CA2195442A1 - Servo-amplifier for controlling a high-ohmic low-voltage source - Google Patents
Servo-amplifier for controlling a high-ohmic low-voltage sourceInfo
- Publication number
- CA2195442A1 CA2195442A1 CA002195442A CA2195442A CA2195442A1 CA 2195442 A1 CA2195442 A1 CA 2195442A1 CA 002195442 A CA002195442 A CA 002195442A CA 2195442 A CA2195442 A CA 2195442A CA 2195442 A1 CA2195442 A1 CA 2195442A1
- Authority
- CA
- Canada
- Prior art keywords
- voltage
- fet
- amplifier
- circuit
- control amplifier
- 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.)
- Abandoned
Links
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
- H03K17/08—Modifications for protecting switching circuit against overcurrent or overvoltage
- H03K17/082—Modifications for protecting switching circuit against overcurrent or overvoltage by feedback from the output to the control circuit
- H03K17/0822—Modifications for protecting switching circuit against overcurrent or overvoltage by feedback from the output to the control circuit in field-effect transistor switches
-
- 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
- H05B41/00—Circuit arrangements or apparatus for igniting or operating discharge lamps
- H05B41/14—Circuit arrangements
- H05B41/36—Controlling
- H05B41/38—Controlling the intensity of light
- H05B41/39—Controlling the intensity of light continuously
- H05B41/392—Controlling the intensity of light continuously using semiconductor devices, e.g. thyristor
- H05B41/3921—Controlling the intensity of light continuously using semiconductor devices, e.g. thyristor with possibility of light intensity variations
- H05B41/3927—Controlling the intensity of light continuously using semiconductor devices, e.g. thyristor with possibility of light intensity variations by pulse width modulation
Landscapes
- Amplifiers (AREA)
- Networks Using Active Elements (AREA)
- Optical Head (AREA)
Abstract
A servo-amplifier for controlling a high-ohmic low-voltage source controllable between two boundary values of a pulse-width-modulated control signal, in which the input side has a galvanic separation and there is an operating voltage supply for the servo-amplifier. In an isolating transformer (1) for galvanic isolation, a circuit (with the components 4, 5, 6, 7) for finding the average of the pulse-width-modulated control signal for imaging the control signal is connected to a secondary winding (3) and the latter is also involved in a voltage multiplication circuit (17) to provide the operating voltage for the servo-amplifier. The servo-amplifier can in particular be protected against incorrect connection.
Description
2 i ~ 2 PCT/DE 95/00901 ,-LLE,P~*~ Tl;:8 A~
T~T TRAI'~SL~.~ION
Description Control amplifier for controlling a high-impedence low-voltage source The invention relates to a control amplifier for controlling a low-voltage source having internal imped-ence, which low-voltage source is connected to two output t~rm~n-l~ and can be controlled between two limit values by means of ; ~ - oh -~g; ng, in detail as claimed in the precharacterizing clause of patent claim 1.
The input side has DC isolation by means of an isolating transformer, and an operating voltage supply for the control _l;fion is provided on the sec~n~ry side.
There are a very wide range of different fields of application for control amplifiers for controlling a low-voltage source. For example, such a control amplifier is required in order to drive electronic ballasts, called ~VGs in German, which can be dimmed. High-; ~ low-voltage sources are also spoken of in this context. For example, a digital signal for a dimming process is supplied via a bus from b~ ;ng system ong;nooring, via a bus coupler and the control amplifier, to a switch-dimmer actuator. The switch-dimmer actuator converts the digital signal into a pulse-width-modulated sigral, and the control amplifier uses this to provide a con~tantly present an~log signal which is supplied to an electronic ballast which can be dimmed, in order to achieve a specific dimming level for a fluorescent lamp. The control signals for the dimming can also be supplied via an infrared controller, rather than via a bus. In this case, control amplifiers are required which are con-trolled between two limit values of the pulse-width-modulated signal.
- REPLACEMENT SHEET
GR 94 P 3387 P - la -An amplifier is thus required auch that a voltage #Ource having an int~rn~ n~e is adjusted in the range of a few volts by ~h~nging the impedence. Such a voltage source is pre~ent in the case of electronic balla~ts which can be dimmed. Furth- ~, there i8 intended to be DC isolation between the control signal ~nd the amplifier to be driven.
In the ca~e of a known control circuit, the control pulaes are ~rpl~d in a DC-i~olated manner (FR-A-2 615 676). In this case, the control signal ~nd operating voltage for controlling an operational a~pli-fier are supplied via ~ tran~former. The sec~n~y winding of the transformer is used to provide the operat-ing voltage. The inform~tion is in this ca~e cnn~n~d in the Amplitude.
- REPLACEMENT SREET
2 ~ 95442 The invéntion is based on the ob;ect of develop-ing a control amplifier which provides a constantly present analog signal at the output ~rom a pulse-width-modulated signal and which satisfies stringent insulation requirements, as exist, for example, in the case of the ~IBA bus from the hu~ an Installation Bus Association.
The indicated object is achieved according to the invention by a control amplifier as claimed in patent claim 1. In this case, a circuit for forming the mean value from the pulse-width-modulated control signal is co~nected to a secondary winding of an isolating trans-former for DC isolation, in order to form the control signal. The e~c-~-l~ry winding can also be inrlll~rd in a voltage multiplier circuit for providing the operating voltage for the control amplifier. In the case of appli-cations for the EIBA bus, the control amplifier can be A~;gn~d for the purpose of proc~ss;ng control signals on the input side in the order of magnitude of one to ten volts. The control ~ _l;fi~r can adv~ntr_ ~usly operate with, in its output stage, a field-effect transistor, FET, whose off-state voltage is at least 400 volts. An off-state voltage of 700 volts is particularly advantage-ous, in order to avoid malfunctions. The control ampli-fier can be ~;sned as a - _ ~t of a switch-dimmer actuator.
According to a dev~l~, t, the control amplifier is protected against overvoltages by means of a measure a8 claimed in claim 3. The field-effect transistor in the output stage i3 in this case driven by a feedback circuit in such a manner that it is switched to the off state if the nominal output voltage is ~-e~A~cl as a result of a voltage supplied to the control amplifier on the output side. This takes place, for example, if an installation mains voltage of 230 volts is applied, for example, instead of the high-impedence low-voltage source in the order of magnitude of 10 volts. By means of a resistor and/or an inductor in the source line of the FET, it is easily possible to ad~ust the maximum permissible drain current in the event of incorrect wiring or an incorrect 21 ~5~42 connection. The control amplifier i~ then protected ngainst incorrect connection.
It is advantageous to protect the field-effect transistor against the aonsequences of its p~rm;nsihle off-~tate voltage being ~- ead~t. For this purpose, the field-effect transistor can be driven by a feedback cir-cuit in ~uch a manner that, if overvoltages are present on the lnput ~ide, which lead to the p~rm; n~hl e off-state voltage of the field-effect transistor being ex-ceeded, this field-effect transistor is briefly switched on. It is simpler and more advantageous to choose the field-effect transiator to be avalanche-resistant.
It is favorable to connect an ; ~ , irre-spective of whether thia is a resistive or an inductive impedence, in series with the field-effect transistor ln order to achieve current limiting, until the field-effect trannistor is switched to the off state.
The invention will now be ~pln;n~ in more detail with reference to an~ ry ' ' ';- t which is shown schematically and roughly in the drawing:
On the input side, the control ~ f;~r has an isolating transformer 1 for DC isolation, in serie~ with which isolating transformer 1 a capacitor 2 for DC volt-age isolation is advantageously connected for ~co--rl ing DC voltage. A circuit for forming the mean value from the pulse-width-modulated control signal which is present on the input side i8 connected to the s~r~n~ry winding 3 of the isolating transformer 1. The formation of the mean value is carried out in the _l~ry: ' ~';- t. by means of a diode 4 and a capacitance 5 as well as the resistor~
6 and 7. The mean value which is formed from the pulse-width-modul~ted signal is present a~ the reference value at the input 8 of an operational amplifier 9. A respect-ive actual value is supplied to the negative control input 10 of the operational : _1; f; ~ 9 from the voltage divider having the resistors 11 and 12, these resistors 11 and 12 being located in a feedback line 14. Via its output 13, the operational amplifier 9 controls the FET
19 in such a manner -~ ~1 9~44~
.
that the actual value and reference value are matched to one another. The term formation o~ a mean value is in this case int~n~s~ also to include other circuita which act in an identical manner overall.
The operating voltage inputs 15 and 16 of the operational _lifier 9 receive their operating voltage from a voltage multiplier circuit 17, a voltage doubler circuit in the _l~ry .' ' ~'~ t.
In the ~ ry ~ t, the gate of a field-effect transiator 19, also called an FET, i8 connected to the output 13 of the operational amplifier 9 via a pro-tective resistor 18. A constant analog aignal, voltage or current, which ia controlled by the FET i9 then present at the output tnrmin-ln 20 and 21. The FET 19 is driven by a feedback circuit - having the c~ _ ~ t~ zener diode 22, resistora 23, 24 and 25 aa well aa the transistor 26 - in such a manner that th- FET 19 is switched to the off state if the nominal output voltage is ~T~e~d- When the zener dlode 22 is forward-biassed, the transiator 26 draws current via its baae-emitter iunction ao that it is awitched to the on atate and the gate electrode of FET 19 is connected to ground. As long aa the transistor 26 is not drawing any current, the reaistor 25 enaures that it is switched off in the stable manner.
If no control voltage ia present on the FET 19, the reaistor 27 ensures that the gate is at reference ground potential. An impedence 28 in the source line of the FET 19 ensures, in particular in conjunction with a resiator 29 and the transistor 26, current limiting by the FET until it can be protected againat overloading as a result of overvoltagea by means of its feedback cir-cuit, which acts as a protection circuit and has the resiators 23, 24 and 25 aa well as the tranaistor 26. In thia caae, tho transistor 26 carries out a double func-tion. If, for example, 0.7 volts, the threshold voltage of the base-emitter ~unction of the transmitter 26, ia ~~ c~nd across the resistor 28, the transi~tor 26 2 1 95~42 drives the gate of the PET 19 closer to referenae ground potential and drives the FET increasingly into the of~
state.
In the , ~ y '~ t, a diode 30 protects the control amplifier against acr;~n~l connection to installation voltage, that is to say for example 230 volts, in that only a DC voltage which is compatible with it i8 8uppl~ed to the FET 19, and this DC voltage cau~es the protection ~ described above to act.
The control amplifier is based on the principle of obtaining its control voltage and its operating voltage from a control voltage supplied on the input Ride .
It is favorable to select an avalanche-resistant FET for protection again~t the off-~tate voltage of the FET 19 being -Y~ee~d. On the other hand, the FET can also be driven by a further feedback circuit, which is not shown in the ~ y c '-';- t, in such a manner that, if overvoltages which would lead to the p~rm;~sihle off-state voltage of the FET being ~Y~e~ are present on the output side o~ the control amplifier, this FET is briefly switched on again.
T~T TRAI'~SL~.~ION
Description Control amplifier for controlling a high-impedence low-voltage source The invention relates to a control amplifier for controlling a low-voltage source having internal imped-ence, which low-voltage source is connected to two output t~rm~n-l~ and can be controlled between two limit values by means of ; ~ - oh -~g; ng, in detail as claimed in the precharacterizing clause of patent claim 1.
The input side has DC isolation by means of an isolating transformer, and an operating voltage supply for the control _l;fion is provided on the sec~n~ry side.
There are a very wide range of different fields of application for control amplifiers for controlling a low-voltage source. For example, such a control amplifier is required in order to drive electronic ballasts, called ~VGs in German, which can be dimmed. High-; ~ low-voltage sources are also spoken of in this context. For example, a digital signal for a dimming process is supplied via a bus from b~ ;ng system ong;nooring, via a bus coupler and the control amplifier, to a switch-dimmer actuator. The switch-dimmer actuator converts the digital signal into a pulse-width-modulated sigral, and the control amplifier uses this to provide a con~tantly present an~log signal which is supplied to an electronic ballast which can be dimmed, in order to achieve a specific dimming level for a fluorescent lamp. The control signals for the dimming can also be supplied via an infrared controller, rather than via a bus. In this case, control amplifiers are required which are con-trolled between two limit values of the pulse-width-modulated signal.
- REPLACEMENT SHEET
GR 94 P 3387 P - la -An amplifier is thus required auch that a voltage #Ource having an int~rn~ n~e is adjusted in the range of a few volts by ~h~nging the impedence. Such a voltage source is pre~ent in the case of electronic balla~ts which can be dimmed. Furth- ~, there i8 intended to be DC isolation between the control signal ~nd the amplifier to be driven.
In the ca~e of a known control circuit, the control pulaes are ~rpl~d in a DC-i~olated manner (FR-A-2 615 676). In this case, the control signal ~nd operating voltage for controlling an operational a~pli-fier are supplied via ~ tran~former. The sec~n~y winding of the transformer is used to provide the operat-ing voltage. The inform~tion is in this ca~e cnn~n~d in the Amplitude.
- REPLACEMENT SREET
2 ~ 95442 The invéntion is based on the ob;ect of develop-ing a control amplifier which provides a constantly present analog signal at the output ~rom a pulse-width-modulated signal and which satisfies stringent insulation requirements, as exist, for example, in the case of the ~IBA bus from the hu~ an Installation Bus Association.
The indicated object is achieved according to the invention by a control amplifier as claimed in patent claim 1. In this case, a circuit for forming the mean value from the pulse-width-modulated control signal is co~nected to a secondary winding of an isolating trans-former for DC isolation, in order to form the control signal. The e~c-~-l~ry winding can also be inrlll~rd in a voltage multiplier circuit for providing the operating voltage for the control amplifier. In the case of appli-cations for the EIBA bus, the control amplifier can be A~;gn~d for the purpose of proc~ss;ng control signals on the input side in the order of magnitude of one to ten volts. The control ~ _l;fi~r can adv~ntr_ ~usly operate with, in its output stage, a field-effect transistor, FET, whose off-state voltage is at least 400 volts. An off-state voltage of 700 volts is particularly advantage-ous, in order to avoid malfunctions. The control ampli-fier can be ~;sned as a - _ ~t of a switch-dimmer actuator.
According to a dev~l~, t, the control amplifier is protected against overvoltages by means of a measure a8 claimed in claim 3. The field-effect transistor in the output stage i3 in this case driven by a feedback circuit in such a manner that it is switched to the off state if the nominal output voltage is ~-e~A~cl as a result of a voltage supplied to the control amplifier on the output side. This takes place, for example, if an installation mains voltage of 230 volts is applied, for example, instead of the high-impedence low-voltage source in the order of magnitude of 10 volts. By means of a resistor and/or an inductor in the source line of the FET, it is easily possible to ad~ust the maximum permissible drain current in the event of incorrect wiring or an incorrect 21 ~5~42 connection. The control amplifier i~ then protected ngainst incorrect connection.
It is advantageous to protect the field-effect transistor against the aonsequences of its p~rm;nsihle off-~tate voltage being ~- ead~t. For this purpose, the field-effect transistor can be driven by a feedback cir-cuit in ~uch a manner that, if overvoltages are present on the lnput ~ide, which lead to the p~rm; n~hl e off-state voltage of the field-effect transistor being ex-ceeded, this field-effect transistor is briefly switched on. It is simpler and more advantageous to choose the field-effect transiator to be avalanche-resistant.
It is favorable to connect an ; ~ , irre-spective of whether thia is a resistive or an inductive impedence, in series with the field-effect transistor ln order to achieve current limiting, until the field-effect trannistor is switched to the off state.
The invention will now be ~pln;n~ in more detail with reference to an~ ry ' ' ';- t which is shown schematically and roughly in the drawing:
On the input side, the control ~ f;~r has an isolating transformer 1 for DC isolation, in serie~ with which isolating transformer 1 a capacitor 2 for DC volt-age isolation is advantageously connected for ~co--rl ing DC voltage. A circuit for forming the mean value from the pulse-width-modulated control signal which is present on the input side i8 connected to the s~r~n~ry winding 3 of the isolating transformer 1. The formation of the mean value is carried out in the _l~ry: ' ~';- t. by means of a diode 4 and a capacitance 5 as well as the resistor~
6 and 7. The mean value which is formed from the pulse-width-modul~ted signal is present a~ the reference value at the input 8 of an operational amplifier 9. A respect-ive actual value is supplied to the negative control input 10 of the operational : _1; f; ~ 9 from the voltage divider having the resistors 11 and 12, these resistors 11 and 12 being located in a feedback line 14. Via its output 13, the operational amplifier 9 controls the FET
19 in such a manner -~ ~1 9~44~
.
that the actual value and reference value are matched to one another. The term formation o~ a mean value is in this case int~n~s~ also to include other circuita which act in an identical manner overall.
The operating voltage inputs 15 and 16 of the operational _lifier 9 receive their operating voltage from a voltage multiplier circuit 17, a voltage doubler circuit in the _l~ry .' ' ~'~ t.
In the ~ ry ~ t, the gate of a field-effect transiator 19, also called an FET, i8 connected to the output 13 of the operational amplifier 9 via a pro-tective resistor 18. A constant analog aignal, voltage or current, which ia controlled by the FET i9 then present at the output tnrmin-ln 20 and 21. The FET 19 is driven by a feedback circuit - having the c~ _ ~ t~ zener diode 22, resistora 23, 24 and 25 aa well aa the transistor 26 - in such a manner that th- FET 19 is switched to the off state if the nominal output voltage is ~T~e~d- When the zener dlode 22 is forward-biassed, the transiator 26 draws current via its baae-emitter iunction ao that it is awitched to the on atate and the gate electrode of FET 19 is connected to ground. As long aa the transistor 26 is not drawing any current, the reaistor 25 enaures that it is switched off in the stable manner.
If no control voltage ia present on the FET 19, the reaistor 27 ensures that the gate is at reference ground potential. An impedence 28 in the source line of the FET 19 ensures, in particular in conjunction with a resiator 29 and the transistor 26, current limiting by the FET until it can be protected againat overloading as a result of overvoltagea by means of its feedback cir-cuit, which acts as a protection circuit and has the resiators 23, 24 and 25 aa well as the tranaistor 26. In thia caae, tho transistor 26 carries out a double func-tion. If, for example, 0.7 volts, the threshold voltage of the base-emitter ~unction of the transmitter 26, ia ~~ c~nd across the resistor 28, the transi~tor 26 2 1 95~42 drives the gate of the PET 19 closer to referenae ground potential and drives the FET increasingly into the of~
state.
In the , ~ y '~ t, a diode 30 protects the control amplifier against acr;~n~l connection to installation voltage, that is to say for example 230 volts, in that only a DC voltage which is compatible with it i8 8uppl~ed to the FET 19, and this DC voltage cau~es the protection ~ described above to act.
The control amplifier is based on the principle of obtaining its control voltage and its operating voltage from a control voltage supplied on the input Ride .
It is favorable to select an avalanche-resistant FET for protection again~t the off-~tate voltage of the FET 19 being -Y~ee~d. On the other hand, the FET can also be driven by a further feedback circuit, which is not shown in the ~ y c '-';- t, in such a manner that, if overvoltages which would lead to the p~rm;~sihle off-state voltage of the FET being ~Y~e~ are present on the output side o~ the control amplifier, this FET is briefly switched on again.
Claims (6)
1. A control amplifier for controlling a low-voltage source having internal impedence, which low-voltage source is connected to two output terminals (20, 21) and can be controlled between two limit values by means of impedence changing, the input side having DC isolation by means of an isolating transformer (1) and an operating voltage supply for the control amplifier being provided on the secondary side, characterized in that a circuit for forming a DC voltage mean value (having the components 4, 5, 6, 7) from a pulse-width-modulated control signal as a reference value is connected to a secondary winding (3) of the isolating transformer (1), and in that an operational amplifier circuit is provided as the control amplifier, which produces the impedence change, the voltage which is in consequence present at the output terminals (20, 21) being used as the actual value, the impedence change being controlled by means of the operational amplifier circuit in such a manner that the actual value and reference value are matched to one another, the secondary winding (3) also being included in the circuit for providing the operating voltage for the operational amplifier circuit, in particular in a voltage multiplier circuit (17).
2. The control amplifier as claimed in claim 1, characterized in that, for the actual value in the order of magnitude from 1 to 10 volts, the operational amplifier circuit has as the output stage a field-effect transistor (19), FET, whose off-state voltage is at least 400 volts.
- 6a -
- 6a -
3. The control amplifier as claimed in claim 2, characterized in that the FET is driven by a feedback circuit (components 23, 24, 22, 25, 26, 27) in such a manner that it is switched to the off-state if the nominal output voltage is exceeded.
4. The control amplifier as claimed in claim 2 or 3, characterized in that the FET (19) is driven by a feedback circuit in such a manner that, in the event of overvoltages being applied on the input side to the control amplifier which would lead to the permissible off-state voltage of the FET (19) being exceeded, this FET (19) is switched on briefly (not illustrated).
5. The control amplifier as claimed in claim 2 or 3, characterized in that FET (19) is selected to be avalanche-resistant.
6. The control amplifier as claimed in one of claims 2 to 5, characterized in that that FET (19) has a impedence (28) connected in its source line.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE4425901A DE4425901A1 (en) | 1994-07-21 | 1994-07-21 | Control amplifier for controlling a high-resistance low voltage source |
| DEP4425901.8 | 1994-07-21 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2195442A1 true CA2195442A1 (en) | 1996-02-08 |
Family
ID=6523824
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002195442A Abandoned CA2195442A1 (en) | 1994-07-21 | 1995-07-10 | Servo-amplifier for controlling a high-ohmic low-voltage source |
Country Status (8)
| Country | Link |
|---|---|
| EP (1) | EP0771492B1 (en) |
| JP (1) | JPH10503068A (en) |
| CN (1) | CN1088291C (en) |
| AT (1) | ATE171575T1 (en) |
| AU (1) | AU691936B2 (en) |
| CA (1) | CA2195442A1 (en) |
| DE (2) | DE4425901A1 (en) |
| WO (1) | WO1996003806A1 (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9503821B2 (en) | 2011-05-19 | 2016-11-22 | Warwick Audio Technologies Limited | Electrostatic transducer |
| US9692372B2 (en) | 2011-05-19 | 2017-06-27 | Warwick Audio Technologies Limited | Amplifier for electrostatic transducers |
| US10349183B2 (en) | 2014-02-11 | 2019-07-09 | Warwick Acoustics Limited | Electrostatic transducer |
| US10785575B2 (en) | 2014-02-11 | 2020-09-22 | Warwick Acoustics Limited | Electrostatic transducer |
| US11825265B2 (en) | 2019-05-07 | 2023-11-21 | Warwick Acoustics Limited | Electrostatic transducer and diaphragm |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19805098A1 (en) * | 1998-02-09 | 1999-08-19 | Wampfler Ag | Circuit arrangement |
| US7280335B2 (en) * | 2004-06-22 | 2007-10-09 | Delphi Technologies, Inc. | Protection circuit and method for protecting a switch from a fault |
| US20070127180A1 (en) * | 2005-12-05 | 2007-06-07 | Yingjie Lin | Short circuit protection for vehicle driver circuit |
| DE102011119065A1 (en) * | 2011-11-22 | 2013-05-23 | Minebea Co., Ltd. | Electrical circuit, particularly output driver for microcontroller, has switching element, and emitter resistor arranged on emitter of output transistor, such that signal input is connected with base of output transistor by series resistor |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4485342A (en) * | 1982-07-27 | 1984-11-27 | General Electric Company | Load driving circuitry with load current sensing |
| DE3433538A1 (en) * | 1984-09-13 | 1986-03-20 | Telefunken electronic GmbH, 7100 Heilbronn | Protective circuit for a power transistor through which the load current flows |
| DE3513170A1 (en) * | 1985-04-12 | 1986-10-16 | Siemens AG, 1000 Berlin und 8000 München | METHOD FOR DRIVING ON AND SWITCHABLE POWER SEMICONDUCTOR COMPONENTS AND DEVICE FOR IMPLEMENTING THE METHOD |
| US4672327A (en) * | 1986-03-10 | 1987-06-09 | Rca Corporation | Self-biasing for enhancement-mode field effect transistors |
| FR2615676B1 (en) * | 1987-05-22 | 1994-05-13 | Matra | STATIC CURRENT LIMITING ELECTRICAL SWITCHING DEVICE |
| US5001386B1 (en) * | 1989-12-22 | 1996-10-15 | Lutron Electronics Co | Circuit for dimming gas discharge lamps without introducing striations |
-
1994
- 1994-07-21 DE DE4425901A patent/DE4425901A1/en not_active Withdrawn
-
1995
- 1995-07-10 DE DE59503721T patent/DE59503721D1/en not_active Expired - Fee Related
- 1995-07-10 AT AT95924184T patent/ATE171575T1/en not_active IP Right Cessation
- 1995-07-10 WO PCT/DE1995/000901 patent/WO1996003806A1/en active IP Right Grant
- 1995-07-10 CA CA002195442A patent/CA2195442A1/en not_active Abandoned
- 1995-07-10 JP JP8505348A patent/JPH10503068A/en active Pending
- 1995-07-10 EP EP95924184A patent/EP0771492B1/en not_active Expired - Lifetime
- 1995-07-10 AU AU28798/95A patent/AU691936B2/en not_active Ceased
- 1995-07-10 CN CN95193526A patent/CN1088291C/en not_active Expired - Fee Related
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9503821B2 (en) | 2011-05-19 | 2016-11-22 | Warwick Audio Technologies Limited | Electrostatic transducer |
| US9692372B2 (en) | 2011-05-19 | 2017-06-27 | Warwick Audio Technologies Limited | Amplifier for electrostatic transducers |
| US10349183B2 (en) | 2014-02-11 | 2019-07-09 | Warwick Acoustics Limited | Electrostatic transducer |
| US10785575B2 (en) | 2014-02-11 | 2020-09-22 | Warwick Acoustics Limited | Electrostatic transducer |
| US11825265B2 (en) | 2019-05-07 | 2023-11-21 | Warwick Acoustics Limited | Electrostatic transducer and diaphragm |
Also Published As
| Publication number | Publication date |
|---|---|
| DE59503721D1 (en) | 1998-10-29 |
| EP0771492B1 (en) | 1998-09-23 |
| EP0771492A1 (en) | 1997-05-07 |
| ATE171575T1 (en) | 1998-10-15 |
| CN1150505A (en) | 1997-05-21 |
| CN1088291C (en) | 2002-07-24 |
| AU2879895A (en) | 1996-02-22 |
| JPH10503068A (en) | 1998-03-17 |
| AU691936B2 (en) | 1998-05-28 |
| WO1996003806A1 (en) | 1996-02-08 |
| DE4425901A1 (en) | 1996-01-25 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |