REMOTE CONTROL SYSTEM

Abstract: An audio/video system comprises a plurality of units of different types and a plurality of units of like types; for in­ stance a plurality of amplifiers, video recorders, monitors, etc. Each unit includes a remote control (RC) receiver. Re­ ceivers of like type units and/or RC receivers of different type units are connected in cascade in order to control all units using only one single remote control (RC) transmitter. This transmitter transmits control packets having a packet header, a characteristic code, and a control command. The characteristic code includes a unit type code defining the type of unit to be controlled and a unit number code defining the specific unit of that type within the string of cascaded like units. The control packet dribbles down the string of cascaded RC receivers until it has reached the unit having that particular unit number.

Description: The present invention generally relates to a remote control system for use with audio and/or video consumer systems, comprising a plurality of units, of the same kind. A(2) Description of the prior art Many methods have been proposed for remotely controlling different units of an audio and/or video system. In a first method each unit has its own receiver and a corresponding transmitter associated therewith. This is often called "individual control". In a second method called "distributed control" all units of the system are connected to a central remote control receiver which routes received control signals to the appropriate unit of the system. In case of individual control, the number of remote control transmitters and receivers is equal to the number of units in the system. This means a waste of material and when the number of units of the system is large, it is difficult to select the appropriate transmitter. In case of distributed control the number of connections is proportional to the number of units which makes installation complicated. In order to avoid all these problems it has already also been proposed to incorporate an individual receiver in each unit of a video/audio system and to use one single transmitter to control each unit. Such transmitter includes a plurality of selection switches, one of each unit of the system. In such transmitter each command is embedded in a control packet having a predetermined format that can be processed by the unit for which it is intended. In such a system problems now arise when two or more units of the same kind, for example two similar VCRs, two similar displays, etc are part of the system. This transmitter cannot distinguish between similar units. It is noted that in EP-A-0 112 548 a remote control transmitter is disclosed which is capable of controlling units of the same kind, but manufactured by different manufacturers and thus requiring control packets of different formats. B. Summary of the invention It is an object of the present invention to provide a remote control system capable of controlling a plurality of like units in an audio and/or video system. It is also an object of the present invention to provide a remote control system which does not show the drawbacks of the individual or distributed remote control system. According to the present invention the control packet also includes a unit type code (VCR, TV) and a unit number code (1, 2, 3, ...). Each receiver being adapted to compare the unit type code and unit number code of the received control packet with an internally store reference unit type code and unit number code and to respond on the control command in the received control packet when the received unit type and unit number code match the corresponding internally stored reference codes. C. Short description of the Figures. Figure 1 is a blockdiagram that shows an application example of the remote control transmitter. Figure 2 shows an example of the transmitting format. Figure 3 is a blockdiagram that shows an example of the remote control receiver. Figure 4 is a blockdiagram that shows an example of the controller, that is provided in each unit. D. Description of an embodiment. Figure 1 shows the transmitter of the remote control system. It comprises a code generator 1 having connected thereto a unit number keyboard 2 for keying in a unit number, a unit selection keyboard 4 for selecting the unit type and a command keyboard 5 for selecting a command. A display 3 is also connected to the code generator 1 for displaying the selected unit number, unit type, and the command. After depression of the selected keys the code generator 1 produces a command packet of the type shown in Figure 2 . It has a packet header, a characteristic code and a command code. This command packet is applied to a modulator 6 and sent wireless by infrared or by ultrasonic rays to a remotely placed receiver. The characteristic code includes a unit type code defining the type of unit to be controlled for instance VCR, and a unit number code defining which one of the defined unit types (so which VCR) must be controlled. To this end the units of the same type are all connected in cascade, so that a command packet dribbles down the cascaded units. One of the units functions thereby as a master unit receiving the signals originally generated by the transmitter. The other units connected in cascade to this master unit are slave units. The principle parts of the receivers in master units and slave units are the same. Such receiver is shown in Figure 3 and includes a demodulator 7 that receives the output of modulator 6, a command routing circuit 8 and a modulator 9. The command routing circuit 8 includes a command controller 10 shown in detail in Figure 4. It has an input for receiving the unit number n selected by the user and sent to the receiver by the remote control transmitter, or produced by a preceding unit. This unit number is applied to a unit number processor 11 in which this unit number is checked. When the unit type is correct and the unit number n is equal to the lowest possible number 0 it is concluded that the command code in the command packet is allocated to this particular unit. When the received unit number n is not equal to the lowest possible number 0, then unit number processor 11 produces a new unit number equal to n-1 which through a gate circuit 14 is applied to a subsequent unit connected in cascade thereto. The unit number selected by the user dribbles down the cascade of units and a one is subtracted therefrom in each unit until it has become 0, and the unit receiving this 0 unit number is controlled by the associated command code. To that end the command controller 10 further includes a command processor 12 which produces a command which is applied to control circuit 13. Unit number processor 11 thus simply includes a subtractor circuit and without the need of special complicated circuitry or special programmes a number of units of the same type can be remotely controlled by the user, using only one remote control transmitter.

Claims: A remote control system for controlling a plurality of units in an audio and/or video system, comprising a transmitter for transmitting a control packet (Fig. 2) including a control command and a unit type code characterizing the kind of unit (TV, VCR, CD-player etc.) which the user wants to control, each of said units has associated therewith a local unit type code, and comprises remote control receiving means (7) for receiving a control packet, and responding means (8, 10) for responding to the control command embedded in the control packet, when appropriate, characterized in that for distinguishing different units of the same kind in the audio and/or video system which are able to respond to the same commands, each unit has allocated thereto a local unit number code (1, 2, 3, ...) indicating its number in the audio and/or video system; the control packet further including a unit number code indicating that unit of the plurality of like units for which the associated command is intended; the responding means (8, 10) of a unit being adapted to respond to a command when the received control packet embedding that command includes both a unit type code and a unit number code matching the local unit type code and the local unit number code of that unit respectively. A remote control system as claimed in Claim 1 wherein one of the remote control receivers associated with the different units is a master receiver adapted to receive the control packet transmitted by the transmitter, and wherein the further remote control receiver associated with the other units of the system are slave receivers which are connected in cascade, which cascade connection of slave receiver is connected in cascade to the master receiver so that a received control packet dribbles down the cascade of receivers. A remote control system as claimed in Claims 1 and 2 wherein in the master and in each slave receiver the same unit number code is stored and each receiver is provided with means (11) for changing the unit number code of the control packet applied thereto, to define a unit having a lower position in the string of remote control receivers.

Inventors: KAWANAKA, YOSHIKAZU
Applicants: N.V. PHILIPS' GLOEILAMPENFABRIEKEN
Application year: 1986
Main classification: H04B1
IPC codes: H04B1