronic technology, the integration level of electronic devices including display devices such as televisions is higher and higher, and thus, higher and higher requirements are being put on the power supply of the display devices.
Taking a television as an example, the design of the system is complex because of the two power supply requirements of a main board power supply and a backlight drive of a Light Emitting Diode (LED) light string in the television. Specifically, in one related design, a resonant conversion circuit (LLC) module is used to output a plurality of dc voltages based on ac power, respectively supplying power to a motherboard and a light string. Each street lamp string corresponds to a direct current-direct current voltage adjustment module, and voltage adjustment is carried out on fixed direct current voltage output by the LLC module so as to meet the voltage requirement of the street lamp string. In another related design, two LLC modules are used to power the motherboard and light string, respectively. The output voltage of the secondary winding of the LLC module is regulated by regulating the alternating voltage of the primary winding of the LLC module corresponding to the lamp string, so that the voltage requirement of the lamp string is met.
Therefore, how to simplify the above power supply circuit is a technical problem to be solved in the art.
Disclosure of Invention
The application provides a display device and a display control method, which are used for simplifying a power supply circuit of the display device.
In a first aspect, the present application provides a display device comprising: the device comprises a transformer, a voltage conversion module, a feedback module and a lamp string group; the voltage conversion modules are in one-to-one correspondence with the lamp string groups, and the lamp string groups comprise first lamp strings and second lamp strings; a first secondary coil and a second secondary coil of the transformer coupled with a primary coil of the transformer; the first secondary coil is used for outputting a first voltage according to the power supply received by the primary coil; a second secondary coil for alternately outputting a second voltage from both ends of the second secondary coil according to the power received by the primary coil; the second secondary coils are in one-to-one correspondence with the lamp string groups; the voltage conversion module is used for generating a superposition voltage according to the first voltage, superposing the superposition voltage to the second voltages at two ends of the corresponding second secondary coil and outputting a superposed third voltage; the feedback module is used for generating a feedback signal according to the output current of the lamp string group and sending the feedback signal to the voltage conversion module, and the feedback signal is used for indicating the voltage conversion module to adjust the third voltage; the first lamp string is connected with one end of a corresponding second secondary coil, and the second lamp string is connected with the other end of the corresponding second secondary coil and is used for emitting light based on a third voltage.
In some embodiments, the voltage conversion module comprises: the voltage adjusting module and the voltage superposition module are used for adjusting the voltage of the power supply; the voltage adjusting module is connected with the output end of the first secondary coil and is used for generating superposition voltage according to the first voltage; the voltage superposition module receives the superposition voltage and is connected with two ends of the second secondary coil, and is used for superposing the superposition voltage to the second voltages at two ends of the corresponding second secondary coil and outputting a superposed third voltage; the feedback signal is used for indicating the voltage adjustment module to adjust the third voltage by adjusting the superposition voltage.
In some embodiments, the voltage superposition module includes a first current equalizing capacitor, a first rectifying diode, a second rectifying diode, a third rectifying diode, and a fourth rectifying diode; one end of the first current equalizing capacitor and one end of the second secondary coil; the other end of the first current equalizing capacitor is connected with the positive electrode of the first rectifying diode and the negative electrode of the second rectifying diode; the positive electrode of the second rectifying diode is connected with the superimposed voltage; the cathode of the first rectifying diode is connected with the anode of the first light string; the negative electrode of the first light string is grounded; the positive electrode of the third rectifying diode is connected with the other end of the second secondary coil and the negative electrode of the fourth rectifying diode, and the positive electrode of the fourth rectifying diode is connected with the superimposed voltage; the cathode of the third rectifying diode is connected with the anode of the second light string; the negative pole of the second string of lights is grounded.
In some embodiments, the voltage adjustment module comprises: a second transistor, a third transistor, a second inductor, and a second capacitor; one end of the second transistor is connected with the output end of the first secondary coil; the other end of the second transistor is connected with one end of the third transistor and one end of the second inductor; the other end of the third transistor is grounded; the other end of the second inductor is used as an output end of the voltage adjusting module to output superposition voltage; one end of the second capacitor is connected with the other end of the second inductor; the other end of the second capacitor is grounded; the control electrode of the second transistor and the control electrode of the third transistor are connected with the feedback module and are used for adjusting the switching frequencies of the second transistor and the third transistor according to the feedback signals so as to adjust the superposition voltage.
In some embodiments, the voltage regulation module further comprises a second diode; the cathode of the second diode is connected with one end of the second capacitor; the positive pole of the second diode is connected with the other end of the second capacitor.
In some embodiments, the display device further comprises a first switching circuit and a first ground resistor; the first switch circuit is positioned between the lamp string group and the first grounding resistor; one end of the first switch circuit is connected with the negative electrode of the first light string and the negative electrode of the second light string, and the other end of the first switch circuit is connected with one end of the first grounding resistor and the input end of the feedback module; the other end of the first grounding resistor is grounded; the first switching circuit is turned on or off based on the duty control signal.
In some embodiments, the display device further comprises: a second switching circuit and a second ground resistor; the second switch circuit is positioned between the lamp string group and the second grounding resistor; one end of the second switch circuit is connected with the negative electrode of the first lamp string and the negative electrode of the second lamp string, and the other end of the second switch circuit is connected with one end of the second grounding resistor; the other end of the second grounding resistor is grounded; and the second switch circuit is used for changing loop current in the analog dimming process and performing analog dimming.
In some embodiments, the second switching circuit comprises: a fifth transistor, a comparator; one end of the fifth transistor is connected with the negative electrode of the first lamp string and the negative electrode of the second lamp string; the other end of the fifth transistor is connected with one end of the second grounding resistor and the inverting input end of the comparator; the non-inverting input end of the comparator inputs the required voltage of the lamp string group, and the output end of the comparator is connected with the grid electrode of the fifth transistor; and adjusting the resistance value of the fifth transistor for changing the loop current and performing analog dimming.
In some embodiments, the number of second secondary coils, voltage conversion modules, and light string groups are all plural; the display device also comprises a plurality of current equalizing inductors; and a current equalizing inductor which is mutually coupled is arranged between two adjacent second secondary coils.
In some embodiments, the display device further comprises a motherboard; the transformer further includes a third secondary coil coupled to the primary coil; a third secondary coil for outputting a fourth voltage according to the power received by the primary coil; the first voltage output by the first secondary coil and the fourth voltage output by the third secondary coil supply power for the main board.
In a second aspect, the present application provides a display control method applied to the display device as in the first aspect, the display control method comprising: receiving a feedback signal, wherein the feedback signal is generated by a feedback module according to the output current of the lamp string group; adjusting the third voltage based on the feedback signal to adjust the third voltage; the third voltage is the working voltage of the lamp string group
The application provides a display device and a display control method, comprising the following steps: the device comprises a transformer, a voltage conversion module, a feedback module and a lamp string group; the voltage conversion modules are in one-to-one correspondence with the lamp string groups, and the lamp string groups comprise first lamp strings and second lamp strings; the first secondary coil of the transformer outputs a first voltage; the two ends of the second secondary coil of the transformer alternately output a second voltage; the second secondary coils are in one-to-one correspondence with the lamp string groups; the voltage conversion module generates a superposition voltage according to the first voltage, and superimposes the superposition voltage on the second voltage to output a third voltage; the feedback module is used for generating a feedback signal and sending the feedback signal to the voltage conversion module so as to adjust the third voltage; the first light string is connected to one end of the second secondary coil, and the second light string is connected to the other end of the second secondary coil for emitting light based on the third voltage. In the application, two lamp strings share the same power supply coil and voltage conversion module, thus simplifying the circuit; meanwhile, stepped power supply is realized by voltage superposition, so that heat loss is reduced.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the application and together with the description, serve to explain the principles of the application.
FIG. 1 is a schematic diagram of a display device with a stand-alone power panel;
fig. 2 is a schematic diagram showing a connection relationship between a power panel and a load of the device;
FIG. 3 is a schematic diagram of a television power architecture;
FIG. 4 is a schematic diagram of a circuit for powering a motherboard and an LED string;
FIG. 5 is a schematic diagram of another circuit configuration for powering a motherboard and an LED string;
FIG. 6 is a schematic diagram of another circuit configuration for powering a motherboard and an LED string;
fig. 7 is a schematic circuit diagram of a display device with two street lamp strings according to an embodiment of the present application;
fig. 8 is a schematic circuit diagram of a voltage conversion module according to an embodiment of the present application;
fig. 9 is a schematic circuit diagram of a voltage superposition module according to an embodiment of the present application;
fig. 10 is a schematic circuit diagram of a voltage adjustment module according to an embodiment of the present application;
fig. 11 is a schematic circuit diagram of another voltage adjustment module according to an embodiment of the application;
fig. 12 is a schematic circuit diagram of a first switch circuit according to an embodiment of the present application;
Fig. 13 is a schematic circuit diagram of a second switching circuit according to an embodiment of the present application;
fig. 14 is a schematic circuit diagram of a display device with four-way light strings according to an embodiment of the present application;
fig. 15 is a schematic circuit diagram of a display device of another four-way light string according to an embodiment of the present application;
fig. 16 is a schematic circuit diagram of a display device of another four-way light string according to an embodiment of the present application;
fig. 17 is a schematic circuit diagram of a display device of another four-way light string according to an embodiment of the present application.
Specific embodiments of the present application have been shown by way of the above drawings and will be described in more detail below. The drawings and the written description are not intended to limit the scope of the inventive concepts in any way, but rather to illustrate the inventive concepts to those skilled in the art by reference to the specific embodiments.
Detailed Description
Reference will now be made in detail to exemplary embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, the same numbers in different drawings refer to the same or similar elements, unless otherwise indicated. The implementations described in the following exemplary examples do not represent all implementations consistent with the application. Rather, they are merely examples of apparatus and methods consistent with aspects of the application.
The terms "first," "second," "third," "fourth" and the like in the description and in the claims and in the above drawings, if any, are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate such that the embodiments of the application described herein may be implemented, for example, in sequences other than those illustrated or otherwise described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
The scene in which the present application is applied and the problems that exist will be described with reference to the drawings. As the demand for information is increasing, various types of display devices, such as computers, televisions, projectors, and the like, are being developed. The power supply circuit is one of the most important circuit structures in the display device, and can provide electric energy for the display device, so that the display device can normally operate. Some display devices are provided with independent power boards, and some display devices integrate the power boards and the main boards into one.
Taking a display device provided with an independent power panel as an example, the structure of the display device will be described, referring to fig. 1, fig. 1 is a schematic structural view of the display device provided with the independent power panel, and as shown in fig. 1, the display device includes a display panel 1, a backlight assembly 2, a main board 3, a power panel 4, a rear case 5, and a base 6. Wherein the display panel 1 is used for presenting pictures to a user; the backlight assembly 2 is located below the display panel 1, usually some optical assemblies, and is used for providing enough brightness and uniformly distributed light sources to enable the display panel 1 to display images normally, the backlight assembly 2 further comprises a back plate 20, the main plate 3 and the power panel 4 are arranged on the back plate 20, some convex hull structures are usually stamped and formed on the back plate 20, and the main plate 3 and the power panel 4 are fixed on the convex hulls through screws or hooks; the rear shell 5 is arranged on the panel 1 in a covering way so as to hide parts of the display device such as the backlight assembly 2, the main board 3, the power panel 4 and the like, thereby having an attractive effect; and a base 6 for supporting the display device.
In some embodiments, fig. 2 is a schematic diagram of connection between a power panel and a load of a display device, as shown in fig. 2, the power panel 4 includes an input terminal 41 and an output terminal 42 (a first output terminal 421, a second output terminal 422, and a third output terminal 423 are shown in the figure), where the input terminal 41 is connected to a mains supply, the output terminal 42 is connected to the load, for example, the first output terminal 421 is connected to an LED light string for lighting a display screen, the second output terminal 422 is connected to an audio device, and the third output terminal 423 is connected to a motherboard. The power panel 4 needs to convert ac mains to dc power required by a load, and the dc power generally has different specifications, for example, 18V for sound, 12V for a panel, and the like.
In some embodiments, taking a television as an example to describe a power architecture of a display device, fig. 3 is a schematic diagram of the power architecture of the television, and as shown in fig. 3, a power panel may specifically include: a rectifier bridge, a power factor correction (Power Factor Correction, PFC) module and a resonant converter (LLC) module, the LLC module including a synchronous rectifier circuit (not shown in fig. 3), the PFC module being connected to the LLC module, the LLC module being connected to a load.
The rectifier bridge is used for rectifying input commercial alternating current and inputting full-wave signals to the PFC module. An electromagnetic interference (Electromagnetic Interference, EMI) filter (not shown in fig. 3) may be connected to the ac power source before it is input to the PFC module, to high frequency filter the input ac power source.
The PFC module can comprise a PFC inductor, a switching power device and a PFC control chip, and mainly performs power factor correction on an input alternating current power supply to output stable direct current bus voltage (such as 380V) to the LLC module. The PFC module can effectively improve the power factor of the power supply and ensure the same phase of voltage and current. Alternatively, in some embodiments, the PFC module may not be provided in the power architecture shown in fig. 3.
The LLC module can adopt a double-MOS tube LLC resonant conversion circuit, and a synchronous rectification circuit is arranged in the LLC module generally and mainly comprises a transformer, a controller, two MOS tubes and a diode. In addition, the LLC module may also include pulse frequency adjustment (Pulse frequency modulation, PFM) circuits, capacitors, inductors, and other components. The LLC module can specifically step down or step up the direct current bus voltage input by the PFC module and output constant voltage to a load. Typically, the LLC module is capable of outputting a variety of different voltages to meet the demands of different loads. Alternatively, in other embodiments, an LLC module such as that shown in FIG. 3 may be replaced with a flyback voltage conversion module that steps down or up the voltage and outputs a constant voltage to the load.
More specifically, taking a display device as an example of a television, fig. 4 is a schematic diagram of a power supply circuit for supplying power to a motherboard and an LED string. After the commercial power alternating current (100V-240V, 50-60 Hz) acquired by the power supply circuit sequentially passes through the filtering rectification module (rectifier bridge), the PFC module and the LLC isolation voltage conversion module, the commercial power alternating current supplies power to a main board of the display device, a plurality of LED lamp strings and other loads (not shown in fig. 4). The first secondary winding in the LLC isolation voltage conversion module provides a first voltage (for example, 12V) to the main board, the second secondary winding provides a second voltage (for example, 18V) to the main board, and the third secondary winding simultaneously provides voltages to the multi-path LED lamp strings.
The LED lamp strings are used for lighting a display screen of a television, the LED components in the LED lamp strings need to work within a certain voltage drop range to achieve rated current, for example, the LED lamp strings with multiple paths of LED lamp strings are 16 paths, under the condition that each path of LED lamp string comprises 9 LED components, the voltage range required by the multiple paths of LED lamp strings is 51.3V-58.5V under the condition of 120mA, and the total current is 1.92A.
Because the working voltage of the LED lamp string is influenced by factors such as working environment, hardware characteristics of the LED components, service life and the like, the LED lamp string needs to be adjusted in real time. Therefore, a voltage adjustment module (buck step-down circuit or boost step-up circuit or buck-boost step-down circuit) is also provided in the power supply circuit. The LED lamp string voltage detection device can detect the working voltage or the working current of the LED lamp string, and sends a feedback signal to the voltage adjustment module according to the change of the working voltage or the working current, so that the voltage adjustment module can adjust the voltage output to the LED lamp string according to the feedback signal, and the stability of the working current of the LED lamp string is further maintained.
As shown in fig. 4, power is supplied to the main board and two LED strings, where a voltage adjustment module, such as a boost circuit, is configured for each LED string. The voltage adjustment module can adjust the fixed voltage output by the third secondary winding according to the real-time current feedback result of each path of LED lamp string and then transmit the fixed voltage to each path of LED lamp string, so that each path of LED lamp string works with rated current, and the damage of elements caused by the fact that excessive current flows through LED components in the LED lamp strings is prevented.
However, in the power supply circuit shown in fig. 4, one voltage adjustment module is provided for each LED string in the power supply circuit. Namely, each path of LED lamp string is added, and a voltage adjusting module is correspondingly added. Therefore, the circuit structure is relatively complex, so that the area of the PCB where the power supply circuit is located is large, and finally the cost of the power supply circuit is increased.
In some embodiments, fig. 5 is a schematic diagram of another circuit structure for supplying power to a motherboard and an LED string, and after the ac mains power (100V-240V, 50-60 Hz) obtained by the power supply circuit sequentially passes through a filtering rectifier module (rectifier bridge), a PFC module, and an LLC isolated voltage conversion module, the ac mains power is supplied to the motherboard, a multi-path LED string, and other loads (not shown in fig. 5) of the display device. Wherein a first secondary winding in the LLC isolated voltage conversion module 1 provides a first voltage (e.g., 12V) to the motherboard and a second secondary winding provides a second voltage (e.g., 18V) to the motherboard; the LLC isolation voltage conversion module 2 provides voltage for two paths of LED lamp strings simultaneously. The LLC isolation voltage conversion module 2 alternately provides working voltage for two paths of LED lamp strings by utilizing the characteristics of alternating current. The controller of the LLC isolation voltage conversion module 2 receives current feedback of the two paths of LED lamp strings, adjusts voltage output by the LLC isolation voltage conversion module 2, and transmits the adjusted voltage to the two paths of LED lamp strings, so that each path of LED lamp string works with rated current, and damage to elements caused by the fact that excessive current flows through LED components in the LED lamp strings is prevented.
The capacitor connected with one output end of the secondary winding of the LLC isolation voltage conversion module 2 plays a role in equalizing current, and is used for equalizing working currents of two paths of LED lamp strings; diodes connected in series between the two output ends of the secondary winding and the LED lamp string play a role in rectification based on unidirectional conduction characteristics; the grounding diode connected with the two output ends of the secondary winding plays a role in stabilizing voltage.
However, in the power supply circuit shown in fig. 5, the output voltage range of the LLC isolated voltage conversion module 2 is limited, and when the current level needs to be changed, the output range of the LLC isolated voltage conversion module 2 is greatly limited. In addition, the display device may have more than two paths of LED strings, and according to the power supply circuit shown in fig. 5, each time two paths of LED strings are added, a secondary winding is correspondingly added to the LLC isolated voltage conversion module 2 to supply power to the newly added LED string. The relatively large number of secondary windings can lead to relatively difficult transformer designs and high cost of complex circuitry.
In some embodiments, fig. 6 is a schematic diagram of still another circuit structure for supplying power to the motherboard and the LED string lights. After the commercial power alternating current (100V-240V, 50-60 Hz) acquired by the power supply circuit sequentially passes through the filtering rectification module (rectifier bridge), the PFC module and the LLC isolation voltage conversion module, the commercial power alternating current supplies power to a main board of the display device, a plurality of LED lamp strings and other loads (not shown in fig. 6). The LLC isolation voltage conversion module comprises four secondary windings, wherein the first secondary winding provides a first voltage (for example, 12V) to the main board, and the second secondary winding provides a second voltage (for example, 18V) to the main board; the second secondary winding and the third secondary winding supply power for the second LED lamp string together; the second secondary winding and the fourth secondary winding supply power for the first LED lamp string together.
Specifically, the 18V voltage output by the second secondary winding is passed through a voltage adjustment module, for example, a boost circuit, to generate a "variable voltage", and is connected to one end of the third secondary winding, and is superimposed with the fixed voltage 2 generated by the third secondary winding, and the superimposed voltage supplies power to the second LED string.
Similarly, the 18V voltage output by the second secondary winding is passed through a voltage adjustment module, for example, a boost circuit, to generate a "variable voltage", and is connected to one end of the fourth secondary winding, and is superimposed with the fixed voltage 1 generated by the fourth secondary winding, and the superimposed voltage supplies power to the first LED string.
In the power supply circuit shown in fig. 6, a mode of overlapping the "variable voltage" and the "fixed voltage" is called "step power supply", which is beneficial to reducing the requirement on the withstand voltage value of elements such as a switching tube and a capacitor in the voltage adjustment module, thereby reducing the cost. However, each additional LED string is provided with a secondary winding and a voltage regulation module, which are respectively added on the LLC isolation voltage conversion module. A relatively large number of secondary windings can lead to relatively difficult transformer design; meanwhile, the circuit structure is relatively complex, so that the area of the PCB where the power supply circuit is located is large, and finally the cost of the power supply circuit is increased.
Based on the display device provided by the application, two LED lamp strings share one secondary coil and a voltage conversion module, wherein the two ends of the secondary coil alternately output 'fixed voltage', and the 'variable voltage' output by the voltage conversion module is superposed, so that 'step power supply' for the two LED lamp strings is realized. The power supply circuit can be simplified, and the heat loss can be reduced.
The following describes the technical scheme of the present application and how the technical scheme of the present application solves the above technical problems in detail with specific embodiments. The following embodiments may be combined with each other, and the same or similar concepts or processes may not be described in detail in some embodiments. Embodiments of the present application will be described below with reference to the accompanying drawings.
Fig. 7 is a schematic circuit diagram of a display device with two street lamp strings according to an embodiment of the present application. As shown in fig. 7, includes: the device comprises a transformer, a voltage conversion module, a feedback module and a lamp string group; the voltage conversion modules are in one-to-one correspondence with the lamp string groups, and the lamp string groups comprise a first lamp string 140 and a second lamp string 150;
in fig. 7, the transformer takes an LLC isolated voltage conversion module as an example, and a first secondary winding 110 and a second secondary winding 120 of the LLC isolated voltage conversion module are coupled to a primary winding 100 of the LLC isolated voltage conversion module; a first secondary coil 110 for outputting a first voltage according to the power received by the primary coil 100; a second secondary coil 120 for alternately outputting a second voltage from both ends of the second secondary coil 120 according to the power received by the primary coil 100; the second secondary coils 120 are in one-to-one correspondence with the lamp string groups; the voltage conversion module is used for generating a superposition voltage according to the first voltage, superposing the superposition voltage to the second voltages at two ends of the corresponding second secondary coil and outputting a superposed third voltage;
The feedback module is used for generating a feedback signal according to the output current of the lamp string group and sending the feedback signal to the voltage conversion module, and the feedback signal is used for indicating the voltage conversion module to adjust the third voltage; the first light string 140 is connected to one end of the corresponding second secondary coil 120, and the second light string 150 is connected to the other end of the corresponding second secondary coil 120, for emitting light based on the third voltage.
The power supply circuit shown in fig. 7 further includes a filtering rectifier module (rectifier bridge) and a PFC module, processes the obtained ac mains power, and supplies power to a main board of the display device, a multi-path LED light string, and other loads (not shown in fig. 7) via the LLC isolated voltage conversion module.
One end of the first secondary coil 110 is grounded, and the center tap of the first secondary coil 110 and the other end of the first secondary coil 110 are connected in series with a rectifier diode to output a first voltage. In fig. 7, the first voltage is exemplified by a dc voltage of 18V. Since the first secondary coil 110 is coupled with the primary coil 100 to induce ac power, ac-dc conversion is required by the above-described rectifying circuit.
In this embodiment, the second secondary coil 120 and the primary coil 100 are coupled to induce alternating current, and the two ends of the second secondary coil alternately output a second voltage, which is equal to a "fixed voltage"; the voltage conversion module adjusts the first voltage output by the first secondary coil according to the feedback signal to generate a superimposed voltage, and the superimposed voltage is equivalent to 'variable voltage'; the voltage conversion module adds the superimposed voltage to the second voltage and outputs a superimposed third voltage. In the embodiment, two lamp strings share the same power supply coil and voltage conversion module, so that the circuit is simplified; meanwhile, the step power supply is realized by utilizing the voltage superposition of the fixed voltage and the variable voltage, so that the heat loss is reduced.
The feedback module may be a current feedback mode or a voltage feedback mode. The feedback module can generate a feedback signal according to the current of the single street lamp string, and can also generate a feedback signal according to the current of the multi-street lamp string. When the single street lamp string is adopted for feedback, the reference current value set in the feedback module is the required working current of the street lamp string. When the two street lamp strings are fed back together, the reference current value set in the feedback module is 2 times of the required working current of one street lamp string. The reference current value is used for comparing with the actual current, and if the actual current is higher than the reference current value, the output feedback signal indicates the voltage adjusting module to reduce the third voltage; if the actual current is equal to the reference current value, the output feedback signal indicates the voltage adjustment module to maintain the third voltage; if the actual current is lower than the reference current value, the output feedback signal indicates the voltage adjusting module to increase the third voltage.
Fig. 7 adopts a mode that two street lamp strings feed back together. Specifically, the feedback module generates a feedback signal according to the total current of the first string light 140 and the second string light 150 in the string light group, and sends the feedback signal to the voltage conversion module to instruct the voltage conversion module to adjust the third voltage. The first string light 140 and the second string light 150 may be directly grounded, or grounded through a grounding circuit Rn. The grounding circuit Rn is favorable for releasing static electricity and avoiding static electricity accumulation.
In some embodiments, fig. 8 is a schematic circuit diagram of a voltage conversion module according to an embodiment of the present application. The voltage conversion module includes: the voltage adjusting module and the voltage superposition module are used for adjusting the voltage of the power supply; the voltage adjusting module is connected with the output end of the first secondary coil and is used for generating superposition voltage according to the first voltage; the voltage superposition module receives the superposition voltage and is connected with two ends of the second secondary coil, and is used for superposing the superposition voltage to the second voltages at two ends of the corresponding second secondary coil and outputting a superposed third voltage; the feedback signal is used for indicating the voltage adjustment module to adjust the third voltage by adjusting the superposition voltage.
Wherein the second voltage corresponds to a "fixed voltage"; the voltage adjustment module adjusts the first voltage according to the feedback signal to output a superimposed voltage, and the superimposed voltage corresponds to a 'variable voltage'. And the voltage superposition module is used for superposing the superposition voltage to the second voltage and outputting a third voltage after superposition to supply power for the lamp string group. The step power supply mode is adopted, so that the heat loss is reduced.
In some embodiments, the voltage superposition module includes a first current equalizing capacitor C1, a first rectifying diode D1, a second rectifying diode D2, a third rectifying diode D3, and a fourth rectifying diode D4;
One end of the first current equalizing capacitor C1 and one end of the second secondary coil; the other end of the first current equalizing capacitor C1 is connected with the positive electrode of the first rectifying diode D1 and the negative electrode of the second rectifying diode D2; the positive electrode of the second rectifying diode D2 is connected with the superimposed voltage; the cathode of the first rectifying diode D1 is connected with the anode of the first light string 140; the negative electrode of the first light string 140 is grounded;
the positive electrode of the third rectifying diode D3 is connected with the other end of the second secondary coil 120 and the negative electrode of the fourth rectifying diode D4, and the positive electrode of the fourth rectifying diode D4 is connected with the superposition voltage; the cathode of the third rectifying diode D3 is connected with the anode of the second light string 150; the negative pole of the second string 150 is grounded.
Fig. 9 is a schematic circuit diagram of a voltage superposition module according to an embodiment of the present application. The primary coil 100 is charged and discharged respectively by the first current equalizing capacitor C1 when turned on and off under the internal control of the LLC isolated voltage converting module.
When the first current-sharing capacitor C1 discharges, the current flows from the first end of the first current-sharing capacitor C1 (i.e., the left end of the first current-sharing capacitor C1 shown in fig. 10) to the second end (i.e., the right end of the first current-sharing capacitor C1 shown in fig. 10), and the electric quantity in the first current-sharing capacitor C1 is released through the loop of the first light string 140. Meanwhile, the superimposed voltage output by the voltage adjustment module is input to the positive electrode of the first rectifying diode D1 through the second rectifying diode D2, and current superimposition occurs at the positive electrode of the first rectifying diode D1, and is input to the first light string 140 from the negative electrode of the first rectifying diode D1.
When the first current equalizing capacitor C1 is charged, the current flows from the second end to the first end of the first current equalizing capacitor C1, the third rectifying diode D3 is turned on, and the electric quantity in the first current equalizing capacitor C1 is released through the loop of the second light string 150. Meanwhile, the superimposed voltage output by the voltage adjustment module is input to the positive electrode of the third rectifying diode D3 through the fourth rectifying diode D4, and current superimposition occurs at the positive electrode of the third rectifying diode D3, and is input to the second light string 150 from the negative electrode of the third rectifying diode D3.
Because the total charges are equal in the charge and discharge processes of the current sharing capacitor, the charges respectively flowing through the two street lamp strings are equal, and the currents of the two street lamp strings are equal, so that the current sharing of the two street lamp strings is realized. If the currents of the two lamp strings are not equal, a voltage difference is generated on the first equalizing capacitor C1, so that the loop voltage drops of the first lamp string 140 and the second lamp string 150 are the same, that is: the impedance is balanced. After several cycles, the current reaches an equal state of equilibrium. Thus, over a long period of time, the currents of the two LED strings are equal.
The loop in which the first light string 140 is located includes a first rectifying diode D1, the first light string 140, a feedback module, a voltage adjusting module, a fourth rectifying diode D4, and a second secondary winding 120; the loop in which the second string light 150 is located includes the second secondary winding 120, the third rectifying diode D3, the second string light 150, the feedback module, the voltage adjusting module, and the second rectifying diode D2.
In the embodiment of the application, two lamp strings share the same power supply coil (namely the second secondary coil 120) and the voltage adjusting module, so that the circuit is simplified; meanwhile, voltage superposition is carried out by using two rectifier diodes, so that stepped power supply for each street lamp string is realized, and heat loss is reduced.
In some embodiments, the voltage adjustment module may be a boost circuit. Specifically, the voltage adjustment module includes: a first inductor L1, a first transistor Q1, a first diode D5, and a first capacitor C2. One end of the first inductor L1 is connected to the output end of the first secondary coil 110; the other end of the first inductor L1 is connected with one end of the first transistor Q1 and the anode of the first diode D5; the other end of the first transistor Q1 is grounded; the cathode of the first diode D5 is used as the output end of the voltage adjusting module to output the superposition voltage; one end of the first capacitor C2 is connected with the cathode of the first diode D5; the other end of the first capacitor C2 is grounded; the control electrode of the first transistor Q1 is connected to the feedback module, and is configured to adjust the switching frequency of the first transistor Q1 according to the feedback signal, so as to adjust the superimposed voltage.
Fig. 10 is a schematic circuit diagram of a voltage adjustment module according to an embodiment of the application. When the first transistor Q1 is turned on, the output end of the first secondary winding 110 continuously outputs the first voltage to charge the first inductor L1, so that the current of the first inductor L1 increases linearly.
When the first transistor Q1 is turned off, the first inductor L1 can only discharge through the first diode D5, and output a superimposed voltage from the cathode of the first diode D5 to the second rectifying diode D2 and the fourth rectifying diode D4, while charging the first capacitor C2; both ends of the capacitor rise and are higher than the input first voltage.
When the first transistor Q1 is turned on again, the first inductor L1 is charged again; meanwhile, due to the unidirectional conductivity of the first diode D5, the first capacitor C2 is discharged, and a superimposed voltage is output to the second rectifying diode D2 and the fourth rectifying diode D4.
By controlling the switching frequency of the first transistor Q1 or selecting the first capacitor C2 having a larger capacity, it is possible to realize continuous output of the superimposed voltage which is higher than the input first voltage. The other end of the first transistor Q1 may be directly grounded, or may be connected to the ground resistor R1 for discharging static electricity and improving safety.
In some embodiments, fig. 10 employs a current feedback approach. The feedback module includes a first driving chip, which is configured to collect actual total currents of the first light string 140 and the second light string 150 in real time, and generate a feedback signal, so that the voltage adjustment module can timely and effectively adjust the voltage, and prevent the excessive current from flowing through the LED assemblies in the first light string 140 and the second light string 150 to cause damage to the components.
In some embodiments, the voltage adjustment module may be a buck step-down circuit. Specifically, the voltage adjustment module includes: the second transistor Q2, the third transistor Q3, the second inductor L2, the second capacitor C2 and the second driving chip. One end of the second transistor Q2 is connected to the output end of the first secondary coil 110; the other end of the second transistor Q2 is connected with one end of the third transistor Q3 and one end of the second inductor L2; the other end of the third transistor Q3 is grounded; the other end of the second inductor L2 is used as an output end of the voltage adjusting module to output superposition voltage; one end of the second capacitor C2 is connected with the other end of the second inductor L2; the other end of the second capacitor C2 is grounded; the control electrode of the second transistor Q2 and the control electrode of the third transistor Q3 are both connected to the feedback module, and are used for adjusting the switching frequencies of the second transistor Q2 and the third transistor Q3 according to the feedback signal so as to adjust the superposition voltage.
Fig. 11 is a schematic circuit diagram of another voltage adjustment module according to an embodiment of the application. The voltage regulation module is a synchronous rectification buck circuit. The adoption of the third transistor Q3 instead of the rectifier diode is beneficial to improving the voltage conversion efficiency.
When the second transistor Q2 is turned on and the third transistor Q3 is turned off, the output end of the first secondary winding 110 continuously outputs the first voltage to charge the second inductor L2, so that the current of the second inductor L2 increases linearly, and at this time, a superimposed voltage is output to the second rectifying diode D2 and the fourth rectifying diode D4, and the second capacitor C3 is charged. When the second transistor Q2 is turned off and the third transistor Q3 is turned on, the second inductor L2 freewheels to discharge through the third transistor Q3, the current of the second inductor L2 decreases linearly, and at this time, a superimposed voltage is output to the second rectifying diode D2 and the fourth rectifying diode D4 through the second capacitor C3 and the gradually decreasing second inductor L2.
By controlling the switching frequencies of the second transistor Q2 and the third transistor Q3, the superimposed voltage can be continuously output, and the superimposed voltage is lower than the input first voltage. The other end of the third transistor Q3 may be directly grounded, or may be connected to the ground resistor R2 for discharging static electricity and improving safety.
In some embodiments, when the synchronous rectification buck circuit shown in fig. 11 is employed, the voltage regulation module further includes a second diode D6; the cathode of the second diode D6 is connected with one end of the second capacitor C3; the anode of the second diode D6 is connected to the other end of the second capacitor C3.
When the voltage adjustment module has no output, the second transistor Q2 is turned off, and the current of the string of lamps flows back to the second secondary winding 120 through the body diode of the third transistor Q3, the second inductor L2, and the fourth current sharing diode D4. When the current is too large, more heat loss is generated on the body diode of the third transistor Q3, and to reduce the heat loss, a new current loop is formed by using the second diode D6, so that the current of the light string group flows back to the second secondary coil 120 from the second diode D6 and the fourth current sharing diode D4. The second diode D6 is a low-power diode such as a schottky diode.
The buck topology and boost topology can be selected according to engineering requirements, for example, the buck topology structure has the advantage of low cost, but the output voltage range is narrow; while boost topology has the advantage of a wider output voltage range, but at a relatively high cost.
In some embodiments, the display device further includes a first switch circuit and a first ground resistor R3; the first switch circuit is positioned between the lamp string group and the first grounding resistor R3; one end of the first switch circuit is connected with the negative electrode of the first light string and the negative electrode of the second light string, and the other end of the first switch circuit is connected with one end of the first grounding resistor R3 and the input end of the feedback module; the other end of the first grounding resistor R3 is grounded; the first switching circuit is turned on or off based on the duty control signal.
Fig. 12 is a schematic circuit diagram of a first switch circuit according to an embodiment of the present application. As shown in fig. 12, for the multiplexing circuit, the voltages of the plurality of secondary coils may have a problem of the cross adjustment rate. The cross regulation rate refers to the influence on one output voltage when the other paths are loaded. For example, when the output voltage of the third secondary coil 130 is heavily loaded, the output voltages of the first and second secondary coils 110 and 120 may be increased. Therefore, when the voltage conversion module is not operated, the second voltage output by the second secondary winding 120 exceeds the operating voltage of the light string set, which causes the light string set to be naturally lighted. That is, the lighting and turning off of the string of lights is uncontrolled.
Therefore, a first switch circuit needs to be added in the loop of the light string set to ensure that the light string set is in an off state when the light string set is not required to emit light. For example, when the display device is in a standby state, the display screen of the display device is normally turned off, i.e., the light string group should be in an off state. The duty control signal (i.e., the PWM control signal shown in fig. 12) and the control signal of the display device state may be synchronized, i.e., when the display device is controlled to be in the standby state, the light string group is controlled to be in the non-light emitting state in synchronization with the duty control signal.
In some embodiments, the first switching circuit comprises: a fourth transistor Q4; one end of the fourth transistor Q4 is connected to the negative electrode of the first string light 140 and the negative electrode of the second string light 150; the other end of the fourth transistor Q4 is connected with one end of the first grounding resistor R3 and the input end of the feedback module; the gate of the fourth transistor Q4 is connected to the duty control signal, and the fourth transistor is turned on or off based on the duty control signal. Referring to fig. 12, when the PWM control signal is at a low level, the fourth transistor Q4 is turned off, and thus the string light group is not lighted.
In the display device of some embodiments, further comprising: a second switching circuit and a second ground resistor R4; the second switch circuit is positioned between the lamp string group and the second grounding resistor R4; one end of the second switching circuit is connected with the negative electrode of the first light string 140 and the negative electrode of the second light string 150, and the other end of the second switching circuit is connected with one end of the second grounding resistor R4; the other end of the second grounding resistor R4 is grounded; and the second switch circuit is used for changing the loop current and performing analog dimming.
Fig. 13 is a schematic circuit diagram of a second switching circuit according to an embodiment of the present application. The analog dimming is achieved by changing the brightness of the light string by changing the current in the loop of the light string. For the requirement of analog dimming, if the current of the light string is smaller, the required operating voltage of the light string is smaller, and the second voltage output by the second secondary winding 120 more easily exceeds the required operating voltage of the light string. When the second voltage output by the second secondary winding 120 is unchanged, the resistance value in the loop is adjusted by the second switch circuit, and the current in the loop is changed. The circuit design is simpler than a method of adjusting the second voltage output from the second secondary winding 120 to achieve dimming.
In some embodiments, the second switching circuit comprises: a fifth transistor Q5, a comparator; one end of the fifth transistor Q5 is connected to the negative electrode of the first string light 140 and the negative electrode of the second string light 150; the other end of the fifth transistor Q5 is connected with one end of the second grounding resistor R4 and the inverting input end of the comparator; the non-inverting input end of the comparator inputs the required voltage of the lamp string group, and the output end of the comparator is connected with the grid electrode of the fifth transistor Q5; the resistance value of the fifth transistor Q5 is adjusted to change the loop current, so as to perform analog dimming.
Referring to fig. 13, the inverting input of the comparator receives the actual total current of the first string of lights 140 and the second string of lights 150, and the comparator typically compares the voltage signals, so the current feedback signal needs to be converted into a voltage feedback signal. The scheme of converting the current feedback signal into the voltage feedback signal is referred to the related art. The non-inverting input of the comparator inputs a reference voltage that is converted based on the reference current. The scheme of converting the reference current signal into the reference voltage signal is referred to the related art. When the voltage feedback signal exceeds the reference voltage, the fifth transistor Q5 can be set to a linear operation state, and the redundant voltage is absorbed on the fifth transistor Q5.
Fig. 13 shows a voltage feedback method. One end of the first feedback resistor R5 is connected with the negative electrode of the first lamp string 140 and the negative electrode of the second lamp string 150, and the other end of the first feedback resistor R5 is connected with one end of the second feedback resistor R6; the other end of the second feedback resistor R6 is grounded; the second driving chip samples from the connection point of the first feedback resistor R5 and the second feedback resistor R6 and sends a voltage feedback signal to the voltage conversion module.
The second driving chip is used for collecting the tawny signal of the connection point of the first feedback resistor R5 and the second feedback resistor R6 in real time, generating a feedback signal, enabling the voltage conversion module to timely and effectively regulate the voltage, and preventing the damage of elements caused by the fact that excessive current flows through the LED components in the first light string 140 and the second light string 150.
Referring to fig. 7 to 13, the display device provided in this embodiment further includes a main board; the transformer further includes a third secondary winding 130 coupled to the primary winding; a third secondary winding 130 for outputting a fourth voltage according to the power received by the primary winding; the first voltage output by the first secondary winding 110 and the fourth voltage output by the third secondary winding 130 supply power to the motherboard. The first voltage is, for example, 18V and the fourth voltage is 12V.
In the display device of some embodiments, the number of the second secondary coil 120, the voltage conversion module and the light string group is plural; the display device also comprises a plurality of current equalizing inductors; and a current equalizing inductor which is mutually coupled is arranged between two adjacent second secondary coils.
Taking a four-way light string as an example, fig. 14 is a schematic circuit diagram of a display device with a four-way light string according to an embodiment of the present application, wherein a boost circuit is taken as an example for the voltage adjustment module. As shown in fig. 14, the lamp string comprises two lamp string groups, four lamp strings: a first light string 140, a second light string 150, a third light string 160, a fourth light string 170; two second secondary coils 120 and 121 correspond to two lamp string groups. Wherein, the current equalizing inductance of mutual coupling is arranged between the two second secondary coils 120 and 121: a third inductance L3 and a fourth inductance L4.
When the winding directions, the winding numbers, and the like of the two second secondary windings 120 and 121 are identical, the current direction in the power supply circuit of the second string light 150 and the current direction in the power supply circuit of the third string light 160 are opposite during the power supply process, and thus an impedance is generated. The third inductor L3 is connected in series in the power supply circuit of the second string light 150, the fourth inductor L4 is connected in series in the power supply circuit of the third string light 160, and the third inductor L3 and the fourth inductor L4 are coupled to each other for balancing the generated impedance.
The feedback module adopts four street lamp strings to feed back together, so that the reference current value set in the feedback module is 4 times of the required working current of one street lamp string. In addition, the principle of the second secondary coil 121 for supplying power to the third light string 160 and the fourth light string 170 will not be described again.
Fig. 15 is a schematic circuit diagram of a display device of another four-way light string according to an embodiment of the present application. In the power supply circuit of the display device for the four-string light, the first switching circuit is located between the four-string light (the first string light 140, the second string light 150, the third string light 160, and the fourth string light 170) and the ground resistor R3, as in fig. 12. For a multiple output circuit, the voltages of multiple secondary windings may have a cross-regulation problem. In order to avoid that the second voltage output by the second secondary coil 120 or 121 exceeds the working voltage of the light string group when the voltage conversion module is not working, the light string group is lightened, and a first switch circuit is added in a loop of the light string group, so that the light string group is in a closed state when the light string group is not required to emit light. Specifically, the first switching circuit includes a fourth transistor Q4, and when the PWM control signal is at a low level, the fourth transistor Q4 is turned off, so that the light string group is not lighted.
Fig. 16 is a schematic circuit diagram of a display device of another four-way light string according to an embodiment of the present application. In the power supply circuit of the display device aiming at the four street lamp strings, the second switch circuit is positioned between the lamp string group and the grounding resistor, and the resistance value in the loop is regulated through the second switch circuit, so that the current in the loop is changed, and the brightness of the lamp string group is regulated. Specifically, when the actual voltage of the lamp string group exceeds the reference voltage, the transistor can be set in a linear working state to share redundant voltage, so that the damage of a circuit caused by overlarge voltage of the lamp string component is avoided. Specifically, the second switching circuit includes a fifth transistor Q5 and a comparator; the inverting input of the comparator receives the actual total current of the first string 140 and the second string 150, and the comparator typically compares the voltage signals, so the current feedback signal needs to be converted into a voltage feedback signal. The scheme of converting the current feedback signal into the voltage feedback signal is referred to the related art. The non-inverting input of the comparator inputs a reference voltage that is converted based on the reference current. The scheme of converting the reference current signal into the reference voltage signal is referred to the related art. When the voltage feedback signal exceeds the reference voltage, the fifth transistor Q5 can be set to a linear operation state, and the redundant voltage is absorbed on the fifth transistor Q5.
Fig. 17 is a schematic circuit diagram of a display device of another four-way light string according to an embodiment of the present application. The voltage adjusting circuit uses a buck step-down circuit as an example, and adopts the synchronous rectification buck step-down circuit shown in fig. 11, and is also provided with a second diode D6. When the voltage adjustment module has no output, the second transistor Q2 is turned off, and the current of the string of lamps flows back to the second secondary winding 120 through the body diode of the third transistor Q3, the second inductor L2, and the fourth current sharing diode D4. When the current is too large, more heat loss is generated on the body diode of the third transistor Q3, and to reduce the heat loss, a new current loop is formed by using the second diode D6, so that the current of the light string group flows back to the second secondary coil 120 from the second diode D6 and the fourth current sharing diode D4. The second diode D6 is a low-power diode such as a schottky diode.
The present embodiment also provides a display control method applied to a display device, where the display device is as shown in fig. 7, and includes: the device comprises a transformer, a voltage conversion module, a feedback module and a lamp string group; a first secondary coil and a second secondary coil of the transformer coupled with a primary coil of the transformer; the first secondary coil is used for outputting a first voltage according to the power supply received by the primary coil; a second secondary coil for alternately outputting a second voltage from both ends of the second secondary coil according to the power received by the primary coil; the second secondary coils are in one-to-one correspondence with the lamp string groups; and the voltage conversion module is used for generating a superposition voltage according to the first voltage, superposing the superposition voltage to the second voltages at two ends of the corresponding second secondary coil and outputting a superposed third voltage.
The display control method provided by the embodiment comprises the following steps: receiving a feedback signal, wherein the feedback signal is generated by a feedback module according to the output current of the lamp string group; adjusting the third voltage by adjusting the superimposed voltage based on the feedback signal; the third voltage is the working voltage of the lamp string group. According to the feedback signals of the real-time current output by each LED lamp string, the first voltage output by the first secondary coil is adjusted to generate the superposition voltage, and the superposition voltage is superposed with the second voltage output by the second secondary coil and then transmitted to each LED lamp string, so that each LED lamp string works with rated current, and the damage of elements caused by the fact that excessive current flows through LED components in the LED lamp strings is prevented. Wherein the superimposed voltage corresponds to a "varying voltage"; the second voltage is equal to a fixed voltage, and the superposition of the second voltage and the fixed voltage realizes step power supply, thereby being beneficial to reducing heat loss; meanwhile, the two lamp strings share the same power supply coil (namely the second secondary coil) and the voltage conversion module, which is beneficial to simplifying the circuit.
The display device and the display control method provided by the embodiment comprise a transformer, a voltage conversion module feedback module and a light string group; the voltage conversion modules are in one-to-one correspondence with the lamp string groups, and the lamp string groups comprise first lamp strings and second lamp strings; a first secondary coil and a second secondary coil of the transformer coupled with a primary coil of the transformer; the first secondary coil is used for outputting a first voltage according to the power supply received by the primary coil; a second secondary coil for alternately outputting a second voltage from both ends of the second secondary coil according to the power received by the primary coil; the second secondary coils are in one-to-one correspondence with the lamp string groups; the voltage conversion module is used for generating a superposition voltage according to the first voltage, superposing the superposition voltage to the second voltages at two ends of the corresponding second secondary coil and outputting a superposed third voltage; the feedback module is used for generating a feedback signal according to the output current of the lamp string group and sending the feedback signal to the voltage conversion module, and the feedback signal is used for indicating the voltage conversion module to adjust the third voltage; the first lamp string is connected with one end of a corresponding second secondary coil, and the second lamp string is connected with the other end of the corresponding second secondary coil and is used for emitting light based on a third voltage. The two lamp strings of the embodiment share the same power supply coil and the voltage conversion module, so that the circuit is simplified; meanwhile, stepped power supply is realized by voltage superposition, so that heat loss is reduced.
Other embodiments of the application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. This application is intended to cover any variations, uses, or adaptations of the application following, in general, the principles of the application and including such departures from the present disclosure as come within known or customary practice within the art to which the application pertains. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the application being indicated by the following claims.
It is to be understood that the application is not limited to the precise arrangements and instrumentalities shown in the drawings, which have been described above, and that various modifications and changes may be effected without departing from the scope thereof. The scope of the application is limited only by the appended claims.

Claims (10)

1. A display device, comprising: the device comprises a transformer, a voltage conversion module, a feedback module and a lamp string group; the voltage conversion modules are in one-to-one correspondence with the lamp string groups, and the lamp string groups comprise first lamp strings and second lamp strings;
a first secondary coil and a second secondary coil of the transformer coupled with a primary coil of the transformer; the first secondary coil is used for outputting a first voltage according to the power supply received by the primary coil;
The second secondary coil is used for alternately outputting a second voltage from two ends of the second secondary coil according to the power supply received by the primary coil; the second secondary coils are in one-to-one correspondence with the lamp string groups;
the voltage conversion module is used for generating a superposition voltage according to the first voltage, superposing the superposition voltage to the second voltages at two ends of the corresponding second secondary coil and outputting a superposed third voltage;
the feedback module is used for generating a feedback signal according to the output current of the lamp string group and sending the feedback signal to the voltage conversion module, and the feedback signal is used for indicating the voltage conversion module to adjust the third voltage;
the first lamp string is connected with one end of the corresponding second secondary coil, and the second lamp string is connected with the other end of the corresponding second secondary coil and is used for emitting light based on the third voltage.
2. The display device of claim 1, wherein the voltage conversion module comprises: the voltage adjusting module and the voltage superposition module are used for adjusting the voltage of the power supply;
the voltage adjusting module is connected with the output end of the first secondary coil and is used for generating superposition voltage according to the first voltage;
The voltage superposition module receives the superposition voltage and is connected with two ends of the second secondary coil, and is used for superposing the superposition voltage to the second voltages at two ends of the corresponding second secondary coil and outputting the superposed third voltage;
the feedback signal is used for indicating the voltage adjustment module to adjust the third voltage by adjusting the superposition voltage.
3. The display device of claim 2, wherein the voltage superposition module comprises a first current sharing capacitor, a first rectifying diode, a second rectifying diode, a third rectifying diode, and a fourth rectifying diode;
one end of the first current equalizing capacitor and one end of the second secondary coil; the other end of the first current equalizing capacitor is connected with the positive electrode of the first rectifying diode and the negative electrode of the second rectifying diode; the positive electrode of the second rectifying diode is connected with the superimposed voltage; the cathode of the first rectifying diode is connected with the anode of the first light string; the negative electrode of the first light string is grounded;
the positive electrode of the third rectifier diode is connected with the other end of the second secondary coil and the negative electrode of the fourth rectifier diode, and the positive electrode of the fourth rectifier diode is connected with the superimposed voltage; the cathode of the third rectifying diode is connected with the anode of the second light string; the negative pole of the second lamp string is grounded.
4. The display device of claim 2, wherein the voltage adjustment module comprises: a second transistor, a third transistor, a second inductor, and a second capacitor;
one end of the second transistor is connected with the output end of the first secondary coil; the other end of the second transistor is connected with one end of the third transistor and one end of the second inductor; the other end of the third transistor is grounded;
the other end of the second inductor is used as an output end of the voltage adjusting module to output the superposition voltage;
one end of the second capacitor is connected with the other end of the second inductor; the other end of the second capacitor is grounded;
the control electrode of the second transistor and the control electrode of the third transistor are connected with the feedback module and are used for adjusting the switching frequency of the second transistor and the switching frequency of the third transistor according to the feedback signal so as to adjust the superposition voltage.
5. The display device of claim 4, wherein the voltage adjustment module further comprises a second diode;
the cathode of the second diode is connected with one end of the second capacitor; the positive pole of the second diode is connected with the other end of the second capacitor.
6. The display device according to claim 1, further comprising a first switch circuit and a first ground resistance;
the first switch circuit is positioned between the lamp string group and the first grounding resistor;
one end of the first switch circuit is connected with the negative electrode of the first lamp string and the negative electrode of the second lamp string, and the other end of the first switch circuit is connected with one end of the first grounding resistor and the input end of the feedback module; the other end of the first grounding resistor is grounded; the first switching circuit is turned on or off based on a duty control signal.
7. The display device according to claim 1, characterized in that the display device further comprises: a second switching circuit and a second ground resistor;
the second switch circuit is positioned between the lamp string group and the second grounding resistor;
one end of the second switch circuit is connected with the negative electrode of the first lamp string and the negative electrode of the second lamp string, and the other end of the second switch circuit is connected with one end of the second grounding resistor; the other end of the second grounding resistor is grounded;
the second switch circuit is used for changing loop current and performing analog dimming.
8. The display device according to claim 7, wherein the second switching circuit includes: a fifth transistor, a comparator;
one end of the fifth transistor is connected with the negative electrode of the first lamp string and the negative electrode of the second lamp string; the other end of the fifth transistor is connected with one end of the second grounding resistor and the inverting input end of the comparator;
the non-inverting input end of the comparator inputs the required voltage of the lamp string group, and the output end of the comparator is connected with the grid electrode of the fifth transistor;
and adjusting the resistance value of the fifth transistor for changing loop current and performing analog dimming.
9. The display device according to claim 1, wherein the number of the second secondary coil, the voltage conversion module, and the light string group are all plural;
the display device also comprises a plurality of current equalizing inductors;
and the current equalizing inductors which are mutually coupled are arranged between two adjacent second secondary coils.
10. A display control method applied to the display device according to any one of claims 1 to 9, characterized in that the method comprises:
receiving a feedback signal, wherein the feedback signal is generated by the feedback module according to the output current of the light string group;
Adjusting the superimposed voltage to adjust the third voltage based on the feedback signal; the third voltage is the working voltage of the lamp string group.
CN202210412214.4A 2022-04-19 2022-04-19 Display device and display control method Pending CN116963353A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
CN202210412214.4A CN116963353A (en) 2022-04-19 2022-04-19 Display device and display control method
CN202280092484.XA CN118786757A (en) 2022-04-19 2022-09-26 Display device
PCT/CN2022/121412 WO2023201988A1 (en) 2022-04-19 2022-09-26 Display apparatus
US18/895,335 US20250016897A1 (en) 2022-04-19 2024-09-24 Display apparatus

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202210412214.4A CN116963353A (en) 2022-04-19 2022-04-19 Display device and display control method

Publications (1)

Publication Number Publication Date
CN116963353A true CN116963353A (en) 2023-10-27

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