A digital remote control transmission apparatus

Abstract: A digital remote control transmission apparatus for conducting a remote control of an apparatus to be controlled by sending a digital signal to the apparatus, which comprises: a transmission code of said digital signal comprising a custom code for distinguishing the apparatus to be controlled, an instruction code for operating said apparatus to be controlled, and a separation code for separating said two codes; the respective bits of said custom code and instruction code being data codes which are represented by the positions of data pulses inserted between synchronization pulses of a predetermined period; and said separation codes being codes which includes no data pulses inserted between two synchronization pulses.

Description: FIELD OF THE INVENTION The present invention relates to a digital remote control apparatus, and more particularly to an improvement in the transmission format of such an apparatus. Such a kind of digital remote control apparatus is used as a remote control apparatus for conducting channel setting, volume adjustment, ON/OFF of the power supply, tape play, tape stop, fast forwarding, rewinding, setting (an advanced programming) of start/stop time, date, channel, and days of the week of video or audio recording in such as a television, a video tape recorder, and an audio tape recorder. It is also used in the selection of cooling, heating, or dehumidification, the setting of temperature and time, ON/OFF of the power supply such as in an air conditioner. In summary, it is used as a remote control apparatus in such as electric appliances, automobiles, robots, and electro medical equipments. BACKGROUND ART Figures 1 and 2 show block constructions of a general digital remote control system. In the Figures the reference numeral 31 designates a transmitting circuit including a key input read circuit 11, a code modulation circuit 12, a timing generator 13, and an oscillator 14. The reference numeral 32 designates a receiving circuit including a preamplifier 18, and a remote control signal demodulation circuit 19. The reference numeral 33 designates a light emitting diode or other light emitting element. The reference numeral 34 designates a photo diode or other light receiving element. The reference numeral 10 designates a key matrix for inputting information to the key input read circuit 11 of the transmitting circuit 31. The reference numeral 15 designates a driver circuit comprising a transistor which receives the information from the code modulation circuit 12 of the transmitting circuit 31 and makes a current in accordance with the information flow through the light emitting element 33. The reference numeral 16 designates a light information transmitted from the light emitting element 33 to the light receiving element 34. In such a system, the information to be sent out is input to the transmitting circuit 31 by the key matrix 10, and this is encoded by the transmitting circuit 31, and this is modulated and transmitted in a light signal 16 by the light emitting diode 33. The transmitted light signal 16 is received by the photo diode 34, and this is demodulated by the receiving circuit 32 to decode the instruction. Figure 3 shows a transmission format in such a kind of transmission system which is already developed by the inventor. The distinction of one bit information "0" and "1" are conducted by the intervals 41 and 42 between the two subsequent pulses as shown in Figure 3. That is, the short time interval 41 from the rising up of the pulse to the rising up of the next pulse (in Figure 3(a)) corresponds to a bit "0", and the long time interval 42 of that (Figure 3(b)) corresponds to a bit "1". These information "0" and "1" of several bits are combined to constitute a word as shown in Figure 4, and the kinds of instructions are distinguished from each other on the basis of the data code of this word. In the example of Figure 4, one word 5 comprises a six bit construction, and in this figure the data bit of the word 5 is "010000". Herein, the code 6 designates the repetition period of the word 5. In this transmission system, however, the length of the word becomes short or long dependent on the number of the bit information "0" (or "1") in a word, and this results in difficulty in the interpretation of data from the unawareness of the length of one word at the receiving side. Furthermore, as shown in Figure 5, when a noise 61 entered between the two pulses which represents the bit "1", this bit "1" is erroneously judged as "00" at the receiving side, leading to a malfunction. This causes a fatal defect in a remote control system. Furthermore, in order to avoid interference between remote control systems, there is a way in which systems are distinguished from each other by a custom code for distinguishing the apparatus to be controlled comprising initial two bits of a transmission data code, while the other subsequent four bits constitute an instruction code for operating the apparatus to be controlled, as in the example of Figure 4. However, in such a kind of technical field, various remote controls having various bit constructions are used, and therefore there is a possibility that there may arise interference which prevents the system from being used as a remote control system when the criteria for judging a bit as "0" or "1" are similar to each other in a case where the number of bits in a word is the same for various systems. EP-A-0162327 discloses a pulse coding arrangement which defines "0" and "1" as discussed above with reference to Figs. 3 and 4. The transmission code is made up of a custom code and an instruction code, separated by a pulse interval four times the length of the pulse interval signifying "0". US-A-3767855 discloses a code arrangement in which synchronizing pulses mark the boundaries between successive time intervals, and each time interval contains an information pulse representing a value depending on the timing of the information pulse in the time interval. Eight possible information pulse timings are defined, so that the timing of the information pulse in a time interval can represent any one of "0" to "7". EP-A-0234948 (published on 2 September 1987) discloses a coding system in which a word contains a plurality of data intervals between successive synchronous pulses at a set frequency, and the timing of a data pulse in a data interval defines data value of the interval as "0" or "1". SUMMARY OF THE INVENTION The present invention provides apparatus for encoding and transmitting input data as set out in claim 1, a method of signalling as set out in claim 13 and a pulsed information signal as set out in claim 14. The remaining claims set out optional features. An embodiment of the present invention provides an improved digital remote control transmission apparatus having a constant word length and having superiority in anti-noise characteristics, and further capable of use with a plurality of independent remote control systems. Embodiments of the present invention will be described with reference to the accompanying drawings. It should be understood that the detailed description and specific embodiment are given by way of illustration only, and various changes and modifications within the scope of the invention as defined in the appended claims will be apparent to those skilled in the art. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a diagram showing the brief block construction of a remote control system of the present invention and the prior art system; Figure 2 is a diagram showing the concrete example of the construction of Figure 1; Figure 3 is a diagram for exemplifying the distinction of the bit information "0" and "1" of the prior art device; Figure 4 is a diagram showing the construction of the transmission code of the data signal of the prior art remote control transmission apparatus; Figure 5 is a diagram showing the state where noises are entered into the bit information "1" of the prior art device; Figure 6 is a diagram showing the construction of the transmission code of the data signal of the remote control transmission system of a first embodimemt of the present invention; Figure 7 is a diagram showing the distinction of the bit information "0" and "1" in the present invention; Figure 8 is a diagram showing the state where the noises are entered to the bit information "0" of the first embodiment; Figure 9 is a diagram showing the code construction of the remote control transmission system of a second embodiment of the present invention; and Figure 10 is a diagram showing the code construction of the remote control transmission system of a third embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to explain the present embodiment in detail, reference will be particularly made to Figure 6. Figure 6 shows a construction of the transmission code of a digital remote control transmission apparatus as an embodiment of the present invention. In Figure 6, the reference numeral 21 designates a synchronization pulse of a predetermined period, and this synchronization pulse is made from the pulse which is output from the timing generator 13 by that pulse being applied to the code modulation circuit 12, which generator 13 receives pulses of a predetermined period from the oscillator 14 shown in Figure 2. The reference numeral 22 designates a data pulse inserted between the synchronization pulses 21. For example, this data pulse is produced by that desired information from the key matrix 10 is read in into the key input read circuit 11, and synchronized with the timings of the timing pulses output from the timing generator 13 thereat, and that the synchronized data is input to the code modulation circuit 12. The reference numeral 1 designates a one bit period corresponding to the period between the synchronization pulses 21. The reference numeral 2 designates a custom code for distinguishing the apparatus to be controlled (at the receiving side). In this embodiment this custom code is constituted in a four bit construction. The reference numeral 3 designates a data code for operating the apparatus to be controlled (instruction code). In this embodiment this data code is constituted in a six bit construction. The reference numeral 4 designates a separation code (separation period) for separating the custom code 2 and the data code 3, which is provided as a characteristics of the present invention. In this embodiment this separation code comprises a code in which data pulses are not inserted between the two synchronization pulses 21. The reference numeral 5 designates a one word of the transmission code, and the reference numeral 6 designates a repetition period. Besides, the construction of the remote control system of the present embodiment is the same as those of Figures 1 and 2. In this embodiment, the distinction of the bit "0" and "1" are made as follows. That is, when the period 23 or 25 from the rising up of the synchronization pulse to the rising up of the data pulse subsequent to the synchronization pulse (or from the falling down of the synchronization pulse to the falling down of the data pulse subsequent thereto) is 1 ms the bit is "0" (Figure 7(a)), and when the former period is 2 ms the bit is "1" (Figure 7(b)). Accordingly, the period 1 of the synchronization pulse 21 is 3 ms. In this embodiment, at first the four bit custom code 2 (which is "1001" in the example of Figure 6) is transmitted, and next the period including no data pulses (separation code) 4 is transmitted, and furthermore the six bit data code 3 (which is "110011" in the example of Figure 6) is transmitted. Accordingly, the one word length of the transmission code 5 which has the same bit number is constant regardless of the number of the "0" (or "1") in the data. For example, the one word length is 33.25 ms (= 3 ms × 11 + 0.25 ms) when the pulse width of the synchronization pulse is 0.25 ms. Thus, the data interpretation is easened. Furthermore, even if a noise 71 as shown in Figure 8 is inserted into the data of bit information "0" it becomes as such that two data pulses are inserted in a bit, and it is possible to prevent the malfunction of the receiving side because it is possible to judge them as noises easily at the receiving side. Furthermore, the transmission code 5 is separated into the custom code 2 and the data code (instruction code) 3, and the period (separation code) 4 representing the boundary therebetween is provided. Accordingly, even if the numbers of bits of the whole of the transmission code are equal to each other, it is possible to produce code systems which do not interfere with each other by changing the number of bits in the custom code and the data code. That is, it is possible to produce a plurality of independent remote control systems with the use of the transmission code having the same number of bits. Figure 9 shows a construction of the transmission code of the second embodiment of the present invention. This second embodiment is different from the first embodiment only in the separation code 4A. This separation code 4A is constructed in such a manner that two data pulses 22 are inserted between two synchronization pulses 21. Also in this second embodiment, at first the four bit custom code 2 (which is "1001" in the example of figure 9) is transmitted as similarly as the first embodiment, and next a separation code 4A including two data pulses is transmitted, and the six bit data code 3 (which is "110011" in the example of Figure 9) is transmitted. In this case, one word length of the transmission code 5 having the same bit number is constant regardless of the number of the data "0" (or "1"). For example, when the pulse width of the synchronization pulses is 0.25 ms, one word length is 33.25 ms (= 3 ms × 11 + 0.25 ms). Furthermore, as the transmission code 5 is separated into the custom code 2 and the data code 3 by providing the separation code 4A as a boundary, it is possible to produce code systems which do not interfere with each other even if the numbers of bits of the whole of the transmission code are equal to each other by changing the number of bits in the custom code and the data code. That is, it is possible to produce a plurality of code systems with the use of the transmission codes having the same number of bits. Figure 10 shows a construction of a transmission code as a third embodiment of the present invention. This third embodiment is different from the first embodiment only in the separation code 4B. This separation code 4B is constituted by the two periods A in which data pulses are not inserted between the two synchronization pulses 21 and the period B in which two data pulses 22 are inserted between two synchronization pulses 21, which period B is inserted between the two periods A. Also in this third embodiment, four bit custom code 2 (which is "1001" in the example of Figure 10) is at first transmitted as similarly as the first embodiment, and subsequent thereto a separation code 4B for separating the custom code and the instruction code is transmitted, and furthermore five bit instruction code 3 (which is "01001" in the example of Figure 10) is transmitted. In this case, one word length of the transmission code 5 having the same bit number is constant regardless of the number of the data "0" (or "1"). For example, the one word length is 36.5 ms (= 3 ms × 12 + 0.5 ms) when the pulse width of the synchronization pulses is 0.5 ms. Furthermore, as the transmission code 5 is separated into the custom code 2 and the instruction code 3 and a separation code 4B representing the boundary therebetween is provided, even if the numbers of bits of the whole of the transmission code are equal to each other, it is possible to produce code systems which do not interfere with each other by changing the number of bits in the custom code 2 and the instruction code 3. That is, it is possible to produce a plurality of code systems with the use of the transmission code having the same number of bits. Furthermore, as the separation code 4B representing the boundary between the custom code 2 and the instruction code 3 is constituted by the period A and the period B having two data pulses between the two synchronization pulses, it is possible to produce code systems which, having different combinations of the periods A and B, do not interfere with each other. In the example of Figure 10, the separation code 4B comprises two periods of A and a period of B in sequence of "ABA", but in this third embodiment it is possible to produce 6 kinds of code systems by only using the separation code 4B in a case where the separation code 4B is a 3 bit code comprising two kinds of periods. It is possible to increase the number of the periods constituting the period 4B in order to produce a larger number of code systems which do not interfere with each other. Furthermore, in the above-illustrated embodiment, the period of the synchronization pulse is 3 ms, the time length between the rising ups of the synchronization pulse and the data pulse which corresponds to the bit "0" is 1 ms, and that which corresponds to the bit "1" is 2 ms, but these tine lengths can be set to any values on a condition that the time lengths may be distinguished from each other as those representing the bit "0" and "1", respectively. Furthermore, the synchronization pulse and the data pulse may be frequency modulated by a particular frequency e.g. 38 KHz so as to conduct a transmission in a narrow frequency band, whereby the anti-noise characteristics of the transmission system is enhanced. Furthermore, a leading pulse having a long pulse width may be inserted before the transmission code so that the arrival of the transmission signal may be easily detected at the receiving side. Furthermore, the pulse widths of the synchronization pulse 21 and the data pulse 22 may be different from each other so as to facilitate the distinction between the two pulses at the receiving side. Furthermore, the number of bits of the custom code and the data code may be different from each other so as to facilitate the distinction between the two codes at the receiving side. Furthermore, in the illustrated embodiment the custom code 2 is transmitted before and the instruction code 3 is transmitted after, but the instruction code 3 can be transmitted before. Furthermore, in the first and second embodiments described above, the period 4 for separating the custom code 2 and the data code 3 comprises only one period of the synchronization pulse, but this may comprise an arbitrary number of periods. Furthermore, the separation code 4B for separating the custom code 2 and the instruction code 3 is made of only 3 periods of the synchronization pulses, but any number of periods can be used arbitrarily as already described. In the above-illustrated third embodiment the period B which constitutes the separation code 4B in combination with the period A has two data pulses between the two synchronization pulses, but the number of the data pulses of the period B can be selected arbitrarily. Furthermore, also in such a case the combination of these periods A and B is not restricted to the "ABA", and it can be changed arbitrarily as described above. As can be seen, in each of the foregoing embodiments the transmission code is constituted by a custom code, an instruction code, and a separation code in such a manner that the respective bit information of "0" or "1" of the custom code and the instruction code is represented by the position of the data pulse inserted between the synchronization pulses of a predetermined period, whereby the data interpretation is easened and anti-noise characteristics is enhanced. Furthermore, interference between remote control systems is reduced, and it is made possible to construct a plurality of independent remote control systems.

Claims: Apparatus for encoding and transmitting input data comprising input means (10, 11) for receiving input data and encoding and transmitting means (12, 15, 33) for encoding the input data and transmitting it as a pulsed information signal (5) comprising a plurality of first pulses (21) occurring at a predetermined repetition frequency thereby to define a plurality of periods (1) of a predetermined duration, each respective period (1) starting at a respective one of the f.irst pulses (21) and ending at the next following one of the first pulses (21), the encoding and transmitting means forming first and second portions (2, 3) of the pulsed information signal (5) and a separation portion (4; 4A; 4B) which separates the first and second portions (2, 3), the encoding and transmitting means forming the said portions such that in the first portion (2) and in the second portion (3) a respective second pulse (22) occurs in each said period (1) of said predetermined duration and the data value carried by the pulsed information signal in each said period (1) of the first portion (2) and in each said period (1) of the second portion (3) is represented by the position of the respective second pulse (22) in the period (1), characterised in that the said separation portion (4; 4A; 4B) comprises at least one said period (1) of said predetermined duration, starting at a respective one of the said first pulses (21) and ending at the next following one of the first pulses (21), in which there are no said second pulses (22) or in which there are a plurality of said second pulses (22). Apparatus according to claim 1, wherein the separation portion (4; 4B) comprises a said period (1) of said predetermined duration, starting at a respective one of said first pulses (21) and ending at the next following one of said first pulses (21), in which there are no said second pulses. Apparatus according to claim 1 or claim 2, wherein the separation portion (4A; 4B) comprises a said period (1) of said predetermined duration, starting at a respective one of said first pulses (21) and ending at the next following one of said first pulses (21), in which there are a plurality of said second pulses. Apparatus according to claim 3, wherein in each said period (1) of the first portion (2) or of the second portion (3) the pulsed information signal carries a first data value if the respective second pulse (22) is at a first position in the period and the pulsed information signal carries a second data value if the respective second pulse (22) is at a second position in the period, and the separation portion comprises a said period (1) of said predetermined duration, starting at a respective one of said first pulses (21) and ending at the next following one of said first pulses (21), in which there is a second pulse at the first position and a second pulse at the second position. Apparatus according to any one of the preceding claims, wherein the said first pulses and the said second pulses have different widths from each other. Apparatus according to any one of the preceding claims, wherein the said first pulses and the said second pulses are modulated on a carrier frequency. Apparatus according to any one of the preceding claims, wherein the first and second portions (2, 3) of the signal contain different numbers of bits. Apparatus according to any one of the preceding claims which is a remote control apparatus and the said pulsed information signal is a control signal for a receiving apparatus. Apparatus according to claim 8, wherein one of the said first and second portions identifies which receiving apparatus a signal is intended for and the other of the first and second portions contains a remote control instruction. Apparatus according to claim 8 or claim 9, wherein the separation portion (4B) comprises at least one said period (1) of said predetermined duration, starting at a respective one of said first pulses (21) and ending at the next following one of said first pulses (21), in which there are no second pulses and at least one said period (1) of said predetermined duration, starting at a respective one of said first pulses (21) and ending at the next following one of said first pulses (21), in which there are a plurality of second pulses, the pattern of the types of period in the separation portion identifying a remote control system of which the apparatus is a part. A receiver arranged to receive and de-code a pulsed signal as specified in any one of claims 1 to 10. A remote control system comprising a transmitter as specified in any one of claims 1 to 10, and a receiver as specified in claim 11. A method of signalling using a pulsed information signal (5) comprising a plurality of first pulses (21) occurring at a predetermined repetition frequency thereby to define a plurality of periods (1) of a predetermined duration, each respective period (1) starting at a respective one of the first pulses (21) and ending at the next following one of the first pulses (21), the pulsed information signal (5) having first and second portions (2, 3) such that in the first portion (2) and in the second portion (3) a respective second pulse (22) occurs in each said period (1) of said predetermined duration and the data value carried by the pulsed information signal in each said period (1) of the first portion (2) and in each said period (1) of the second portion (3) is represented by the position of the respective second pulse (22) in the period (1), and the pulsed information signal (5) also having a separation portion (4; 4A; 4B) which separates the first and second portions (2, 3), characterised in that the said separation portion (4; 4A; 4B) comprises at least one said period (1) of said predetermined duration, starting at a respective one of the said first pulses (21) and ending at the next following one of the first pulses (21), in which there are no said second pulses (22) or in which there are a plurality of said second pulses (22). A pulsed information signal (5) comprising a plurality of first pulses (21) occurring at a predetermined repetition frequency thereby to define a plurality of periods (1) of a predetermined duration, each respective period (1) starting at a respective one of the first pulses (21) and ending at the next following one of the first pulses (21), the pulsed information signal having first and second portions (2, 3) such that in the first portion (2) and in the second portion (3) a respective second pulse (22) occurs in each said period (1) of said predetermined duration and the data value carried by the pulsed information signal in each said period (1) of the first portion (2) and in each said period (1) of the second portion (3) is represented by the position of the respective second pulse (22) in the period (1), and the pulsed information signal (5) also having a separation portion (4; 4A; 4B) which separates the first and second portions (2, 3), characterised in that the said separation portion (4; 4A; 4B) comprises at least one said period (1) of said predetermined duration, starting at a respective one of the said first pulses (21) and ending at the next following one of the first pulses (21), in which there are no said second pulses (22) or in which there are a plurality of said second pulses (22).

Inventors: HIROMA MASAKO, HONGO KATSUNOBU, KOBAYASHI HIROSHI, SHICHINOHE DAISUKE, SUDA SHINJI, HIROMA, MASAKO, HONGO, KATSUNOBU, KOBAYASHI, HIROSHI, SHICHINOHE, DAISUKE, SUDA, SHINJI, HIROMA, MASAKO MITSUBISHI DENKI K.K., HONGO, KATSUNOBU MITSUBISHI DENKI K.K., KOBAYASHI, HIROSHI MITSUBISHI DENKI K.K., SHICHINOHE, DAISUKE MITSUBISHI DENKI K.K., SUDA, SHINJI MITSUBISHI DENKI K.K.
Applicants: MITSUBISHI ELECTRIC CORP, MITSUBISHI DENKI KABUSHIKI KAISHA
Application year: 1987
Main classification: G08C19
IPC codes: G08C19