GB2385732A - Infrared LED driver for a remote control transmitter - Google Patents

Infrared LED driver for a remote control transmitter Download PDF

Info

Publication number
GB2385732A
GB2385732A GB0301134A GB0301134A GB2385732A GB 2385732 A GB2385732 A GB 2385732A GB 0301134 A GB0301134 A GB 0301134A GB 0301134 A GB0301134 A GB 0301134A GB 2385732 A GB2385732 A GB 2385732A
Authority
GB
United Kingdom
Prior art keywords
transistor
infrared led
led driver
pulse signal
infrared
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.)
Granted
Application number
GB0301134A
Other versions
GB0301134D0 (en
GB2385732B (en
Inventor
Yasutaka Kataoka
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.)
SMK Corp
Original Assignee
SMK Corp
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 SMK Corp filed Critical SMK Corp
Publication of GB0301134D0 publication Critical patent/GB0301134D0/en
Publication of GB2385732A publication Critical patent/GB2385732A/en
Application granted granted Critical
Publication of GB2385732B publication Critical patent/GB2385732B/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • G—PHYSICS
    • G08—SIGNALLING
    • G08C—TRANSMISSION SYSTEMS FOR MEASURED VALUES, CONTROL OR SIMILAR SIGNALS
    • G08C23/00—Non-electrical signal transmission systems, e.g. optical systems
    • G08C23/04—Non-electrical signal transmission systems, e.g. optical systems using light waves, e.g. infrared
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/11—Arrangements specific to free-space transmission, i.e. transmission through air or vacuum
    • H04B10/114—Indoor or close-range type systems
    • H04B10/1141—One-way transmission
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/11—Arrangements specific to free-space transmission, i.e. transmission through air or vacuum
    • H04B10/114—Indoor or close-range type systems
    • H04B10/1143—Bidirectional transmission
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/11—Arrangements specific to free-space transmission, i.e. transmission through air or vacuum
    • H04B10/114—Indoor or close-range type systems
    • H04B10/1149—Arrangements for indoor wireless networking of information
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q9/00—Arrangements in telecontrol or telemetry systems for selectively calling a substation from a main station, in which substation desired apparatus is selected for applying a control signal thereto or for obtaining measured values therefrom

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Electromagnetism (AREA)
  • Signal Processing (AREA)
  • Computer Hardware Design (AREA)
  • Manufacturing & Machinery (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Power Engineering (AREA)
  • Computing Systems (AREA)
  • General Physics & Mathematics (AREA)
  • Led Devices (AREA)
  • Optical Communication System (AREA)
  • Selective Calling Equipment (AREA)

Abstract

The invention provides a simple and stable infrared light emitting diode (LED) drive circuit for preventing an LED from emitting a continuous intense infrared light when a fault occurs. The driver circuit comprises a voltage source 2, a first transistor 5 connected in series with an LED 4, a second transistor 7 connected in parallel with the LED and a set of operation keys 8 for generating pulse signals. During normal operation when any of the operation keys are pressed a pulse is applied to the base of the series transmitter resulting in current flowing to the LED. If the emitter and collector of the series transistor are short circuited however, the parallel transistor becomes active to prevent current flowing to the LED when operation keys are not pressed. Application is to a remote control transmitter or other communication appliance such as an electronic notebook or personal digital assistant.

Description

INFRARED LED DRIVER
FOR REMOTE CONTROL TRANSMITTER
5 The present invention relates to a driving circuit for an infrared light emitting diode used in a remote control transmitter for remotely controlling various electric appliances such as a television receiver, air conditioner and audio system.
10 Users of the remote control transmitter for the above-mentioned electric appliances press the key pads to generate a pulse signal modulated by a transmission data corresponding to the pressed keys, thereby driving an infrared light emitting diode (infrared LED).
The electric appliance receives the infrared light signal by using a 15 sensor such as a photodiode.
One of the conventional driving circuit for the infrared LED used in the remote control transmitter is shown in Figure 2.
The cathode of battery 102 is grounded at GND 101, while the battery anode is connected with resistance 103 which is connected in 20 series with the anode of the infrared LED.
Further, the cathode of the infrared LED is connected with the collector of transistor 105 of which emitter is grounded at GND 101.
The base of transistor 105 is connected with pulse signal output terminal 109, through resistance 106 if necessary.
25 Infrared LED 104 emits infrared light, in accordance with the pulse signal.
Operation key 108 is also shown in Figure 1.
However, the above-explained conventional infrared LED driver has a disadvantage that an intense infrared light is continuously
emitted by a continuous current in the infrared LED, when transistor 105 has a trouble such as a short circuit between the emitter and the collector, or when transmission pulse signal output terminal (CAAR) 109 becomes at a continuous high level due to some 5 trouble.
Further, an accidental exposure of a human eye to an intense infrared light becomes an issue of safety recently.
Accordingly, a protection circuit as shown in Figure 3 is designed in order to solve those disadvantages.
10Transistor 120 is connected in series with transistor 110 in such a manner that infrared LED 104 does not emit light, even when transistor 110 has a trouble. Further, direct current cut condensers 111, 121 as well as counter electromotive force protection diodes 112, 122 are provided in order to suppress base currents of transistor 15110,120, respectively, even when transmission pulse signal output terminal (CAAR) 109 becomes at a continuous high level due to some trouble. However, the above-explained protection circuit has a disadvantage that additional electric parts are required, the current 20 in the infrared LED is lowered by an increased collector to emitter voltage due to the additional transistor connected in series, and a waveform of the pulse signal passing through the dc cut condensers 111,112 is distorted by charge and discharge in the condensers, when the remote controller is operated.
It would be desirable to be able to provide a simple and stable infrared LED driver for preventing the LED from emitting a continuous intense infrared light, when there occurs a single trouble mode defined by only one trouble in one of active elements in the
infrared LED driver in the remote control transmitter.
The infrared LED driver of the present invention comprises: a first NPN transistor connected with the infrared LED connected in a forward direction with a voltage source power; and a second NPN 5 transistor of which collector is connected with the anode of the LED and of which emitter is connected with the cathode of the LED.
The second NPN transistor is connected in parallel with the LED.
Here, the base of the first transistor is connected with the pulse signal output terminal.
10 The second NPN transistor bypasses the current which might pass through the LED, if the first NPN transistor has a trouble.
Thus, the LED is not allowed to emit infrared light.
The first and/or second transistors may be of PNP type, so as to operate the base at low level. Further, the first and/or second 15 transistors may be a P channel or N channel MOSFET. Further, the first transistor may be a NPN transistor, while the second transistor may be P channel FET, and so on. There is no limitation of selecting transistors for first and second transistor, as far as the transistors can be turned on and off.
20 Furthermore, in the present invention, the second transistor is in active state by activating its base, for example, by raising the base of the NPN transistor at high level, when the remote controller does not transmit a pulse output signal, or the remote controller is in a standby state.
25 According to the present invention, the infrared LED is not allowed to emit infrared light by activating, during the time when the remote controller does not transmit the pulse signal, the second transistor connected in parallel with the infrared LED. Therefore, the infrared LED does not emit infrared light, even when the first
transistor has a trouble such as a short circuit.
Further, the infrared LED does not emit infrared light, at any case of single trouble mode when the first transistor has a trouble in a turnedoff mode, when the second transistor has a trouble in a 5 turned-off or short circuit mode, when the CARR terminal has a trouble in a turned-off mode, or when the infrared LED has a trouble in a turned-off or short circuit mode.
Thus, the infrared LED driver of the present invention is a simple and stable driver, due to a fewer electronic parts compared with the 10 conventional driver. Further, the infrared LED driver of the present invention does not distort the pulse waveform.
By way of example only, the invention will now be described in greater detail with reference to the accompanying drawings of 1 5 which: Figure 1 is an exemplary circuit diagram of the infrared LED driver of the present invention.
Figure 2 is a circuit diagram of one of the conventional infrared LED driver.
20 Figure 3 is a circuit diagram of one of the conventional infrared LED driver with elements for circuit protection.
Preferred embodiment of the present invention is explained, referring to Figure 1.
The cathode of power source (battery) 2 is grounded at GND 1, 25 while the anode is connected, through resistance 3, with infrared LED 4 in a forward direction.
The cathode of infrared LED 4 is connected with the collector of first transistor 5 and its emitter is grounded at GND 1.
The base of transistor 5 is connected, through resistance 6, with
pulse signal output terminal (CARR) 9 of an integrated circuit.
Infrared LED is connected in parallel with second NPN transistor 7 in such a manner that the collector of the NPN transistor 7 is connected with the anode of infrared LED 4 and the emitter of the 5 NPN transistor 7 is connected with the cathode of infrared LED 4.
Further, the base of transistor 7 is connected with terminals D0 of the IC, through an operation key 8. The transistor 7 is turned on, or in other words, the base of the NPN transistor 7 is made high (if the second transistor is of PNP in place of NPN transistor, the base 10 of the PNP transistor is made low), when the pulse signal is not outputted, or in other words, when any one of operation keys in any row not pressed.
When the emitter and collector of first transistor 5 are short-circuited due to a trouble, the battery current flows in second 15 transistor 7, thereby inhibiting infrared LED 4 from emitting infrared light, because the anode to cathode voltage becomes lower than a forward direction threshold voltage for emitting infrared light. Second transistor 7 is made active except the case when the pulse 20 signal is outputted. Therefore, the battery current bypasses transistor 7. Accordingly, infrared LED does not emit infrared light, in a troubled state wherein the pulse signal output terminal (CARR) is made normally high, resulting in a normally on state of first transistor 5.
25 On the other hand, when operation key 8 is pressed for remote control signal transmission, the base voltage of second transistor 7 is made low, thereby tuning off second transistor 7 in order to allow infrared LED to emit infrared light in accordance with the pulse signal applied to the base of first transistor 5. In this case, the anode
to cathode voltage of said infrared LED is greater than a forward direction threshold voltage for emitting infrared light, when said second transistor is turned off when any one of said set of operation keys in any row is not pressed.
5 The infrared LED driver of the present invention may be applied to any appliances relating the infrared communication wherein infrared light is emitted by a pulse signal, such as electronic pocket notebook, portable digital assistant, code-less headphone, or infrared communication between audio visual systems.

Claims (9)

1. An infrared LED driver for an infrared communication appliance which comprises: a voltage source; 5 a set of operation keys for generating a pulse signal; a pulse signal output terminal for outputting said pulse signal; an infrared LED connected with said voltage source in a forward direction; a first transistor connected in series with said infrared LED; and 10 a second transistor connected in parallel with said infrared LED, wherein: the base of said first transistor is connected with said pulse signal output terminal; and the base of said second transistor is connected with said set of 15 operation keys.
2. The infrared LED driver according to claim 1, wherein said infrared communication appliance is a remote control transmitter, electronic pocket notebook, personal digital assistance, code-less headphone, or audio visual appliance for communicating with 20 another audio visual appliance.
3. The infrared LED driver according to claim 1 or claim 2, wherein said second transistor is turned on, when said pulse signal output terminal does not output any pulse signal, while said second transistor is turned off, when said pulse signal output terminal 25 outputs a pulse signal.
4. The infrared LED driver according to any one of claims 1 to 3, wherein said first transistor is a PNP or NPN transistor, while said second transistor is a PNP or NPN transistor.
5. The infrared LED driver according to any one of claims 1 to 4,
wherein said first transistor is a P channel or N channel MOSFET, while said second transistor is a P channel or N channel MOSFET.
6. The infrared LED driver according to any one of claims 1 to 3, wherein either of said first or said second transistor is a NPN or 5 PNP transistor, while the other of said first or said second transistor is a P channel or N channel MOSFET.
7. The infrared LED driver according to claim 3, wherein the anode to cathode voltage of said infrared LED is lower than a forward direction threshold voltage for emitting infrared light, when 10 said second transistor is turned on when any one of said set of operation keys in any row is not pressed.
8. The infrared LED driver according to claim 3, wherein the anode to cathode voltage of said infrared LED is greater than a forward direction threshold voltage for emitting infrared light, when 15 said second transistor is turned off when any one of said set of operation keys in any row is not pressed.
9. An infrared LED driver for an infrared communication appliance substantially as described with reference to and as illustrated by Fig. 1 of the accompanying drawings.
GB0301134A 2002-02-20 2003-01-17 Infrared led driver for remote control transmitter Expired - Fee Related GB2385732B (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2002043735A JP3639818B2 (en) 2002-02-20 2002-02-20 Infrared light emitting diode drive circuit for remote control transmitter

Publications (3)

Publication Number Publication Date
GB0301134D0 GB0301134D0 (en) 2003-02-19
GB2385732A true GB2385732A (en) 2003-08-27
GB2385732B GB2385732B (en) 2005-07-20

Family

ID=19192756

Family Applications (1)

Application Number Title Priority Date Filing Date
GB0301134A Expired - Fee Related GB2385732B (en) 2002-02-20 2003-01-17 Infrared led driver for remote control transmitter

Country Status (3)

Country Link
JP (1) JP3639818B2 (en)
DE (1) DE10303450B4 (en)
GB (1) GB2385732B (en)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4720100B2 (en) * 2004-04-20 2011-07-13 ソニー株式会社 LED driving device, backlight light source device, and color liquid crystal display device
JP4720099B2 (en) * 2004-04-20 2011-07-13 ソニー株式会社 Constant current drive device, backlight light source device, and color liquid crystal display device
CN110442272A (en) * 2019-07-08 2019-11-12 广州华欣电子科技有限公司 A kind of driving circuit of infrared signal, processing circuit and infrared touch panel
CN117334036B (en) * 2023-12-01 2024-09-24 荣耀终端有限公司 Infrared remote control method and terminal equipment

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH02128533A (en) * 1988-11-09 1990-05-16 Toshiba Corp Optical transmission circuit
JPH02305296A (en) * 1989-05-19 1990-12-18 Sanyo Electric Co Ltd Remote control transmission equipment
JPH0334477A (en) * 1989-06-30 1991-02-14 Sony Corp Light-emitting diode drive circuit
US5140175A (en) * 1989-06-24 1992-08-18 Mitsubishi Rayon Co., Ltd. Light-emitting diode drive circuit with fast rise time and fall time
US5742133A (en) * 1995-09-07 1998-04-21 Siemens Aktiengesellschaft Driver circuit for an led
JPH118588A (en) * 1997-06-16 1999-01-12 Furukawa Electric Co Ltd:The Optical transmitter

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5616901A (en) * 1995-12-19 1997-04-01 Talking Signs, Inc. Accessible automatic teller machines for sight-impaired persons and print-disabled persons

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH02128533A (en) * 1988-11-09 1990-05-16 Toshiba Corp Optical transmission circuit
JPH02305296A (en) * 1989-05-19 1990-12-18 Sanyo Electric Co Ltd Remote control transmission equipment
US5140175A (en) * 1989-06-24 1992-08-18 Mitsubishi Rayon Co., Ltd. Light-emitting diode drive circuit with fast rise time and fall time
JPH0334477A (en) * 1989-06-30 1991-02-14 Sony Corp Light-emitting diode drive circuit
US5742133A (en) * 1995-09-07 1998-04-21 Siemens Aktiengesellschaft Driver circuit for an led
JPH118588A (en) * 1997-06-16 1999-01-12 Furukawa Electric Co Ltd:The Optical transmitter

Also Published As

Publication number Publication date
DE10303450B4 (en) 2007-07-19
DE10303450A1 (en) 2003-08-21
JP2003243711A (en) 2003-08-29
GB0301134D0 (en) 2003-02-19
GB2385732B (en) 2005-07-20
JP3639818B2 (en) 2005-04-20

Similar Documents

Publication Publication Date Title
US6330091B1 (en) IR receiver using IR transmitting diode
KR970002763B1 (en) Remote control system
US6388468B1 (en) Circuit and method for operating a MOSFET control circuit with a system operating voltage greater than a maximum supply voltage limit
CA2311435C (en) Capacitor regulated high efficiency driver for light emitting diode
JPS5816818B2 (en) Infrared remote control transmitter
US6944483B1 (en) Portable radio terminal with infrared communication function and communication method for portable radio terminal
US4264896A (en) Regulator arrangement useful in an infrared remote control transmitter
US7126308B2 (en) Interface circuit with power converter with interface circuit and electric vehicle with power converter
GB2385732A (en) Infrared LED driver for a remote control transmitter
US20060033548A1 (en) Circuit for translating voltage signal levels
EP0469244A2 (en) Light emitting element drive circuit
CN110798325A (en) Power supply circuit capable of automatically adjusting power supply voltage
KR100934002B1 (en) Output Enhancement Circuit and Remote Controller Using the Same
JP2001325824A (en) Led drive circuit for backlight at portable terminal
US6931209B2 (en) Remote commander
JP4098214B2 (en) Infrared transmitter circuit and electronic device
CN210518926U (en) Drive circuit for optical communication
CN212163777U (en) Chip pin multiplexing circuit
US6812740B2 (en) Low-voltage drive circuit and method for the same
AU2008315207B2 (en) Infrared transmitter
US7095055B2 (en) Optical transmitter module
US20240204773A1 (en) Current driver
JP3488088B2 (en) Light emitting diode drive circuit
CN217470193U (en) Air purifier audio amplifier amount of wind volume allotment circuit
JP2003124564A (en) Drive controller of semiconductor laser

Legal Events

Date Code Title Description
PCNP Patent ceased through non-payment of renewal fee

Effective date: 20080117