JP2016042669A - Signal input/output device and display apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a signal input/output device that can suppress occurrence of waveform distortion and reduction of amplitude in signals input to video equipment, etc. (video processor, etc.) through an input/output common terminal, and a display apparatus having the same.SOLUTION: A signal input/output device 1 has a first terminal 11 for inputting signals, a second terminal 21 for inputting/outputting signals, a first signal processor 10 for processing signals input through the first terminal 11, a second signal processor 20 for processing signals input through the second terminal 21, a signal output unit 30 for receiving and processing the signals processed by the first signal processor 10 and outputting the processed signals to the second terminal 21, and an impedance adjuster 24 which is provided on a signal transmission path between the second terminal 21 and the second signal processor 20 and adjusts an impedance viewed from the second terminal 21 to a predetermined impedance.SELECTED DRAWING: Figure 1

Description

  The present disclosure relates to a signal input / output device that inputs and outputs signals, and a display device including the same.

  Patent Document 1 discloses a signal input / output circuit in a video apparatus. This signal input / output circuit includes an input / output shared terminal capable of inputting / outputting a signal. The signal input / output circuit includes an input buffer, an output buffer, a resistor, and the like (signal processing unit). The signal input / output circuit outputs a signal input from an external device or the like via the input / output shared terminal to the input system signal processing circuit of the video device via the signal processing unit. The signal input / output circuit outputs a signal output from the output system signal processing circuit of the video equipment to an external device via the signal processing unit and the input / output common terminal. Furthermore, Patent Document 1 discloses a configuration in which impedance matching is performed by using a resistor included in a signal processing unit as a termination resistor when an input / output shared terminal is used as an input terminal.

JP-A-7-38817

  In the input / output circuit of the video equipment described in Patent Document 1, impedance matching may not be performed properly even when the resistor is a termination resistor. In this case, waveform distortion or amplitude reduction may occur in a signal input to the input system signal processing circuit (video processing unit) via the input / output shared terminal.

  The present disclosure relates to a signal input / output device capable of suppressing the occurrence of waveform distortion and amplitude reduction in a signal input to a video device or the like (video processing unit or the like) via an input / output shared terminal, and a display including the same Providing equipment.

  A signal input / output device according to a first aspect of the present disclosure includes a first terminal for inputting a signal, a second terminal for inputting / outputting a signal, and a first signal processing for processing a signal input via the first terminal. A second signal processing unit that processes a signal input via the second terminal, a signal output unit that inputs and processes the signal processed by the first signal processing unit, and outputs the processed signal to the second terminal; An impedance adjusting unit that is provided on the signal transmission path between the second terminal and the second signal processing unit and adjusts the impedance viewed from the second terminal to a predetermined impedance.

  A signal input / output device according to a second aspect of the present disclosure includes a first terminal for inputting a signal, a second terminal for inputting / outputting a signal, and a first signal processing for processing a signal input via the first terminal. A second signal processing unit that processes a signal input via the second terminal, a signal processed by the first signal processing unit, and a second signal processing unit. Between the signal output section for outputting to the signal transmission path between them and the upstream and downstream sides of the output position of the output of the signal output section to the signal transmission path in the signal transmission path, as viewed from the second terminal An impedance adjusting unit that adjusts to a predetermined impedance.

  A signal input / output device according to a third aspect of the present disclosure includes a terminal for inputting / outputting a signal, a signal processing unit for processing a signal input via the terminal, a signal output unit for outputting a predetermined signal to the terminal, An impedance adjusting unit that is provided between the terminal and the signal processing unit and adjusts the impedance viewed from the terminal to a predetermined impedance.

  A signal input / output device according to a fourth aspect of the present disclosure includes a terminal that inputs and outputs a signal, a signal processing unit that processes a signal input through the terminal, and a signal transmission path between the terminal and the signal processing unit A signal output unit that outputs a predetermined signal to the signal transmission line, and a signal transmission line that is provided across the upstream side and the downstream side of the output position of the output of the signal output unit to the signal transmission line. An impedance adjustment unit for adjustment.

  A display device according to a fifth aspect of the present disclosure includes the signal input / output device according to each aspect of the present disclosure, and a display unit that displays an image indicated by a signal output from the signal input / output device.

  According to the signal input / output device of the present disclosure, the impedance adjustment unit suppresses the occurrence of waveform distortion and amplitude reduction in a signal input to video equipment (video processing unit, etc.) via a common terminal for input and output. can do. Further, according to the display device of the present disclosure, since the waveform distortion and the amplitude reduction of the signal input from the signal input / output device to the display unit are suppressed, a video ghost is displayed on the display unit of the display device. Is suppressed.

1 is a block diagram illustrating an electrical configuration of a signal input / output device according to Embodiment 1. FIG. 5 is a diagram illustrating a specific example of a third filter circuit of the signal input / output device according to Embodiment 1. FIG. 6 is a diagram illustrating a specific example of an impedance adjustment unit of the signal input / output device according to Embodiment 1. FIG. FIG. 3 is a diagram illustrating characteristics such as impedance viewed from a first terminal of the signal input / output device according to the first embodiment. It is a figure which shows the characteristics, such as an impedance seen from the 2nd terminal, and the output waveform in a 2nd buffer circuit when the impedance adjustment part of the signal input / output device which concerns on Embodiment 1 does not exist. It is a figure which shows the characteristics, such as an impedance seen from the 2nd terminal of the signal input / output device which concerns on Embodiment 1, and the output waveform in a 2nd buffer circuit. 6 is a block diagram illustrating an electrical configuration of a signal input / output device according to Embodiment 2. FIG. It is a figure which shows the specific example of the part of the upstream of a connection point among the impedance adjustment parts of the signal input / output device which concerns on Embodiment 2. FIG. 10 is a block diagram illustrating an electrical configuration of a display device according to Embodiment 3. FIG. It is a figure explaining the effect in the display apparatus which concerns on Embodiment 3. FIG. FIG. 6 is a block diagram illustrating an electrical configuration of a signal input / output device according to a fourth embodiment. FIG. 9 is a block diagram illustrating an electrical configuration of a signal input / output device according to a fifth embodiment. FIG. 10 is a block diagram illustrating an electrical configuration of a display device according to a sixth embodiment. FIG. 10 is a block diagram illustrating an electrical configuration of a signal output unit of a signal input / output device according to a seventh embodiment. FIG. 10 is a block diagram illustrating an electrical configuration of a signal input / output device according to an eighth embodiment. is there.

  Hereinafter, embodiments will be described in detail with reference to the drawings as appropriate. However, more detailed description than necessary may be omitted. For example, detailed descriptions of already well-known matters and repeated descriptions for substantially the same configuration may be omitted. This is to avoid the following description from becoming unnecessarily redundant and to facilitate understanding by those skilled in the art. The inventor (s) provides the accompanying drawings and the following description in order for those skilled in the art to fully understand the present disclosure, and is intended to limit the subject matter described in the claims. Not what you want.

(Background of the present invention)
A display device (video equipment) may include an input terminal for analog video signals such as RGB video signals. In addition, the display device may include an input / output terminal shared by analog video signal input and output.

  Further, the display device may include both an input terminal and an input / output terminal. The analog video signal input to the input terminal is input to the display unit (video processing unit) via a first signal processing unit having a filter circuit and a buffer circuit, for example. The video signal input to the input / output terminal is input to the display unit via a second signal processing unit having a filter circuit and a buffer circuit, for example. In this case, the video signal input to the input terminal may be output from the input / output terminal. In order to realize this, a signal output unit that outputs the video signal output from the first signal processing unit to the input / output terminal is required.

  However, the provision of the signal output section affects the impedance viewed from the input / output terminal, and there is no difference between the impedance of the external device connected to the input / output terminal and its connection cable and the impedance viewed from the input / output terminal. Matching may occur, and as a result, waveform distortion and amplitude reduction may occur in the video signal, resulting in a problem that a ghost appears in the video.

  The present disclosure adopts the following configuration for the purpose of solving the above problem.

(Embodiment 1)
1. Configuration FIG. 1 is a block diagram illustrating an electrical configuration of the signal input / output device according to the first embodiment.

  The signal input / output device 1 of the present embodiment has two signal input systems, a first signal input system S1 and a second signal input system S2. The output side of the first signal input system S1 is connected to the input side of the second signal input system S2 via the signal output unit 30. The signal input / output device 1 inputs an RGB video signal. FIG. 1 shows a portion for inputting or outputting one signal of RGB video signals. In the present embodiment, the case where the input / output signal is an RGB video signal will be described. However, the present disclosure describes the case where the input / output signal is an analog video signal or an analog audio signal other than the RGB video signal. Is also applicable.

1-1. First Signal Input System The first signal input system S1 includes a first terminal 11 and a first signal processing unit 10.

  The first terminal 11 is a terminal dedicated to signal input.

  The first signal processing unit 10 processes a signal input via the first terminal 11. The first signal processing unit 10 includes a first filter circuit 12 (LPF1) and a first buffer circuit 13 (BUF1).

  The first filter circuit 12 is a low-pass filter. The first filter circuit 12 receives the first input signal and outputs a first pass signal that has passed a frequency band equal to or lower than a predetermined frequency among all frequency bands of the first input signal. For example, the first filter circuit 12 can remove a noise component flowing in from an external device and a connection cable connected to the first terminal 11.

  The first buffer circuit 13 is an amplifier having a high input impedance and a low output impedance. The first buffer circuit 13 receives the first passage signal and outputs a first output signal. The first buffer circuit 13 suppresses the influence of the input impedance of a unit (A / D conversion unit 101 described later) connected to the output side of the first input processing unit on the impedance viewed from the first terminal 11.

  The first signal processing unit 10 adjusts the impedance viewed from the first terminal 11 to a predetermined impedance in a predetermined frequency band that can be taken by the RGB video signal (hereinafter, appropriately referred to as “frequency band of the RGB video signal”). The predetermined impedance is an impedance that matches the output impedance of the external device and the connection cable connected to the first terminal 11, and is, for example, 50 ohms.

1-2. Second Signal Input System The second signal input system S2 includes a second terminal 21, a second signal processing unit 20, and an impedance adjustment unit 24.

  The second terminal 21 is a common terminal for signal input and signal output.

  The second signal processing unit 20 processes a signal input via the second terminal 21. The second signal processing unit 20 includes a second filter circuit 22 (LPF2) and a second buffer circuit 23 (BUF2).

  The second filter circuit 22 is a low pass filter. The second filter circuit 22 receives the second input signal and outputs a second pass signal that has passed through a frequency band equal to or lower than a predetermined frequency in the entire frequency band of the second input signal. For example, the second filter circuit 22 can remove noise components flowing in from an external device and a connection cable connected to the second terminal 21.

  The second buffer circuit 23 is an amplifier having a high input impedance and a low output impedance. The second buffer circuit 23 receives the second passage signal and outputs a second output signal. The second buffer circuit 23 suppresses the influence of the input impedance of a unit (A / D conversion unit 101 described later) connected to the output side of the second input processing unit on the impedance viewed from the second terminal 21.

  The impedance adjustment unit 24 (MAT) is provided on the signal transmission path between the second terminal 21 and the second signal processing unit 20. The impedance adjustment unit 24 is a circuit for adjusting impedance mismatch caused by the signal output unit 30 being connected to the transmission path of the second signal input system S2, and in the frequency band of the RGB video signal, The impedance viewed from the two terminals 21 is adjusted to a predetermined impedance. The predetermined impedance is an impedance that matches the output impedance of the external device and the connection cable connected to the second terminal 21 and is, for example, 50 ohms.

1-3. Signal Output Unit The signal output unit 30 is a circuit provided for outputting a signal input from the first terminal 11 from the second terminal 21. The input of the signal output unit 30 is connected to the output of the first signal processing unit 10 (connection point J1), and the output is connected to the second terminal 21 (input side of the second signal processing unit 20) (connection point J2). . The signal output unit 30 receives the first output signal, processes the input first output signal, and outputs it to the second terminal 21. The signal output unit 30 includes an amplifier circuit 32 (AMP) and a third filter circuit 31 (LPF3).

  The amplifier circuit 32 is an amplifier having a low input impedance and a high output impedance. The amplifier circuit 32 receives the first output signal and outputs an amplified signal obtained by amplifying the first output signal.

  The third filter circuit 31 is a low-pass filter. The third filter circuit 31 receives the amplified signal from the amplifier circuit 32, and passes the third passing signal that has passed through a frequency band equal to or lower than a predetermined frequency out of the entire frequency band of the amplified signal to the second terminal 21 (second terminal). 21 on the signal transmission path between the second signal processing unit 20 and the second signal processing unit 20.

  In the frequency band of the RGB video signal, the signal output unit 30 is connected to the output impedance of the external device and the connection cable connected to the second terminal 21 by the amplifier circuit 32 and the third filter circuit 31, and viewed from the second terminal 21. Impedance matching with the input impedance.

1-4. Components of Third Filter Circuit A specific example of the third filter circuit 31 of the signal output unit 30 will be described. The third filter circuit 31 includes at least one element of a resistor R, a capacitor C, and an inductor L. FIG. 2 is a diagram illustrating some specific examples of the third filter circuit of the signal input / output device according to the first embodiment. The third filter circuit 31 can take various configurations. 2A to 2H, the left end side is connected to the amplifier circuit 32 side, and the right end side is connected to the connection point J2 side.

  For example, in the example illustrated in FIG. 2A, the third filter circuit 31 is configured with a T-type circuit including a resistor R, an inductor L, and a capacitor C.

  In the example shown in FIG. 2B, the third filter circuit 31 is configured by a π-type circuit including an inductor L and capacitors C connected to both ends of the inductor L.

  In the example shown in FIG. 2C, the third filter circuit 31 is configured by an L-type circuit including an inductor L and a capacitor C.

  In each example shown in FIG. 2, instead of the capacitor C, another capacitive element may be provided. For example, instead of the capacitor C, an ESD element such as a varistor may be provided.

1-5. Components of Impedance Adjustment Unit A specific example of the impedance adjustment unit 24 of the second signal input system S2 will be described. The impedance adjusting unit 24 can be configured by at least one element of the resistor R, the capacitor C, and the inductor L.

  The impedance adjustment unit 24 can take various configurations. FIG. 3 is a diagram illustrating some specific examples of the impedance adjustment unit 24 of the signal input / output device according to the first embodiment. 3A to 3O, the left end side is connected to the connection point J2 side, and the right end side is connected to the second buffer circuit 23 side.

  For example, in the example shown in FIG. 3A, the impedance adjusting unit 24 includes an inductor L provided in series.

  In the example shown in FIG. 3B, the impedance adjusting unit 24 includes a capacitor C provided in parallel.

  In the example shown in FIG. 3C, the impedance adjusting unit 24 includes a resistor R provided in series.

  In each example shown in FIG. 3, instead of the capacitor C, another capacitive element may be provided. For example, instead of the capacitor C, an ESD element such as a varistor may be provided.

1-6. Determination of the circuit configuration and various electrical characteristics of the impedance adjustment unit The determination of the circuit configuration and various electrical characteristics (resistance value, capacitance value, inductor value) of the impedance adjustment unit 24 is performed from the connection point J2 to the signal output unit 30 side. Set according to the impedance when looking at. For example, when the impedance when the signal output unit 30 is viewed from the connection point J2 is capacitive, the impedance viewed from the second terminal 21 is set to a predetermined impedance by making the impedance of the impedance adjustment unit 24 inductive. Then, the circuit configuration and various electrical characteristics are determined. On the other hand, when the impedance when the signal output unit 30 side is viewed from the connection point J2 is inductive, the impedance viewed from the second terminal 21 is changed by making the impedance of the impedance adjustment unit 24 capacitive. The circuit configuration and various electrical characteristics are determined so as to obtain a predetermined impedance.

2. Operation The operation of the signal input / output device 1 of the present embodiment will be described with reference to FIG. The operation mode of the signal input / output device 1 includes the following three operation modes. The first operation mode is an operation mode in which a signal is input to the first terminal 11, the input signal is output to the A / D conversion unit 101 via the first signal processing unit 10, and not output to the second terminal 21. It is. In the second operation mode, a signal is input to the first terminal 11, the input signal is output to the A / D conversion unit 101 via the first signal processing unit 10, and the second signal is output via the signal output unit 30. This is an operation mode of outputting to the terminal 21. The third operation mode is an operation mode in which a signal is input to the second terminal 21 and the input signal is output to the A / D conversion unit 101 via the second signal processing unit 20.

2-1. First Operation Mode When one of the RGB signals is input to the first terminal 11, the input signal passes through the first filter circuit 12 and the first buffer circuit 13 of the first signal processing unit 10. And output to the A / D converter 101.

  At this time, the first signal processing unit 10 performs impedance matching between the output impedance of the external device and the connection cable connected to the first terminal 11 and the input impedance viewed from the first terminal 11 in the frequency band of the RGB video signal. I do. Thereby, the waveform distortion of the signal input to the first terminal 11 and output to the A / D conversion unit 101 and the decrease in the amplitude level are suppressed.

2-2. Second Operation Mode When one of RGB signals is input to the first terminal 11, the input signal is the first filter circuit 12, the first buffer circuit 13, and the signal of the first signal processing unit 10. The signal is output to the second terminal 21 via the amplifier circuit 32 and the third filter circuit 31 of the output unit 30. Therefore, if an external device is connected to the second terminal 21, a signal similar to the signal input to the second terminal 21 can be output to the external device.

  At this time, the signal output unit 30 and the impedance adjustment unit 24 are connected to the output impedance of the external device and the connection cable connected to the second terminal 21 and the input impedance viewed from the second terminal 21 in the frequency band of the RGB video signal. Perform impedance matching. Thereby, the waveform distortion of the signal input to the first terminal 11 and output from the second terminal 21 and the decrease of the amplitude level are suppressed.

2-3. Third Operation Mode When one of the RGB signals is input to the second terminal 21, the input signal is input to the impedance adjustment unit 24, the second filter circuit 22 of the second signal processing unit 20, the second The data is output to the A / D conversion unit 101 via the buffer circuit 23.

  In this case, in this embodiment, the impedance adjusting unit 24 adjusts the impedance viewed from the second terminal 21 (the input impedance of the second terminal 21) to be a predetermined impedance in the frequency band of the RGB video signal. Yes. Therefore, the output impedance of the device or cable connected to the second terminal 21 and the input impedance of the second terminal 21 substantially match (match). As a result, the influence of impedance mismatch on the signal input to the second terminal 21 is suppressed, and the input signal is satisfactorily input to the A / D conversion unit 101. That is, the distortion of the waveform of the signal input to the second terminal 21 and output to the A / D converter 101 and the decrease in the amplitude level are suppressed.

3. Problems and Effects of Impedance Adjustment Unit, etc. Problems that occur when the output of the first signal processing unit 10 as shown in FIG. 1 is connected between the second terminal 21 and the second signal processing unit 20 will be described. FIG. 4A is a diagram illustrating characteristics such as impedance viewed from the first terminal 11 of the signal input / output device 1 according to the first embodiment. 4B is a diagram illustrating characteristics such as impedance viewed from the second terminal 21 and an output waveform in the second buffer circuit when the impedance adjustment unit 24 of the signal input / output device 1 according to the first embodiment is not present. is there. FIG. 4C is a diagram illustrating characteristics such as impedance viewed from the second terminal 21 of the signal input / output device 1 according to the first embodiment and an output waveform in the second buffer circuit. 4A (a), FIG. 4B (a), and FIG. 4C (a) are shown as Smith charts. 4A, 4B, and 4C, Δ1 indicates a position where the frequency is 14 MHz, Δ2 indicates a frequency of 65 MHz, Δ3 indicates a frequency of 108 MHz, and Δ4 indicates a position where the frequency is 162 MHz.

  Since the first signal input system S1 is impedance matched, as shown in FIG. 4A (a), when the frequency is, for example, 162 MHz or less, the impedance viewed from the first terminal 11 indicates 50 ohms. Not far from P. Therefore, as shown in FIG. 4A (b), the VSWR of the first signal input system S1 is kept in the range of 2 or less when the frequency is 162 MHz or less, for example.

  Here, let us consider a case where the impedance adjustment unit 24 does not exist in the configuration in which the output of the first signal processing unit 10 as shown in FIG. 1 is connected between the second terminal 21 and the second signal processing unit 20. In this case, the characteristics such as impedance viewed from the second terminal 21 of the signal input / output device 1 are far from the point P indicating 50 ohms as the frequency increases, as shown in FIG. 4B (a). Therefore, as shown in FIG. 4B (b), when the frequency is higher than 14 MHz, the VSWR of the second signal input system S2 exceeds 2, and further increases as the frequency increases. In this case, as shown in FIG. 4B (c), the signal at 162 MHz, which is the frequency of Δ4, is distorted in the signal waveform at the output of the second buffer circuit 23 as compared with the case of FIG. 4C (c). And amplitude drop occurs. Such a shift in impedance characteristics is considered to be caused by the impedance of the signal output unit 30. Therefore, in the present embodiment, the impedance adjustment unit 24 is inserted for impedance matching.

  By inserting the impedance adjusting unit 24, as shown in FIG. 4C (a), when the frequency is, for example, 162 MHz or less, the impedance viewed from the second terminal 21 is not significantly separated from the point P indicating 50 ohms. Further, as shown in FIG. 4C (b), the VSWR of the second signal input system S2 is maintained in a range of 2 or less when the frequency is, for example, 162 MHz or less. In this case, as for the signal at 162 MHz, which is the frequency of Δ4, the signal waveform is not distorted and the amplitude is not reduced at the output of the second buffer circuit 23 as shown in FIG. 4C (c).

  According to the signal input / output device 1 of the present embodiment, in the configuration in which the output of the first signal processing unit 10 is connected between the second terminal 21 and the second signal processing unit 20 by inserting the impedance adjustment unit 24. However, impedance matching as viewed from the second terminal 21 can be achieved, and the VSWR characteristics can be improved.

(Embodiment 2)
A signal input / output device according to Embodiment 2 will be described. FIG. 5 is a block diagram illustrating an electrical configuration of the signal input / output device according to the second embodiment. In the first embodiment, the impedance adjustment unit 24 is provided on the downstream side of the connection point J2. In this embodiment, the impedance adjustment unit is provided across the upstream side and the downstream side of the connection point J2. The other configuration is the same as that of the first embodiment. Therefore, it demonstrates centering around the structure of an impedance adjustment part.

1. Configuration 1-1. Configuration of Impedance Adjustment Unit The portion 24 on the downstream side of the connection point J2 in the impedance adjustment unit can be configured in the same manner as that described with reference to FIG. In this embodiment, the same reference numeral 24 as that of the impedance adjustment unit of the first embodiment is attached to the downstream portion.

  The portion 25 on the upstream side of the connection point J2 in the impedance adjustment unit can take various configurations. FIG. 6 is a diagram illustrating a specific example of a portion upstream of the connection point J2 in the impedance adjustment unit of the signal input / output device 1A according to the second embodiment. In each specific example shown in FIGS. 6A to 6L, the left end side is connected to the second terminal 21 side, and the right end side is connected to the connection point J2 side.

  For example, in the example illustrated in FIG. 6A, the impedance adjustment unit is configured by a T-type circuit including an inductor L and a capacitor C.

  In the example shown in FIG. 6B, the portion 25 on the upstream side of the connection point J2 in the impedance adjustment unit includes an inductor L provided in series.

  In the example shown in FIG. 6C, the portion 25 on the upstream side of the connection point J2 in the impedance adjustment unit includes a capacitor C provided in parallel.

  In each example shown in FIG. 6, instead of the capacitor C, another capacitive element may be provided. For example, instead of the capacitor C, an ESD element such as a varistor may be provided.

1-2. Determination of the circuit configuration and various electrical characteristics of the impedance adjustment unit The determination of the circuit configuration and various electrical characteristics of the upstream side portion 25 and the downstream side portion 24 of the impedance adjustment unit starts from the connection point J2, as in the first embodiment. What is necessary is just to determine according to the impedance when the 3 filter circuit 31 side is seen.

2. Operation and Effect In the signal input / output device 1A of the present embodiment, the signal flow when a signal is input to the first terminal 11 or the second terminal 21 is the same as that of the first embodiment. In the present embodiment, the impedance adjustment unit is provided across the upstream side and the downstream side of the connection point J2. Also by this, the impedance viewed from the second terminal 21 can be adjusted, and the same effect as in the first embodiment can be obtained.

(Embodiment 3)
In this embodiment, a display device to which the signal input / output devices 1 and 1A of Embodiment 1 or 2 are applied will be described. FIG. 7 is a block diagram illustrating an electrical configuration of the display device according to the third embodiment. In the present embodiment, a case where the display device 100 is a projector that projects an image on the display screen 104 will be described.

  The display device 100 includes a signal input / output device 1 (1A), an A / D conversion unit 101, a signal processing unit 102, and a light projecting unit 103. Note that the signal input / output device 1 (1A) and the A / D converter 101 are provided in correspondence with the R, G, and B colors of the RGB signal. The A / D conversion unit 101, the signal processing unit 102, and the light projecting unit 103 are examples of a display unit.

  The signal input / output device 1 (1A) has the same configuration as the signal processing device 1 (1A) of the first or second embodiment.

  The A / D conversion unit 101 converts one signal (analog signal) of the RGB signals output from the signal processing device 1 (1A) into a digital signal and outputs the digital signal.

  The signal processing unit 102 performs predetermined image processing or the like on the digital signal output from the A / D conversion unit 101 to generate and output an image signal for display.

  The light projecting unit 103 generates and projects projection light based on the image signal output from the signal processing unit 102.

  FIG. 8 is a diagram for explaining an effect in the display device to which the signal input / output device according to the first embodiment is applied. FIG. 8A is a diagram showing a display image by a display device of a conventional signal input / output device that does not have an impedance adjustment unit. FIG. 8B is a diagram illustrating a display image by the signal input / output device according to the first embodiment.

  As shown in FIG. 8A, when the impedance adjustment unit is not provided, in addition to the original image (shown by a solid line), impedance mismatch between the connection cable side of the external device and the signal input / output unit As a result, VSWR deteriorated and a ghost image (shown by a broken line) was generated. Note that the distance between the original image and the ghost image is a distance corresponding to the length of the cable connected to the terminal.

  In the present embodiment, the signal input / output device 1 (1A) has an impedance adjustment unit that matches the impedance between the connection cable side of the external device and the signal input / output device 1 (1A). Is maintained at a value of 2 or less, for example. Therefore, as shown in FIG. 8B, the generation of a ghost image is suppressed.

(Embodiment 4)
A signal input / output device according to Embodiment 4 will be described. FIG. 9 is a block diagram illustrating an electrical configuration of the signal input / output device according to the fourth embodiment.

  The signal input / output device 2 of the present embodiment has a configuration in which the first signal input system S1 is omitted from the signal input / output device 1 of the first embodiment. The output of another unit (D / A conversion unit 105 in the example of FIG. 9) is input to the signal output unit 30, and a signal from the other unit can be output from the input / output terminal 21. Yes. Other configurations are the same as those of the first embodiment, including the configuration of the impedance adjustment unit 24 and the like. Therefore, these descriptions are omitted.

  According to the present embodiment, when only one signal input system is provided, signal waveform distortion and amplitude reduction can be suppressed as in the first embodiment.

(Embodiment 5)
A signal input / output device according to Embodiment 5 will be described. FIG. 10 is a block diagram illustrating an electrical configuration of the signal input / output device 2A according to the fifth embodiment. In the signal input / output device 2 according to the fourth embodiment, the impedance adjustment unit 24 is provided on the downstream side of the connection point J2. However, in the signal input / output device 2A according to the present embodiment, the impedance adjustment unit is the second embodiment. Similarly, the connection point J2 is provided across the upstream side and the downstream side, and includes an upstream portion 25 and a downstream portion 24. Other configurations are the same as those in the fourth embodiment. Also according to the present embodiment, the impedance viewed from the second terminal 21 can be adjusted, and the same effect as in the first embodiment can be obtained.

(Embodiment 6)
In the present embodiment, a display device to which the signal input / output devices 2 and 2A of the fourth or fifth embodiment are applied will be described. FIG. 11 is a block diagram illustrating an electrical configuration of a display device to which the signal input / output device according to the sixth embodiment is applied. In the present embodiment, a case where the display device 200 is a projector that projects an image on the display screen 104 will be described.

  The display device 200 includes a signal input / output device 2 (2A), a D / A conversion unit 105, an A / D conversion unit 101, a signal processing unit 102, a light projecting unit 103, and a storage unit 106. Note that the signal input / output device 2 (2A) and the A / D converter 101 are provided corresponding to the R, G, and B colors of the RGB signal.

  The storage unit 106 stores a digital video signal in a predetermined format.

  The signal input / output device 2 (2A) has the same configuration as that of the signal processing device of the fourth or fifth embodiment.

  The A / D converter 101 converts one signal (analog signal) of the RGB signals output from the signal input / output device 2 (2A) into a digital signal and outputs the digital signal.

  The signal processing unit 102 performs predetermined image processing or the like on the digital signal output from the A / D conversion unit 101 to generate and output an image signal for display. Further, the signal processing unit 102 reads out the digital video signal from the storage unit 106, performs predetermined processing, and outputs it to the D / A conversion unit 105.

  The D / A conversion unit 105 converts the digital video signal output from the signal processing unit 102 into an analog format video signal (one of RGB signals) and outputs the analog video signal.

  The light projecting unit 103 generates and projects projection light based on the image signal output from the signal processing unit 102.

  Also in this embodiment, since the signal input / output device 2 (2A) has an impedance adjustment unit that matches the impedance between the connection cable side of the external device and the signal input / output unit, the VSWR is, for example, 2 Maintained at the following values: Therefore, the generation of ghost images is suppressed.

(Embodiment 7)
In the first to sixth embodiments, the signal output unit 30 is configured by two circuits of the third filter circuit 31 and the amplifier circuit 32 connected in series, but is not limited thereto. The signal output unit 30 may be configured as shown in FIG. FIG. 12 is a block diagram illustrating an electrical configuration of a signal output unit of the signal input / output device according to the seventh embodiment. 12A to 12E, the left end side is connected to the connection point J1 side, and the right end side is connected to the connection point J2 side.

  In the example illustrated in FIG. 12A, the signal output unit 30 includes an inductor L and an amplifier circuit AMP that are connected in series, and a capacitor C that is connected in parallel on the downstream side thereof. Instead of the capacitor C, the third filter circuit 31 of each of the above embodiments may be provided in series on the downstream side of the amplifier circuit AMP.

  In the example shown in FIG. 12B, the signal output unit 30 includes a T-type filter circuit and an amplifier circuit AMP that are connected in series, and a capacitor C that is connected in parallel on the downstream side. The T-type filter circuit includes two inductors L connected in series and a capacitor C connected in parallel between the two inductors L. Instead of the capacitor C, the third filter circuit 31 of each of the above embodiments may be provided in series on the downstream side of the amplifier circuit AMP.

  In the example shown in FIG. 12C, the signal output unit 30 is configured by connecting an amplifier circuit AMP and a buffer circuit BUF in series.

  In the example shown in FIG. 12D, the signal output unit 30 is configured by connecting an L-type filter circuit and a buffer circuit BUF in series. The L-type filter circuit includes an inductor L connected in series to the buffer circuit BUF and a capacitor C connected in parallel to the inductor L.

  In the example shown in FIG. 12E, the signal output unit 30 is configured by connecting an L-type filter circuit, a buffer circuit BUF, and an L-type filter circuit in series. Each L-type filter circuit includes an inductor L connected in series to the buffer circuit BUF and a capacitor C connected in parallel to the inductor L.

  Also in each example of the present embodiment, the impedance viewed from the second terminal 21 can be adjusted by appropriately applying the specific example of the impedance adjusting unit described above. Note that the signal input / output device of the present embodiment can be applied to the display device of the third or sixth embodiment.

(Embodiment 8)
In the signal input / output devices of the first to sixth embodiments, the second signal processing unit 20 is configured by two circuits of the second filter circuit 22 and the second buffer circuit 23 connected in series, but is not limited thereto. Absent. The second signal processing unit 20 may be configured as shown in FIG. FIG. 13 is a block diagram illustrating an electrical configuration of the signal input / output device according to the eighth embodiment.

  In the signal input / output device 3 shown in FIG. 13A, the second signal processing unit 20 is configured by connecting an amplifier circuit 61 and a buffer circuit 62 in series. The signal output unit 30 may be any of those described in the above embodiments.

  In the signal input / output device 4 shown in FIG. 13B, the second signal processing unit 20 includes an amplifier circuit 71 disposed on the sub board, an amplifier circuit 73 and a buffer circuit 74 connected in series on the main board. The amplifier circuit 71 on the sub-board and the amplifier circuit 73 on the main board are connected in series via a cable 72. The signal output unit 30 can be any of those described in the above embodiments.

  Also in each example of the present embodiment, the impedance viewed from the terminal 21 can be adjusted by appropriately applying the specific example of the impedance adjusting unit described above. Note that the signal input / output devices 3 and 4 of the present embodiment can be applied to the display device 100 or 200 of the third or sixth embodiment.

(Effects etc.)
The signal input / output device 1 according to the first embodiment includes a first terminal 11 for inputting a signal, a second terminal 21 for inputting / outputting a signal, and a first signal processing unit that processes a signal input via the first terminal 11. 10, a second signal processing unit 20 that processes a signal input via the second terminal 21, and a signal that is processed by inputting the signal processed by the first signal processing unit 10 and that is output to the second terminal 21 An output unit 30 and an impedance adjusting unit 24 that is provided on a signal transmission path between the second terminal 21 and the second signal processing unit 20 and adjusts the impedance viewed from the second terminal 21 to a predetermined impedance.

  Thereby, the impedance seen from the 2nd terminal 21 which inputs and outputs a signal can be adjusted to predetermined impedance. That is, impedance matching can be performed. Therefore, waveform distortion and amplitude are added to a signal (a signal output from the second signal processing unit 20 to the A / D conversion unit 101) input to the A / D conversion unit 101 via the shared second terminal 21 for input and output. Generation | occurrence | production of a fall can be suppressed.

  The signal input / output device 1A according to the second embodiment includes a first terminal 11 that inputs a signal, a second terminal 21 that inputs and outputs a signal, and a first signal processing unit that processes a signal input via the first terminal 11. 10, a second signal processing unit 20 that processes a signal input via the second terminal 21, a signal processed by the first signal processing unit 10, and a second signal 21 and a second signal A signal output unit 30 that outputs to the signal transmission path between the processing unit 20 and the signal transmission path, the output of the signal output unit 30 is provided across the upstream and downstream sides of the output position to the signal transmission path; Impedance adjustment units 24 and 25 for adjusting the impedance viewed from the second terminal 21 to a predetermined impedance.

  Thereby, the impedance seen from the 2nd terminal 21 which inputs and outputs a signal can be adjusted to predetermined impedance. That is, impedance matching can be performed. Therefore, waveform distortion and amplitude are added to a signal (a signal output from the second signal processing unit 20 to the A / D conversion unit 101) input to the A / D conversion unit 101 via the shared second terminal 21 for input and output. Generation | occurrence | production of a fall can be suppressed.

  The signal input / output devices 2, 3, and 4 according to the fourth, seventh, and eighth embodiments include a terminal 21 that inputs and outputs signals, a signal processing unit 20 that processes a signal input via the terminal 21, and a predetermined signal at the terminal 21. Is provided between the terminal 21 and the signal processing unit 20, and an impedance adjusting unit 24 that adjusts the impedance viewed from the terminal to a predetermined impedance.

  Thereby, the impedance seen from the terminal which inputs and outputs a signal can be adjusted to a predetermined impedance. That is, impedance matching can be performed. Therefore, waveform distortion and amplitude reduction occur in a signal (a signal output from the signal processing unit 20 to the A / D conversion unit 101) input to the A / D conversion unit 101 via the common terminal 21 for input and output. Can be suppressed.

  The signal input / output device 2A according to the fifth embodiment includes a terminal 21 for inputting / outputting a signal, a signal processing unit 20 for processing a signal input via the terminal 21, and signal transmission between the terminal 21 and the signal processing unit 20. The signal output unit 30 that outputs a predetermined signal to the path, and the signal transmission path is provided across the upstream side and the downstream side of the output position of the output of the signal output unit 30 to the signal transmission path. Impedance adjusting units 24 and 25 for adjusting to a predetermined impedance.

  Thereby, the impedance seen from the terminal which inputs and outputs a signal can be adjusted to a predetermined impedance. That is, impedance matching can be performed. Therefore, waveform distortion and amplitude reduction are caused in a signal (a signal output from the second signal processing unit 20 to the A / D conversion unit 101) input to the A / D conversion unit 101 via the common terminal 21 for input and output. Generation | occurrence | production can be suppressed.

  In the signal input / output devices of the first to sixth embodiments, each signal processing unit 10, 20 or signal output unit 30 is a circuit in which at least two of a filter circuit, a buffer circuit, and an amplifier circuit are connected in series with each other. Including.

  Thereby, the characteristic of the 1st signal processing part 10, the 2nd signal processing part 20, or the signal output part 30 can be set according to the characteristics, such as an external apparatus connected to a terminal, and a connection cable.

  In the signal input / output devices of Embodiments 1 to 6, the impedance adjustment unit 24 (25) includes at least one of a resistor R (resistive element), a capacitor C (capacitive element), and an inductor L (inductive element). Contains elements.

  Thereby, the characteristic of the impedance adjustment part 24 (25) can be set according to the impedance based on the characteristic of the external device connected to the terminal 21 or a connection cable.

  The display device 100 (200) according to the third and sixth embodiments includes the signal input / output device (1, 1A, 2, 2A, 3, 4) according to any one of the first, second, fourth, fifth, seventh, and eighth embodiments. And a display unit for displaying an image indicated by a signal output from the signal input / output device (1, 1A, 2, 2A, 3, 4). The display unit includes one corresponding to the above embodiment among the A / D conversion unit 101, the signal processing unit 102, the light projecting unit 103, the display screen 104, the D / A conversion unit 105, and the storage unit 106.

  Thereby, waveform distortion and amplitude reduction of a signal input to the display unit of the display device via the signal input / output device are suppressed. Therefore, it is possible to suppress the display of a video ghost on the display unit of the display device.

(Other embodiments)
The configuration of the impedance adjustment unit 24 (25) is not limited to that illustrated in FIG. The impedance adjustment unit 24 (25) may have another configuration as long as the impedance viewed from the second terminal 21 can be adjusted to a predetermined impedance. For example, the impedance adjustment unit 24 (25) can be configured by at least one of a resistor R, a capacitor C, and an inductor L.

  The configuration of the third filter circuit 31 shown in FIG. 3 is an example. According to the impedance adjustment unit 24 (25) of the present disclosure, it is possible to adjust the impedance even when the configuration of the third filter circuit 31 is another configuration.

  The configurations of the first signal processing unit 10, the second signal processing unit 20, and the signal output unit 30 in each of the embodiments are examples. Each of the first signal processing unit 10, the second signal processing unit 20, and the signal output unit 30 can be configured by a circuit in which at least two of a filter circuit, a buffer circuit, and an amplifier circuit are connected in series. .

  In the third and sixth embodiments, the case where the display device 100 (200) is a projector has been described. However, the present invention is not limited to this. The display device 100 (200) may be any display device as long as it displays the video indicated by the input signal. For example, the display device may be a liquid crystal display device, a cathode ray tube display device, or a plasma display device.

  The signal input / output device of each of the above embodiments inputs and outputs RGB video signals. However, in the signal input / output device of the present disclosure, an input / output signal may be an analog signal other than an RGB video signal, such as an analog video signal or an analog audio signal. In that case, parameters such as components such as an impedance adjustment unit may be set based on a frequency band that can be normally taken by input / output signals. In the signal input / output device of the present disclosure, the input / output signal may be a digital signal. Even in this case, the impedance adjustment unit can suppress the occurrence of waveform distortion and amplitude reduction in the digital signal input via the common terminal for input and output.

  As described above, the embodiments have been described as examples of the technology in the present disclosure. For this purpose, the accompanying drawings and detailed description are provided. Accordingly, among the components described in the accompanying drawings and the detailed description, not only the components essential for solving the problem, but also the components not essential for solving the problem in order to illustrate the above technique. May also be included. Therefore, it should not be immediately recognized that these non-essential components are essential as those non-essential components are described in the accompanying drawings and detailed description. Moreover, since the above-mentioned embodiment is for demonstrating the technique in this indication, a various change, replacement, addition, abbreviation, etc. can be performed in a claim or its equivalent range.

  The present disclosure is widely applicable to a signal input / output device having an input / output terminal for inputting / outputting a signal, a display device including the same, and the like.

1, 1A, 2, 2A, 3, 4 Signal input / output device 10 First signal processing unit 11 First terminal 12 First filter circuit 13 First buffer circuit 20 Second signal processing unit 21 Second terminal 22 Second filter circuit 23 Second buffer circuit 24 Impedance adjustment unit, upstream part of impedance adjustment unit 25 downstream part of impedance adjustment unit 30 signal output unit 31 third filter circuit 32 amplifier circuit 100, 200 display device 101 A / D conversion unit 102 signal Processing unit 103 Projecting unit 104 Display screen 105 D / A conversion unit 106 Storage unit C Capacitor J1 Connection point J2 Connection point L Inductor R Resistance S1 First signal input system S2 Second signal input system

Claims (7)

A first terminal for inputting a signal;
A second terminal for inputting and outputting signals;
A first signal processing unit for processing a signal input via the first terminal;
A second signal processing unit for processing a signal input via the second terminal;
A signal output unit that inputs and processes the signal processed by the first signal processing unit and outputs the signal to the second terminal;
An impedance adjustment unit that is provided on a signal transmission path between the second terminal and the second signal processing unit and adjusts the impedance viewed from the second terminal to a predetermined impedance;
Signal input / output device. A first terminal for inputting a signal;
A second terminal for inputting and outputting signals;
A first signal processing unit for processing a signal input via the first terminal;
A second signal processing unit for processing a signal input via the second terminal;
A signal output unit that inputs and processes the signal processed by the first signal processing unit and outputs the signal to a signal transmission path between the second terminal and the second signal processing unit;
In the signal transmission line, an impedance adjustment unit that is provided across the upstream side and the downstream side of the output position of the signal output unit to the signal transmission line, and adjusts the impedance viewed from the second terminal to a predetermined impedance. And comprising
Signal input / output device. A terminal for inputting and outputting signals;
A signal processing unit for processing a signal input via the terminal;
A signal output unit for outputting a predetermined signal to the terminal;
An impedance adjustment unit that is provided between the terminal and the signal processing unit and adjusts the impedance viewed from the terminal to a predetermined impedance;
Signal input / output device. A terminal for inputting and outputting signals;
A signal processing unit for processing a signal input via the terminal;
A signal output unit that outputs a predetermined signal to a signal transmission path between the terminal and the signal processing unit;
In the signal transmission path, an impedance adjustment unit that is provided across the upstream side and the downstream side of the output position of the output of the signal output unit to the signal transmission path, and adjusts the impedance viewed from the terminal to a predetermined impedance; Comprising
Signal input / output device. Each signal processing unit or the signal output unit includes a circuit in which at least two of a filter circuit, a buffer circuit, and an amplifier circuit are connected in series with each other,
The signal input / output device according to any one of claims 1 to 4. The impedance adjustment unit includes at least one of a resistance element, a capacitive element, and an inductive element.
The signal input / output device according to claim 1. The signal input / output device according to any one of claims 1 to 6,
A display unit for displaying an image indicated by a signal output from the signal input / output device,
Display device.

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