WO2013175862A1

WO2013175862A1 - Led drive apparatus, television receiver, and lighting apparatus

Info

Publication number: WO2013175862A1
Application number: PCT/JP2013/059294
Authority: WO
Inventors: 占部　大三
Original assignee: シャープ株式会社
Priority date: 2012-05-25
Filing date: 2013-03-28
Publication date: 2013-11-28

Abstract

An LED drive apparatus (1) that is provided with a current mirror circuit (120) commonly connected to each of a plurality of LED rows (L1-Ln) is also provided with: an MIN circuit (130), which outputs the smallest voltage among the voltages applied to respective current control resistors (R1-Rn); and an LED drive control circuit (140), which controls the LED rows (L1-Ln) corresponding to output of the MIN circuit (130).

Description

LED driving device, television receiver and lighting device

The present invention relates to an LED driving device for driving an LED.

In recent years, light-emitting elements such as LEDs (light-emitting diodes) have been used as surface light sources such as backlights for liquid crystal displays. An LED drive circuit device for driving an illumination device (LED illumination device) using an LED as a surface light source is generally a circuit device having a so-called current mirror circuit for causing a constant current to flow in an LED array arranged in a plane. known.

The current mirror circuit includes a plurality of transistors connected in series to a plurality of LED rows. The plurality of transistors include a reference column transistor in which the collector base is short-circuited and a plurality of transistors in other columns. In the transistors in the other columns, the bases of the transistors in the other columns and the bases of the reference column transistors are connected in common.

Each LED row may be open due to a broken line or a broken LED. Therefore, Patent Document 1 discloses a technique in which, when a reference row has an open failure, a normal LED row is used as the reference row so that the LEDs are not turned off.

Japanese Patent Publication “Patent No. 4669382 (issued on April 13, 2011)”

However, the conventional technology as described above has a problem that it cannot detect when the other LED rows are in an open state, only detecting the open state of the reference row. This will be described with reference to FIG.

FIG. 5 is a diagram showing an example of a conventional LED driving device. As shown in FIG. 5, the LED drive device 5 includes an LED circuit 51, a current mirror circuit 52, an LED drive control circuit 53, and a booster circuit 54.

The LED circuit 51 emits light by the output voltage supplied from the booster circuit 54. As shown in FIG. 5, the LED circuit 51 includes LED rows L1 to Ln (n is a natural number) in which a plurality of LEDs are connected in series. In each of the LED strings L1 to Ln, one of the end LEDs (the other LED is not connected to the anode terminal) is connected to the booster circuit 54, and the other end LED (the other LED is connected to the cathode terminal). The one not connected) is connected to the collector terminals of the transistors T1 to Tn included in the current mirror circuit 52.

The current mirror circuit 52 includes transistors T1 to Tn (n is a natural number). The collector terminals of the transistors T1 to Tn are respectively connected to the cathode terminals of the LEDs at the ends of the LED rows L1 to Ln of the LED circuit 51 (LEDs to which no other LED is connected to the cathode terminal). The emitter terminals of the transistors T1 to Tn are grounded via current control resistors R1 to Rn, respectively. The current control resistors R1 to Rn have the same resistance value.

Here, the transistor T1 is a reference column transistor (referred to as a reference column transistor) in which the collector base is short-circuited, and the base terminal of the transistor T1 is commonly connected to the base terminals of the transistors T2 to Tn.

The LED drive control circuit 53 detects the voltage applied to the current control resistor R1 connected to the reference column transistor T1. That is, the LED drive control circuit 53 can detect the voltage between the current control resistor R1 and GND. The LED drive control circuit 53 feeds back the detected voltage (detected voltage result) to the booster circuit 54 so as to maintain the voltage corresponding to the current (LED current) flowing through the set LED reference column.

The booster circuit 54 is connected to one of the LEDs at the end of the LED rows L1 to Ln of the LED circuit 51 (the other LED is not connected to the anode terminal). The booster circuit 54 boosts the input voltage based on the detection voltage result fed back from the LED drive control circuit 53, and outputs a voltage (output voltage) relating to each anode terminal connected to the booster circuit 54. Thereby, the LED current can be controlled.

As is clear from FIG. 5, the conventional LED driving device is configured to detect only the voltage applied to the current control resistor R1 connected to the downstream side of the LED row of the reference row, and therefore, the open state of the LED reference row is determined. Although it can be detected, the open state of other LED strings cannot be detected.

In the technique of Cited Document 1, when the reference row is in the open state, the normal LED row is set as the reference row, but the reference row is not in the open state and other LED rows are open. The open LED string cannot be detected.

Furthermore, the technique of the cited document 1 has a configuration in which a current switching circuit is provided for each of all the LED strings that can serve as a reference string, so that the circuit scale becomes large.

The present invention has been made in view of the above problems, and an object thereof is to realize an LED driving device capable of detecting the open state of LED rows other than the reference row.

In order to solve the above problems, an LED driving device of the present invention is an LED driving device including a current mirror circuit commonly connected to each of a plurality of LED rows, and is downstream of each of the plurality of LED rows. A detection circuit that outputs a minimum voltage among the voltages applied to the resistors arranged on the side, and a control unit that controls driving of the plurality of LED rows according to the output of the detection circuit. It is a feature.

The LED driving device of the present invention is an LED driving device including a current mirror circuit commonly connected to each of the plurality of LED rows, and a voltage applied to a resistor disposed on the downstream side of each of the plurality of LED rows. And a control means for controlling the plurality of LED rows in accordance with the output of the detection circuit.

Therefore, even if LED rows other than the LED row of the reference row are in the open state, the LED driving device has an effect that the open state can be detected.

1 is a circuit diagram illustrating an example of an LED drive device according to Embodiment 1. FIG. FIG. 5 is a circuit diagram illustrating an example of an LED drive device according to a second embodiment. 6 is a circuit diagram illustrating an example of an LED drive device according to Embodiment 3. FIG. FIG. 6 is a circuit diagram illustrating an example of an LED drive device according to a fourth embodiment. It is the circuit diagram which showed an example of the conventional LED drive device.

<Embodiment 1>
The LED drive device according to this embodiment will be described with reference to FIG. FIG. 1 is a circuit diagram illustrating an example of an LED driving device according to the present embodiment.

(LED drive device 1)
As shown in FIG. 1, the LED drive device 1 includes an LED circuit 110, a current mirror circuit 120, a MIN circuit (detection circuit) 130, an LED drive control circuit (control means, open detection means, first current control means) 140, TV A drive control circuit (control means) 150, a booster circuit 160, and current control resistors R1 to Rn (n is a natural number) are provided.

The LED circuit 110 emits light by an output voltage supplied from a booster circuit 160 described later. As shown in FIG. 1, the LED circuit 110 includes LED rows L1 to Ln (n is a natural number) in which a plurality of LEDs are connected in series. In this specification, the LED row is also called a channel (CH).

In each of the LED rows L1 to Ln, one of the end LEDs (the other LED not connected to the anode terminal) is connected to the booster circuit 160, and the other end LED (the other LED is connected to the cathode terminal). The one not connected) is connected to the collector terminals of the transistors T1 to Tn included in the current mirror circuit 120.

The current mirror circuit 120 includes transistors T1 to Tn (n is a natural number). The collector terminals of the transistors T1 to Tn are connected to the cathode terminals of the LEDs at the ends of the LED rows L1 to Ln of the LED circuit 110 (LEDs to which no other LED is connected to the cathode terminal), respectively. The emitter terminals of the transistors T1 to Tn are connected to the MIN circuit 130 and grounded via the current control resistors R1 to Rn. The current control resistors R1 to Rn have the same resistance value.

Here, the transistor T1 is a reference column transistor (referred to as a reference column transistor) in which the collector base is short-circuited, and the base terminal of the transistor T1 is commonly connected to the base terminals of the transistors T2 to Tn. Therefore, the base voltages and base currents of the transistors T1 to Tn are equal, and the collector currents are equal. Therefore, the LED current having the same value as the LED current flowing in the LED string L1 (referred to as the LED reference string) connected to the reference string transistor T1 flows in the LED strings other than the LED reference string (LED strings L2 to Ln). Therefore, the LED rows L1 to Ln can be illuminated uniformly.

The MIN circuit 130 is connected to a potential point between the emitter terminals of the transistors T1 to Tn of the current mirror circuit 120 and the current control resistors R1 to Rn connected to the emitter terminals, and the MIN circuit 130 is connected to the LED strings L1 to Ln. The minimum voltage among the voltages applied to the resistors arranged on the respective downstream sides is output. That is, the MIN circuit 130 detects the voltage applied to each of the current control resistors R1 to Rn. Then, the MIN circuit 130 outputs the minimum voltage (minimum voltage) among the detected voltages to the LED open detection terminal of the LED drive control circuit 140.

The LED drive control circuit 140 has an LED open detection terminal and an LED current control terminal. A voltage applied to the current control resistor R1 connected to the reference column transistor T1 is supplied to the LED open detection terminal of the LED drive control circuit 140. Therefore, the LED drive control circuit 140 can detect the voltage between the current control resistor R1 and GND. The LED drive control circuit 140 detects a voltage reflecting the current (LED current) flowing through the LED reference column, and maintains the voltage corresponding to the current (LED current) flowing through the set LED reference column. The detected voltage (detected voltage result) is fed back to the booster circuit 160.

Further, the LED drive control circuit 140 checks whether or not the minimum voltage supplied from the MIN circuit 130 to the LED open detection terminal is lower than a predetermined voltage (detection voltage). When the minimum voltage falls below a predetermined voltage (for example, about 0.1 V), the LED drive control circuit 140 is in the open state of the LED string to which the minimum voltage is applied among the LED strings L1 to Ln (LED Open). That is, the LED drive control circuit 140 detects that the LED rows L1 to Ln include an open LED row. Note that the value of the detection voltage is not limited to this, and can be set according to the detection capability of the LED drive control circuit 140. When the LED drive control circuit 140 detects the LED open, the LED drive control circuit 140 feeds back an error signal to the TV drive control circuit 150.

When receiving an error signal from the LED drive control circuit 140, the TV drive control circuit 150 (1) feeds back the drive stop signal to the LED drive control circuit 140 and / or (2) feeds back the boost STOP to the boost circuit 160. To do. When the LED drive control circuit 140 receives the drive stop signal, the LED drive control circuit 140 stops driving the LED circuit 110.

The booster circuit 160 is connected to one of the LEDs at the end of the LED rows L1 to Ln of the LED circuit 110 (the other LED is not connected to the anode terminal). The booster circuit 160 boosts the input voltage based on the detection voltage result fed back from the LED drive control circuit 140, and outputs a voltage (output voltage) relating to each anode terminal connected to the booster circuit 160. Thereby, the LED current can be controlled.

Further, when the booster circuit 160 receives the boost STOP from the TV drive control circuit 150, the booster circuit 160 stops boosting the input voltage.

As described above, the LED drive device 1 according to the present embodiment is the smallest of the voltages applied to the current mirror circuit 120 commonly connected to each of the plurality of LED rows L1 to Ln and each of the current control resistors R1 to Rn. A MIN circuit 130 for outputting the voltage of the LED, and an LED drive control circuit 140 for controlling the plurality of LED rows L1 to Ln according to the output of the MIN circuit 130.

In the case of an LED driving device that detects only the voltage applied to the resistor connected to the downstream side of the reference row, only the open state of the reference row is detected, and the LED row in the open state is included in the other LED rows. I can't detect that. Therefore, such an LED drive device drives the plurality of LED rows even though the LED rows in an open state are included in the plurality of LED rows.

However, according to the above configuration, the MIN circuit 130 outputs the smallest voltage among the voltages applied to the current control resistors R1 to Rn arranged downstream of each of the plurality of LED strings L1 to Ln. Then, the LED drive control circuit 140 detects the open state of each of the plurality of LED arrays L1 to Ln based on the voltage value output from the MIN circuit 130. For example, the drive state of the LED circuit 110 and the plurality of LED arrays The plurality of LED strings L1 to Ln are controlled by controlling the voltage applied to the LED array.

Therefore, the LED drive device 1 can detect the open state even if the LED rows other than the LED row of the reference row are open.

<Embodiment 2>
In the first embodiment, the LED drive control circuit 140 controls the LED current by detecting the voltage of the reference column. However, the voltage detected to control the LED current may be a voltage other than the reference column. . In the present embodiment, an LED drive device that controls LED current from voltages applied to all LED rows will be described.

The LED driving device according to this embodiment will be described with reference to FIG. FIG. 2 is a circuit diagram illustrating an example of the LED driving device according to the present embodiment. For convenience of explanation, members having the same functions as those in the drawings described in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

(LED drive device 2)
As shown in FIG. 2, the LED drive device 2 includes an LED circuit 110, a current mirror circuit 120, a MIN circuit (detection circuit) 230, an LED drive control circuit (control means, open detection means, second current control means) 240, TV A drive control circuit (control means) 150, a booster circuit 160, and current control resistors R1 to Rn (n is a natural number) are provided.

The MIN circuit 230 is connected to a potential point between the emitter terminals of the transistors T1 to Tn of the current mirror circuit 120 and the current control resistors R1 to Rn connected to the emitter terminals, and the current control resistors R1 to Rn. The voltage applied to each of these is detected. Then, the MIN circuit 230 outputs the minimum voltage (minimum voltage) among the detected voltages to the LED open detection terminal of the LED drive control circuit 240.

Also, the MIN circuit 230 detects the total forward voltage (Total Vf) of each LED row. The total forward voltage of the LED strings is the sum of the forward voltages Vf between the anodes and the cathodes of the plurality of LEDs in each LED string. The MIN circuit 230 detects the maximum total forward voltage (maximum voltage) among the detected total forward voltages. Specifically, when the anode voltages of the plurality of LEDs in each LED row are common, the MIN circuit 230 detects the minimum cathode voltage from the cathode voltage = the anode voltage−the total forward voltage of each LED row. . Thereafter, the MIN circuit 230 outputs the minimum cathode voltage (minimum cathode voltage) to the LED current control terminal of the LED drive control circuit 240.

The LED drive control circuit 240 has an LED open detection terminal and an LED current control terminal. The LED drive control circuit 240 detects the minimum value of the current (LED current) flowing through each LED array from the minimum cathode voltage supplied from the MIN circuit 230 to the LED current control terminal, and outputs a detection voltage result based on the LED current. Feedback is provided to the booster circuit 160.

Further, the LED drive control circuit 240 confirms whether or not the minimum voltage supplied from the MIN circuit 230 to the LED open detection terminal is lower than a predetermined voltage (detection voltage). When the minimum voltage falls below a predetermined voltage (for example, about 0.1 V), the LED drive control circuit 240 determines that one of the LED strings L1 to Ln is open (LED open). To do. Note that the value of the detection voltage is not limited to this, and can be set according to the detection capability of the LED drive control circuit 240. When the LED drive control circuit 240 detects the LED open, the LED drive control circuit 240 feeds back an error signal to the TV drive control circuit 150.

As described above, by detecting the maximum total forward voltage, the LED voltage can be adjusted to the LED row having the maximum total forward voltage among the LED rows. Therefore, it is possible to avoid the LED power shortage of the LED row having the total forward voltage larger than that of the LED reference row.

<Embodiment 3>
In the above-described first embodiment, the configuration in which the TV drive control circuit 150 feeds back the boost STOP to the booster circuit 160 has been described, but the present invention is not limited to this. In the present embodiment, a configuration in which the LED drive control circuit feeds back the boost STOP to the booster circuit will be described.

The LED driving device according to this embodiment will be described with reference to FIG. FIG. 3 is a circuit diagram illustrating an example of the LED driving device according to the present embodiment. For convenience of explanation, members having the same functions as those in the drawings described in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

(LED drive device 3)
As shown in FIG. 3, the LED drive device 3 includes an LED circuit 110, a current mirror circuit 120, a MIN circuit (detection circuit) 130, an LED drive control circuit (control means, open detection means, first current control means) 340, TV A drive control circuit (control means) 350, a booster circuit 360, and current control resistors R1 to Rn (n is a natural number) are provided.

The LED drive control circuit 340 has an LED open detection terminal and an LED current control terminal. A voltage applied to the current control resistor R1 connected to the reference column transistor T1 is supplied to the LED open detection terminal of the LED drive control circuit 340. Therefore, the LED drive control circuit 340 can detect the voltage between the current control resistor R1 and GND. The LED drive control circuit 340 detects a current (LED current) flowing through the LED reference string from the detected voltage, and feeds back a detection voltage result based on the LED current to the booster circuit 360.

Further, the LED drive control circuit 340 confirms whether or not the minimum voltage supplied from the MIN circuit 130 to the LED open detection terminal is lower than a predetermined voltage (detection voltage). When the minimum voltage falls below a predetermined voltage (for example, about 0.1 V), the LED drive control circuit 340 determines that one of the LED strings L1 to Ln is open (LED open). To do. Note that the value of the detection voltage is not limited to this, and can be set according to the detection capability of the LED drive control circuit 340. When the LED drive control circuit 340 detects LED open, the LED drive control circuit 340 feeds back an error signal to the TV drive control circuit 350.

Further, when the LED drive control circuit 340 detects the LED open, the LED drive control circuit 340 feeds back the boost STOP to the boost circuit 360.

When receiving an error signal from the LED drive control circuit 340, the TV drive control circuit 350 feeds back a drive stop signal to the LED drive control circuit 340. When the LED drive control circuit 340 receives the drive stop signal, the LED drive control circuit 340 stops driving the LED circuit 110.

The booster circuit 360 is connected to one of the LEDs at the end of the LED rows L1 to Ln of the LED circuit 110 (the other LED is not connected to the anode terminal). The booster circuit 360 boosts the input voltage using the LED current supplied from the LED drive control circuit 340 and outputs a voltage (output voltage) relating to each anode terminal connected to the LED drive control circuit 340. Thereby, the LED current can be controlled. Further, when the booster circuit 360 receives the boost STOP from the LED drive control circuit 340, the booster circuit 360 stops boosting the input voltage.

Thus, the LED drive device 3 may have a configuration in which the LED drive control circuit 340 feeds back the boost STOP to the boost circuit 360.

<Embodiment 4>
The configuration in which the LED drive control circuit feeds back the boost STOP to the booster circuit is also applicable to an LED drive device that controls the LED current from the voltages applied to all the LED strings.

The LED driving device according to the present embodiment will be described with reference to FIG. FIG. 4 is a circuit diagram illustrating an example of the LED driving device according to the present embodiment. For convenience of explanation, members having the same functions as those in the drawings described in the embodiment are given the same reference numerals, and descriptions thereof are omitted.

(LED drive device 4)
As shown in FIG. 4, the LED drive device 4 includes an LED circuit 110, a current mirror circuit 120, a MIN circuit (detection circuit) 230, an LED drive control circuit (control means, open detection means, second current control means) 440, TV A drive control circuit (control means) 350, a booster circuit 360, and current control resistors R1 to Rn (n is a natural number) are provided.

The LED drive control circuit 440 has an LED open detection terminal and an LED current control terminal. The LED drive control circuit 440 detects the minimum value of the current (LED current) flowing through each LED row from the minimum cathode voltage supplied from the MIN circuit 230 to the LED current control terminal, and outputs a detection voltage result based on the LED current. Feedback is provided to the booster circuit 360.

Further, the LED drive control circuit 440 checks whether or not the minimum voltage supplied from the MIN circuit 230 to the LED open detection terminal is lower than a predetermined voltage (detection voltage). When the minimum voltage falls below a predetermined voltage (for example, about 0.1 V), the LED drive control circuit 440 determines that one of the LED strings L1 to Ln is open (LED open). To do. Note that the value of the detection voltage is not limited to this, and can be set according to the detection capability of the LED drive control circuit 440. When the LED drive control circuit 440 detects an LED open, the LED drive control circuit 440 feeds back an error signal to the TV drive control circuit 350.

Further, when the LED drive control circuit 440 detects the LED open, it feeds back the boost STOP to the boost circuit 360.

As described above, the LED drive device 4 may have a function in which the MIN circuit 230 detects the maximum total forward voltage, and the LED drive control circuit 440 may feed back the boost STOP to the boost circuit 360.

<Application example>
The LED drive device of each embodiment mentioned above can be used suitably as a drive device which drives the LED backlight of display apparatuses, such as a television receiver, for example. It can also be used as a drive circuit for a lighting device. Such a display device and a lighting device are also included in the scope of the invention described in this specification.

(Example of software implementation)
Finally, the LED

drive control circuits

140, 240, 340 and 440 in the LED drive devices 1 to 4 can be replaced by software control means using a CPU (Central Processing Unit).

In this case, the LED driving devices 1 to 4 include a CPU that executes instructions of a program that realizes each function, a ROM (Read Memory) that stores the program, a RAM (Random Access Memory) that expands the program, and the program And a storage device (recording medium) such as a memory for storing various data. The object of the present invention is a record in which the program code (execution format program, intermediate code program, source program) of the control program of the LED driving devices 1 to 4 which is software for realizing the above-described functions is recorded so as to be readable by a computer This can also be achieved by supplying the medium to the LED driving devices 1 to 4 and reading and executing the program code recorded on the recording medium by the computer (or CPU or MPU).

Examples of the recording medium include tapes such as magnetic tapes and cassette tapes, magnetic disks such as floppy (registered trademark) disks / hard disks, and disks including optical disks such as CD-ROM / MO / MD / DVD / CD-R. IC cards (including memory cards) / optical cards, semiconductor memories such as mask ROM / EPROM / EEPROM (registered trademark) / flash ROM, or PLD (Programmable logic device) and FPGA (Field Programmable Gate Logic circuits such as (Array) can be used.

Alternatively, the LED driving devices 1 to 4 may be configured to be connectable to a communication network, and the program code may be supplied via the communication network. The communication network is not particularly limited as long as it can transmit the program code. For example, the Internet, intranet, extranet, LAN, ISDN, VAN, CATV communication network, virtual private network (Virtual Private Network), telephone line network, mobile communication network, satellite communication network, etc. can be used. The transmission medium constituting the communication network may be any medium that can transmit the program code, and is not limited to a specific configuration or type. For example, even with wired lines such as IEEE 1394, USB, power line carrier, cable TV line, telephone line, ADSL (Asymmetric Digital Subscriber Line) line, infrared rays such as IrDA and remote control, Bluetooth (registered trademark), IEEE 802.11 wireless, HDR ( It can also be used by wireless such as High Data Rate, NFC (Near Field Communication), DLNA (Digital Living Network Alliance), mobile phone network, satellite line, terrestrial digital network. The present invention can also be realized in the form of a computer data signal embedded in a carrier wave in which the program code is embodied by electronic transmission.

The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

(Summary)
As described above, the LED driving device according to the present embodiment is an LED driving device including a current mirror circuit commonly connected to each of the plurality of LED rows, and is provided downstream of each of the plurality of LED rows. A detection circuit that outputs a minimum voltage among the voltages applied to the arranged resistors, and a control unit that controls driving of the plurality of LED rows in accordance with the output of the detection circuit are provided. Yes.

In the case of an LED driving device that detects only the voltage applied to the resistor connected to the downstream side of the reference row, only the open state of the reference row is detected, and the LED row in the open state is included in the other LED rows. I can't detect that. For this reason, the LED drive device drives the plurality of LED rows even though the LED rows in the open state are included in the plurality of LED rows.

However, according to the above configuration, the detection circuit outputs the smallest voltage among the voltages applied to the control resistors arranged on the downstream side of each of the plurality of LED rows. And a control means can detect that the LED row | line | column which is in an open state is contained in several LED row | line | column by the value of the voltage which the said detection circuit output.

Therefore, the LED driving device according to the present embodiment can detect the open state even if the LED rows other than the LED row of the reference row are open. Therefore, the control means can control, for example, the driving state of the plurality of LED strings, the voltage applied to the plurality of LED strings, and the like according to the value of the voltage.

The LED driving device further includes an open detection unit configured to detect that the plurality of LED rows include an open LED row when a voltage output from the detection circuit is lower than a predetermined voltage. Preferably, the control means controls the plurality of LED strings depending on whether or not the open detection means detects that an open LED string is included.

According to the above configuration, the open detection means detects that the plurality of LED strings include open LED strings when the voltage output from the detection circuit falls below a predetermined voltage. And if a control means detects that the LED row | line | column of an open state is contained, it can control the drive state of several LED row | line | column, the voltage concerning several LED row | line | column, etc., for example. Therefore, the LED driving device according to the present embodiment has an effect that the open state can be detected more appropriately even if the LED rows other than the LED row of the reference row are in the open state.

Further, in the LED drive device, the control unit supplies current to the plurality of LED rows in accordance with a voltage applied to a resistor arranged on the downstream side of the LED row of the reference row among the plurality of LED rows. It is preferable to provide first current control means for controlling the current.

According to the above configuration, the current flowing through the LED rows in the reference row can be made to flow through the LED rows other than the reference row, so that the current flowing through all the LED rows can be suitably controlled. .

Further, in the LED driving device, the detection circuit further has a function of outputting a maximum voltage among voltages applied to each of the plurality of LED arrays, and the control unit is configured to output the detection circuit. It is preferable to include a second current control unit that controls a current supplied to the plurality of LED strings in accordance with the maximum voltage.

According to the above configuration, by outputting the maximum voltage among the voltages applied to each of the plurality of LED arrays, it is possible to match the voltage to the LED array having the maximum voltage among the LED arrays. Therefore, it is possible to avoid the shortage of power in the LED row having such a higher voltage than the LED row in the reference row.

Further, in the LED driving device, it is preferable that the control means controls whether or not to stop the current supply to the plurality of LED rows in accordance with the output of the detection circuit.

According to the above configuration, the driving of the plurality of LED rows can be suitably controlled according to the output of the detection circuit.

Note that a television receiver and an illumination device including the LED driving device are also included in the scope of the present invention.

The LED drive device of the present invention can be suitably used for a light source of a lighting fixture, a backlight of a display such as a television receiver, and a mobile phone.

DESCRIPTION OF SYMBOLS 1 LED drive device 110 LED circuit 120 Current mirror circuit 130 MIN circuit (detection circuit)
140 LED drive control circuit (control means, open detection means, first current control means)
150 TV drive control circuit (control means)
160 Booster circuit 2 LED drive device 230 MIN circuit (detection circuit)
240 LED drive control circuit (control means, open detection means, second current control means)
3 LED drive device 340 LED drive control circuit (control means, open detection means, first current control means)
350 TV drive control circuit (control means)
360 Booster circuit 4 LED drive device 440 LED drive control circuit (control means, open detection means, second current control means)
L1 to Ln LED string T1 to Tn Transistors R1 to Rn Current control resistor

Claims

An LED driving device including a current mirror circuit commonly connected to each of a plurality of LED rows,
A detection circuit that outputs a minimum voltage among the voltages applied to the resistors arranged on the downstream side of each of the plurality of LED rows;
Control means for controlling the driving of the plurality of LED rows in accordance with the output of the detection circuit;
An LED driving device comprising:
When the voltage output from the detection circuit falls below a predetermined voltage, it further comprises an open detection means for detecting that the plurality of LED strings include an open LED string,
2. The LED according to claim 1, wherein the control unit controls the plurality of LED rows according to whether or not the open detection unit detects that an open LED row is included. 3. Drive device.
The control means is a first current control means for controlling a current to be supplied to the plurality of LED rows in accordance with a voltage applied to a resistor arranged downstream of the LED row of the reference row among the plurality of LED rows. The LED driving device according to claim 1, further comprising:
The detection circuit further has a function of outputting the maximum voltage among the voltages applied to each of the plurality of LED strings,
The said control means is equipped with the 2nd current control means which controls the electric current supplied to these LED row | line | column according to the said maximum voltage which the said detection circuit output, The 1st or 2 characterized by the above-mentioned. LED drive device.
5. The control unit according to claim 1, wherein the control unit controls whether or not to stop the current supply to the plurality of LED arrays in accordance with an output of the detection circuit. 6. LED drive device.
A plurality of LEDs;
The LED driving device according to any one of claims 1 to 5,
A television receiver comprising:
A plurality of LEDs;
The LED driving device according to any one of claims 1 to 5,
A lighting device comprising: