DE9309814U1 - Standby circuit for electrical consumers - Google Patents

Description

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Siemens AG

Standby circuit for electrical consumers 5

The invention relates to a standby circuit for electrical consumers that can be controlled by a remote control.

Standby circuits are circuits for electrical consumers that are kept in operation while the other functional units of the consumer are switched off in order to receive signals sent by a "remote control" and to switch the device on when a signal identifier for switching on is detected. Since a standby circuit is constantly in operation, it should be implemented in such a way that it consumes as little power loss as possible.

A known standby circuit uses a switching power supply to supply power to the consumer. A switching power supply essentially contains a transformer, a switching device by which the current flow through the transformer is switched on and off, and a device for controlling the switching device. The control device has a standby operating mode in which essentially only the secondary winding feeding the infrared receiving and decoding device is in operation, while the windings feeding the other circuit parts of the device are operated in idle mode. Since the control device and the corresponding part of the transformer are constantly switched on during the standby phase, a relatively

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high power dissipation, which is usually in the order of 10 watts.

In another known standby circuit, in addition to the power supply unit that supplies the consumer, another transformer is provided through which the actual standby circuit is supplied. During standby mode, the power supply unit is switched off. Since the additional transformer and the standby circuit are permanently switched on, a relatively high level of power is also consumed here, which is approximately in the order of 1 watt.

The object of the invention "is to provide a standby circuit that has low power loss.

This task is solved by a standby circuit for electrical consumers with a detector device through which a signal sent by a remote control is received and, when a received signal is detected, a decoder device is switched on, through which the signal sent by the remote control is decoded and, when a command to switch on is decoded, a power supply to the consumer is switched on.

Advantageous further developments are specified in the subclaims.

In standby mode, only the detector is permanently switched on. The decoder is normally switched off and is only switched on when a remote control signal is received. The circuit for the detector can react with high resistance.

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This ensures low continuous power consumption in standby mode.

When using a switching power supply, various implementation options are conceivable. The detector and decoder can either be arranged together on the primary side or on the secondary side of the switching power supply transformer, or separately on both the primary and secondary sides of the transformer. In the first and last case, the detector is supplied directly from the mains supply, after rectification if necessary. In the case of the secondary-side arrangement, the detector can be supplied from an energy storage device. When using a capacitor as an energy storage device, the capacitor must be recharged when the voltage falls below a minimum level due to the start-up operation of the switching power supply. When using a rechargeable battery as an energy storage device, charging can take place when the consumer is started up. On the other hand, the detector can be supplied with power by voltage division and 0 rectification in the current path of the Y capacitors arranged on the primary side.

The invention is explained in more detail below with reference to the figures shown in the drawing. Identical elements are provided with the same reference numerals. They show:

FIG 1 shows a basic circuit diagram of a standby circuit according to the invention,

FIG 2 a design with primary side arrangement of the detector and secondary side arrangement of the decoder,

FIG 3 a design with primary side arrangement of detector and decoder,

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FIG 4 a version with secondary side arrangement of detector and decoder,

FIG 5 shows the power supply of the detector in a secondary arrangement according to FIG 4, FIG 6 shows the basic circuit diagram of a detector and FIG 7 shows a detailed version of the detector.

A standby circuit according to the invention contains, according to FIG 1, a power supply device 1, which can be, for example, a power converter, in particular a switching power supply. At an input 5, the switching power supply 1 is supplied with a direct current voltage obtained by rectification, e.g. by a bridge rectifier. At least one secondary output 8 of the switching power supply 1 provides a direct current voltage converted to a different voltage level for operating functional units of the consumer. A control unit 2 is supplied with power through a secondary output 7. The control unit 2 contains at least one decoder device 3, by which a signal sent by a remote control, usually an infrared signal, is decoded and converted into corresponding control signals. The remote control signal contains, among other things, commands for switching the consumer on and off. The reception of an infrared signal is detected in a detector device 4. Any command contained in the infrared signal is not taken into account. If an infrared signal is detected by the detector 4, the device 2 is switched on. This can be done by appropriate switching measures for switching on in the device 2 itself or by activating the corresponding power supply output 7 of the switching power supply 1. The switched on decoder 3 of the control device

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Device 2 then decodes the signal sent by the remote control. For this purpose, a further infrared receiver and preamplifier can be provided in device 2, the output signal of which is fed into decoder 3. Alternatively, an amplified signal can be generated in detector 4 from the infrared signal received there and fed into decoder 3 for decoding.

For the arrangement of the decoder 3 and the detector 4 with respect to

of the switching power supply 1 and for their power supply, various designs are possible. The devices 3, 4 can be supplied with power both from the primary side and from the secondary side of the switching power supply 1. In addition, the detector 4 can be arranged on the primary side and the decoder 3 on the secondary side of the switching power supply. The corresponding embodiments are shown in Figures 2 to 5. Signals that are transmitted from the primary side to the secondary side of the switching power supply 1 are always galvanically decoupled.

0 This can be achieved, for example, by a transformer or a combination of light-emitting diode and phototransistor.

In FIG 2, the detector 4 is on the primary side of the switching power supply 1, the decoder 3 on the secondary side. The switching power supply 1 contains a transformer 10, in whose primary winding a switching transistor 11 is connected. The switching transistor 11 chops the current flow through the primary winding of the transformer 10, whereby it is controlled by a device 12. The device 12 is usually an integrated circuit. The switching power supply 1 is supplied on the primary side at a connection 14 by a rectified

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Mains voltage, which is related to primary ground 13. The decoder 4 is also supplied by the rectified mains voltage at connection 14. An output 15 of the decoder 4 is connected to a corresponding input of the control IC 12 of the switching power supply 1, so that the switching power supply 1 is switched on when there is an active signal at connection 15. This is the case when an infrared signal sent by a remote control is detected by the detector 4. The switching power supply 1 is expediently operated in an operating mode in which only the control device 2 described below is switched on, while other functional units of the consumer remain switched off. This operating mode of the switching power supply is known from the prior art mentioned at the beginning.

The standby circuit also contains the control device 2, which is supplied by a secondary winding 16 of the transformer 10 of the switching power supply 1. The control device 2 contains the decoder 3 and an infrared preamplifier 9. After the switching power supply 1 has been switched on in the presence of an infrared signal, the infrared signal is also received by the preamplifier 9, which amplifies the signal and feeds it to the decoder 3. Depending on the command decoded from the infrared signal, the decoder 3 controls the standby circuit. If the infrared signal does not contain a decodable command, for example if an infrared signal is received from a remote control that does not belong to the consumer, the switching power supply 1 is switched off again. If a command to switch on the consumer is decoded, the switching power supply 1 and the corresponding secondary winding 16 are kept switched on, so that the control device 2 remains active. For

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For this feedback, the detector 4 has a feedback input 17, with which its output 15 is kept in the active state. The signal is transmitted via a galvanic coupling 19. In addition, the entire switching power supply 1 and thus the connected consumer are switched on by the control device 2. When decoding a signal to switch off the consumer, the standby circuit is brought into the initial state. In order to activate the standby circuit by manual operation, a further connection 18 is provided, which is connected, for example, to a switch-on contact, e.g. a wiper contact.

The detector 4 remains switched on continuously. It can be implemented with high resistance so that little power loss is consumed. The switched-on power supply 1 and the control device 2, whose decoder 3 is usually a complex integrated circuit, consume a relatively high power loss compared to the detector 4. They are therefore only switched on when an infrared signal is detected. The power loss of the entire circuit in standby mode therefore remains relatively low compared to conventional solutions.

In the embodiment according to FIG 3, the decoder 3 is arranged on the primary side of the switching power supply 1. When the detector 4 detects an infrared signal, its output 15 is activated. This switches on the decoder 3. This can be achieved, for example, by supplying the decoder 3 with voltage via the connection 15. The decoder 3 is also supplied with the received and amplified infrared signal via an output 21 of the detector 4.

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signal 21. If a signal to switch on the consumer is detected by the decoder 3, the switching power supply 1 and thus the consumer is switched on via its output 22. The output 22 is fed back to the input 17 of the detector 4 in order to keep the decoder 3 switched on for decoding a switch-off command. It is expedient for the decoder 3 to only detect switch-on and switch-off signals. The decoder 3 can therefore be implemented with little circuitry and thus low power consumption. This means that it can be supplied via the output 15 of the detector 4 without any problems. The decoding of further control functions is carried out by another decoder, which is supplied from the secondary side of the switching power supply 1 and is only activated when the consumer is switched on.

The arrangement of the decoder 3 on the primary side ensures that the switching power supply 1 is only switched on when an infrared signal for switching on is received from the remote control belonging to the consumer. All other infrared signals have no effect on the switching power supply 1. Thus, in comparison to the embodiment according to FIG 1, the control circuit contained in the switching power supply 1 does not require an extra operating mode for feeding the secondary-side infrared receiver and decoder. Advantageously, the amplified infrared signal present at the output 21 of the detector 4 can be tapped at an internal circuit node of the detector 4 without any significant circuit effort.

In FIG 4 an embodiment is shown in which both the detector 4 and the decoder 3 are on the secondary

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side of the switching power supply 1. The detector 4 is supplied with voltage during the standby phase from an energy storage device. In the present case, the energy storage device is a capacitor 34, which is charged from the secondary side of the switching power supply 1. The decoder 3 is switched off so that it does not consume any power. The capacitor 34 is discharged by the power requirement of the detector 4. When the voltage falls below a minimum level, a signal is activated at an output 35 of the detector 4, which is coupled to the primary side of the switching power supply 1 via an optocoupler 31 and switches the switching power supply 1 on until the capacitor 34 is charged to its full voltage again. The start-up operation of the switching power supply 1 is generally sufficient for this.

The signal present at the output 35 of the detector 4 can be tapped at an internal circuit node of the detector 4 without significant circuit effort.

If the decoder 3 is a circuit manufactured using complementary MOS technology, the decoder is conveniently switched off by switching off the clock of the circuit 3 via connection 15. The decoder 3 is switched on when an infrared signal is detected by the detector 4. This is fed to the decoder 3 in an amplified form via the output 21 of the detector 4. When a signal to switch on the consumer is detected, the decoder 3 switches the output 32 to active, which is also fed back to the primary side of the switching power supply 1. The outputs 32, 35 of the decoder 3 and detector 4 are ORed in the switching element 30.

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In comparison to conventional standby circuits, only the detector 4 is switched on during the standby phase, but not the decoder 3. The switching power supply 1 is only switched on briefly in start-up mode to charge the capacitor 34. This means that the power loss is low. In addition, no standby mode setting is required for the switching power supply 1.

As an alternative to the capacitor 34 shown in FIG 4 as an energy storage device, a rechargeable battery can also be used. It is assumed that the battery capacity is sufficient to supply the detector 4 with power until the device is switched on. Only then is the battery recharged.

Instead of the secondary-side supply of the detector and/or decoder devices 4 and 3 arranged on the secondary side, a primary-side supply can also be provided. The corresponding design of this power supply is shown in FIG 5. The AC mains voltage applied to terminals 40, 41 is rectified in a bridge rectifier circuit 42 and is present at terminal 14 with respect to primary ground 13. Two capacitors 43, 44 connected in series are usually provided between terminals 40, 41 to suppress interference, the connection point of which is connected to secondary ground, i.e. ground connection 33. The capacitors 43, 44 are usually referred to as Y capacitors. According to the invention, a capacitor 45 is connected between capacitor 43 and secondary ground connection 33 to divide the voltage of the alternating circuit. The alternating voltage applied to the capacitor 45 is converted into a rectifier network consisting of diodes 46, 47 and a capacitor 48

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rectified and smoothed. The voltage on the capacitor 48 is thus present with respect to the secondary mass 33. The detector 4 operating on the secondary side is connected to the connecting terminals 49, 50 of the capacitor 48 for the power supply.

The power supply for the detector 4 shown in FIG 5 can be implemented with little circuitry effort. Since the detector 4 has a low power consumption and can be fed with a low supply voltage if dimensioned accordingly, the requirement with regard to the dielectric strength of the capacitor 45 is comparatively low.

When using an infrared remote control, one of the infrared detectors described below is expediently used for the detector circuit 4. The basic circuit diagram of the infrared detector is shown in FIG. 6. The infrared detector 4 has a connection 60 for a reference potential and a supply connection 61. The emitter-collector path of a pnp bipolar transistor 63 is located between the connection 61 and an output connection 62. The base and emitter of the transistor 63 are connected via a resistor 64. The base of the transistor 63 is connected to the reference connection 60 via a diode 65 sensitive to infrared light. The diode 65 supplies an increasing blocking current for increasing illumination intensity. The input terminal pair 60, 61 is connected to a DC supply voltage. A diode-capacitor rectifier circuit 66 can be used to connect to an alternating voltage.

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When light of a wavelength characteristic of the photodiode 65 hits it, its blocking current increases, so that a cross current flows through the resistor 64 between the connection terminals 60, 61. The voltage now dropping across the base-emitter path switches on the transistor 63. The input voltage between the terminals 60, 61 is now present at the terminals 60, 62. The output 62 is thus activated.

A detailed circuit diagram of a detector that has a high gain and high-pass character and is therefore particularly suitable for standard infrared signals from a remote control is shown in FIG 7. The detector contains a rectifying and smoothing element 66 on the input side. The input-side connection terminals 60, 72 can be connected to both an alternating voltage and a direct voltage. The photodiode 65 is connected to the center connection of a voltage divider 71a, 71b. This protects the photodiode 65 from high blocking voltages. A capacitor 73 is connected to the cathode of the photodiode 65. The capacitor 73 acts as a high-pass filter so that only rapidly changing brightness signals, such as those usually emitted by infrared transmitters, are processed. The circuit thus remains insensitive to brightness fluctuations in daylight or the low-frequency modulated light from incandescent lamps. The capacitor 73 is followed on the output side by a first amplifier stage 67, which in turn is followed by a second amplifier stage. The amplifier stage 68 contains a Darlington circuit 76 on the output side, which ensures high amplification. The amplifier circuit 68 has high

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matching character. Due to the total amplification of the amplifiers 67, 68 connected in series, the detector has a high amplification that is sufficient even for weak incoming infrared signals. The circuits 69, 70 ensure that the operating point is set and stabilized independently, so that adjustment of the circuit is not necessary. The output of the amplifier 68 switches the pnp bipolar transistor 63. The collector connection 62 controls the excitation winding of a relay 77. As a result, the output 15 of the detector has sufficient current driving capacity. In order to separate the emitter-collector current path of the transistor 63 from the rest of the detector, its emitter is supplied with current independently via a diode-capacitor rectifier 78, 7 9. The capacitor 80 connected to the output side of the amplifier stage 68, which together with the resistors 64, 82, 83 acts as an integrator, allows a suitably selected inertia to be achieved for the switching function of the detector, so that the transistor 63 is not switched in the event of a short, possibly disturbed reception signal. The signal input 17 for a switch-on contact and the signal input 18 for the feedback act on the circuit node 81, which is connected to the base of the Darlington circuit 76. A further input, not shown, can be coupled to node 81, which is connected to a timer. In time-controlled devices, this timer is used to briefly switch on the detector and a control device controlled by the detector, which then determines whether a time condition for switching on the device exists.

The detector according to FIG 7 can be operated with both direct and alternating voltage. When operating on

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It is recommended that the primary side of the switching power supply be supplied with a voltage equal to the mains voltage. For secondary operation, a supply voltage that is also suitable for operating digital integrated circuits (e.g. 5 V) is advantageous. The circuit shown can therefore be used for different supply voltage levels if the components used are suitably dimensioned. The power consumption is in the milliwatt range. The circuit can easily be implemented as an integrated circuit. It can also be used as an infrared amplifier and detector for other applications not related to standby circuits.

Claims (11)

6 1 3 9 9 Protection claims 1. Standby circuit for electrical consumers with a detector device (4) by which a signal sent by a remote control is received and, when a received signal is detected, a decoder device (3) is switched on, by which the signal sent by the remote control is decoded and, when a command to switch on is decoded, a power supply (1) of the consumer is switched on. 2. Standby circuit according to claim 1, characterized in that the detector device (4) is supplied from the primary side of a power converter (1), that the decoder device (3) is supplied from the secondary side of the power converter (1), that the detector device (4), when detecting the received signal, switches the power converter (1) into a state in which the decoder device (3) is supplied with power. 3. Standby circuit according to claim 2, characterized in that a further detector device (9) is supplied from the secondary side of the power converter (1) and that an output signal of the further detector device (9) is fed to the decoder device (3). 4. Standby circuit according to claim 1, characterized in that the detector device (4) is supplied from the primary side of a power converter (1), that the decoder unit 6 1 3 9 9 EN device (3) is supplied from the primary side of the power converter (1) and that the signal received by the detector device (4) is fed to the decoder device (3) in an amplified manner.
5 5. Standby circuit according to claim 1, characterized in that the decoder device (3) is supplied from the secondary side of a power converter (1), that the detector device (4) is supplied from an energy store (34) which is recharged from the secondary side of the power converter (1), and that the signal received by the detector device (4') is fed to the decoder device (3) in an amplified form. 6. Standby circuit according to claim 5, characterized in that the energy storage device is a capacitor (34), that the detector device (4) generates a voltage monitoring signal by which the part of the power converter (1) feeding the detector device (4) is switched on when a minimum voltage is undershot, and by which the power converter (1) can be switched off when a target voltage is reached. 7. Standby circuit according to claim 1, characterized in that the decoder device (3) is supplied from the secondary side of a power converter (1), that the detector device (4) is fed by a voltage divider (43, 44, 45) and by a rectifier device (46, 47, 48) from a current path which is connected between the connection for a 6 1 3 9 9 OE alternating voltage fed into the primary side of the power converter (1) and a reference terminal (33) of the secondary side of the power converter (1). 8. Standby circuit according to one of claims 1 to 7, characterized in that the detector device (4) contains: - a bipolar transistor (63) whose emitter-collector path is connected between an input terminal (61) and an output terminal (62), - a resistance element (64) connected between the emitter and base of the bipolar transistor (63) and - a light-sensitive switching element (65) having a first terminal for a reference potential and a second terminal coupled to the base of the bipolar transistor (63). 9. Standby circuit according to claim 8, characterized in that the detector device (3) contains at least one signal amplifier device (67, 68) with high-pass properties, the input-output signal path of which is connected between the second connection of the light-sensitive switching element (65) and the base of the bipolar transistor (63). 10. Standby circuit according to claim 9, characterized in that an integrating element (82, 83, 80) is connected between the base of the bipolar transistor (63) and the connection for the reference potential (60). 11. Standby circuit according to one of claims 1 to 7, G 1 3 9 9 EN characterized in that the power converter (1) is a switching power supply which contains a control device (12) for controlling the operating states of the switching power supply and a transformer (10).