Television remote control system for selectively controlling external apparatus through the AC power line

A remote control system utilizes a portion of television receiver system to control an external appliance through the AC power supply line. The user enters an appliance control command into the keyboard of the television remote control unit. Inside the television receiver, the appliance control command is encoded and modulated onto a carrier signal which is transmitted on the AC power supply line. An external appliance control module, also connected to the AC power supply line, is located near the external appliance for detecting the encoded appliance control command and for selectively controlling the AC power supplied to the external appliance.

FIELD OF THE INVENTION 
This invention relates to remote control systems in television receivers. 
BACKGROUND OF THE INVENTION 
Many television receivers include a remote control system which typically 
has a keyboard with pushbuttons for turning the television on and off, for 
controlling the sound level, and for selecting channels. 
SUMMARY OF THE INVENTION 
The present invention is concerned with a television remote control system 
that enables a user to control appliances external to the television 
receiver. For example, house lights may be turned on and off by 
appropriate command through the television remote control unit. 
In a specific embodiment of the present invention, the television remote 
control unit is used to transmit appliance control data as well as 
television function control data to the television receiver. Inside the 
television receiver, a decoder decodes the transmitted data. When the data 
is of a first predetermined type, television function control apparatus 
responds to control television functions. When the data is of a second 
predetermined type, appliance control apparatus responds to encode the 
data to form an appliance control signal suitable for controlling an 
external appliance. The appliance control signal is modulated and 
transmitted to the external appliance through the alternating current (AC) 
power supply line.

DETAILED DESCRIPTION 
FIG. 1 shows an arrangement whereby an electrically operated device which 
receives power from the AC line, indicated as an appliance 58 which may be 
an electric light, a relay, a motor, etc., is controlled by using a 
television remote control unit 10. The television remote control unit 10 
comprises a keyboard 32 for entering data, an encoder 34 for generating a 
digitally encoded message in accordance with the data entered, and a 
transmitter 36 for generating a carrier signal modulated in accordance 
with the encoded message. A crystal oscillator 38 provides a stable 
carrier frequency for the transmitter 36. A television remote control unit 
which uses infrared (IR) light as the transmitted carrier signal is 
described in the "RCA Engineer", published April 1980, pages 34-37, which 
is hereby incorporated by reference. 
The television receiver 11 includes a TV (television) portion 12 comprising 
a tuner 20, a picture tube 28, an on-screen channel number display 
generator 21, an audio amplifier 26, a speaker 30, a signal processing 
circuit 22, and a power supply 23 which function as a conventional 
television receiver. TV portion 12 further includes a remote control 
receiver 40 for receiving the carrier signal transmitted from remote 
control unit 10 and extracting the modulating signal and a decoder 42 for 
decoding the digitally encoded message. The digitally decoded message is 
applied to TV controller 24 and channel number display generator 21 which 
are responsive to predetermined data relating to television control 
functions and apply control signals to respective television components. 
Typical television control functions include channel selection by means of 
tuner 20, sound level adjustment including a MUTE function which 
eliminates the audio portion of the TV program by means of audio amplifier 
26, television on/off control by means of the power supply 23, and 
"channel number recall" for causing the channel number of the presently 
selected channel to be displayed within the image produced by picture tube 
28. 
Control of devices, such as appliance 58, external to the television 
receiver 11 is provided by an appliance control encoder 46 and an AC line 
modulator 48, the latter being connected to the AC power lines 50 and 52, 
within television receiver 11. A light emitting diode (LED) 44 is mounted 
on television receiver 11 to provide an indication when the television 
remote control system is being used to control external devices. An 
appliance control module 55 is connected between the AC lines 50, 52 and 
the external appliance 58. The appliance control module includes apparatus 
which function as an AC line demodulator 54 and an appliance control 
decoder 56. 
As indicated by the legends next to the buttons on keyboard 32, the same 
pushbuttons that control TV portion 12 are also used to control remote 
appliances. Specifically, the appliance control mode is entered by 
pressing button 9 (COMMAND). In the United States, there is no television 
channel number that has a 9 as the tens digit. Thus, the shared use of the 
9 button is desirable since an additional button for mode selection is not 
needed. Since 9 does not correspond to the tens digit of a valid channel 
number, or any other television control function, TV controller 24 ignores 
it as well as further data. However, appliance control encoder 46 is 
enabled to decode further data. At this point, appliance control encoder 
46 provides power to the appliance control LED 44 to indicate to the user 
that the system is in the appliance control mode. 
Six separate appliances may be controlled from the remote control unit 10. 
To control a specific appliance, one of buttons 1 through 6 is pressed. 
Appliance control encoder 46 recognizes data after the COMMAND data (i.e. 
that corresponding to a 9 in the tens digit of a selected channel number) 
and provides a corresponding encoded appliance control signal to AC line 
modulator 48. The AC line modulator 48 superimposes an encoded signal 
corresponding to the appliance control signal onto the AC voltage on power 
lines 50 and 52. 
The encoded signal on the AC power lines is detected by AC line demodulator 
54 which couples a decoded appliance control signal to appliance control 
decoder 56. The appliance control decoder 56 recognizes its unique code 
(between 1 and 6) and is activated to receive further commands, e.g., to 
cause AC power to be coupled or decoupled from appliance 58. 
After an appliance is selected by pressing one of the buttons 1 through 6, 
the selected appliance is then controlled by pressing one of the buttons 
7, 8, 9, CHANNEL UP, or CHANNEL DOWN corresponding to an appliance control 
command. For example, if button 7 is pressed, appliance 58 will turn on. 
If button 8 is pressed, appliance 58 will turn off. If CHANNEL UP is 
pressed, the illumination will grow brighter so long as that button is 
pressed down (assuming that appliance 58 is a lamp). If the CHANNEL DOWN 
is pressed, the illumination will grow dimmer so long as that button is 
pressed down. To control other appliances (not shown) a different button 
between 1 and 6 is pressed and subsequent commands are entered. The ALL ON 
button will turn on all lights. The ALL OFF button will turn off all 
devices. 
Appliance control mode is disabled by pressing the RECALL button. 
Alternatively, appliance control mode is automatically disabled after 16 
seconds during which no appliance data is entered. Disabling appliance 
control mode returns the television remote control system to its normal 
television control function. The above described control functions are 
summarized in Table I below. 
TABLE I 
______________________________________ 
Button Command 
______________________________________ 
9 Enable Control Mode 
1-6 Select particular device for 
control 
7 Turn selected device on 
8 Turn selected device off 
9 Turn all lights on 
0 Turn all devices off 
CHANNEL UP Increase AC power to 
selected device 
CHANNEL DOWN Decrease AC power to 
selected device 
RECALL Disable Control Mode 
______________________________________ 
FIG. 2 shows further details of the television receiver 11 and appliance 
control encoder 46. An IR sensitive diode 60 is coupled to a preamplifier 
62 and a digital decoder 64. The output of the digital decoder 64 is a 
data buss comprising data bits A0, A1, A2, A3, CH UP, and CH DN. The data 
buss is connected to a microprocessor 68, and, through NOR gates 100 and 
buffer amplifiers 101, to TV controller 24 and channel number display 
generator 21 (FIG. 1). 
Microprocessor 68 is also coupled through buffer amplifiers 103 to a pair 
of multiplexers 70 and 72 which control an ultrasonic encoder 74. The 
output of the ultrasonic encoder 74 is a sequential digital data signal 
representative of the appliance control data and is fed to an ultrasonic 
transmitter 76 which provides an ultrasonic signal to an ultrasonic 
command console 82. The ultrasonic command module 82 comprises an 
ultrasonic receiver 78, an appliance control unit 80, and an AC line 
modulator 48 which re-encodes the appliance control data as a second 
sequential digital data signal for transmission on the AC power lines. In 
such manner, the command module 82 communicates with compatible appliance 
control modules AP1, AP2, and AP3 over the 120 VAC power lines. 
The link between the television receiver and the AC power lines is provided 
by using commercially available products from BSR, Ltd., Blauvelt, N.Y. 
Specifically, BSR Model CC401 ultrasonic cordless controller, which 
contains the ultrasonic encoder 74 (IC type 7928) and the ultrasonic 
transmitter 76, is modified and interfaced to the television receiver. A 
BSR Ltd. Model UC301 ultrasonic command console 82 is connected to the AC 
power lines. Compatible remote modules AP1, AP2, and AP3 for controlling 
appliances including dimmer modules for controlling lights, are available 
from BSR Ltd. 
The multiplexers 70 and 72 simulate the button depressions that are the 
normal input to the ultrasonic encoder 74. That is, a pushbutton keyboard 
is normally connected to ultrasonic encoder 74 so that for each button 
depression thereof, one of pins 1, 28 and 25 is connected to one of pins 
16 through 23. Multiplexer 70, an eight line-to-one line switch, and 
multiplexer 72, a four line-to-one line switch (both available from RCA 
Corporation as integrated circuit (IC) types CD4051 and CD4052 
respectively), are controlled by microprocessor 68 to selectively 
interconnect appropriate pins of ultrasonic encoder 74. 
For example, when the A, B, and C inputs to multiplexer 70 (from 
microprocessor 68) are at logical 1, 0, and 1 respectively (and the 
inhibit input to multiplexer 70 is at logic 0), then pin 18 of the 
ultrasonic encoder 74 is selected by multiplexer 70. Simultaneously, if 
the A and B inputs to multiplexer 72 are at logic 1 and 0 respectively, 
then pin 1 of the ultrasonic encoder 74 is selected by multiplexer 72. 
Since the output of multiplexer 72 is connected to the input to 
multiplexer 70, pins 1 and 18 of the ultrasonic encoder 74 are connected 
together. When the inhibit signal is at logic 1, multiplexers 70 and 72 do 
not interconnect any pins of the ultrasonic encoder 74. 
Table II below gives the pin connection assignments corresponding to 
respective appliance control signals generated by the ultrasonic encoder 
74. Continuing the above example, when pins 1 and 18 of the ultrasonic 
encoder 74 are connected together, the ultrasonic encoder 74 will send out 
an appliance control signal corresponding to appliance 5. As a further 
example, when pins 25 and 20 are connected together, the ultrasonic 
encoder 74 will generate an appliance control signal corresponding to the 
ON command. Device codes 7-16, shown in parenthesis in Table II, are 
unused since only device codes 1-6 are used in the present embodiment. 
TABLE II 
______________________________________ 
Pin 1 
Pin 28 Pin 25 
______________________________________ 
Pin 23 (15) (16) Dim 
Pin 22 (11) (12) Off 
Pin 21 (13) (14) All Off 
Pin 20 3 4 On 
Pin 19 (7) (8) Bright 
Pin 18 5 6 All lamps on 
Pin 17 1 2 Unused 
Pin 16 (9) (10) Unused 
______________________________________ 
The particular television receiver used in the present embodiment is an RCA 
1981 Model FER498WR wherein the data buss comprising data bits A0, A1, A2, 
A3, CH UP, and CH DN operates as follows. When the CHANNEL UP button at 
the remote control keyboard is pressed, the CH UP bit goes low (logic 0 in 
positive logic notation), and the CH DN bit goes high (logic 1 in positive 
logic notation). When the CHANNEL DOWN button is pressed, the CH DN bit 
goes low and the CH UP bit goes high. When no buttons are pressed, CH UP 
and CH DN bits are both normally high. The CH UP and CH DN bits also serve 
as a strobe signal for the remaining data bits A0, A1, A2, and A3. That 
is, bits A0 through A3 transmit data corresponding to buttons 0 through 9 
in complemented binary form. However, the data on bits A0 through A3 is 
valid for controlling appliances only when CH UP and CH DN data bits are 
both low. Microprocessor 68 causes data bits CH UP and CH DN to both 
become low when it detects that the appliance control mode has been 
entered by button 9 (COMMAND) having been pressed. Table III, below, 
summarizes the data buss codes for respective buttons on the remote 
control unit keyboard. 
TABLE III 
______________________________________ 
Mul- Mul- 
ti- ti- 
plex- plex- 
Data Buss er er 
CH CH 72 70 In- 
Button DN UP A3 A2 A1 A0 BA CBA hibit 
______________________________________ 
0 (ALL OFF) 
0 0 1 1 1 1 11 010 0 
1 0 0 1 1 1 0 01 110 0 
2 0 0 1 1 0 1 10 110 0 
3 0 0 1 1 0 0 01 011 0 
4 0 0 1 0 1 1 10 011 0 
5 0 0 1 0 1 0 01 101 0 
6 0 0 1 0 0 1 10 101 0 
7 (ON) 0 0 1 0 0 0 11 011 0 
8 (OFF) 0 0 0 1 1 1 11 001 0 
9 (ALL ON) 
0 0 0 1 1 0 11 101 0 
CH UP 1 0 X X X X 11 100 0 
(BRIGHT) 
CH DN 0 1 X X X X 11 000 0 
(DIM) 
RECALL 0 0 0 0 0 0 XX XXX 1 
______________________________________ 
X = Don't care states 
In an unmodified television receiver, the data buss output (A0, A1, A2, A3, 
CH UP, and CH DN) of digital decoder 64 is directly connected to the data 
buss input (A0', A1', A2', A3', CH UP', and CH DN) of TV controller 24 
(FIG. 1). See RCA Service data 1980 C-7-S1 for a schematic (MCR1011A) 
corresponding to digital decoder 64, and a schematic (MCS009A) 
corresponding to TV controller 24. In the present embodiment, buffers 101 
and OR gates 100 are interposed between digital decoder 64 and TV 
controller 24 to connect respective bits of the data buss through 
appropriate non-inverting amplifiers. Buffers 101 and OR gates 100 may be 
realized using IC Types 7417, and CD4071 respectively. Resistors 90, 91, 
92 93, 94, 95, 96, 97, 98 and 99 are connected to provide the proper 
voltage level for respective data bit lines. 
Also, in normal operation, the data bits A0', A1', A2' and A3' (in addition 
to transmitting signals representing data entered at the remote control 
unit) are also used to transfer data between the TV controller 24 and the 
channel numbers display generator 21 (FIG. 1). Specifically, when data 
bits CH UP and CH DN (the strobe signals) are both high, data bits A0', 
A1', A2', and A3' are used to transmit data from the TV controller 24 to 
the channel number display generator 21 which data represents the units 
digit of the currently selected viewing channel. Consider for example, the 
channel selection 43. After the 4 digit is entered, the TV controller 
generates signals to the channel number display generator to display a 
"4-" on the television screen. At that time, data bits A0', A1', A2', and 
A3' represent a digital code for a "-", i.e., a hexidecimal code E or the 
binary code 0111 respectively. After the 3 digit is entered, data bits A0' 
through A3' represent the digital code for a "3". The dual use of the data 
bits A0' through A3' for both entering data and displaying channel 
selection is advantageously used by the microprocessor 68 for detecting 
when the user has selected a channel with a 9 in the tens digit. 
A microprocessor adaptable for use with the present invention is a type 
8748 available from Intel Corporation. Ports P10, P11, P12, P13, P14 and 
P15 are connected to respective data bits A0, A1, A2, A3, CH UP, and CH 
DN. Port P26 is connected to drive LED 44 through resistor R1 and 
transistor Q1 in emitter follower configuration. Port 17 is connected to 
OR gates 100 for disabling the strobe signals (CH UP and CH DN) from the 
TV controller when the system is in appliance control mode. Data bits DB0, 
DB1, DB2, and DB3 are connected to receive respective data bits A0', A1', 
A2', and A3' through buffer amplifiers 102 (IC Type CD4050). Ports P20, 
P21, P22, P23, P24 and P25 are connected through buffer amplifiers 103 (IC 
Type 7417) to control multiplexers 70 and 72. Resistors 83, 84, 85, 86 and 
87 are pull-up resistors which provide proper signal level inputs to 
multiplexers 70 and 72. 
The 8748 microprocessor is provided with an integral erasable read only 
memory, which is useful for developing prototype programs. However, in 
production, a microprocessor or other controller with mask programmable 
read only memory would be more economical. 
Microprocessor 68 is programmed to provide control functions and data 
translation functions between digital decoder 64 and multiplexers 70 and 
72. Table III lists the required control signal inputs to multiplexers 70 
and 72 for each corresponding data buss code. A flow chart of the control 
program for the microprocessor 68 is shown in FIG. 3. 
The operation of the system of FIG. 2 will be considered in conjunction 
with the flow chart of FIG. 3. Initially, port P17 is set low, enabling OR 
gates 100 to transmit CH UP and CH DN signals to the TV controller. Also, 
port P25 is set high, inhibiting operating of multiplexers 70 and 72, and 
port P26 is set low so that LED 44 is off. 
After initialization, microprocessor 68 reads data representing each 
subsequent button entry on ports P10 through P15. When a 9 digit is 
received (step 110), the microprocessor proceeds (in step 111) to read 
data bits DB0 through DB3. If data bits DB0 through DB3 represent a "-" 
(Code E), then the tens digit of a selected channel is equal to 9 and 
appliance control mode is entered in step 112, which turns on appliance 
control LED 44 by setting port P26 high. Port P17 is also set high in 
appliance control mode, disabling OR gates 100 so that CH UP and CH DN 
signals are not transmitted to the TV controller. The CH UP and CH DN 
signals (the strobe signals) are thus disabled so that subsequent 
appliance control data will not inadvertently interfere with regular 
television control functions. 
For each subsequent digit received, i.e., data representing 0 through 9, CH 
UP or CH DN, a corresponding output on ports P20 through P25 is generated 
by the program (step 118) to multiplexers 70 and 72 in accordance with the 
relationship given in Table III. If no button is pressed for 16 seconds, 
appliance control mode is terminated (step 116) by setting port P26 low 
which turns off LED 44 (step 122), and setting port P17 low enabling OR 
gates 100 which enables CH UP and CH DN signals to be gated to the TV 
controller. Alternatively, if the code for the RECALL button was received 
in step 120, then P26 and P17 are set low terminating appliance control 
mode (step 122). The program then returns to the beginning (step 122). 
The use of readily available ultrasonic components provides a convenient 
interface between the television receiver and the AC power line which 
minimizes the risk that low power circuits in the television receiver will 
be accidently exposed to 120 VAC line voltage. Also, the ultrasonic 
encoder 74 and ultrasonic transmitter 76 may be contained inside the 
television receiver, while the ultrasonic command console, which has a 
keyboard for alternate data entry, can be placed at any convenient 
location near the television receiver. However, the ultrasonic link has a 
relatively slow response and increases total system cost. Therefore, a 
mass produced system would be made more cost effective using a direct 
interface between the television receiver and the AC power line, thereby 
eliminating the ultrasonic link. Also, isolation between the appliance 
control encoder and the AC power lines may be achieved by the use of an 
optical isolator. 
More than six appliances may be controlled by providing additional buttons 
on the remote control keyboard, as well as additional encoding and 
decoding apparatus to accommodate the additional device codes. The 
disclosed system may also be configured to provide for programmability of 
external appliances. For example, microprocessor 68 may be arranged to be 
programmable by the user to turn selected appliances on and off at future 
dates and times. Furthermore, for cost effectiveness, the control function 
performed by the microprocessor 68 can be advantageously combined with the 
control functions provided in the television receiver, thereby eliminating 
the need for a separate microprocessor.