Transmitting device, transmitting method, receiving device and receiving method

Abstract

The object of the present invention is to enable good signal transmission between multiple daisy chain devices at low cost. A transmitting device generates multiple signals with different voltage levels and transmits the signals to a communication line at different time points. For example, multiple signals with different voltage levels are generated by multiple drivers or by one driver. On the receiving side, since it is possible to immediately determine whether it is a given information to be passed to the next stage based only on the difference in voltage level without logically analyzing the content of the signal, the cost of components such as memory and the inspection cost are unnecessary, so cost reduction can be achieved.

Description

Technical Field

[0001] The present technology relates to a transmitting device, a transmitting method, a receiving device, and a receiving method, and more particularly to a transmitting device, a transmitting method, a receiving device, and a receiving method for performing signal transmission between a plurality of daisy-chained devices. Background Art

[0002] For example, patent document 1 discloses a technology as a multi-node communication technology of daisy-chain multi-devices, in which the same information is sent from a master node to all nodes in a daisy-chain multi-node network, and the slave node side sends and receives information based on a slave address assigned to the slave node side.

[0003] In this multi-node communication of daisy-chained multi-devices, in the case of a system in which the communication information with the previous level is not desired to be sent to the next level, the intermediate node needs to have the function of storing data in a memory and determining whether to send the data to the next level, which results in additional costs for components such as memory, verification costs, etc.

[0004] Reference List

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2017-135711 Summary of the Invention

[0007] Problems to be solved by the present invention

[0008] The purpose of this technology is to achieve optimal signal transmission between multiple daisy-chain devices at a low cost.

[0009] Solution to the problem

[0010] One concept of this technology is

[0011] A sending device, comprising:

[0012] a signal generating unit that generates a plurality of signals having different voltage levels; and

[0013] The signal transmitting unit outputs the plurality of signals having different voltage levels to the communication line at different timings.

[0014] In the present technology, the signal generating unit generates multiple signals with different voltage levels. For example, the signal generating unit can be configured to generate multiple signals with different voltage levels through multiple drivers. In addition, for example, the signal generating unit can be configured to generate multiple signals with different voltage levels through a single driver. In addition, for example, the signal generating unit can be configured to generate multiple signals with different voltage levels through current driving. The signal transmitting unit outputs the multiple signals with different voltage levels to the communication line at different timings.

[0015] As described above, in this technology, multiple signals with different voltage levels are output to the communication line at different timings. Therefore, the receiving side can immediately determine whether the signal is information to be passed to the next stage based solely on the difference in voltage level, without logically analyzing the signal content. This reduces costs by eliminating the need for components such as memory and verification.

[0016] Note that the present technology may also include, for example, a determination unit that determines whether a communication line is connected to a receiving device corresponding to multiple signals with different voltage levels. In this case, for example, the determination unit may be configured to make the determination based on the voltage level of the communication line when a predetermined current is drawn from the communication line. Alternatively, in this case, for example, the determination unit may be configured to make the determination based on the voltage level of the power supply line when a switch inserted in the power supply line is open. By including such a determination unit, failures on the receiving side can be prevented.

[0017] In addition, the present technology may further include, for example, a signal receiving unit that receives multiple signals having different voltage levels from a communication line at different timings. In this case, for example, the signal receiving unit may be configured to transmit a portion of the multiple signals having different voltage levels to a subsequent stage via the communication line. By including the signal receiving unit described above, multiple signals having different voltage levels transmitted via the communication line can be received.

[0018] In addition, another concept of this technology is

[0019] A receiving device, comprising:

[0020] The signal receiving unit receives a plurality of signals having different voltage levels from the communication line at different timings.

[0021] In the present technology, a signal receiving unit receives multiple signals having different voltage levels from a communication line at different timings. For example, the signal receiving unit may include a comparator having thresholds corresponding to the multiple signals having different voltage levels. Furthermore, for example, the signal receiving unit may be configured to transmit a portion of the multiple signals having different voltage levels to a subsequent stage via the communication line. In this case, for example, a voltage level conversion unit may also be provided to convert the voltage level of the signal transmitted to the subsequent stage to another voltage level.

[0022] As described above, in this technology, multiple signals with different voltage levels are received from a communication line at different timings. Therefore, it is possible to immediately determine whether the signal is information to be passed to a subsequent stage based solely on the difference in voltage level, without logically analyzing the signal content. Furthermore, the cost of components such as memory and verification costs are not required, thereby reducing costs.

[0023] Effects of the Invention

[0024] According to the present technology, signal transmission can be preferably performed between a plurality of daisy-chain devices at low cost. Note that the effects described in this specification are merely examples and are not limited thereto, and other effects may be present. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a diagram showing a configuration example of a transmission system as a first embodiment.

[0026] Figure 2 1 is a diagram illustrating an example of a sequence of communication between a source device and a sink device, and communication between the source device and a cable.

[0027] Figure 3 It is shown that by modifying Figure 1 A diagram showing an example of a configuration of a transmission system obtained by using a transmission system.

[0028] Figure 4 is a diagram showing a configuration example of a transmission system as a second embodiment.

[0029] Figure 5 is a diagram showing a configuration example of a transmission system as a third embodiment.

[0030] Figure 6 is a diagram showing a configuration example of a transmission system as a fourth embodiment.

[0031] Figure 7 1 is a diagram illustrating an example of a sequence of communication between a source device and a sink device, and communication between the source device and a cable.

[0032] Figure 8 is a diagram showing a configuration example of a transmission system as a fifth embodiment.

[0033] Figure 9 is a diagram illustrating control of a threshold value for maintaining high output data quality.

[0034] Figure 10 is a diagram showing a configuration example of a transmission system in the case where a conventional cable is connected.

[0035] Figure 11 is a diagram showing a configuration example of a transmission system as a sixth embodiment.

[0036] Figure 12 : is a diagram showing a configuration example of a transmission system configured to determine whether a cable is a compliant cable or a non-compliant cable by using a power supply line.

[0037] Figure 13 is a diagram showing a configuration example of a transmission system as a seventh embodiment.

[0038] Figure 14 is a diagram showing a configuration example of a transmission system as an eighth embodiment.

[0039] Figure 15 10 is a diagram showing an example of a sequence of communication between a source device and a sink device, and communication between the source device 100 and a cable. DETAILED DESCRIPTION

[0040] Hereinafter, a mode for carrying out the present invention (hereinafter referred to as an "embodiment") will be described. Note that the description will be given in the following order.

[0041] 1. Example

[0042] 2. Modification

[0043] <1. Example>

[0044] [Transmission system configuration]

[0045] "First embodiment"

[0046] Figure 1 The configuration example of the transmission system 10A as the first embodiment is shown. The transmission system 10A is, for example, an HDMI transmission system using HDMI as a digital interface, but is not limited thereto. Note that "HDMI" is a registered trademark.

[0047] This transmission system 10A includes a source device 100, a sink device 200, and a cable 300 connecting these devices. This transmission system 10A is configured so that the source device 100 and the sink device 200, as well as the source device 100 and the cable 300, can communicate with each other independently, and the transmission and reception of signals between the source device 100 and the cable 300 are not transmitted to the sink device 200.

[0048] The voltage level of the signal output from the source device 100 to the communication line is changed between when the source device 100 and the sink device 200 communicate with each other and when the source device 100 and the cable 300 communicate with each other, thereby enabling independent communication. The cable 300 is configured so that: at the voltage level at which the source device 100 and the sink device 200 communicate with each other, the signal from the source device 100 is transmitted to the sink device 200 as is, and at the voltage level at which the source device 100 and the cable 300 communicate with each other, the signal from the source device 100 is received but not transmitted to the sink device 200. The term "as is" herein includes signals that are logically the same but electrically different (such as having different voltage levels).

[0049] For example, when the cable is an HDMI cable, a DDC line, a common line, or the like can be used as the communication line, but the communication line is not limited to these.

[0050] Source device 100 includes controller (Ctrl.1) 101, driver (Drv.1) 102, comparator (Comp.1) 103, controller (Ctrl.2) 104, driver (Drv.2) 105, and comparator (Comp.2) 106. Drivers 102 and 105 form a signal generating unit and a signal transmitting unit, while comparators 103 and 106 form a signal receiving unit.

[0051] The controller 101 transmits transmit data to the driver 102 and receives receive data from the comparator 103. The driver 102 generates a signal with a voltage level of 0V to 2.5V corresponding to the transmit data sent from the controller 101, and outputs the signal to the communication line 410. In this case, for example, the logic "0" of the transmit data is 0V, and the logic "1" is 2.5V. A signal is input from the communication line 410 to the positive input terminal of the comparator 103, and a threshold value V1 is provided to the negative input terminal of the comparator 103. Here, the threshold value V1 is set to a value between 0V and 2.5V, for example, 1.25V. The comparator 103 outputs "0" when the signal level is lower than the threshold value V1, and outputs "1" when the signal level is equal to or greater than the threshold value V1.

[0052] The controller 104 sends the transmission data to the driver 105 and receives the reception data from the comparator 106. The driver 105 generates a signal with a voltage level of 2.5V to 5V corresponding to the transmission data sent from the controller 104, and outputs the signal to the communication line 410. In this case, for example, the logic "0" of the transmission data is 2.5V, and the logic "1" is 5V. The signal is input from the communication line 410 to the positive input terminal of the comparator 106, and the threshold value Vth1 is provided to the negative input terminal of the comparator 106. Here, the threshold value Vth1 is set to a value between 2.5V and 5V, for example, 3.25V. The comparator 106 outputs "0" when the signal level is lower than the threshold value Vth1, and outputs "1" when the signal level is equal to or greater than the threshold value Vth1.

[0053] Cable 300 includes controller (Ctrl.3) 301, driver (Drv.3) 302, comparator (Comp.3) 303, driver (Drv.4) 304, and comparator (Comp.4) 305. Drivers 302 and 304 form a signal generating unit and a signal transmitting unit, while comparators 303 and 305 form a signal receiving unit.

[0054] Controller 301 transmits transmit data to driver 302 and receives receive data from comparator 303. Driver 302 generates a signal with a voltage level of 2.5V to 5V corresponding to the transmit data sent from controller 301 and outputs the signal to communication line 410. In this case, for example, the logic "0" of the transmit data is 2.5V, and the logic "1" is 5V. A signal is input from communication line 410 to the positive input terminal of comparator 303, and a threshold value Vth1 is provided to the negative input terminal of comparator 303. Comparator 303 outputs "0" when the signal level is lower than threshold value Vth1, and outputs "1" when the signal level is equal to or greater than threshold value Vth1.

[0055] The driver 304 and the comparator 305 are connected in parallel and inserted in the communication line 410. The driver 304 receives a signal from the communication line 410 on the sink device 200 side and outputs a signal having a voltage level converted from 0V to 5V to 0V to 2.5V to the communication line 410 on the source device 100 side.

[0056] A signal is input from the communication line 410 on the source device 100 side to the positive input terminal of the comparator 305, and a threshold value Vth2 is provided to the negative input terminal of the comparator 305. Here, the threshold value Vth2 is set to a value between 0V and 2.5V, for example, 1.25V. The comparator 305 outputs 0V when the signal level is lower than the threshold value Vth2, and outputs 5V when the signal level is equal to or greater than the threshold value Vth2. In other words, when the voltage level of the signal on the communication line 410 on the sink device 200 side is between 0V and 2.5V, the comparator 305 converts the signal to a voltage level of 0V to 5V so that the legacy sink device 200 can also receive the signal, and outputs the converted signal to the communication line 410 on the sink device 200 side. The comparator 305 is provided so that signals with voltage levels of 0V to 2.5V are transmitted to the sink device 200 as is, but signals with voltage levels of 2.5V to 5V are blocked so that these signals are not transmitted to the sink device 200.

[0057] The sink device 200 is a conventional sink device. The sink device 200 includes a controller (Ctrl.5) 201, a driver (Drv.5) 202, and a comparator (Comp.5) 203. The driver 202 forms a signal generating unit and a signal transmitting unit. The comparator 203 forms a signal receiving unit.

[0058] The controller 201 transmits transmit data to the driver 202 and receives receive data from the comparator 203. The driver 202 generates a signal with a voltage level of 0V to 5V corresponding to the transmit data sent from the controller 201, and outputs the signal to the communication line 410. In this case, for example, the logic "0" of the transmit data is 0V, and the logic "1" is 5V. A signal is input from the communication line 410 to the positive input terminal of the comparator 203, and a threshold value V2 is provided to the negative input terminal of the comparator 203. Here, the threshold value V2 is set to a value between 0V and 5V, for example, 2.5V. The comparator 203 outputs "0" when the signal level is lower than the threshold value V2, and outputs "1" when the signal level is equal to or greater than the threshold value V1.

[0059] The threshold value V1 of the comparator 103 and the threshold value Vth2 of the comparator 305 are, for example, 1.25 V, and therefore, these comparators 103 and 305 can receive (detect) signals with voltage levels of 0 V to 2.5 V, but cannot receive (cannot detect) signals with voltage levels of 2.5 V to 5 V. In addition, the threshold value Vth1 of the comparators 106 and 303 is, for example, 3.75 V, and therefore, these comparators 106 and 303 can receive (detect) signals with voltage levels of 2.5 V to 5 V, but cannot receive (cannot detect) signals with voltage levels of 0 V to 2.5 V.

[0060] exist Figure 1 In the transmission system 10A, the driver 102, the comparator 103, the driver 304, the comparator 305, the driver 202, and the comparator 203 are circuits used by the source device 100 and the sink device 200 to transmit and receive information to and from each other.

[0061] A case where data is transmitted from the source device 100 to the sink device 200 will be described. In this case, transmission data is transmitted from the controller 101 of the source device 100 to the driver 102. The driver 102 generates a signal with a voltage level of 0V to 2.5V corresponding to the transmission data, and outputs the signal to the communication line 410. The signal with a voltage level of 0V to 2.5V is input from the communication line 410 to the positive input terminal of the comparator 305 of the cable 300.

[0062] In the comparator 305, the threshold Vth2 is, for example, 1.25V, so a signal with a voltage level of 0V to 2.5V is received (detected), converted into a signal with a voltage level of 0V to 5V, and output to the communication line 410. The signal with a voltage level of 0V to 5V is input from the communication line 410 to the positive input terminal of the comparator 203 of the sink device 200. Since the threshold V2 is 2.5V in the comparator 203, the signal with a voltage level of 0V to 5V is received (detected), and the received data as the output data of the comparator 203 is transmitted to the controller 201.

[0063] Note that in this case, in the cable 300, a signal with a voltage level of 0 V to 2.5 V is also input from the communication line 410 to the positive input terminal of the comparator 303. In the comparator 303, the threshold value Vth1 is, for example, 3.75 V, so the signal with a voltage level of 0 V to 2.5 V is not received (not detected). That is, in this case, the output of the comparator 303 remains "0", and the controller 301 of the cable 300 cannot receive data.

[0064] Next, a case where data is transmitted from the sink device 200 to the source device 100 will be described. In this case, the transmission data is transmitted from the controller 201 of the sink device 200 to the driver 202. The driver 202 generates a signal with a voltage level of 0V to 5V corresponding to the transmission data and outputs the signal to the communication line 410. The signal with a voltage level of 0V to 5V is input from the communication line 410 to the driver 304 of the cable 300.

[0065] In the driver 304, the signal with a voltage level of 0V to 5V is converted into a signal with a voltage level changed from 0V to 5V to 0V to 2.5V, and is output to the communication line 410. The signal with a voltage level of 0V to 2.5V is input from the communication line 410 to the positive input terminal of the comparator 103 of the source device 100. In the comparator 103, since the threshold V1 is, for example, 1.25V, the signal with a voltage level of 0V to 2.5V is received (detected), and the received data as the output data of the comparator 103 is transmitted to the controller 101.

[0066] Note that in this case, in the cable 300, a signal with a voltage level of 0 V to 2.5 V is also input from the communication line 410 to the positive input terminal of the comparator 303. In the comparator 303, the threshold value Vth1 is, for example, 3.75 V, so the signal with a voltage level of 0 V to 2.5 V is not received (not detected). That is, in this case, the output of the comparator 303 remains "0", and the controller 301 of the cable 300 cannot receive data.

[0067] In addition, Figure 1 In the transmission system 10A, the driver 105, the comparator 106, the driver 302, and the comparator 303 are circuits used by the source device 100 and the cable 300 to transmit and receive information to and from each other.

[0068] The following describes a case where data is transmitted from the source device 100 to the cable 300. In this case, the transmission data is transmitted from the controller 104 of the source device 100 to the driver 105. The driver 105 generates a signal with a voltage level of 2.5V to 5V corresponding to the transmission data and outputs the signal to the communication line 410. The signal with a voltage level of 2.5V to 5V is input from the communication line 410 to the positive input terminal of the comparator 303 of the cable 300. In the comparator 303, since the threshold value Vth1 is, for example, 3.75V, the signal with a voltage level of 2.5V to 5V is received (detected), and the received data is transmitted to the controller 301 as the output data of the comparator 303.

[0069] Note that in this case, in the cable 300, a signal with a voltage level of 2.5 V to 5 V is also input from the communication line 410 to the positive input terminal of the comparator 305. In the comparator 305, the threshold Vth2 is, for example, 1.25 V, so the signal with a voltage level of 2.5 V to 5 V is not received (not detected). That is, in this case, the output of the comparator 305 remains at 5 V, and the signal is not transmitted to the sink device 200 side.

[0070] Next, a description will be given of a case where data is transmitted from the cable 300 to the source device 100. In this case, the transmission data is transmitted from the controller 301 of the cable 300 to the driver 302. The driver 302 generates a signal corresponding to the transmission data at a voltage level of 2.5V to 5V and outputs the signal to the communication line 410. The signal at a voltage level of 2.5V to 5V is input from the communication line 410 to the positive input terminal of the comparator 106 of the source device 100. In the comparator 106, since the threshold value Vth1 is, for example, 3.75V, the signal at a voltage level of 2.5V to 5V is received (detected), and the received data, which is the output data of the comparator 106, is transmitted to the controller 104.

[0071] Note that in this case, in the cable 300, a signal with a voltage level of 2.5 V to 5 V is also input from the communication line 410 to the positive input terminal of the comparator 305. In the comparator 305, the threshold Vth2 is, for example, 1.25 V, so the signal with a voltage level of 2.5 V to 5 V is not received (not detected). That is, in this case, the output of the comparator 305 remains at 5 V, and the signal is not transmitted to the sink device 200 side.

[0072] Figure 2 An example of a sequence of communication between the source device 100 and the sink device 200, and communication between the source device 100 and the cable 300 is shown. Part A indicates a portion in which the source device 100 and the sink device 200 communicate with each other using a signal with a voltage level of 0 V to 2.5 V, and part B indicates a portion in which the source device 100 and the cable 300 communicate with each other using a signal with a voltage level of 2.5 V to 5 V.

[0073] Here, since these communications are performed over the same communication line 410, the A and B parts do not perform communications that overlap in time, and communication is established only when the timing of these communications deviates. For example, when the master device is the source device 100, the source device 100 determines whether to communicate with the sink device 200 or the cable 300. Although detailed description is omitted, in this case, it is necessary to adjust the A and B parts to deviate from each other, and arbitration is required so that when one node declares communication, the other node does not transmit a signal.

[0074] As mentioned above, in Figure 1In the transmission system 10A shown, the source device 100 and the sink device 200, as well as the source device 100 and the cable 300, can communicate with each other independently, and the transmission and reception of signals between the source device 100 and the cable 300 are not transmitted to the sink device 200. In this case, without logically analyzing the content of the signal, the cable 300 can immediately determine whether it is information to be transmitted to the sink device 200 at the next stage based solely on the difference in voltage level, and the cost of components such as memory, verification cost, etc. is unnecessary, and the cost can be reduced.

[0075] Note that in Figure 1 In the illustrated configuration of the transmission system 10A, the source device 100 includes the controller 101 and the controller 104 , but these controllers may be configured as one controller.

[0076] In addition, a case has been described in which: Figure 1 In the configuration of the transmission system 10A shown, the source device 100 has separate drivers for generating and transmitting signals with a voltage level of 0V to 2.5V and a signal with a voltage level of 2.5V to 5V, and has separate comparators for receiving each signal. Figure 3 In the transmission system 10A' shown, a configuration in which one is used for each of them is conceivable. That is, the driver has the driver 102', and the comparator has the comparator 103', which is provided with the threshold value V1 / Vth1.

[0077] "Second Embodiment"

[0078] Figure 4 A configuration example of a transmission system 10B as a second embodiment is shown. Figure 4 In the embodiment, the same reference numerals are used to represent Figure 1 , and their detailed descriptions will be omitted as appropriate. This transmission system 10B includes a source device 100, a sink device 200, and a cable 300 connecting these devices. This transmission system 10B is configured so that the sink device 200 and the source device 100, as well as the sink device 200 and the cable 300, can communicate with each other independently, and the transmission and reception of signals between the sink device 200 and the cable 300 are not transmitted to the source device 100.

[0079] The voltage level of the signal output from the sink device 200 to the communication line is changed between when the sink device 200 and the source device 100 are communicating and when the sink device 200 and the cable 300 are communicating, thereby enabling independent communication. The cable 300 is configured so that: at a voltage level at which the sink device 200 and the source device 100 communicate with each other, the signal from the sink device 200 is directly transmitted to the source device 100, and at a voltage level at which the sink device 200 and the cable 300 communicate with each other, the signal from the sink device 200 is received but not transmitted to the source device 100.

[0080] The sink device 200 includes a controller 101, a driver 102, a comparator 103, a controller 104, a driver 105, and a comparator 106. Although detailed description is omitted, this is similar to Figure 1 The configuration of the source device 100 in the transmission system 10A is similar.

[0081] The cable 300 includes a controller 301, a driver 302, a comparator 303, a driver 304, and a comparator 305. Although detailed description is omitted, this is similar to Figure 1 The configuration of the cable 300 in the transmission system 10A is similar. However, the connection direction of the cable 300 is opposite to that in the case of the transmission system 10A.

[0082] The source device 100 is a conventional source device. The source device 100 includes a controller 201, a driver 202, and a comparator 203. Although detailed description is omitted, this is similar to Figure 1 The configuration of the sink 200 in the transmission system 10A is similar.

[0083] Although detailed description is omitted, Figure 4 The communication operation between the sink device 200 and the source device 100 in the transmission system 10B shown is similar to Figure 1 The communication operation between the source device 100 and the sink device 200 in the transmission system 10A is described in detail. Figure 4 The communication operation between the sink device 200 and the cable 300 in the transmission system 10B shown is similar to Figure 1 The communication operation between the source device 100 and the cable 300 in the transmission system 10A is shown.

[0084] As mentioned above, in Figure 4In the transmission system 10B shown, the sink device 200 and the source device 100, as well as the sink device 200 and the cable 300, can communicate with each other independently, and the transmission and reception of signals between the sink device 200 and the cable 300 are not transmitted to the source device 100. In this case, without logically analyzing the content of the signal, the cable 300 can immediately determine whether it is information to be transmitted to the subsequent source device 100 based solely on the difference in voltage level, and the cost of components such as memory, verification cost, etc. is unnecessary, and the cost can be reduced.

[0085] "Third embodiment"

[0086] Figure 5 A configuration example of a transmission system 10C as a third embodiment is shown. Figure 5 In the embodiment, the same reference numerals are used to represent Figure 1 The transmission system 10C includes a source device 100, a sink device 200, and a cable 300 connecting these devices.

[0087] The transmission system 10C is configured so that the source device 100 and the sink device 200, the source device 100 and the cable 300, and the sink device 200 and the cable 300 can communicate with each other independently, and the transmission and reception of signals between the source device 100 and the cable 300 are not transmitted to the sink device 200, and the transmission and reception of signals between the sink device 200 and the cable 300 are not transmitted to the source device 100.

[0088] The voltage level of the signal output from the source device 100 to the communication line is changed between when the source device 100 and the sink device 200 communicate with each other and when the source device 100 and the cable 300 communicate with each other, thereby enabling independent communication. Similarly, the voltage level of the signal output from the sink device 200 to the communication line is changed between when the sink device 200 and the source device 100 communicate with each other and when the sink device 200 and the cable 300 communicate with each other, thereby enabling independent communication.

[0089] The cable 300 is configured so that, at a voltage level at which the source device 100 and the sink device 200 communicate with each other, the signal from the source device 100 is transmitted as is to the sink device 200, and at a voltage level at which the source device 100 and the cable 300 communicate with each other, the signal from the source device 100 is received but not transmitted to the sink device 200. Furthermore, the cable 300 is configured so that, at a voltage level at which the sink device 200 and the source device 100 communicate with each other, the signal from the sink device 200 is transmitted directly to the source device 100, and at a voltage level at which the sink device 200 and the cable 300 communicate with each other, the signal from the sink device 200 is received but not transmitted to the source device 100.

[0090] The source device 100 includes a controller 101, a driver 102, a comparator 103, a controller 104, a driver 105, and a comparator 106. Although detailed description is omitted, this is similar to Figure 1 The configuration of the source device 100 in the transmission system 10A is similar.

[0091] The cable 300 includes a controller 301, a driver 302, a comparator 303, a comparator (Comp.4) 306, a controller (Ctrl.6) 307, a driver (Drv.6) 308, a comparator (Comp.6) 309, and a comparator (Comp.8) 310. Although detailed description is omitted, the controller 301, the driver 302, and the comparator 303 are similar to the controller 301. Figure 1 The controller 301 , the driver 302 , and the comparator 303 in the transmission system 10A are similar.

[0092] Controller 307 transmits transmit data to driver 308 and receives receive data from comparator 309. Driver 308 generates a signal with a voltage level of 2.5V to 5V corresponding to the transmit data sent from controller 307 and outputs this signal to communication line 410. In this case, for example, the logical "0" of the transmission data is 2.5V, and the logical "1" is 5V. A signal is input from communication line 410 to the positive input terminal of comparator 309, and a threshold value Vth1 is provided to the negative input terminal of comparator 309. Comparator 309 outputs "0" when the signal level is lower than threshold value Vth1, and outputs "1" when the signal level is equal to or greater than threshold value Vth1.

[0093] Comparator 306 and comparator 310 are connected in parallel and inserted into communication line 410. A signal is input from communication line 410 on the source device 100 side to the positive input terminal of comparator 306, and a threshold value Vth2 is provided to the negative input terminal of comparator 306. Comparator 306 outputs 0V when the signal level is lower than threshold value Vth2, and outputs 2.5V when the signal level is equal to or greater than threshold value Vth2. Comparator 306 is provided so that signals with voltage levels of 0V to 2.5V are transmitted to sink device 200 as is, but signals with voltage levels of 2.5V to 5V are blocked so that these signals are not transmitted to sink device 200.

[0094] In addition, a signal is input from the communication line 410 on the sink device 200 side to the positive input terminal of the comparator 310, and a threshold value Vth2 is provided to the negative input terminal of the comparator 310. The comparator 310 outputs 0 V when the signal level is lower than the threshold value Vth2, and outputs 2.5 V when the signal level is equal to or greater than the threshold value Vth2. The comparator 310 is provided so that signals with voltage levels of 0 V to 2.5 V are transmitted to the source device 100 as they are, but signals with voltage levels of 2.5 V to 5 V are cut off so that these signals are not transmitted to the source device 100.

[0095] The sink device 200 includes a controller (Ctrl.5) 201, a driver (Drv.5) 204, a comparator (Comp.5) 205, a controller (Ctrl.7) 206, a driver (Drv.7) 207, and a comparator (Comp.7) 208. The drivers 204 and 207 form a signal generating unit and a signal transmitting unit, while the comparators 205 and 208 form a signal receiving unit.

[0096] The controller 201 sends transmit data to the driver 204 and receives receive data from the comparator 205. The driver 204 generates a signal with a voltage level of 0V to 2.5V corresponding to the transmit data sent from the controller 201, and outputs the signal to the signal line 410. In this case, for example, the logic "0" of the transmit data is 0V, and the logic "1" is 2.5V. A signal is input from the communication line 410 to the positive input terminal of the comparator 205, and a threshold value Vth2 is provided to the negative input terminal of the comparator 205. The comparator 205 outputs "0" when the signal level is lower than the threshold value Vth2, and outputs "1" when the signal level is equal to or greater than the threshold value Vth2. Here, as described above, the threshold value Vth2 is set to a value between 0V and 2.5V, for example, 1.25V.

[0097] Controller 206 sends transmit data to driver 207 and receives receive data from comparator 208. Driver 207 generates a signal with a voltage level of 2.5V to 5V corresponding to the transmit data sent from controller 206 and outputs this signal to communication line 410. In this case, for example, the logic "0" of the transmit data is 2.5V, and the logic "1" is 5V. A signal is input from communication line 410 to the positive input terminal of comparator 208, and a threshold value Vth1 is provided to the negative input terminal of comparator 208. Comparator 208 outputs "0" when the signal level is lower than threshold value Vth1, and outputs "1" when the signal level is equal to or greater than threshold value Vth1.

[0098] A case where data is transmitted from the source device 100 to the sink device 200 will be described. In this case, the transmission data is transmitted from the controller 101 of the source device 100 to the driver 102. The driver 102 generates a signal with a voltage level of 0V to 2.5V corresponding to the transmission data and outputs the signal to the communication line 410. The signal with a voltage level of 0V to 2.5V is input from the communication line 410 to the positive input terminal of the comparator 306 of the cable 300.

[0099] In the comparator 306, since the threshold Vth2 is, for example, 1.25 V, a signal with a voltage level of 0 V to 2.5 V is received (detected) and output as a signal with a voltage level of 0 V to 2.5 V to the communication line 410. The signal with a voltage level of 0 V to 2.5 V is input from the communication line 410 to the positive input terminal of the comparator 205 of the sink device 200. In the comparator 205, since the threshold Vth2 is 1.25 V, a signal with a voltage level of 0 V to 2.5 V is received (detected), and the received data as the output data of the comparator 205 is transmitted to the controller 201.

[0100] Note that in this case, in the cable 300, a signal with a voltage level of 0 V to 2.5 V is also input from the communication line 410 to the positive input terminal of the comparator 303. In the comparator 303, the threshold value Vth1 is, for example, 3.75 V, so the signal with a voltage level of 0 V to 2.5 V is not received (not detected). That is, in this case, the output of the comparator 303 remains "0", and the controller 301 of the cable 300 cannot receive data.

[0101] Furthermore, in this case, in the cable 300, a signal with a voltage level of 0 V to 2.5 V is also input from the communication line 410 to the positive input terminal of the comparator 309. In the comparator 309, the threshold value Vth1 is, for example, 3.75 V, so the signal with a voltage level of 0 V to 2.5 V is not received (not detected). That is, in this case, the output of the comparator 309 remains "0", and the controller 307 of the cable 300 cannot receive data.

[0102] Next, a case where data is transmitted from the sink device 200 to the source device 100 will be described. In this case, the transmission data is transmitted from the controller 201 of the sink device 200 to the driver 204. The driver 204 generates a signal with a voltage level of 0V to 2.5V corresponding to the transmission data and outputs the signal to the communication line 410. The signal with a voltage level of 0V to 2.5V is input from the communication line 410 to the positive input terminal of the comparator 310 of the cable 300.

[0103] In the comparator 310, the threshold Vth2 is, for example, 1.25 V, so a signal with a voltage level of 0 V to 2.5 V is received (detected) and output as a signal with a voltage level of 0 V to 2.5 V to the communication line 410. The signal with a voltage level of 0 V to 2.5 V is input from the communication line 410 to the positive input terminal of the comparator 103 of the source device 100. In the comparator 103, the threshold V1 is 1.25 V, so a signal with a voltage level of 0 V to 2.5 V is received (detected), and the received data as the output data of the comparator 103 is transmitted to the controller 101.

[0104] Note that in this case, in the cable 300, a signal with a voltage level of 0 V to 2.5 V is also input from the communication line 410 to the positive input terminal of the comparator 309. In the comparator 309, the threshold value Vth1 is, for example, 3.75 V, so the signal with a voltage level of 0 V to 2.5 V is not received (not detected). That is, in this case, the output of the comparator 309 remains "0", and the controller 307 of the cable 300 cannot receive data.

[0105] Furthermore, in this case, in the cable 300, a signal with a voltage level of 0 V to 2.5 V is also input from the communication line 410 to the positive input terminal of the comparator 303. In the comparator 303, the threshold value Vth1 is, for example, 3.75 V, so the signal with a voltage level of 0 V to 2.5 V is not received (not detected). That is, in this case, the output of the comparator 303 remains "0", and the controller 301 of the cable 300 cannot receive data.

[0106] Next, a description will be given of a case where data is transmitted from the source device 100 to the cable 300. In this case, the transmission data is transmitted from the controller 104 of the source device 100 to the driver 105. The driver 105 generates a signal corresponding to the transmission data at a voltage level of 2.5V to 5V and outputs the signal to the communication line 410. The signal at a voltage level of 2.5V to 5V is input from the communication line 410 to the positive input terminal of the comparator 303 of the cable 300. In the comparator 303, since the threshold value Vth1 is, for example, 3.75V, the signal at a voltage level of 2.5V to 5V is received (detected), and the received data is transmitted to the controller 301 as the output data of the comparator 303.

[0107] Note that in this case, in the cable 300, a signal with a voltage level of 2.5 V to 5 V is also input from the communication line 410 to the positive input terminal of the comparator 306. In the comparator 306, the threshold Vth2 is, for example, 1.25 V, so the signal with a voltage level of 2.5 V to 5 V is not received (not detected). That is, in this case, the output of the comparator 306 remains at 2.5 V, and the signal is not transmitted to the sink device 200 side.

[0108] Next, a description will be given of a case where data is transmitted from the cable 300 to the source device 100. In this case, the transmission data is transmitted from the controller 301 of the cable 300 to the driver 302. The driver 302 generates a signal corresponding to the transmission data at a voltage level of 2.5V to 5V and outputs the signal to the communication line 410. The signal at a voltage level of 2.5V to 5V is input from the communication line 410 to the positive input terminal of the comparator 106 of the source device 100. In the comparator 106, since the threshold value Vth1 is, for example, 3.75V, the signal at a voltage level of 2.5V to 5V is received (detected), and the received data is transmitted as the output data of the comparator 106 to the controller 104.

[0109] Note that in this case, in the cable 300, a signal with a voltage level of 2.5 V to 5 V is also input from the communication line 410 to the positive input terminal of the comparator 306. In the comparator 306, the threshold Vth2 is, for example, 1.25 V, so the signal with a voltage level of 2.5 V to 5 V is not received (not detected). That is, in this case, the output of the comparator 306 remains at 2.5 V, and the signal is not transmitted to the sink device 200 side.

[0110] Next, a description will be given of a case where data is transmitted from the sink device 200 to the cable 300. In this case, the transmission data is transmitted from the controller 206 of the sink device 200 to the driver 207. The driver 207 generates a signal corresponding to the transmission data at a voltage level of 2.5V to 5V and outputs the signal to the communication line 410. The signal at a voltage level of 2.5V to 5V is input from the communication line 410 to the positive input terminal of the comparator 309 of the cable 300. In the comparator 309, since the threshold value Vth1 is, for example, 3.75V, the signal at a voltage level of 2.5V to 5V is received (detected), and the received data, which is the output data of the comparator 309, is transmitted to the controller 307.

[0111] Note that in this case, in the cable 300, a signal with a voltage level of 2.5 V to 5 V is also input from the communication line 410 to the positive input terminal of the comparator 310. In the comparator 310, the threshold Vth2 is, for example, 1.25 V, so the signal with a voltage level of 2.5 V to 5 V is not received (not detected). That is, in this case, the output of the comparator 310 remains at 2.5 V, and the signal is not transmitted to the source device 100 side.

[0112] Next, a case where data is transmitted from the cable 300 to the sink device 200 will be described. In this case, the transmission data is transmitted from the controller 307 of the cable 300 to the driver 308. The driver 308 generates a signal with a voltage level of 2.5V to 5V corresponding to the transmission data and outputs the signal to the communication line 410. The signal with a voltage level of 2.5V to 5V is input from the communication line 410 to the positive input terminal of the comparator 208 of the sink device 200. In the comparator 208, since the threshold value Vth1 is, for example, 3.75V, the signal with a voltage level of 2.5V to 5V is received (detected), and the received data is transmitted to the controller 206 as the output data of the comparator 208.

[0113] Note that in this case, in the cable 300, a signal with a voltage level of 2.5 V to 5 V is also input from the communication line 410 to the positive input terminal of the comparator 310. In the comparator 310, the threshold Vth2 is, for example, 1.25 V, so the signal with a voltage level of 2.5 V to 5 V is not received (not detected). That is, in this case, the output of the comparator 310 remains at 2.5 V, and the signal is not transmitted to the source device 100 side.

[0114] As mentioned above, in Figure 5In the transmission system 10C shown, the source device 100 and the sink device 200, the source device 100 and the cable 300, and the sink device 200 and the cable 300 can communicate with each other independently. Signals transmitted and received between the source device 100 and the cable 300 are not transmitted to the sink device 200, and signals transmitted and received between the sink device 200 and the cable 300 are not transmitted to the source device 100. In this case, without logically analyzing the content of the signal, the cable 300 can immediately determine whether the signal is to be transmitted to the sink device 200 or the source device 100 at the subsequent stage based solely on the difference in voltage level. This eliminates the need for components such as memory and verification costs, and can reduce costs.

[0115] Note that in Figure 5 In the configuration of the transmission system 10C shown, the source device 100 includes the controller 101 and the controller 104, but these controllers may be configured as one controller. In addition, a case has been described in which Figure 5 In the configuration of the transmission system 10C shown, the source device 100 has separate drivers for generating and transmitting a signal with a voltage level of 0V to 2.5V and a signal with a voltage level of 2.5V to 5V, and has a separate comparator for receiving each signal. However, a configuration in which one is used for each of them is conceivable (see Figure 3 Although detailed description is omitted, this is similar for the sink device 200.

[0116] "Fourth Embodiment"

[0117] Figure 6 A configuration example of a transmission system 10D as a fourth embodiment is shown. Figure 6 In the embodiment, the same reference numerals are used to represent Figure 1 , and their detailed description will be omitted as appropriate. The transmission system 10D communicates via, for example, an inter-integrated circuit (I2C). As is well known, since I2C is driven by current, data "0" and "1" are generated by subtracting the current from the pull-up resistor.

[0118] Driver (Drv.1) 102 of source device 100 and driver (Drv.4) 304 of cable 300 draw current through resistor R1, thereby obtaining a signal with a voltage level of 0V to 2.5V. Since the signal input to the positive input terminal of comparator (Comp.1) 103 is generated by drawing current from the 5V power supply via resistor R1, threshold V1 is also generated by drawing current from the 5V power supply via resistor R1. Therefore, it can follow fluctuations in the 5V power supply (such as noise) and improve signal stability. Although not shown, this is similar for comparator (Comp.2) 106, comparator (Comp.3) 303, comparator (Comp.4) 305, and comparator (Comp.5) 203.

[0119] Note that in the case of I2C, the communication line consists of two lines, namely, serial data (SDA) and serial clock (SCL). Therefore, it is necessary to install the above circuit on both SDA and SCL. However, the present technology is not limited to I2C, and in the case of a system in which a clock is superimposed on data in the case of a protocol that does not initially require a clock, or similar cases, it is sufficient to install the above circuit on one communication line.

[0120] Figure 7 An example of a sequence of communication between the source device 100 and the sink device 200, and communication between the source device 100 and the cable 300 in the transmission system 10D is shown. Part A indicates a portion in which the source device 100 and the sink device 200 communicate with each other using a signal with a voltage level of 0 V to 2.5 V, and part B indicates a portion in which the source device 100 and the cable 300 communicate with each other using a signal with a voltage level of 2.5 V to 5 V.

[0121] In this case, since the signal is generated by drawing current from the 5V power supply via a resistor, the signal crosses the threshold value Vth1 at the first falling edge and the last rising edge in section A. Therefore, the output data of the comparator 303 of the cable 300 changes from "1" to "0" at the falling edge and from "0" to "1" at the rising edge, and the controller 301 of the cable 300 needs to ignore such change information. For example, as an ignoring method, a method that can be conceived is a method in which, if no signal appears within a certain period of time after falling edge detection, it is determined that it is a section in which communication is performed between the source device 100 and the sink device 200.

[0122] Although detailed description is omitted, Figure 6 The transmission system 10D shown is Figure 1 The transmission system 10A is configured in a similar manner to perform Figure 1The communication operation is similar to that of the transmission system 10A, and provides Figure 1 The transmission system 10A has a similar effect, except that the transmission system 10D is driven by current as described above. Note that although Figure 6 The transmission system 10D shown corresponds to Figure 1 transmission system 10A, but in a similar manner it can be thought of corresponding to Figure 5 Configuration of the transmission system 10C.

[0123] "Fifth Embodiment"

[0124] Figure 8 FIG. 1 shows a configuration example of a transmission system 10E as a fifth embodiment. Figure 6 The transmission system 10D of the transmission system 10E also performs communication via, for example, I2C. Figure 8 In the embodiment, the same reference numerals are used to represent Figure 6 The components in FIG. 1 correspond to the components in FIG. 1 , and their detailed description will be omitted as appropriate.

[0125] In the source device 100, a driver (Drv.6) 107 that drives in synchronization with the driver (Drv.2) 105 is connected to the negative input terminal on the threshold side of the comparator (Cmp.1) 103. Figure 6 The transmission system 10D is configured similarly.

[0126] In the source device 100, when the driver 107 is connected, as shown in FIG. Figure 9 As shown, in section B, where communication is performed between the source device 100 and the cable 300, the threshold V1 of the comparator (Cmp. 1) 103 changes according to the signal with a voltage level of 2.5V to 5V generated by driving the driver 105. Therefore, in the comparator (Cmp. 1) 103, the voltage difference between the signal with a voltage level of 2.5V to 5V input to the positive input terminal and the threshold V1 input to the negative input terminal can always be maintained above a certain level. Therefore, even in the case where, for example, noise is added to the signal with a voltage level of 2.5V to 5V, it is possible to prevent an erroneous signal from being output to the output side of the comparator 103. In other words, the quality of the output data of the comparator 103 can be maintained high.

[0127] Note that although detailed description is omitted, in the cable 300, by connecting a driver that is driven synchronously with the driver (Drv. 3) 302 to the negative input terminal on the threshold side of the comparator (Cmp. 4), similar to the comparator 103 of the above-mentioned source device 100, the quality of the output data of the comparator 305 can be kept high.

[0128] "Sixth Embodiment"

[0129] In each of the above-described embodiments, the cable 300 corresponds to the present technology. Figure 10 The transmission system 10' is shown with a conventional cable 300' connected. Figure 10 In the embodiment, the same reference numerals are used to represent Figure 8 In the transmission system 10', the source device 100 and the sink device 200 are respectively Figure 8 The source device 100 and the sink device 200 in the transmission device 10E are the same.

[0130] exist Figure 10 In the case of the transmission system 10' of the conventional embodiment, when communication is performed between the source device 100 and the sink device 200, since the source device 100 does not know whether the connected cable 300' is a compatible cable or a non-compatible cable, a signal having a voltage level of 0V to 2.5V is output from the driver 102 to the communication line 410. However, if the sink device 200 is conventional, it may not be possible to receive a signal having a voltage level of 0V to 2.5V. Therefore, it is preferable that the source device 100 transmits a signal after determining whether the connected cable is a compatible cable or a non-compatible cable.

[0131] Figure 11 A configuration example of a transmission system 10F as a sixth embodiment is shown. Figure 11 In the embodiment, the same reference numerals are used to represent Figure 8 The components in FIG. 1 correspond to the components in FIG. 1 , and their detailed description will be omitted as appropriate.

[0132] In the cable 300, the pull-up resistor R4 is connected to the point P1 on the source device 100 side of the communication line 410. In the sink device 200, the pull-up resistor R4 is set to a value different from the value of the pull-up resistor R2 connected to the communication line. In addition, in the source device 100, the constant current circuit 111 is connected to the point Q1 of the communication line 410 on the cable 300 side. Then, in the source device 100, the voltage at the point Q1 is monitored by the voltage monitoring unit 112. Other Figure 8 The transmission system 10E is configured similarly.

[0133] In the source device 100, when current is drawn in the constant current circuit 111, Figure 11 The transmission system 10F is connected to the compatible cable 300 and is connected to the conventional cable 300' (see Figure 10), the voltage value at point Q1 monitored by the voltage monitoring unit 112 (the voltage value of the communication line 410) is different. Therefore, the source device 100 can determine whether the connected cable is a compatible cable or a non-compatible cable, and can perform appropriate operations depending on whether the cable is a compatible cable or a non-compatible cable.

[0134] Note that as a method for the source device 100 to determine whether the connected cable is a compatible cable or an incompatible cable, it is conceivable to use a line other than a communication line. For example, Figure 12 A configuration example of a transmission system 10F' is shown, and the transmission system 10F' is configured to perform determination using a power supply line.

[0135] This transmission system 10F' has a configuration in which a source device 100 and a sink device 200 are connected through a cable 300. The source device 100 includes a transmission and reception circuit 120, a controller 121, and a voltage monitoring unit 122. The transmission and reception circuit 120 collectively represents, for example Figure 8 The controller 121 is a communication function unit of the source device 100 of the transmission system 10E. The controller 121 is a component that controls the entire source device 100.

[0136] In the source device 100, a switch SW1 is inserted into the 5V power supply line 420. The opening and closing of this switch SW is controlled by the controller 121. In the source device 100, a point S1 on the cable 300 side is connected to the 5V power supply via the resistor R11 from the switch SW1. The voltage monitoring unit 122 monitors the voltage at this point S1.

[0137] The cable 300 has a transmit and receive circuit 320. The transmit and receive circuit 320 collectively represent, for example, Figure 8 The communication function unit of the cable 300 of the transmission system 10E. In the cable 300, the point S2 of the 5V power supply line 420 is grounded via the resistor R12. In addition, the sink device 200 includes a transmission and reception circuit 220. The transmission and reception circuit 220 collectively represent, for example Figure 8 The communication function unit of the sink device 200 of the transmission system 10E.

[0138] When detecting that a cable is connected in some way, the source device 100 turns on the switch SW1 as shown in the figure, determines whether the connected cable is a compatible cable or a non-compatible cable based on the voltage value at the point S2 monitored by the voltage monitoring unit 122, and performs appropriate operations according to whether the cable is a compatible cable or a non-compatible cable. In this case, Figure 12In the case where the compatible cable 300 is connected as in the transmission system 10F' of FIG. 1 , the voltage value at the point S1 is a voltage obtained by dividing 5 V by the resistors R11 and R12. On the other hand, in the case where the conventional cable 300' (see FIG. 1 ) as a non-compatible cable is connected Figure 10 ), the voltage value at point S1 remains at 5V.

[0139] Seventh Embodiment

[0140] Figure 13 The following illustrates a configuration example of a transmission system 10G as a seventh embodiment. This transmission system 10G includes a source device 100, an intermediate device 500 such as a repeater device, a sink device 200, and a conventional cable 300' connecting these devices. Note that in the example shown in the figure, there is only one intermediate device 500, but multiple intermediate devices can be daisy-chained. This transmission system 10G is configured so that the source device 100 and the sink device 200, as well as the source device 100 and the intermediate device 500, can independently communicate with each other, and that signal transmission and reception between the source device 100 and the intermediate device 500 are not transmitted to the sink device 200.

[0141] The source device 100 includes a controller 101, a driver 102, a comparator 103, a controller 104, a driver 105, and a comparator 106. Although detailed description is omitted, this is similar to Figure 1 The configuration of the source device 100 in the transmission system 10A is similar.

[0142] The intermediate device 500 includes a controller (Ctrl.3) 501, a driver (Drv.3) 502, a comparator (Comp.3) 503, a driver (Drv.4) 504, and a comparator (Comp.4) 505. Although detailed description is omitted, this is similar to Figure 1 The configuration of the cable 300 in the transmission system 10A is similar.

[0143] The sink device 200 is a conventional source device. The source device 200 includes a controller 201, a driver 202, and a comparator 203. Although detailed description is omitted, this is similar to Figure 1 The configuration of the sink 200 in the transmission system 10A is similar.

[0144] Although detailed description is omitted, Figure 13 The communication operation between the source device 100 and the sink device 200 in the transmission system 10G shown is similar to Figure 1 The communication operation between the source device 100 and the sink device 200 in the transmission system 10A is described in detail. Figure 13The communication operation between the source device 100 and the intermediate device 500 in the transmission system 10G shown is similar to Figure 1 The communication operation between the source device 100 and the cable 300 in the transmission system 10A is shown.

[0145] As mentioned above, in Figure 13 In the illustrated transmission system 10G, the source device 100 and the sink device 200, as well as the source device 100 and the intermediate device 500, can communicate independently with each other, and the transmission and reception of signals between the source device 100 and the intermediate device 500 are not transmitted to the sink device 200. In this case, without logically analyzing the content of the signal, the intermediate device 500 can immediately determine whether the signal is to be passed to the subsequent sink device 200 based solely on the difference in voltage level. This eliminates the need for components such as memory and verification costs, and reduces costs. For example, in an HDMI repeater device, signals between the source device and the repeater device may not be passed to the sink device, but the data needs to be stored in memory and analyzed to determine whether it will be transmitted to the sink device.

[0146] Notice, Figure 13 The transmission system 10G shown is capable of performing communication between the source device 100 and the intermediate device 500, but a configuration capable of performing communication between the sink device 200 and the intermediate device 500 and a configuration capable of performing both communication between the source device 100 and the intermediate device 500 and communication between the sink device 200 and the intermediate device 500 are also conceivable (see Figure 4 and Figure 5 ).

[0147] "Eighth Embodiment"

[0148] In each of the above-described embodiments, an example has been shown in which two signals having different voltage levels are processed, but an example in which three or more signals having different voltage levels are processed is also conceivable. Figure 14 A configuration example of a transmission system 10H as an eighth embodiment is shown. This transmission system 10H is an example of processing three signals having different voltage levels.

[0149] This transmission system 10H includes a source device 100, a sink device 200, and cables 300-1 and 300-2 connecting these devices. This transmission system 10H is configured so that the source device 100 and the sink device 200, the source device 100 and the cable 300-1, and the source device 100 and the cable 300-2 can communicate with each other independently, and the transmission and reception of signals between the source device 100 and the cables 300-1 and 300-2 are not transmitted to the subsequent stage.

[0150] The voltage level of the signal output from the source device 100 to the communication line is changed between when the source device 100 and the sink device 200 are communicating and when the source device 100 and the cables 300-1 and 300-2 are communicating, thereby enabling independent communication. The cables 300-1 and 300-2 are configured so that: at the voltage level at which the source device 100 and the sink device 200 communicate with each other, the signal from the source device 100 is directly transmitted to the sink device 200, and at the voltage level at which the source device 100 and the cables 300-1 and 300-2 communicate with each other, the signal from the source device 100 is received but not transmitted to the subsequent stage.

[0151] The source device 100 includes a controller (Ctrl. 1) 101 , a driver (Drv. 1) 102 , a comparator (Comp. 1) 103 , a controller (Ctrl. 10) 108 , a driver (Drv. 10) 109 , and a comparator (Comp. 10) 110 .

[0152] The controller 101 sends transmit data to the driver 102 and receives receive data from the comparator 103. The driver 102 generates a signal with a voltage level of 1.7V to 3.3V corresponding to the transmit data sent from the controller 101, and outputs the signal to the communication line 410. In this case, for example, the logic "0" of the transmit data is 1.7V, and the logic "1" is 3.3V. A signal is input from the communication line 410 to the positive input terminal of the comparator 103, and a threshold value V1 is provided to the negative input terminal of the comparator 103. Here, the threshold value V1 is set to a value between 1.7V and 3.3V, for example, 2.5V. The comparator 103 outputs "0" when the signal level is lower than the threshold value V1, and outputs "1" when the signal level is equal to or greater than the threshold value V1.

[0153] Controller 108 transmits transmit data to driver 109 and receives receive data from comparator 110. Driver 109 generates a signal corresponding to the transmit data sent from controller 108 and outputs the signal to communication line 410. When communicating with cable 300-1, a signal having a voltage level of 0V to 1.7V is generated and output to communication line 410. In this case, for example, the logical "0" of the transmit data is 0V, and the logical "1" is 1.7V. In addition, when communicating with cable 300-2, a signal having a voltage level of 3.3V to 5V is generated and output to communication line 410. In this case, for example, the logical "0" of the transmit data is 3.3V, and the logical "1" is 5V.

[0154] A signal is input from the communication line 410 to the positive input terminal of the comparator 110, and a threshold value Vth1 / Vth3 is provided to the negative input terminal of the comparator 110. The threshold value Vth3 is set to a value between 0 V and 1.7 V, for example, 0.85 V, and the threshold value Vth1 is set to a value between 3.3 V and 5 V, for example, 4.15 V. The comparator 110 outputs "0" when the signal level is lower than the threshold value Vth1 / Vth3, and outputs "1" when the signal level is equal to or greater than the threshold value Vth1 / Vth3.

[0155] The cable 300 - 1 includes a controller (Ctrl. 3 ) 301 - 1 , a driver (Drv. 3 ) 302 - 1 , a comparator (Comp. 3 ) 303 - 1 , a comparator (Comp. 11 ) 305 - 1 , and a comparator (Comp. 12 ) 306 - 1 .

[0156] Controller 301-1 transmits transmit data to driver 302-1 and receives receive data from comparator 303-1. Driver 302-2 generates a signal with a voltage level of 3.3V to 5V corresponding to the transmit data sent from controller 301-1 and outputs the signal to communication line 410. In this case, for example, the logic "0" of the transmit data is 3.3V, and the logic "1" is 5V. A signal is input from communication line 410 to the positive input terminal of comparator 303-1, and a threshold value Vth1 is provided to the negative input terminal of comparator 303-1. Comparator 303-1 outputs "0" when the signal level is lower than threshold value Vth1, and outputs "1" when the signal level is equal to or greater than threshold value Vth1.

[0157] Comparators 305-1 and 306-1 are connected in parallel and inserted into the communication line 410. A signal is input from the communication line 410 on the source device 100 side to the positive input terminal of the comparator 305-1, and the threshold value Vth2 / Vth3 is provided to the negative input terminal of the comparator 305-1. The threshold value Vth2 is set to a value between 1.7V and 3.3V, for example, 2.5V. The comparator 305-1 outputs the signal detected by the threshold value Vth2 / Vth3 as a signal having the same voltage level. That is, when the input signal is a signal having a voltage level of 1.7V to 3.3V, this is detected (received) at the threshold value Vth2 and outputted as a signal having a voltage level of 1.7V to 3.3V. In addition, when the input signal is a signal having a voltage level of 0.1V to 7V, this is detected (received) at the threshold value Vth3 and outputted as a signal having a voltage level of 0.1V to 7V.

[0158] A signal is input from the communication line 410 on the cable 300-2 side to the positive input terminal of the comparator 306-1, and the threshold value Vth2 / Vth3 is provided to the negative input terminal of the comparator 306-1. Similar to the comparator 305-1, the comparator 306-1 outputs the signal detected at the threshold value Vth2 / Vth3 as a signal having the same voltage level.

[0159] The cable 300 - 2 includes a controller (Ctrl. 12 ) 301 - 2 , a driver (Drv. 12 ) 302 - 2 , a comparator (Comp. 12 ) 303 - 2 , a driver (Drv. 13 ) 304 - 2 , and a comparator (Comp. 13 ) 305 - 2 .

[0160] Controller 301-2 transmits transmit data to driver 302-2 and receives receive data from comparator 303-2. Driver 302-2 generates a signal with a voltage level of 0V to 1.7V corresponding to the transmit data sent from controller 301-2 and outputs the signal to communication line 410. In this case, for example, the logic "0" of the transmit data is 0V, and the logic "1" is 1.7V. A signal is input from communication line 410 to the positive input terminal of comparator 303-2, and a threshold value Vth3 is provided to the negative input terminal of comparator 303-2. Comparator 303-2 outputs "0" when the signal level is lower than threshold value Vth3, and outputs "1" when the signal level is equal to or greater than threshold value Vth3.

[0161] The driver 304-2 and the comparator 305-2 are connected in parallel and inserted in the communication line 410. The driver 304-2 receives a signal from the communication line 410 on the sink device 200 side and outputs a signal whose voltage level has been converted from 0V to 5V to 1.7V to 3.3V to the communication line 410 on the cable 300-1 side.

[0162] A signal is input from the communication line 410 on the cable 300-1 side to the positive input terminal of the comparator 305-2, and a threshold value Vth2 is provided to the negative input terminal of the comparator 305-2. The comparator 305-2 outputs 0V when the signal level is lower than the threshold value Vth2, and outputs 5V when the signal level is equal to or greater than the threshold value Vth2. In other words, when the voltage level of the signal on the communication line 410 on the cable 300-1 side is 1.7V to 3.3V, the comparator 305-2 converts the signal to a voltage level of 0V to 5V so that the legacy sink device 200 can also receive the signal, and outputs the converted signal to the communication line 410 on the sink device 200 side. The comparator 305-2 is provided so that signals with voltage levels of 1.7V to 3.3V are transmitted to the sink device 200 as is, but signals with voltage levels of 0V to 1.7V are blocked so that these signals are not transmitted to the sink device 200.

[0163] The sink device 200 is a conventional sink device and includes a controller (Ctrl.5) 201, a driver (Drv.5) 202, and a comparator (Comp.5) 203.

[0164] The controller 201 transmits transmit data to the driver 202 and receives receive data from the comparator 203. The driver 202 generates a signal with a voltage level of 0V to 5V corresponding to the transmit data sent from the controller 201, and outputs the signal to the communication line 410. In this case, for example, the logic "0" of the transmit data is 0V, and the logic "1" is 5V. A signal is input from the communication line 410 to the positive input terminal of the comparator 203, and a threshold value V2 is provided to the negative input terminal of the comparator 203. Here, the threshold value V2 is set to a value between 0V and 5V, for example, 2.5V. The comparator 203 outputs "0" when the signal level is lower than the threshold value V2, and outputs "1" when the signal level is equal to or greater than the threshold value V1.

[0165] The following describes a case where data is transmitted from the source device 100 to the sink device 200. In this case, the transmission data is transmitted from the controller 101 of the source device 100 to the driver 102. The driver 102 generates a signal with a voltage level of 1.7V to 3.3V corresponding to the transmission data and outputs the signal to the communication line 410. The signal with a voltage level of 1.7V to 3.3V is input from the communication line 410 on the source device 100 side to the positive input terminal of the comparator 305-1 of the cable 300-1. In the comparator 305-1, the signal with a voltage level of 1.7V to 3.3V is detected at the threshold value Vth2 and is directly output to the communication line 410 on the cable 300-2 side.

[0166] A signal having a voltage level of 1.7 V to 3.3 V is input from the communication line 410 on the cable 300-1 side to the positive input terminal of the comparator 305-2 of the cable 300-2. In the comparator 305-2, the signal having a voltage level of 1.7 V to 3.3 V is detected at the threshold value Vth2, converted into a signal having a voltage level of 0 V to 5 V, and output to the communication line 410 on the sink device 200 side.

[0167] A signal having a voltage level of 0 to 5 V is input from the communication line 410 on the cable 300-2 side to the positive input terminal of the comparator 203 of the sink device 200. Since the threshold V2 is 2.5 V, the signal having a voltage level of 0 to 5 V is detected in the comparator 203, and the received data as the output data of the comparator 203 is transmitted to the controller 201.

[0168] In this case, in the cable 300-1, a signal having a voltage level of 1.7 V to 3.3 V is also input to the positive input terminal of the comparator 303-1 from the communication line 410. In the comparator 303-1, the threshold value Vth1 is, for example, 4.15 V, so the signal having a voltage level of 1.7 V to 3.3 V is not detected. That is, in this case, the output of the comparator 303-1 remains "0", and the controller 301-1 of the cable 300-1 cannot receive data.

[0169] Similarly, in the cable 300-2, a signal having a voltage level of 1.7 V to 3.3 V is also input to the positive input terminal of the comparator 303-2 from the communication line 410. In the comparator 303-2, the threshold Vth3 is, for example, 0.85 V, so the signal having a voltage level of 1.7 V to 3.3 V is not detected. That is, in this case, the output of the comparator 303-2 remains "1", and the controller 301-2 of the cable 300-2 cannot receive data.

[0170] Note that, although not described, similar operations are performed in the case where data is transmitted from the sink device 200 to the source device 100, and the source device 100 receives the data, but the cables 300-1, 300-2 do not receive the data.

[0171] Next, we will describe a case where data is transmitted from the source device 100 to the cable 300-1. In this case, the transmission data is transmitted from the controller 108 of the source device 100 to the driver 109. The driver 109 generates a signal with a voltage level of 3.3V to 5V corresponding to the transmission data and outputs this signal to the communication line 410. The signal with a voltage level of 3.3V to 5V is input from the communication line 410 to the positive input terminal of the comparator 303-1 of the cable 300-1. In the comparator 303-1, since the threshold value Vth1 is, for example, 4.15V, the signal with a voltage level of 3.3V to 5V is detected, and the received data, which is the output data of the comparator 303-1, is transmitted to the controller 301-1.

[0172] In this case, in the cable 300-1, a signal having a voltage level of 3.3V to 5V is also input to the positive input terminal of the comparator 305-1 from the communication line 410. In the comparator 305-1, the threshold value Vth2 / Vth3 is applied to the negative input terminal, so the signal having a voltage level of 3.3V to 5V is not detected. In other words, the signal having a voltage level of 3.3V to 5V is not transmitted to the cable 300-2 or the sink device 200 in the subsequent stage.

[0173] Note that, although not described, similar operations are performed when data is transmitted from the cable 300-1 to the source device 100, and the source device 100 receives the data, but the data is not transmitted to the cable 300-2 and the sink device 200 in the subsequent stage.

[0174] Next, we will describe a case where data is transmitted from the source device 100 to the cable 300-2. In this case, the transmission data is transmitted from the controller 108 of the source device 100 to the driver 109. The driver 109 generates a signal with a voltage level of 0V to 1.7V corresponding to the transmission data and outputs this signal to the communication line 410. This 0V to 1.7V voltage level signal is input from the communication line 410 to the positive input terminal of the comparator 305-1 of the cable 300-1. In the comparator 305-1, the voltage level of 0V to 1.7V is detected at the threshold value Vth3 and is directly output to the communication line 410 on the cable 300-2 side.

[0175] A signal with a voltage level of 0V to 1.7V is input from the communication line 410 on the cable 300-1 side to the positive input terminal of the comparator 303-2 of the cable 300-2. In the comparator 303-2, since the threshold value Vth3 is, for example, 0.85V, the signal with a voltage level of 0V to 1.7V is detected, and the received data as the output data of the comparator 303-2 is transmitted to the controller 301-2.

[0176] In this case, in the cable 300-2, a signal with a voltage level of 0V to 1.7V is also input to the positive input terminal of the comparator 305-2 from the communication line 410. In the comparator 305-2, the threshold value Vth2 is provided to the negative input terminal of the comparator 305-2, so the signal with a voltage level of 0V to 1.7V is not detected. In other words, the signal with a voltage level of 0V to 1.7V is not transmitted to the sink device 200 in the next stage.

[0177] Furthermore, in this case, in the cable 300-1, a signal with a voltage level of 0 V to 1.7 V is also input to the positive input terminal of the comparator 303-1 from the communication line 410. In the comparator 303-1, the threshold value Vth1 is, for example, 4.15 V, so the signal with a voltage level of 0 V to 1.7 V is not detected. That is, in this case, the output of the comparator 303-1 remains "0", and the controller 301-1 of the cable 300-1 cannot receive data.

[0178] Note that, although not described, a similar operation is performed when data is transmitted from the cable 300-2 to the source device 100, and the source device 100 receives the data, but the data is not transmitted to the sink device 200 in the subsequent stage, and the cable 300-1 does not receive the data.

[0179] Figure 15 This figure shows an example of a sequence of communication between the source device 100 and the sink device 200, communication between the source device 100 and the cable 300-1, and communication between the source device 100 and the cable 300-2. Section B indicates a portion where communication between the source device 100 and the sink device 200 is performed using a signal with a voltage level of 1.7V to 3.3V. Section A indicates a portion where communication between the source device 100 and the cable 300-2 is performed using a signal with a voltage level of 0V to 1.7V. Section C indicates a portion where communication between the source device 100 and the cable 300-1 is performed using a signal with a voltage level of 3.3V to 5V.

[0180] As mentioned above, in Figure 14 In the illustrated transmission system 10H, the source device 100 and the sink device 200, the source device 100 and the cable 300-1, and the source device 100 and the cable 300-2 can communicate independently with each other, and the transmission and reception of signals between the source device 100 and the cables 300-1 and 300-2 are not transmitted to the next stage. In this case, without logically analyzing the content of the signal, the cables 300-1 and 300-2 can immediately determine whether the information is to be passed to the next stage based solely on the difference in voltage level. This eliminates the need for components such as memory and verification costs, and can reduce costs.

[0181] <2. Modifications>

[0182] Note that in the above embodiment, a transmission system in which a source device and a sink device are connected via an HDMI cable has been described as an example. However, since the present technology can be similarly applied to cables using the mechanism defined by the "VESA Plug and Display (P&D) Specification" for both the transmitting and receiving devices, the technology can also be applied to DVI, MHL, DisplayPort, etc. In addition, it goes without saying that the present technology can also be similarly applied to USB cables, etc.

[0183] In addition, although the preferred embodiments of the present disclosure have been described in detail with reference to the accompanying drawings, the technical scope of the present disclosure is not limited to such examples. Obviously, a person skilled in the art to which the present disclosure belongs can conceive of various changes and modifications within the scope of the technical ideas described in the claims, and it is understood that these changes and modifications belong to the technical scope of the present disclosure.

[0184] Additionally, the present technology may also adopt the following configurations.

[0185] (1) A sending device comprising:

[0186] a signal generating unit that generates a plurality of signals having different voltage levels; and

[0187] The signal transmitting unit outputs the plurality of signals having different voltage levels to the communication line at different timings.

[0188] (2) The transmitting device according to (1) above,

[0189] The signal generating unit generates the plurality of signals with different voltage levels through a plurality of drivers.

[0190] (3) The transmitting device according to (1) above,

[0191] The signal generating unit generates the plurality of signals with different voltage levels through a driver.

[0192] (4) The transmitting device according to any one of (1) to (3) above,

[0193] The signal generating unit generates the plurality of signals with different voltage levels by current driving.

[0194] (5) The transmitting device according to any one of (1) to (4) above,

[0195] A determination unit is further included that determines whether the communication line is connected to a receiving device corresponding to the plurality of signals having different voltage levels.

[0196] (6) The transmitting device according to (5) above,

[0197] The determination unit makes the determination based on a voltage level of the communication line when a predetermined current is drawn from the communication line.

[0198] (7) The transmitting device according to (5) above,

[0199] The determination unit makes the determination based on a voltage level of the power supply line when a switch inserted in the power supply line is turned off.

[0200] (8) The transmitting device according to any one of (1) to (7) above,

[0201] A signal receiving unit is further included that receives the plurality of signals having different voltage levels from the communication line at different timings.

[0202] (9) The transmitting device according to (8) above,

[0203] The signal receiving unit transmits a portion of the plurality of signals having different voltage levels to a subsequent stage via the communication line.

[0204] (10) A sending method, comprising:

[0205] generating a plurality of signals having different voltage levels; and

[0206] The plurality of signals having different voltage levels are output to the communication line at different timings.

[0207] (11) A receiving device comprising:

[0208] The signal receiving unit receives a plurality of signals having different voltage levels from the communication line at different timings.

[0209] (12) The receiving device according to (11) above,

[0210] The signal receiving unit includes a comparator having thresholds corresponding to the plurality of signals having different voltage levels.

[0211] (13) The receiving device according to (11) or (12) above,

[0212] The signal receiving unit transmits a portion of the plurality of signals having different voltage levels to a subsequent stage via the communication line.

[0213] (14) The receiving device according to (13) above,

[0214] A voltage level conversion unit is further included, which converts a voltage level of a signal transmitted to a subsequent stage into another voltage level.

[0215] (15) A receiving method comprising:

[0216] A plurality of signals having different voltage levels are received from the communication line at different timings.

[0217] Label list

[0218] 10A to 10H, 10' transmission system

[0219] 100 Source Equipment

[0220] 101, 104 controllers

[0221] 102, 105 drivers

[0222] 103, 106 Comparator

[0223] 111 Constant Current Circuit

[0224] 112 Voltage Monitoring Unit

[0225] 120 Transmit and Receive Circuits

[0226] 121 Controller

[0227] 122 Voltage Monitoring Unit

[0228] 200 sink equipment

[0229] 201, 206 controllers

[0230] 202, 204, 207 drivers

[0231] 203, 205, 208 comparators

[0232] 220 Transmit and Receive Circuits

[0233] 300, 300-1, 300-2, 300' cables

[0234] 301, 301-1, 301-2, 307 controllers

[0235] 302, 302-1, 302-2, 304, 304-2, 308 drivers

[0236] 303, 303-1, 303-2, 305, 305-1, 305-2, 306, 306-1, 309, 310 Comparators

[0237] 320 Transmit and Receive Circuits

[0238] 410 communication lines

[0239] 420 power supply line

[0240] 500 Intermediate Device

[0241] 501 Controller

[0242] 502, 504 drivers

[0243] 503, 505 comparators

Claims

1. A sending device, comprising: a first driver configured to generate a first signal having a first voltage level among different voltage levels and output the first signal to the communication line at a first timing; a second driver configured to generate a second signal having a second voltage level among the different voltage levels, and output the second signal to the communication line at a second timing different from the first timing; a first comparator including a negative input terminal and a positive input terminal, wherein the first signal and the second signal are input to the positive input terminal of the first comparator, and a first voltage threshold having a first voltage level is input to the negative input terminal of the first comparator; a second comparator including a negative input terminal and a positive input terminal, wherein the first signal and the second signal are input to the positive input terminal of the second comparator, and a second voltage threshold having a second voltage level is input to the negative input terminal of the second comparator; as well as a third driver that drives in synchronization with the second driver, the third driver being connected to the negative input terminal of the first comparator so that the first voltage threshold changes according to a second signal generated by driving the second driver, wherein the transmitting device determines whether the communication line is connected to the receiving device based on a voltage level at a specific point on the communication line when current is drawn from the communication line, wherein the specific point is a point on the communication line located on one side of a cable connecting the transmitting device and the receiving device, Wherein, when it is determined that the communication line is connected to the receiving device, the third driver changes the first voltage threshold based on the second voltage level of the second signal generated by the second driver.

2. The transmitting device according to claim 1, in, The first driver and the second driver generate a first signal and a second signal having different voltage levels through current driving.

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