JP2010114636A - Information processing apparatus and mode switching method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To cancel a power saving mode from the reception side to transmit data utilizing clock components extracted from reception signals. <P>SOLUTION: The information processing apparatus includes: a first part including a first signal transmitting unit for coding a first data into a waveform not including a DC component and having a polarity inverted in each half cycle of a clock and transmitting it to a second part, a current detecting unit for detecting a current amount flowing to a signal line, and a transmission control unit for transmitting the signal of the first data to the second pat in a first mode, stopping the signal transmission of the first data in a second mode and switching to the first mode corresponding to the change of the current amount detected in the second mode; and a second part including a clock detecting unit for detecting the clock from the polarity inverting cycle of the signal of the first data, a second signal transmitting unit for coding a second data into a waveform not including the DC component using the clock and transmitting it in synchronism with the clock, and a load control unit for changing the current amount in the second mode. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an information processing apparatus and a mode switching method.

  In mobile terminals typified by mobile phones and the like, a movable member is often used at a connection portion between an operation portion operated by a user and a display portion on which information is displayed. For example, a folding cellular phone opening / closing structure is typical. Furthermore, recent mobile phones are equipped with a video viewing function, an image capturing function, etc. in addition to a call function and an e-mail function. It is done. For example, when using the video viewing function, the user will want to store the operation part unnecessary for viewing by directing the display part toward the user. In this way, when using a mobile phone as a normal phone, as a digital camera, or as a television receiver, the orientation and position of the display part can be easily changed for each application. A structure that can be made is required.

  However, a large number of signal lines and power lines are wired at the connection portion between the operation portion and the display portion. For example, several tens of wires are connected in parallel to the display portion (see FIG. 1). For this reason, when a movable member capable of complicated movement as described above is used for the connection portion, the reliability of such wiring is significantly lowered. For these reasons, the technology has shifted from a parallel transmission system to a serial transmission system (see FIG. 2) in order to reduce the number of signal lines in the connection portion. Of course, a technical shift for the same reason occurs not only in the world of mobile phones but also in the world of various electronic devices that require complex wiring. In addition to the above, the reason for serialization is to reduce radiated electromagnetic noise (EMI; Electro Magnetic Interference).

  In the serial transmission method as described above, transmission data is transmitted after being encoded by a predetermined method. As this encoding method, for example, an NRZ (Non Return to Zero) code method, a Manchester code method, an AMI (Alternate Mark Inversion) code method, or the like is used. For example, Patent Document 1 below discloses a technique for transmitting data using an AMI code, which is a typical example of a bipolar code. In the same document, a technique is disclosed in which a data clock is expressed by an intermediate value of a signal level and transmitted, and the data clock is reproduced on the receiving side based on the signal level.

Japanese Patent Laid-Open No. 3-109984

  Among the above encoding methods, the signal of the NRZ encoding method includes a direct current component. Therefore, it is difficult to transmit an NRZ code signal together with a DC component such as a power supply. On the other hand, the signal of the Manchester code system or the AMI code system does not include a DC component. Therefore, it can be transmitted together with a DC component such as a power source. In addition, the present inventor has developed an encoding technique that does not include a DC component and can easily extract a clock component from a received signal. In this technique, for input data including first and second bit values different from each other, the first bit value is expressed by a plurality of first amplitude values, and the second bit value is expressed by the first bit value. It is expressed by a second amplitude value different from the amplitude value, and is encoded so that the same amplitude value is not continuously taken and the polarity of the amplitude value is inverted every cycle. By using this technique, it is possible to regenerate the clock based on the clock component extracted from the received signal. In addition, a bidirectional transmission technique has been developed that can transmit data in the reverse direction from the receiving side to the transmitting side while using this technique. Here, the side that transmits the above-mentioned code that can be recovered by the clock is called the transmitting side.

  In the bidirectional transmission technology, data is transmitted in the time-division or the same time in the reverse direction from the reception side to the transmission side using the clock detected from the data signal transmitted from the transmission side to the reception side. That's it. However, in a predetermined operation mode such as the power save mode, data transmission from the transmission side to the reception side is stopped. For this reason, when shifting to such an operation mode, the clock cannot be recovered on the receiving side, and data transmission in the reverse direction from the receiving side to the transmitting side becomes impossible. As a result, a signal for resuming data transmission from the transmission side to the reception side in accordance with an operation of a switch or the like provided on the reception side cannot be transmitted in the reverse direction from the reception side to the transmission side.

  Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide a code that does not include a DC component and can easily extract a clock component from a received signal. New and improved information processing apparatus and mode switching method capable of canceling the operation mode from the receiving side in the operation mode in which data transmission from the transmitting side to the receiving side is stopped in the configuration to be used Is to provide.

  In order to solve the above problems, according to an aspect of the present invention, an information processing apparatus including the following first module and second module is provided.

  The first module encodes the first transmission data into a waveform that does not include a direct current component and whose polarity is inverted every half cycle of the clock, and transmits the first transmission data to the second module through a predetermined signal line. A signal transmission unit; a current detection unit configured to detect an amount of current flowing through the predetermined signal line; and a signal of the first transmission data transmitted to the second module in the first mode; Transmission control that stops transmission of the signal of the first transmission data in the mode, and switches to the first mode in accordance with a change in the amount of current detected by the current detection unit in the second mode Part.

  The second module includes a clock detection unit that detects the clock based on a polarity inversion period of the signal of the first transmission data transmitted through the predetermined signal line, and a clock detected by the clock detection unit. A second signal transmission unit that encodes the second transmission data into a waveform that does not include a DC component and transmits the second transmission data to the first module in synchronization with the clock; and the predetermined signal in the second mode. And a load controller that changes the amount of current flowing through the signal line.

  Further, the information processing apparatus described above may be configured as follows. For example, the load control unit changes the amount of current flowing through the predetermined signal line in a predetermined pattern.

  The predetermined signal line includes a power line for transmitting a power signal supplied from a DC power source. In this case, the first module further includes a signal superimposing unit that superimposes the power signal on the signal of the first transmission data to generate a superimposed signal. Further, the first signal transmission unit transmits the superimposed signal to the second module. The second module further includes a signal separation unit that separates the superimposed signal into the power signal and the first transmission data signal.

  In addition, a first time zone in which a signal is transmitted from the first signal transmission unit and a second time zone in which a signal is transmitted from the second signal transmission unit are divided on the time axis. Also good.

  The second signal transmission unit may be configured to transmit the second transmission data signal in synchronization with the first transmission data signal transmitted through the predetermined signal line. Good. In this case, the first module extracts a signal of the second transmission data by subtracting the signal of the first transmission data from the signal multiplexed on the predetermined signal line. It further has a part. The second module extracts a signal of the first transmission data by subtracting the signal of the second transmission data from the signal multiplexed on the predetermined signal line. It has further.

  In order to solve the above-described problem, according to another aspect of the present invention, in the first mode, the first module does not include a DC component and has a polarity every half cycle of the clock. A first signal transmission step of encoding first transmission data in a waveform to be inverted and transmitting the first transmission data to a second module through a predetermined signal line; and the second module transmitted from the first module A clock detection step for detecting the clock based on the polarity inversion period of the signal of the first transmission data, and encoding the second transmission data in a waveform that does not include a DC component using the clock detected in the clock detection step And the second signal transmission step of transmitting to the first module in synchronization with the clock is executed, and the mode is changed from the first mode to the second mode. The step of causing the first module to stop signal transmission of the first transmission data is executed, and in the second mode, the amount of current flowing through the predetermined signal line is changed in the second module. A load control step, a current detection step in which the first module detects an amount of current flowing through the predetermined signal line, and a second mode when a change in the amount of current is detected in the current detection step. And a control step of switching to the first mode is provided.

  In order to solve the above problem, according to another aspect of the present invention, a program for causing a computer to realize the functions of the information processing apparatus can be provided. Furthermore, a computer-readable recording medium on which the program is recorded can be provided.

  As described above, according to the present invention, data transmission from the transmission side to the reception side is stopped in a configuration using a code that does not include a DC component and can easily extract a clock component from the reception signal. It is possible to cancel the operation mode from the receiving side when the operation mode is set.

  Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In addition, in this specification and drawing, about the component which has the substantially same function structure, duplication description is abbreviate | omitted by attaching | subjecting the same code | symbol.

[About the flow of explanation]
Here, the flow of explanation regarding the embodiment of the present invention described below will be briefly described. First, with reference to FIG. 1, a technical problem of a portable terminal or the like that employs a parallel transmission method will be briefly described. Next, with reference to FIG. 2 to FIG. 6, problems with the signal transmission technology adopting the serial transmission method will be described. Next, a novel signal transmission technique devised to solve the problems of the signal transmission technique adopting the serial transmission method will be described with reference to FIGS. In addition, technical problems of such a new signal transmission technology will be described.

  Based on the technical features and problems of the above-described novel signal transmission technology, a technology for extending the technology related to the new scheme to bidirectional transmission (hereinafter, “expansion scheme”) will be described with reference to FIGS. 14 to 16. Next, a technical problem in the expansion method will be described with reference to FIGS. 17 and 18. Next, a functional configuration of the mobile terminal and a mode switching method according to the embodiment that can solve the above technical problems will be described with reference to FIGS. 19 and 20. Finally, the technical idea of the embodiment will be summarized and the effects obtained from the technical idea will be briefly described.

(Description item)
1: Arrangement of issues 1-1: Parallel transmission method 1-2: Serial transmission method 1-3: Data transmission method using power line 2: Basic technology 1 (new method)
3: Fundamental technology 2 (Expansion to new bidirectional transmission; Expansion method)
4: Embodiment 4-1: Functional configuration of portable terminal 500 4-2: About return method from power save mode 4-3: Summary

<1: Arrangement of issues>
First, prior to a detailed description of a technique according to an embodiment of the present invention, problems to be solved by the embodiment will be briefly summarized.

[1-1: Parallel transmission system]
First, a configuration example of the mobile terminal 100 adopting the parallel transmission method will be briefly described with reference to FIG. FIG. 1 is an explanatory diagram illustrating a configuration example of a mobile terminal 100 adopting a parallel transmission method. In FIG. 1, a mobile phone is schematically drawn as an example of the mobile terminal 100. However, the scope of application of the technology according to the following description is not limited to mobile phones.

  As shown in FIG. 1, a mobile terminal 100 mainly includes a display unit 102, a liquid crystal unit 104 (LCD), a connection unit 106, an operation unit 108, a baseband processor 110 (BBP), and a parallel signal line. 112. However, LCD is an abbreviation for Liquid Crystal Display. The display unit 102 may be referred to as a display side (D) and the operation unit 108 may be referred to as a main body side (M). In the following description, a case where a video signal is transmitted from the main body side to the display side will be described as an example. Of course, the following technique is not limited to this.

  As shown in FIG. 1, the display unit 102 is provided with a liquid crystal unit 104. The liquid crystal unit 104 displays the video signal transmitted through the parallel signal line 112. The connection unit 106 is a member that connects the display unit 102 and the operation unit 108. The connection member forming the connection unit 106 has a structure that can rotate the display unit 102 180 degrees in the ZY plane, for example. In addition, the connection member has a structure in which the display unit 102 can be rotated in the XZ plane so that the portable terminal 100 can be folded. Note that the connecting member may have a structure that allows the display unit 102 to move in a free direction.

  The baseband processor 110 is an arithmetic processing unit that provides communication control of the portable terminal 100 and an application execution function. The parallel signal output from the baseband processor 110 is transmitted to the liquid crystal unit 104 of the display unit 102 through the parallel signal line 112. A large number of signal lines are wired in the parallel signal line 112. For example, in the case of a mobile phone, the number of signal lines n is about 50. The transmission speed of the video signal is about 130 Mbps when the resolution of the liquid crystal unit 104 is QVGA. The parallel signal line 112 is wired so as to pass through the connection unit 106.

  That is, a large number of signal lines forming the parallel signal line 112 are wired to the connection unit 106. As described above, when the movable range of the connecting portion 106 is expanded, the risk of damage to the parallel signal line 112 due to the movement increases. As a result, the reliability of the parallel signal line 112 is impaired. On the other hand, if the reliability of the parallel signal line 112 is to be maintained, the movable range of the connecting portion 106 is restricted. For these reasons, the serial transmission method is increasingly used in mobile phones and the like for the purpose of achieving both the freedom of the movable member forming the connection portion 106 and the reliability of the parallel signal line 112. Also, serialization of transmission lines is being promoted from the viewpoint of radiated electromagnetic noise (EMI).

[1-2: Serial transmission method]
A configuration example of the mobile terminal 130 adopting the serial transmission method will be briefly described with reference to FIG. FIG. 2 is an explanatory diagram showing a configuration example of the mobile terminal 130 adopting the serial transmission method. In FIG. 2, a mobile phone is schematically drawn as an example of the mobile terminal 130. However, the scope of application of the technology according to the following description is not limited to mobile phones. Further, constituent elements having substantially the same functions as those of the mobile terminal 100 of the parallel transmission system shown in FIG. 1 are assigned the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 2, the mobile terminal 130 mainly includes a display unit 102, a liquid crystal unit 104 (LCD), a connection unit 106, and an operation unit 108. Further, the mobile terminal 130 includes a baseband processor 110 (BBP), parallel signal lines 132 and 140, a serializer 134, a serial signal line 136, and a deserializer 138.

  Unlike the portable terminal 100 described above, the portable terminal 130 transmits a video signal by a serial transmission method through a serial signal line 136 wired to the connection unit 106. Therefore, the operation unit 108 is provided with a serializer 134 for serializing the parallel signal output from the baseband processor 110. On the other hand, the display unit 102 is provided with a deserializer 138 for parallelizing serial signals transmitted through the serial signal line 136.

  The serializer 134 converts the parallel signal output from the baseband processor 110 and input via the parallel signal line 132 into a serial signal. The serial signal converted by the serializer 134 is input to the deserializer 138 through the serial signal line 136. Then, the deserializer 138 restores the input serial signal to the original parallel signal and inputs it to the liquid crystal unit 104 through the parallel signal line 140.

  For example, a data signal encoded by the NRZ encoding method is transmitted to the serial signal line 136 alone, or a data signal and a clock signal are transmitted together. The number k of serial signal lines 136 is significantly smaller than the number n of parallel signal lines 112 included in the mobile terminal 100 of FIG. 1 (1 ≦ k << n). For example, the number k of wirings can be reduced to about several. For this reason, it can be said that the degree of freedom regarding the movable range of the connection portion 106 to which the serial signal line 136 is wired is much greater than that of the connection portion 106 to which the parallel signal line 112 is wired. At the same time, it can be said that the reliability of the serial signal line 136 is high. A differential signal such as LVDS is usually used for the serial signal flowing through the serial signal line 136. However, LVDS is an abbreviation for Low Voltage Differential Signal.

(Functional configuration)
Here, the functional configuration of the mobile terminal 130 adopting the serial transmission method will be described with reference to FIG. FIG. 3 is an explanatory diagram showing an example of a functional configuration of the mobile terminal 130 adopting the serial transmission method. However, FIG. 3 is an explanatory diagram drawn centering on the functional configuration of the serializer 134 and the deserializer 138, and descriptions regarding other components are omitted.

(Serializer 134)
As illustrated in FIG. 3, the serializer 134 includes a P / S conversion unit 152, an encoder 154, an LVDS driver 156, a PLL unit 158, and a timing control unit 160.

  As shown in FIG. 3, a parallel signal (P-DATA) and a parallel signal clock (P-CLK) are input to the serializer 134 from the baseband processor 110. The parallel signal input to the serializer 134 is converted into a serial signal by the P / S converter 152. The serial signal converted by the P / S converter 152 is input to the encoder 154. The encoder 154 adds a header or the like to the serial signal and inputs it to the LVDS driver 156. The LVDS driver 156 transmits the input serial signal to the deserializer 138 by a differential transmission method using LVDS.

  On the other hand, the parallel signal clock input to the serializer 134 is input to the PLL unit 158. The PLL unit 158 generates a serial signal clock from the parallel signal clock and inputs the serial signal clock to the P / S conversion unit 152 and the timing control unit 160. The timing control unit 160 controls the transmission timing of the serial signal by the encoder 154 based on the input serial signal clock.

(Deserializer 138)
As shown in FIG. 3, the deserializer 138 is mainly configured by an LVDS receiver 172, a decoder 174, an S / P converter 176, a clock recovery unit 178, a PLL unit 180, and a timing control unit 182. The

  As shown in FIG. 3, a serial signal is transmitted from the serializer 134 to the deserializer 138 by a differential transmission method using LVDS. This serial signal is received by the LVDS receiver 172. The serial signal received by the LVDS receiver 172 is input to the decoder 174 and the clock recovery unit 178. The decoder 174 detects the head portion of the data with reference to the header of the input serial signal and inputs it to the S / P converter 176. The S / P converter 176 converts the input serial signal into a parallel signal (P-DATA). The parallel signal converted by the S / P converter 176 is output to the liquid crystal unit 104.

  On the other hand, the clock regeneration unit 178 refers to a reference clock input from the outside, and regenerates the parallel signal clock from the serial signal clock using the built-in PLL unit 180. The parallel signal clock recovered by the clock recovery unit 178 is input to the decoder 174 and the timing control unit 182. The timing control unit 182 controls the reception timing based on the parallel signal clock input from the clock recovery unit 178. The parallel signal clock (P-CLK) input to the timing control unit 182 is output to the liquid crystal unit 104.

  As described above, the parallel signal (P-DATA) and the parallel signal clock (P-CLK) input from the baseband processor 110 to the serializer 134 are converted into a serial signal and transmitted to the deserializer 138. The input serial signal is restored to the original parallel signal and the parallel signal clock by the deserializer 138, and is output to the liquid crystal unit 104.

  Like the mobile terminal 130 described above, the transmission line is serialized by converting the parallel signal into a serial signal and transmitting it. As a result, the movable range of the portion where the serial signal line is arranged is expanded, and the degree of freedom regarding the arrangement of the display unit 102 is improved. Therefore, for example, when viewing a television broadcast or the like using the mobile terminal 130, the mobile terminal 130 can be deformed so that the arrangement of the display unit 102 is horizontally long when viewed from the user. With the improvement in the degree of freedom, the usage of the mobile terminal 130 is expanded, and various usage forms such as viewing of video and music in addition to various functions as a communication terminal are born.

[1-3: Data transmission method using power line]
In the mobile terminal 130 described above, a Manchester coding method (see FIG. 5) or an AMI coding method (see FIG. 6) that does not include a DC component can be used as the coding method. In this way, an encoded signal that does not include a DC component can be transmitted by being superimposed on the power supply. Therefore, a technique for applying the power line transmission method to the mobile terminal 130 will be described. The portable terminal 230 is a configuration example using this technology.

(Functional configuration)
First, the functional configuration of the mobile terminal 230 capable of transmitting data using a power supply line will be described with reference to FIG. FIG. 4 is an explanatory diagram illustrating an example of a functional configuration of the mobile terminal 230 that can transmit data using a power line. However, FIG. 4 is an explanatory diagram drawn centering on the functional configuration of the serializer 134 and the deserializer 138, and descriptions regarding other components are omitted. In addition, among the constituent elements of the mobile terminal 230, constituent elements having substantially the same functional configuration as the mobile terminal 130 already described are denoted by the same reference numerals, and detailed description thereof is omitted.

(Serializer 134)
As illustrated in FIG. 4, the serializer 134 includes a P / S conversion unit 152, an encoder 154, an LVDS driver 156, a PLL unit 158, a timing control unit 160, and a superimposition unit 232.

  As shown in FIG. 4, a parallel signal (P-DATA) and a parallel signal clock (P-CLK) are input to the serializer 134 from the baseband processor 110. The parallel signal input to the serializer 134 is converted into a serial signal by the P / S converter 152. The serial signal converted by the P / S converter 152 is input to the encoder 154. The encoder 154 adds a header or the like to the serial signal, encodes the signal with a DC component-free (or less) method such as the Manchester encoding method, and inputs the encoded signal to the LVDS driver 156.

  The LVDS driver 156 converts the input serial signal into LVDS and inputs it to the superimposing unit 232. The superimposing unit 232 superimposes the signal input from the LVDS driver 156 on the power supply line and transmits the signal to the deserializer 138. For example, the superimposing unit 232 couples a signal with a capacitor and a power source with a choke coil. For example, a coaxial cable is used as a transmission line for the power supply line. The power supply line is a line provided for supplying power from the operation unit 108 to the display unit 102.

  Meanwhile, the parallel signal clock input to the serializer 134 is input to the PLL unit 158. The PLL unit 158 generates a serial signal clock from the parallel signal clock and inputs the serial signal clock to the P / S conversion unit 152 and the timing control unit 160. The timing control unit 160 controls the transmission timing of the serial signal by the encoder 154 based on the input serial signal clock.

(Deserializer 138)
As shown in FIG. 4, the deserializer 138 mainly includes an LVDS receiver 172, a decoder 174, an S / P conversion unit 176, a clock recovery unit 178, a PLL unit 180, a timing control unit 182, and a separation unit. 234.

  As shown in FIG. 4, the deserializer 138 transmits a signal in which a power source and a serial signal are superimposed through a power line (coaxial cable). The frequency spectrum of this superimposed signal is as shown in FIG. As shown in FIG. 5, it can be seen that the frequency spectrum of the Manchester code does not have a direct current component, and therefore can be transmitted together with the power source (DC).

  Refer to FIG. 4 again. The superimposed signal is separated into a serial signal and a power source by the separation unit 234. For example, the separation unit 234 extracts a serial signal by cutting a DC component with a capacitor, and extracts a power source by cutting a high-frequency component with a choke coil. The serial signal separated by the separation unit 234 is received by the LVDS receiver 172.

  The serial signal received by the LVDS receiver 172 is input to the decoder 174 and the clock recovery unit 178. The decoder 174 detects the head portion of the data with reference to the header of the input serial signal, decodes the serial signal encoded by the Manchester encoding method or the like, and inputs it to the S / P converter 176. The S / P converter 176 converts the input serial signal into a parallel signal (P-DATA). The parallel signal converted by the S / P converter 176 is output to the liquid crystal unit 104.

  On the other hand, the clock regeneration unit 178 refers to a reference clock input from the outside, and regenerates the parallel signal clock from the serial signal clock using the built-in PLL unit 180. The parallel signal clock recovered by the clock recovery unit 178 is input to the decoder 174 and the timing control unit 182. The timing control unit 182 controls the reception timing based on the parallel signal clock input from the clock recovery unit 178. The parallel signal clock (P-CLK) input to the timing control unit 182 is output to the liquid crystal unit 104.

  As described above, the portable terminal 230 can transmit a power source and a serial signal (video signal or the like) using a single coaxial cable. Therefore, there is only one wiring connecting the operation unit 108 and the display unit 102, the mobility of the display unit 102 is improved, and the mobile terminal 230 can be deformed into a complicated shape. As a result, the usage of the portable terminal 230 is expanded and the convenience for the user is improved.

(Organization of issues 1)
As described above, in order to freely change the relative positional relationship between the operation unit 108 and the display unit 102, the parallel transmission method as in the portable terminal 100 described above has a disadvantage. Therefore, by providing the serializer 134 and the deserializer 138 as in the mobile terminal 130 described above, serial transmission of a video signal or the like is possible, and the movable range of the display unit 102 is expanded. Furthermore, taking advantage of the characteristics of the encoding method used in the mobile terminal 130, the mobility of the display unit 102 is further improved by using a method in which a signal is superimposed on the power line and transmitted.

  However, as shown in FIGS. 3 and 4, in the mobile terminals 130 and 230, a PLL unit 180 (hereinafter referred to as “PLL”) is used to regenerate the clock of the received serial signal. This PLL is necessary for extracting a clock from a signal encoded by the Manchester encoding method or the like. However, since the power consumption of the PLL itself is not small, providing the PLL increases the power consumption of the mobile terminals 130 and 230 accordingly. Such an increase in power consumption is a very big problem for small devices such as mobile phones.

  Against the background of these problems, there is a need for a technique that eliminates the need for providing a PLL on the deserializer 138 side. In view of such technical problems, a new signal transmission method has been devised that transmits a signal using a code that does not include a DC component and does not require a PLL circuit during clock recovery. In the following description, this signal transmission method may be simply referred to as a new method.

<2: Basic technology 1 (new method)>
Hereinafter, a new signal transmission method (new method) for transmitting a signal using a code that does not include a DC component and that can regenerate a clock without using a PLL will be described. First, an AMI (Alternate Mark Inversion) code, which is the basis for explaining a new encoding method, will be briefly described. Then, the functional configuration and encoding method of the mobile terminal 300 according to the new method will be described.

(Signal waveform of AMI code)
First, the signal waveform of the AMI code and its characteristics will be briefly described with reference to FIG. FIG. 6 is an explanatory diagram illustrating an example of a signal waveform of the AMI code. However, in the following description, A is an arbitrary positive number.

  The AMI code is a code that represents data 0 as a potential 0 and data 1 as a potential A or -A. However, the potential A and the potential -A are alternately repeated. That is, after data 1 is expressed by potential A, when data 1 appears next, data 1 is expressed by potential -A. Thus, since the data is expressed by repeating the polarity inversion, the AMI code does not include a DC component. The codes having the same type of characteristics as the AMI codes are expressed by PR (1, -1), PR (1, 0, -1), PR (1, 0, ..., -1), for example. There is a partial response method. A transmission code using polarity inversion is called a bipolar code. A dicode method or the like can also be used. Here, an AMI code with a duty of 100% will be described as an example.

  FIG. 6 schematically shows AMI codes with bit intervals T1, T2,..., T14. In the figure, data 1 appears at bit intervals T2, T4, T5, T10, T11, T12, and T14. When the potential is A in the bit interval T2, the potential is -A in the bit interval T4. Further, the potential is A at the bit interval T5. As described above, the amplitude corresponding to the data 1 is alternately inverted between plus and minus. This is the polarity inversion described above.

  On the other hand, all the data 0 is expressed by the potential 0. With such an expression, the AMI code does not include a DC component, but the potential 0 may continue as seen in the bit intervals T6,..., T9 in FIG. Thus, when the potential 0 continues, it is difficult to extract a clock component from this signal waveform without using a PLL. Therefore, in the new system, a technique is used in which a clock component is included in an AMI code (and a code having characteristics equivalent thereto) for transmission.

(Functional configuration)
Here, the functional configuration of the mobile terminal 300 according to the new method will be described with reference to FIG. FIG. 7 is an explanatory diagram illustrating a functional configuration example of the mobile terminal 300 according to the new method. However, FIG. 7 is an explanatory diagram drawn centering on the functional configuration of the serializer 134 and the deserializer 138, and descriptions regarding other components are omitted. In addition, among the constituent elements of the mobile terminal 300, constituent elements having substantially the same functional configuration as the mobile terminal 130 described above are denoted by the same reference numerals, and detailed description thereof is omitted.

(Serializer 134)
As illustrated in FIG. 7, the serializer 134 includes a P / S conversion unit 152, an LVDS driver 156, a PLL unit 158, a timing control unit 160, and an encoder 312. The main difference from the mobile terminal 130 described above lies in the function of the encoder 312.

  As shown in FIG. 7, the parallel signal (P-DATA) and the parallel signal clock (P-CLK) are input to the serializer 134 from the baseband processor 110. The parallel signal input to the serializer 134 is converted into a serial signal by the P / S converter 152. The serial signal converted by the P / S conversion unit 152 is input to the encoder 312. The encoder 312 adds a header or the like to the serial signal and encodes it with a predetermined encoding method.

  Here, a method of generating an encoded signal in the encoder 312 will be described with reference to FIG. FIG. 8 is an explanatory diagram showing an example of an encoding method according to the new scheme. FIG. 8 shows a code generation method based on the AMI code. However, the new method is not limited to this, and is similarly applied to a code having the same characteristics as the AMI code. For example, the present invention can also be applied to bipolar codes, partial response codes, and the like.

  The signal shown in FIG. 8C is a signal encoded by a new encoding method. In this signal, data 1 is expressed by a plurality of potentials A1 (-1, -3, 1, 3), and data 0 is expressed by a plurality of potentials A2 (-2, 2) different from the potential A1. . However, this signal is configured to invert the polarity, and is configured not to be continuously at the same potential. For example, referring to a section in which data 0 continues in the bit interval T6,..., T9, the potentials are −2, 2, −2, 2. By using such a code, it is possible to reproduce the clock component by detecting both rising and falling edges even if the same data value appears continuously.

  The encoder 312 includes an adder ADD in order to generate the above code. As shown in FIG. 8, for example, the encoder 312 encodes the input serial signal into an AMI code (A) and inputs the encoded signal to the adder ADD. Furthermore, the encoder 312 generates a clock (B) having a frequency (2 / Fb) that is half the transmission rate Fb of the AMI code, and inputs the clock (B) to the adder ADD. However, the amplitude of the clock is N times the AMI code (N> 1; N = 2 in the example of FIG. 8). Then, the encoder 312 adds the AMI code and the clock by the adder ADD to generate a code (C). At this time, the AMI code and the clock are synchronously added with their edges aligned.

  Refer to FIG. 7 again. The serial signal encoded by the encoder 312 is input to the LVDS driver 156. The LVDS driver 156 transmits the input serial signal to the deserializer 138 by a differential transmission method using LVDS. On the other hand, the parallel signal clock input to the serializer 134 is input to the PLL unit 158. The PLL unit 158 generates a serial signal clock from the parallel signal clock and inputs the serial signal clock to the P / S conversion unit 152 and the timing control unit 160. The timing control unit 160 controls the transmission timing of the serial signal by the encoder 312 based on the input serial signal clock.

(Deserializer 138)
As shown in FIG. 7, the deserializer 138 mainly includes an LVDS receiver 172, an S / P conversion unit 176, a timing control unit 182, a clock detection unit 332, and a decoder 334. The main difference from the deserializer 138 provided in the mobile terminal 130 is the presence of the clock detection unit 332 having no PLL.

  As shown in FIG. 7, a serial signal is transmitted from the serializer 134 to the deserializer 138 by a differential transmission method using LVDS. This serial signal is received by the LVDS receiver 172. The serial signal received by the LVDS receiver 172 is input to the decoder 334 and the clock detection unit 332. The decoder 334 detects the head portion of the data with reference to the header of the input serial signal, and decodes the serial signal encoded according to the encoding method used by the encoder 312.

  Here, a decoding method by the decoder 334 will be described with reference to FIG. As described above, the serial signal is encoded in the format shown in FIG. Therefore, the decoder 334 can decode the original serial signal by determining whether the amplitude of this signal is A1 or A2.

  In order to determine the amplitude A1 (-1, -3, 1, 3) corresponding to the data 1 and the amplitude A2 (-2, 2) corresponding to the data 0, 4 shown in FIG. Two thresholds (L1, L2, L3, L4) are used. Therefore, the decoder 334 compares the amplitude of the input signal with the above four thresholds to determine whether the amplitude is A1 or A2, and decodes the original serial signal. This decoding process will be described later (see FIGS. 10 to 13).

  Refer to FIG. 7 again. The serial signal decoded by the decoder 334 is input to the S / P converter 176. The S / P converter 176 converts the input serial signal into a parallel signal (P-DATA). The parallel signal converted by the S / P converter 176 is output to the liquid crystal unit 104.

  On the other hand, the clock detection unit 332 detects a clock component from the input signal. As described above, by using the code shown in FIG. 8C, the clock component compares the amplitude with the threshold L0 (potential 0) to determine the polarity of the amplitude, and the polarity inversion period is set. Based on this, the clock component can be detected. Therefore, the clock detection unit 332 does not need to use a PLL when detecting the clock component of the signal. As a result, the power consumption of the deserializer 138 can be reduced.

  The clock detected by the clock detection unit 332 is input to the decoder 334 and the timing control unit 182. The timing control unit 182 controls the reception timing based on the clock input from the clock detection unit 332. Further, the clock (P-CLK) input to the timing control unit 182 is output to the liquid crystal unit 104.

  In this way, a code that does not include a DC component (see FIG. 9) and can regenerate the clock component from the polarity inversion period is used. By using this code, it is not necessary to use a PLL for clock detection executed in the deserializer 138, and the power consumption of the mobile terminal can be greatly reduced. Note that the frequency spectrum of the code used in the new method has a shape as shown in FIG. 9, for example. A line spectrum appears at the frequency Fb / 2 of the clock added by the adder ADD of the encoder 312, and in addition, a broad frequency spectrum of the AMI code appears. In this frequency spectrum, there are null points at frequencies Fb, 2Fb, 3Fb,.

(About details of decryption processing)
Next, the details of the decoding process in the new method will be described with reference to FIGS. FIG. 10 is an explanatory diagram illustrating a circuit configuration example of the clock detection unit 332. FIG. 11 is an explanatory diagram illustrating a circuit configuration example of the decoder 334. FIG. 12 is an explanatory diagram illustrating a configuration example of a determination table for data determination. FIG. 13 is an explanatory diagram showing a received signal waveform (the eye pattern is shown in the figure) when the new method is applied.

(Circuit configuration example of the clock detection unit 332)
First, referring to FIG. As shown in FIG. 10, the function of the clock detection unit 332 is realized by a comparator 352.

  The comparator 352 receives as input data the amplitude value of the signal encoded by the new method. When input data is input, the comparator 352 compares the input amplitude value with a predetermined threshold value. For example, the comparator 352 determines whether or not the input data is a value larger than a predetermined threshold value. The comparator 352 is for extracting a clock from a new code (see FIG. 8C). Therefore, the threshold value L0 is used as the predetermined threshold value.

  For example, when the input data is a value larger than a predetermined threshold, the comparator 352 outputs a determination value (for example, 1) indicating that the input data is a value larger than the predetermined threshold. On the other hand, when the input data is a value smaller than the predetermined threshold, the comparator 352 outputs a determination value (for example, 0) indicating that the input data was not a value larger than the predetermined threshold. The output result of the comparator 352 is input to the decoder 334 and the timing control unit 182 as a clock.

(Circuit configuration example of decoder 334)
Reference is now made to FIG. As shown in FIG. 11, the function of the decoder 334 is realized by a plurality of comparators 354, 356, 358, 360 and a data determination unit 362. In addition, the data determination unit 362 is provided with a storage unit 364. The storage unit 364 stores a determination table for data determination shown in FIG.

  Different thresholds are set in the plurality of comparators 354, 356, 358, and 360. For example, the threshold value L1 is set for the comparator 354, the threshold value L2 is set for the comparator 356, the threshold value L3 is set for the comparator 358, and the threshold value L4 is set for the comparator 360. However, as shown in FIG. 8C, the threshold values L1, L2, L3, and L4 satisfy the relationship of L1> L2> L3> L4.

  First, the amplitude values of signals encoded by the new method are input to the plurality of comparators 354, 356, 358, 360 as input data. At this time, the same input data is input to the plurality of comparators 354, 356, 358, 360 in parallel.

  When the input data is input, the comparator 354 compares the input data with the threshold value L1, and determines whether or not the input data is larger than the threshold value L1. When the input data is a value larger than the threshold value L1, the comparator 354 outputs a determination value (for example, 1) indicating that the input data is a value larger than the threshold value L1. On the other hand, when the input data is not a value larger than the threshold value L1, the comparator 354 outputs a determination value (for example, 0) indicating that the input data is not a value larger than the threshold value L1.

  Similarly, the comparator 356 compares the input data with the threshold value L2, and determines whether or not the input data is larger than the threshold value L2. Further, the comparator 358 compares the input data with the threshold value L3, and determines whether or not the input data has a value larger than the threshold value L3. Further, the comparator 360 compares the input data with the threshold value L4, and determines whether or not the input data has a value greater than the threshold value L4. Determination values output from the plurality of comparators 354, 356, 358, 360 are input to the data determination unit 362.

  The data determination unit 362 determines the bit value indicated by the input data based on the determination values output from the plurality of comparators 354, 356, 358, 360. At this time, the data determination unit 362 refers to the determination table for data determination (see FIG. 12) stored in the storage unit 364, and determines the bit value indicated by the input data based on this determination table. As a determination table for data determination, for example, a table as shown in FIG. 12 is used. As illustrated in FIG. 12, in this determination table, a bit value (0 or 1) is associated with each combination of values output from the plurality of comparators 354, 356, 358, and 360.

  For example, consider the case where the output value of the comparator 354 is 1. In this case, the input data is a value larger than the threshold value L1. As described above, the relationship of L1> L2> L3> L4 is defined for the threshold value. From this relationship, the output values of the comparators 356, 358, and 360 should be 1. Referring to FIG. 8C, the bit value corresponding to the amplitude having a value larger than the threshold value L1 is 1. Therefore, in the determination table, a combination of all the output values of the comparators 354, 356, 358, and 360 and a bit value of 1 are described in association with each other.

  Consider other conditions. Here, for convenience of explanation, the output values of the comparators 354, 356, 358, and 360 are expressed as d1, d2, d3, and d4, respectively, and the combination is expressed as (d1, d2, d3, d4). For example, the combination of (d1, d2, d3, d4) = (0, 1, 1, 1) means that the input data d is L1> d> L2. Referring to FIG. 8C, when the input data d is L1> d> L2, the bit value is 0.

  Similarly, the combination of (d1, d2, d3, d4) = (0, 0, 1, 1) means that the input data d is L2> d> L3. Referring to FIG. 8C, when the input data d is L2> d> L3, the bit value is 1. The combination of (d1, d2, d3, d4) = (0, 0, 0, 1) means that the input data d is L3> d> L4. Referring to FIG. 8C, when the input data d is L3> d> L4, the bit value is 0. Furthermore, the combination of (d1, d2, d3, d4) = (0, 0, 0, 0) means that the input data d is L4> d. Referring to FIG. 8C, when the input data d is L4> d, the bit value is 1.

  In this way, combinations of output values output from the comparators 354, 356, 358, and 360 can be associated with bit values, and correspondences between such combinations and bit values are summarized in a table format. What is the determination table illustrated in FIG. The data determination unit 362 refers to such a determination table and determines a bit value based on a combination of output values output from the plurality of comparators 354, 356, 358, 360. The bit value determined by the data determination unit 362 is input to the S / P conversion unit 176.

(Organization of issues 2)
As described above, the code of the new system is very excellent in that it does not include a DC component and can regenerate a clock without using a PLL circuit. Therefore, a signal can be transmitted by being superimposed on a DC power source as in the mobile terminal 230 described above, and there is no need to provide a PLL on the receiving side as in the mobile terminal 300 described above. By the way, the technology of the new system described by taking the configuration of the mobile terminal 300 as an example relates to one-way signal transmission.

  However, various devices in addition to the liquid crystal unit 104 are provided in the display unit 102 constituting a recent portable terminal or the like. For example, the liquid crystal unit 104 may be provided with a touch panel, a camera, an operation switch, or the like. Therefore, in such a portable device, not only image data is transmitted to the liquid crystal unit 104 but also various data are transmitted from the display unit 102 to the operation unit 108. That is, in such a portable terminal or the like, it is necessary to be able to bidirectionally transmit data between the display unit 102 and the operation unit 108.

  However, if the PLL circuit of the operation unit 108 is omitted using the above-described new method code, a clock used for data transmission cannot be generated on the display unit 102 side when data is transmitted from the operation unit 108 to the display unit 102. . On the other hand, if the operation unit 108 is provided with a PLL circuit, problems such as an increase in power consumption and an increase in circuit scale described in the above (Summary 1) will occur. Therefore, on the premise that the above-described new system code is used, a technique has been devised that enables data transmission from the operation unit 108 to the display unit 102 without providing a PLL circuit in the operation unit 108.

<3: Fundamental technology 2 (Expansion to new bidirectional transmission; Expansion method)>
Hereinafter, a technique for extending the data transmission method according to the above new method to bidirectional transmission will be described. In the following description, the data transmission method according to the technology is referred to as an extended method. This extended method extracts a clock from a signal transmitted from the operation unit 108 to the display unit 102 without using a PLL circuit, and transmits the signal from the display unit 102 to the operation unit 108 using the clock. About.

(Configuration example of portable terminal 400)
First, the functional configuration of the mobile terminal 400 according to the expansion method will be described with reference to FIGS. FIG. 14 is an explanatory diagram showing an appearance of the mobile terminal 400 according to the expansion method. FIG. 15 is an explanatory diagram illustrating a configuration example of the mobile terminal 400 according to the expansion method. FIG. 16 is an explanatory diagram illustrating a functional configuration example of the mobile terminal 400 according to the expansion method. However, substantially the same functional configuration as that of the mobile terminals 130, 230, and 300 described above will be denoted by the same reference numerals, and redundant description will be omitted.

(Necessity of bidirectional transmission)
First, referring to FIG. A mobile terminal 400 shown in FIG. 14 mainly includes a display unit 102, a connection unit 106, and an operation unit 108. In addition, the display unit 102 is provided with an imaging unit 402 and an operation switch 404. The portable terminal 400 is an example of a configuration that requires bidirectional transmission of data between the display unit 102 and the operation unit 108. The same applies to the case where the display unit 102 is provided with a touch panel or the like.

  Similar to the mobile terminal 130 shown in FIG. 2, the display unit 102 of the mobile terminal 400 is provided with a liquid crystal unit 104 to display an image or the like. Such image data is transmitted from the operation unit 108 to the display unit 102. An imaging unit 402 provided in the display unit 102 provides a camera function for photographing a subject. The operation switch 404 provided in the display unit 102 is an operation unit used for selecting a music piece or switching a shuffle function when the portable terminal 400 is used as a music player, for example. Further, the operation switch 404 may be used as a manner mode switch, a shutter switch, or the like.

  Data of an image captured by the imaging unit 402 is transmitted from the display unit 102 to the operation unit 108. Similarly, an operation signal output by operating the operation switch 404 is transmitted from the display unit 102 to the operation unit 108. As described above, in an electronic device such as the portable terminal 400, bidirectional data transmission is performed between the display unit 102 and the operation unit 108. Therefore, the mobile terminal 400 according to the present embodiment realizes bidirectional data transmission while serializing the transmission line passing through the connection unit 106 and sufficiently securing the movable range of the connection unit 106.

(Functional configuration)
Next, the functional configuration of the mobile terminal 400 according to the expansion method will be described with reference to FIGS. 15 and 16. FIG. 15 is an explanatory diagram showing an overall configuration of the mobile terminal 400 according to the expansion method. FIG. 16 is an explanatory diagram showing a main functional configuration necessary for realizing the above-described bidirectional transmission in the functional configuration of the mobile terminal 400 according to the expansion method.

(About overall configuration)
First, referring to FIG. As shown in FIG. 15, the display unit 102 of the mobile terminal 400 is provided with a liquid crystal unit 104, an imaging unit 402, an operation switch 404, and a serializer / deserializer 408 (SER / DES). The operation unit 108 of the portable terminal 400 is provided with a baseband processor 110 and a serializer / deserializer 406 (SER / DES).

  One of the differences from the portable terminal 130 shown in FIG. 2 is that the display unit 102 is provided with an imaging unit 402 and an operation switch 404. Furthermore, another difference is that the serializer 134 and the deserializer 138 of the mobile terminal 130 are replaced with serializers / deserializers 406 and 408, respectively. In the following description, the serializer / deserializer 406 provided in the operation unit 108 may be expressed as SER / DES (M). Further, the serializer / deserializer 408 provided in the display unit 102 may be referred to as SER / DES (D).

(From the operation unit 108 to the display unit 102)
First, a signal flow from the operation unit 108 toward the display unit 102 will be described. A parallel signal of image data displayed on the liquid crystal unit 104 is generated by the baseband processor 110. The parallel signal generated by the baseband processor 110 is converted into a serial signal by the serializer / deserializer 406. The signal serialized by the serializer / deserializer 408 is input to a serializer / deserializer 408 provided in the display unit 102 via a serial signal line passing through the connection unit 106. The serializer / deserializer 408 converts the serial signal input via the serial signal line into a parallel signal and inputs the parallel signal to the liquid crystal unit 104.

(From the display unit 102 to the operation unit 108)
Next, the flow of signals from the display unit 102 toward the operation unit 108 will be described. As described above, examples of the signal directed from the display unit 102 to the operation unit 108 include a signal of image data captured by the imaging unit 402 and an operation signal output by operating the operation switch 404. Here, as an example, a case where a signal of image data captured by the imaging unit 402 is transmitted will be described. The parallel signal output from the imaging unit 402 is converted into a serial signal by the serializer / deserializer 408 and input to the serializer / deserializer 406 of the operation unit 108 via a serial transmission line passing through the connection unit 106. The serializer / deserializer 406 converts a serial signal input via the serial transmission line into a parallel signal and inputs the parallel signal to the baseband processor 110.

  With the above-described flow, the portable terminal 400 realizes bidirectional data transmission between the display unit 102 and the operation unit 108. Hereinafter, the functional configuration of the serializer / deserializer 406 and 408 for realizing such bidirectional transmission will be described in more detail.

(Details of functional configuration)
Reference is now made to FIG. FIG. 16 illustrates a functional configuration of the mobile terminal 400 centering on the serializer / deserializer 406 and 408. However, the description of a part of the configuration of the P / S conversion unit 152 and the like drawn in FIG. 7 (the portable terminal 300) is omitted. Furthermore, the portable terminal 400 employs a mode in which a signal is transmitted by being superimposed on a DC power supply, similarly to the portable terminal 230 shown in FIG. Of course, the application range of the technology related to the expansion method is not limited to the case where the transmission means is a power supply line.

  As described above, the mobile terminal 400 includes the serializer / deserializer 406 (SER / DES (M)) and the serializer / deserializer 408 (SER / DES (D). The signal line is also used as a power line for supplying DC power from the operation unit 108 to the display unit 102. In the following description, the signal line is used. , SER / DES (M) may be simply expressed as (M), and SER / DES (D) may be simply expressed as (D).

  As illustrated in FIG. 16, the serializer / deserializer 406 (M) includes an encoder 412, a driver 414, a combiner / distributor 416, a superimposing unit 418, a receiver 420, and a decoder 422. The serializer / deserializer 408 (D) includes a separator 432, a combiner / distributor 434, a receiver 436, a clock detector 438, a decoder 440, a bandpass filter 442 (BPF), an encoder 444, and a driver 446. Have

(SER / DES (M) → SER / DES (D))
First, processing for transmitting data (TX DATA1) from the serializer / deserializer 406 (M) to the serializer / deserializer 408 (D) will be described.

  As illustrated in FIG. 16, transmission data (TX DATA1) and a transmission clock (TX CLK1) are input to the serializer / deserializer 406 (M). It is assumed that the transmission data (TX DATA1) is serialized when it is input to the encoder 412. The transmission clock (TX CLK1) is input to the encoder 412 and the decoder 422. When the transmission data (TX DATA1) and the transmission clock (TX CLK1) are input, the encoder 412 adds the transmission clock (TX CLK1) to the transmission data (TX DATA1) and transmits the transmission data, as in the above-described new method. Is encoded.

  When the transmission data (TX DATA1) is expressed by an AMI code and the transmission speed is Fb, the encoder 412 generates a code of a new method as in FIG. 8C. The code generated by the encoder 412 is input to the combiner / distributor 416 via the driver 414. The combiner / distributor 416 is means for distributing the signal line leading to the encoder 412 and the signal line leading to the decoder 422 in order to realize bidirectional transmission. For data transmission, the code input to the combiner / distributor 416 is input to the superimposing unit 418.

  The superimposing unit 418 also receives a DC power supply. The code input to the superimposing unit 418 is superimposed on the DC power source. Then, the superimposed signal generated by the superimposing unit 418 is input to the separation unit 432 of the serializer / deserializer 408 (D) via a coaxial cable. The separation unit 432 separates the input superimposed signal into a DC power source and a code. The DC power source separated by the separation unit 432 is supplied to the display unit 102.

  On the other hand, the code separated by the separation unit 432 is input to the combiner / distributor 434. The combiner / distributor 434 is a means for distributing the signal line leading to the decoder 440 and the signal line leading to the encoder 444 in order to realize bidirectional transmission. For data reception, the code input to the combiner / distributor 434 is input to the clock detector 438 and the decoder 440 via the receiver 436. The clock detection unit 438 detects a clock from the input code. At this time, the clock detection unit 438 detects the clock using the same method as the clock detection unit 332 included in the mobile terminal 300 described above.

  The clock detected by the clock detection unit 438 is supplied to the liquid crystal unit 104 and input to the decoder 440. However, the frequency of the clock (RX CLK2) detected by the clock detection unit 438 is Fb / 2. The decoder 440 uses the clock (RX CLK2) input from the clock detection unit 438, performs decoding processing on the input code, and generates reception data (RX DATA2). The reception data (RX DATA2) is 2-bit parallel reception data synchronized with the clock (RX CLK2) detected by the clock detection unit 438. The reception data (RX DATA2) generated by the decoder 440 in this way is input to the liquid crystal unit 104.

  The processing for transmitting data (TX DATA1) from the serializer / deserializer 406 (M) to the serializer / deserializer 408 (D) has been described above. Next, processing for transmitting data (TX DATA2) from the serializer / deserializer 408 (D) to the serializer / deserializer 406 (M) will be described.

(SER / DES (D) → SER / DES (M))
As described above, in order to transmit data (TX DATA2) from the serializer / deserializer 408 (D) to the serializer / deserializer 406 (M), a transmission clock is required on the serializer / deserializer 408 (D) side. However, if a PLL circuit is provided on the serializer / deserializer 408 (D) side in order to generate a transmission clock, power consumption increases.

  Therefore, in the expansion method, a contrivance is made so that a transmission clock is supplied from the serializer / deserializer 406 (M) to the serializer / deserializer 408 (D). A time division transmission (TDD) method is used for data transmission between the serializer / deserializer 406 and 408. Accordingly, the time slot is divided between the case where data is transmitted in the forward direction from the serializer / deserializer 406 (M) to the serializer / deserializer 408 (D) and the case where data is transmitted in the reverse direction.

  For data transmission from the serializer / deserializer 406 (M) to the serializer / deserializer 408 (D), the code shown in FIG. 8C is used. Further, the serializer / deserializer 406 (M) continues to transmit the clock signal shown in (B) of FIG. 8 to the serializer / deserializer 408 (D) even in the time zone in which it does not transmit data. That is, the clock signal having the frequency (Fb / 2) and the amplitude (2, -2) is continuously transmitted to the serializer / deserializer 408 (D) even in the time zone in which the serializer / deserializer 408 (D) transmits data.

  Therefore, the serializer / deserializer 408 (D) transmits data using the clock signal received from the serializer / deserializer 406 (M) when transmitting data. The clock signal transmitted from the serializer / deserializer 406 (M) is input to the clock detector 438 via the separator 432, the combiner / distributor 434, and the receiver 436. Therefore, the clock detection unit 438 detects a clock from the input signal and inputs it to the bandpass filter 442. Normally, the clock detected by the clock detection unit 438 contains a lot of jitter. Therefore, the clock detected by the clock detection unit 438 is input to the bandpass filter 442 in order to suppress jitter.

  The clock whose jitter is suppressed by the band pass filter 442 is input to the encoder 444. Transmission data (TX DATA2) is input to the encoder 444. The transmission data (TX DATA2) is encoded by the encoder 444 in a predetermined method. However, the transmission line through which transmission data (TX DATA2) is transmitted is the same as the transmission line through which a clock signal is transmitted from the serializer / deserializer 406. Therefore, transmission data (TX DATA2) needs to be encoded so as to be synchronized with the clock output from the bandpass filter 442. When the clock signal shown in FIG. 8B is input, the transmission data (TX DATA2) is encoded so that the component of the frequency Fb / 2 is synchronized with the clock signal.

  For example, when the transmission data (TX DATA2) is 1, the encoder 444 outputs an upward convex pulse having an amplitude (1, −1) for one period, and when the transmission data (TX DATA2) is 0, the amplitude (1, −1) A downward convex pulse is output for one cycle. At this time, the frequency of the pulse train corresponding to the transmission data (TX DATA2) is Fb / 2. The transmission data (TX DATA2) is thus encoded into a pulse train having an amplitude (1, −1). The transmission data (TX DATA2) encoded by the encoder 444 is input to the combiner / distributor 434 via the driver 446.

  The combiner / distributor 434 adds the code having the amplitude (1, −1) input from the encoder 444 and the clock of the amplitude (2, −2) transmitted from the serializer / deserializer 406 (M). The code added by the combiner / distributor 434 has an amplitude (3, -3) when the transmission data (TX DATA2) is 1 and an amplitude (1, -1) when the transmission data is 0. It will be a thing. The code generated by the combiner / distributor 434 is sent to the coaxial cable via the separator 432 and transmitted to the serializer / deserializer 406 (M).

  In the serializer / deserializer 406 (M), the code of the transmission data (TX DATA2) transmitted through the coaxial cable is input to the decoder 422 via the superimposing unit 418, the combiner / distributor 416, and the receiver 420. The decoder 422 decodes data based on the amplitude value of the input code. For example, when the amplitude value is (3, -3), the data bit value is determined to be 1, and when the amplitude value is (1, -1), the data bit value is determined to be 0. At this time, the decoder 422 decodes the data using the transmission clock (TX CLK1) used for transmission of the transmission data (TX DATA1).

  In the first place, the clock used by the serializer / deserializer 408 (D) for data transmission is the transmission clock (TX CLK1) transmitted from the serializer / deserializer 406 (M). Therefore, the decoder 422 does not need to detect the clock from the input code. The data (RX DATA1) decoded by the decoder 422 and the clock (RX CLK1) are input to the baseband processor 110.

  The processing for transmitting data (TX DATA2) from the serializer / deserializer 408 (D) to the serializer / deserializer 406 (M) has been described above. In this way, data transmission from the serializer / deserializer 408 (D) to the serializer / deserializer 406 (M) is realized without using a PLL.

(About data transmission method)
Next, a data transmission method according to the extended scheme will be described with reference to FIG. FIG. 17 is an explanatory diagram illustrating an example of a data transmission method according to the extended method.

  FIG. 17 shows a data frame FL transmitted between the serializer / deserializer 406 and 408 by the TDD (Time Division Duplex) method. The data frame FL includes time slot 1 (SL1; M → D) for transmitting data from the serializer / deserializer 406 (M) to the serializer / deserializer 408 (D). Further, the data frame FL includes a time slot 2 (SL2; D → M) for transmitting data from the serializer / deserializer 408 (D) to the serializer / deserializer 406 (M).

  The frame length of the data frame FL is Tf. The frame length Tf is determined based on the transmission rate required in each transmission direction (M → D, D → M). Further, a time slot T1 is assigned to time slot 1 (SL1; M → D), and a time slot T2 is assigned to time slot 2 (SL2; D → M). For example, when the image data captured by the imaging unit 402 has a smaller data amount than the image data displayed on the liquid crystal unit 104, the relationship of T1> T2 is established.

  In FIG. 17, the codes transmitted in part (a) and (b) of time slots 1 and 2 are enlarged. In part (a) of the time slot 1, the code D1 is transmitted from the serializer / deserializer 406 (M) to the serializer / deserializer 408 (D). Therefore, the code D1 transmitted in the time zone (a) is a code of the new method shown in (C) of FIG. 8, and has six amplitude values. Further, the bit values corresponding to the amplitude values of the respective bit intervals in the code D1 are shown in the lower part of the code D1.

  On the other hand, in part (b) of the time slot 2, the code D2 is transmitted from the serializer / deserializer 408 (D) to the serializer / deserializer 406 (M). In the figure, a clock CLK is shown together with a reference D2. This clock CLK has been transmitted from the serializer / deserializer 406 (M). Therefore, this clock CLK is a clock having a transmission rate Fb / 2. As described above, the code D2 is generated by synchronously adding the clock CLK to a code expressed by pulses of amplitudes (1, −1) having different convex directions. In addition, the clock CLK added at this time has the jitter suppressed by the band pass filter 442.

  The data transmission rate from the serializer / deserializer 406 (M) to the serializer / deserializer 408 (D) was Fb. However, since the transmission speed of the clock acquired by the encoder 444 is Fb / 2, the data transmission speed from the serializer / deserializer 408 (D) to the serializer / deserializer 406 (M) is Fb / 2. The bit value corresponding to each bit interval is shown in the lower part of the symbol D2. By referring to this bit value and the clock CLK together, it can be seen that the transmission speed of the code D2 is Fb / 2.

  However, it is also possible to set the transmission speed of the code D2 to Fb by setting the transmission speed of the clock transmitted from the serializer / deserializer 406 (M) to Fb in the time slot 2 time slot. The reason why the transmission speed of the clock is Fb / 2 in the above example is that the clock used for the generation process of the code D1 transmitted in the time slot 1 is continuously transmitted to the serializer / deserializer 408 (D). It is in the configuration. With this configuration, it is not necessary to change the frequency of the clock generated in the serializer / deserializer 406 (M) for each time slot. Therefore, the clock speed used for data transmission in the time slot 2 can be appropriately changed according to the embodiment.

(Organization of issues 3)
The signal transmission method according to the extended method has been described above. Here, with reference to FIG. 18 and FIG. 19, a technical problem of the expansion method will be described. FIG. 18 schematically shows the overall configuration of the portable terminal 400 according to the expansion method shown in FIG. FIG. 19 is an explanatory diagram showing an example of a method for shifting to the power save mode.

  First, referring to FIG. The functional configuration of the mobile terminal 400 has been described in detail with reference to FIG. Here, only a part necessary for explaining the problem of the portable terminal 400 will be schematically described. For convenience of explanation, the serializer / deserializer 406 (M) and the superimposing unit 418 are separately shown. Similarly, the serializer / deserializer 408 (D) and the separation unit 432 are described separately.

  As described above, the portable terminal 400 is provided with the operation unit 108 and the display unit 102.

  In the operation unit 108, the data generated by the baseband processor 110 (BBP) is encoded by the serializer / deserializer 406 (M). At this time, a clock is input from the PLL unit 158 to the serializer / deserializer 406 (M) and is used for the above encoding process. However, in the PLL unit 158, the frequency of the clock generated by the clock generator is converted to a desired frequency. The data signal generated by the encoding process by the serializer / deserializer 406 (M) is superimposed on the power supply by the superimposing unit 418 and transmitted to the display unit 102 through one coaxial cable.

  On the other hand, in the display unit 102, the separation unit 432 separates the power source from the signal on which the power source is superimposed by the superimposing unit 418, and extracts a data signal. The data signal extracted by the separation unit 432 is input to the serializer / deserializer 408 (D). In the serializer / deserializer 408, the clock detection unit 438 detects a clock from the data signal, and the data is decoded using the clock. Data decoded by the serializer / deserializer 408 (D) is input to the liquid crystal unit 104.

  The display unit 102 is provided with operation means such as an imaging unit 402 and an operation switch 404. Data of an image captured by the imaging unit 402, control data generated by operating the operation switch 404, and the like are input to the serializer / deserializer 408 (D). As described above, in the expansion method, bidirectional transmission is possible, and these data can be transmitted from the display unit 102 to the operation unit 108. For example, when data is input from the imaging unit 402 and the operation switch 404, the serializer / deserializer 408 (D) encodes the data using the clock detected by the clock detection unit 438 and transmits the data from the operation unit 108. Transmit in the reverse direction in synchronization with the clock signal.

  As described above, when data is transmitted from the display unit 102 to the operation unit 108, the data is encoded using the clock detected by the clock detection unit 438. Therefore, in the expansion method, it is assumed that the operation unit 108 always transmits a clock signal (or a data signal including a clock component) to the display unit 102. Accordingly, when the clock signal is not transmitted from the operation unit 108 to the display unit 102, data transmission from the display unit 102 to the operation unit 108 cannot be performed.

  As a condition for stopping data transmission from the operation unit 108 to the display unit 102, for example, a transition to the power save mode is conceivable. Usually, when the portable terminal 400 is folded or when a user operation is not performed for a certain period of time, it is often set to shift to the power save mode. In the power save mode, in order to reduce the power consumption of the mobile terminal 400, for example, the backlight of the liquid crystal unit 104 is turned off and the screen display is not performed. Therefore, data transmission from the operation unit 108 to the display unit 102 is stopped. However, the operation switch 404 may be operated in the power save mode. In such a case, control data output in response to the operation of the operation switch 404 cannot be transmitted from the display unit 102 to the operation unit 108.

  For example, when the mobile terminal 400 is a mobile phone with a music player function, the mobile terminal 400 is provided with operation buttons and the like used for music playback control as the operation switch 404. When such a portable terminal 400 is used as a music player, the user often folds and uses the portable terminal 400. At this time, if the portable terminal 400 shifts to the power save mode, the user cannot perform playback control of the music player. For such a problem, for example, it is conceivable that the operation switch 404 is not provided in the display unit 102 but is provided in the operation unit 108. However, when the portable terminal 400 is folded, the display unit 102 is positioned on the front side. In consideration of user operability and design, it is preferable to provide the operation switch 404 on the display unit 102.

  Note that the transition to the power save mode in the expansion method is performed as shown in FIG. FIG. 19 is an explanatory diagram showing a mode switching operation when a process for shifting to the power save mode occurs while the bidirectional transmission process shown in FIG. 17 is in progress. As shown in FIG. 19, data transmission is performed between the serializer / deserializer 406 (M) and the serializer / deserializer 408 (D) in the time slots 1 and 2 assigned to the time zones T1 and T2. Yes.

  At this time, when the portable terminal 400 is folded or a transition operation to the power save mode is performed, a notification of transition to the power save mode is sent from the serializer / deserializer 406 (M) to the serializer / deserializer 408 (D). Communicated. In the example of FIG. 19, this transition notification is transmitted in the time slot 1 corresponding to the time zone T3. When the notification of transition to the power save mode is transmitted to the serializer / deserializer 408 (D), the serializer / deserializer 406 (D) switches the operation mode to the power save mode and stops supplying the clock to the serializer / deserializer 408 (D). To do.

  As described above, when the clock supply to the serializer / deserializer 408 (D) is stopped, the serializer / deserializer 408 (D) cannot transmit data to the serializer / deserializer 406 (M). Therefore, even if the operation switch 404 is operated, a control signal output according to the operation cannot be transmitted to the operation unit 108. For example, the power save mode cannot be canceled according to the operation of the operation switch 404. As a result, in the power save mode, no operation can be performed on the display unit 102 side.

  As described above, when the expansion method is adopted, the display unit 102 is in a mode in which the clock supplied from the operation unit 108 to the display unit 102 is stopped as in the power save mode (hereinafter simply referred to as the power save mode). There is a problem that data input from the control unit 108 cannot be transmitted to the operation unit 108. Therefore, in an embodiment to be described later, a technique is proposed in which when the operation switch 404 of the display unit 102 is operated in the power save mode, the power save mode can be canceled according to the operation.

  Although the music player function has been described as an example here, the type of the operation switch 404 provided on the display unit 102 is not limited to the playback control button of the music player. For example, a manner mode setting button for setting the manner mode can be given as an example. Further, the above-described new method and expansion method are intended to reduce power consumption by eliminating the need for using a PLL in the display unit 102. However, the codes used in the new method and the extended method are characterized in that they can be superimposed on a DC power source and a clock component can be easily extracted from a received signal. Therefore, it is possible to apply the characteristics of the codes of the new method and the extended method well and use them for other purposes. It should be noted that the embodiments to be described later are technologies developed with a view to applications having such other purposes, and the purpose and application range thereof are not limited to those of the above-described new method and extended method. . Furthermore, as described above, the content of the problem in the embodiment appears in a method of bidirectional transmission using a signal that does not include a DC component and is encoded with a code that includes a clock component. Please be careful.

<4: Embodiment>
Hereinafter, an embodiment of the present invention will be described. In the present embodiment, in order to solve the technical problem described in the above (Organization of Problem 3), the power save mode can be canceled in accordance with the operation performed on the display unit 102 side in the power save mode state. The technology to make it. In this embodiment as well, the technology for encoding transmission data by the above-mentioned new method and the bidirectional transmission technology according to the extended method are adopted as an example. However, the technique according to the present embodiment is not limited to the example shown below, and is widely applied to a method of bidirectional transmission using a signal that does not include a DC component and is encoded with a code that includes a clock component. The

[4-1: Functional configuration of portable terminal 500]
First, the functional configuration of the mobile terminal 500 according to the present embodiment will be described with reference to FIG. However, constituent elements having substantially the same functions as those of the portable terminal 400 shown in FIG. 18 are given the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 20, the mobile terminal 500 is provided with an operation unit 108 and a display unit 102. The operation unit 108 includes a baseband processor 110, a PLL unit 158, a serializer / deserializer 406 (M), and a current detection unit 502. On the other hand, the display unit 102 includes a liquid crystal unit 104, an imaging unit 402, an operation switch 404, a serializer / deserializer 408 (D), and a load control unit 504. The main difference between the portable terminal 400 described above is the presence or absence of the current detection unit 502 and the load control unit 504.

  First, the operation of the portable terminal 500 in the data transmission mode in which a clock is supplied from the operation unit 108 to the display unit 102 will be described. In the operation unit 108, the data generated by the baseband processor 110 (BBP) is encoded by the serializer / deserializer 406 (M). At this time, a clock is input from the PLL unit 158 to the serializer / deserializer 406 (M) and used for the encoding process. However, in the PLL unit 158, the frequency of the clock generated by the clock generator is converted to a desired frequency. The data signal generated by the encoding process by the serializer / deserializer 406 (M) is superimposed on the power supply by the superimposing unit 418 and transmitted to the display unit 102 through one coaxial cable.

  On the other hand, in the display unit 102, the separation unit 432 separates the power source from the signal on which the power source is superimposed by the superimposing unit 418, and extracts a data signal. The data signal extracted by the separation unit 432 is input to the serializer / deserializer 408 (D). In the serializer / deserializer 408, the clock detection unit 438 detects a clock from the data signal, and the data is decoded using the clock. Data decoded by the serializer / deserializer 408 (D) is input to the liquid crystal unit 104. Also, image data captured by the imaging unit 402, control data generated by operating the operation switch 404, and the like are input to the serializer / deserializer 408 (D) and transmitted to the operation unit 108.

  Next, the operation in the power save mode will be described. As described above, in the power save mode, no clock is supplied from the serializer / deserializer 406 (M) to the serializer / deserializer 408 (D). Therefore, even if the operation switch 404 is operated, a control signal output according to the operation cannot be transmitted to the serializer / deserializer 406 (M). Therefore, in this embodiment, when the operation switch 404 is operated, the amount of weak current flowing from the operation unit 108 to the display unit 102 is changed to perform power saving mode release control. Means related to the release control are a load control unit 504 and a current detection unit 502.

  Even in the power save mode, a weak current i is supplied from the operation unit 108 to the display unit 102. Further, the current i is very small compared to the data transmission mode. Normally, the current i in the power save mode is a current amount on the order of μA. In the power save mode, the operation of the clock generator of the operation unit 108 and the PLL unit 158 is also stopped. When the operation switch 404 is operated in the power save mode, a control signal is input from the operation switch 404 to the load control unit 504. Therefore, the load control unit 504 changes the current i by the current Δi according to the control signal input from the operation switch 404. For example, the load control unit 504 causes the current Δi to flow for a predetermined time To according to the control signal.

  When the current Δi flows from the load control unit 504, the current Δi is detected by the current detection unit 502 provided in the operation unit 108. The current detection unit 502 is provided with a current detection resistor Rd. In addition, since the current i is supplied from the operation unit 108, when the current Δi is caused to flow by the load control unit 504, a voltage drop ΔV is generated across the resistor Rd. The voltage drop ΔV generated at this time is ΔV = Rd · Δi. For example, when To = 10 (msec), Δi = 20 (mA), and Rd = 0.5 (Ω), ΔV = 10 (mV). This voltage drop ΔV is detected by the current detector 502.

  As described above, since the current i flowing in the power save mode is on the order of μA, when a current of about Δi = 20 (mA) flows, the current change can be clearly detected by the current detection unit 502. However, since the voltage drop ΔV due to the resistor Rd also occurs in the data transmission mode, the current Δi and the value of the resistor Rd are appropriately determined according to the current consumption amount of the mobile terminal 500 in the power save mode and the data transmission mode. Is preferred. In order to avoid erroneous detection of the current Δi, it is preferable to encode the current Δi into a predetermined pattern as shown in FIG.

  When the current detection unit 502 detects a voltage drop ΔV caused by the current Δi, the current detection unit 502 inputs a detection notification of the current Δi to the baseband processor 110 as an interrupt signal. When this detection notification is input, the baseband processor 110 resumes the operation of the clock generator and the PLL unit 158 and shifts to the data transmission mode. When the mode is shifted to the data transmission mode, the data signal including the clock component is transmitted again from the serializer / deserializer 406 (M) toward the serializer / deserializer 408 (D). As a result, data can be transmitted again from the display unit 102 toward the operation unit 108. Note that the operations of the current detection unit 502 and the load control unit 504 are performed only in the power save mode.

[4-2: How to return from power save mode]
As described above, the mobile terminal 500 according to the present embodiment operates in accordance with the operation of the operation switch 404 provided on the display unit 102 even in the power save mode by the operations of the load control unit 504 and the current detection unit 502. Save mode can be canceled. Here, the overall flow of the release processing will be briefly described with reference to FIG. FIG. 21 is an explanatory diagram showing a flow of return processing from the power save mode to the data transmission mode according to the present embodiment.

  As shown in FIG. 21, a notification of transition to the power save mode is transmitted from the operation unit 108 to the display unit 102, and the supply of the clock to the display unit 102 is stopped (S0). Thereafter, the power save mode is set, and the state where the clock supply from the operation unit 108 to the display unit 102 is stopped is maintained. In this state, when the operation switch 404 is operated at a certain time (S1), a current Δi is caused to flow by the load control unit 504, and a current Δi is detected by the current detection unit 502 of the operation unit 108 (S2). In response to the detection result, the power save mode is canceled, and clock supply from the operation unit 108 to the display unit 102 is started again (S3). When the clock supply is started, bidirectional transmission is resumed between the operation unit 108 and the display unit 102.

  As described above, in the present embodiment, the power save mode according to the operation of the display unit 102 while the clock supply from the operation unit 108 to the display unit 102 is stopped by shifting to the power save mode. A technology for realizing the release of is provided. In particular, the technique uses the code that can reproduce the clock without providing a PLL in the display unit 102, and transmits the data signal encoded with the code using a single coaxial cable. Applicable to the method. As described above, the technology according to the present embodiment changes the current amount according to the operation of the display unit 102, detects the change in the current amount at the operation unit 108, and cancels the power save mode according to the detection result. It is to do. With such a configuration, the above-described mode switching can be performed without providing a special control line used for mode switching or the like.

[4-3: Summary]
Finally, the functional configuration of the mobile terminal according to the present embodiment and the operational effects obtained by the functional configuration will be briefly summarized.

  First, the functional configuration of the mobile terminal according to the present embodiment can be expressed as follows. The portable terminal includes a first module corresponding to the operation unit 108 and a second module corresponding to the display unit 102.

  The first module encodes the first transmission data into a waveform that does not include a direct current component and whose polarity is inverted every half cycle of the clock, and transmits the first transmission data to the second module through a predetermined signal line. A signal transmission unit; As described above, since the first transmission data signal does not include a DC component, it can be transmitted by being superimposed on the power signal supplied from the DC power supply. The first transmission data signal includes a clock component in the form of polarity inversion. Therefore, it is possible to regenerate the clock by detecting the polarity inversion period included in the first transmission data signal.

  In addition, the first module includes a current detection unit that detects the amount of current flowing through the predetermined signal line. The first module transmits the first transmission data signal to the second module in the first mode, and stops the transmission of the first transmission data signal in the second mode. Part. The transmission control unit switches to the first mode in accordance with a change in the amount of current detected by the current detection unit in the second mode. As described above, in the first mode, the first transmission data signal is transmitted to the second module. On the other hand, in the second mode, the first transmission data signal is not transmitted to the second module.

  As will be described later, the second module is configured to regenerate a clock from a signal of first transmission data transmitted from the first module. Therefore, in the second module, the clock cannot be reproduced unless the signal of the first transmission data is transmitted. Therefore, in the second mode, data cannot be transmitted from the second module to the first module. However, current is supplied from the first module to the second module through a predetermined signal line. Therefore, as described later, the second module transmits a signal for urging mode switching by changing the amount of current flowing through a predetermined signal line. The current detector detects the change in current. Further, when a current change is detected by the current detection unit, mode switching control is executed by the transmission control unit. By adopting such a configuration, even in the second mode, the mode switching control can be performed from the second module side.

  The second module includes a clock detection unit that detects the clock based on a polarity inversion period of the signal of the first transmission data transmitted through the predetermined signal line. As described above, the first transmission data signal includes the clock component. Therefore, the clock detection unit can regenerate the clock from the first transmission data signal. The second module encodes the second transmission data into a waveform that does not include a DC component using the clock detected by the clock detection unit, and transmits the second transmission data to the first module in synchronization with the clock. A second signal transmission unit; As described above, the second module is configured to transmit the second transmission data using the clock detected from the signal of the first transmission data. However, in the second mode, the clock used for transmitting the second transmission data cannot be reproduced. Therefore, the second module has a load control unit that changes the amount of current flowing through the predetermined signal line in the second mode, and executes mode switching control using the change in the amount of current. . As a result, mode switching control can be performed without using an extra signal line for mode switching.

  The load control unit may be configured to change the amount of current flowing through the predetermined signal line in a predetermined pattern. By adopting such a configuration, it is possible to suppress erroneous detection by the above-described current detection unit and more reliably detect a current change for mode switching control.

  The first module may further include a signal superimposing unit that generates a superimposed signal by superimposing a power signal supplied from a DC power supply on the signal of the first transmission data. In this case, the first signal transmission unit transmits the superimposed signal to the second module through a power line. Furthermore, the second module further includes a signal separation unit that separates the superimposed signal into the power signal and the first transmission data signal. With such a configuration, it is possible to perform power supply and data transmission with a single power line, and a portion for physically connecting the first and second modules for power supply and data transmission. The number of cables wired to can be reduced to one. It should be noted that the power signal flowing through the power supply line is also used for the mode switching control.

  In addition, a first time zone in which a signal is transmitted from the first signal transmission unit and a second time zone in which a signal is transmitted from the second signal transmission unit are divided on the time axis. Also good. Similar to the above-described extended method, bidirectional data transmission may be realized based on the time division transmission method.

  On the other hand, the second signal transmission unit may be configured to transmit the second transmission data signal in synchronization with the first transmission data signal transmitted through the predetermined signal line. Good. In this case, the first module extracts a signal of the second transmission data by subtracting the signal of the first transmission data from the signal multiplexed on the predetermined signal line. It further has a part. The second module extracts a signal of the first transmission data by subtracting the signal of the second transmission data from the signal multiplexed on the predetermined signal line. It has further. With such a configuration, the first transmission data signal and the second transmission data signal can be transmitted in the same time zone.

(Remarks)
The serializer / deserializer 406 (M) is an example of a first signal transmission unit. The current detection unit 502 and the resistor Rd are examples of the current detection unit. The baseband processor 110 is an example of a transmission control unit. The serializer / deserializer 408 (D) is an example of a second signal transmission unit. The coaxial cable is an example of a predetermined signal line. The superimposing unit 418 is an example of a signal superimposing unit. The separation unit 432 is an example of a signal separation unit. The signal subtracting unit described later is an example of first and second signal extracting units. The portable terminal 500 is an example of an information processing apparatus. However, examples of the information processing apparatus include a mobile phone, a portable game machine, an imaging device, a notebook PC, an electronic dictionary, a printer, a facsimile, and other information home appliances. In particular, the above technique is preferably used in an electronic device that includes a movable part and generates power supply and data transmission between two or more components connected by the movable part.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to the example which concerns. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

  For example, in the above embodiment, the AMI code has been described as an example of the code input to the adder ADD, but the technique of the present invention is not limited to this. As described above, various bipolar codes and partial response codes PR (1, -1), PR (1, 0, -1), PR (1, 0, ..., 0, -1), etc. Used. Thus, a code format using polarity inversion is preferably used. Such codes can also be generated by bit shift or the like. As described above, several modifications can be assumed for the code generation method.

  Further, in the above-described embodiment, as an example of the technique for realizing bidirectional transmission, the above-described extended method for realizing bidirectional transmission in a time division manner has been described. However, the application range of the embodiment is not limited to this. For example, a full-duplex transmission method that allows the time at which data is transmitted from the display unit 102 to the operation unit 108 and the time at which data transmission is performed from the operation unit 108 to the display unit 102 may be adopted. When this method is applied, data signals in both directions are multiplexed in the signal line. Therefore, the display unit 102 and the operation unit 108 are provided with components that separate the multiplexed signal into data signals for each direction. For example, the component includes a signal subtracting unit that subtracts the data signal transmitted by itself and extracts the data signal transmitted by the other party.

It is explanatory drawing which shows the example of 1 structure of a portable terminal. It is explanatory drawing which shows the example of 1 structure of a portable terminal. It is explanatory drawing which shows the function structural example of the portable terminal which concerns on serial transmission. It is explanatory drawing which shows the function structural example of the portable terminal which concerns on serial transmission. It is explanatory drawing which shows an example of the frequency spectrum of Manchester code | symbol. It is explanatory drawing which shows an example of the signal waveform of an AMI code | symbol. It is explanatory drawing which shows the function structural example of the portable terminal which concerns on a new system. It is explanatory drawing which shows the signal generation method which concerns on a new system. It is explanatory drawing which shows an example of the frequency spectrum of the signal which concerns on a new system. It is explanatory drawing which shows the circuit structural example of a clock detection part. It is explanatory drawing which shows the circuit structural example of a decoder. It is explanatory drawing which shows the structural example of the determination table for data determination. It is explanatory drawing which shows the relationship between a received signal waveform and the threshold value for data determination. It is explanatory drawing which shows the example of 1 structure of the portable terminal which concerns on an expansion system. It is explanatory drawing which shows the example of 1 structure of the portable terminal which concerns on an expansion system. It is explanatory drawing which shows the function structural example of the portable terminal which concerns on an expansion system. It is explanatory drawing which shows an example of the signal transmission method which concerns on an extended system. It is explanatory drawing which shows the schematic structural example of the portable terminal which concerns on an expansion system. It is explanatory drawing which shows the transfer method to the power save mode which concerns on an expansion system. It is explanatory drawing which shows one structural example of the portable terminal which concerns on one Embodiment of this invention. It is explanatory drawing which shows the cancellation | release method of the power save mode which concerns on the same embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Portable terminal 102 Display part 104 Liquid crystal part 106 Connection part 108 Operation part 110 Baseband processor 112,132,140 Parallel signal line 130 Portable terminal 134 Serializer 136 Serial signal line 138 Deserializer 152 P / S conversion part 154,312,412, 444 Encoder 156 LVDS driver 158, 180 PLL unit 160 Timing control unit 172, 420, 436 Receiver 174, 334, 422, 440 Decoder 176 S / P conversion unit 178 Clock recovery unit 182 Timing control unit 230 Mobile terminal 232 Superimposition unit 234 Separation Unit 300 portable terminal 332 clock detection unit 352, 354, 356, 358, 360 comparator 362 data determination unit 364 storage unit 400 portable terminal 402 Imaging unit 404 Operation switch 406, 408 Serializer / deserializer 414, 446 Driver 416, 434 Synthesizer / distributor 418 Superimposing unit 432 Separating unit 438 Clock detecting unit 442 Band pass filter 500 Portable terminal 502 Current detecting unit 504 Load control unit Rd Resistance ADD Addition vessel

Claims (6)

A first signal transmission unit that encodes the first transmission data into a waveform that does not include a direct current component and whose polarity is inverted every half cycle of the clock, and transmits the first transmission data to the second module through a predetermined signal line;
A current detector for detecting the amount of current flowing through the predetermined signal line;
In the case of the first mode, the signal of the first transmission data is transmitted to the second module, and in the case of the second mode, the transmission of the signal of the first transmission data is stopped. A transmission control unit that switches to the first mode in accordance with a change in the amount of current detected by the current detection unit in the mode;
A first module having:
A clock detection unit for detecting the clock based on a polarity inversion period of the signal of the first transmission data transmitted through the predetermined signal line;
A second signal transmission unit that encodes the second transmission data into a waveform that does not include a DC component using the clock detected by the clock detection unit, and transmits the second transmission data to the first module in synchronization with the clock;
A load control unit that changes an amount of current flowing through the predetermined signal line in the second mode;
Said second module comprising:
An information processing apparatus comprising:   The information processing apparatus according to claim 1, wherein the load control unit changes the amount of current flowing through the predetermined signal line in a predetermined pattern. The predetermined signal line is a power line for transmitting a power signal supplied from a DC power source,
The first module further includes a signal superimposing unit that superimposes the power signal on the signal of the first transmission data to generate a superimposed signal,
The first signal transmission unit transmits the superimposed signal to the second module,
The information processing apparatus according to claim 2, wherein the second module further includes a signal separation unit that separates the superimposed signal into the power signal and the signal of the first transmission data.   A first time zone in which a signal is transmitted from the first signal transmission unit and a second time zone in which a signal is transmitted from the second signal transmission unit are divided on a time axis. Item 4. The information processing apparatus according to Item 1. The second signal transmission unit transmits the signal of the second transmission data in synchronization with the signal of the first transmission data transmitted through the predetermined signal line;
The first module further includes a first signal extraction unit that subtracts the signal of the first transmission data from the signal multiplexed on the predetermined signal line to extract the signal of the second transmission data. Have
The second module further includes a second signal extraction unit that subtracts the signal of the second transmission data from the signal multiplexed on the predetermined signal line to extract the signal of the first transmission data. The information processing apparatus according to claim 1. In the first mode,
The first module is
A first signal transmission step that encodes the first transmission data into a waveform that does not include a DC component and whose polarity is inverted every half cycle of the clock, and transmits the first transmission data to the second module through a predetermined signal line;
The second module comprises:
A clock detection step of detecting the clock based on a polarity inversion period of the signal of the first transmission data transmitted from the first module;
A second signal transmission step of encoding the second transmission data into a waveform not including a DC component using the clock detected in the clock detection step, and transmitting the second transmission data to the first module in synchronization with the clock;
Is executed,
A step of causing the first module to stop signal transmission of the first transmission data when the mode is changed from the first mode to the second mode;
In the case of the second mode,
A load control step of changing the amount of current flowing through the predetermined signal line by the second module;
The first module is
A current detection step of detecting an amount of current flowing through the predetermined signal line;
A control step of switching from the second mode to the first mode when a change in current amount is detected in the current detection step;
The mode switching method is executed.

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