JP6793763B2 - Semiconductor devices, video display systems, and signal processing methods - Google Patents

Description

The present invention relates to a semiconductor device, an image display system, and a signal processing method.

In recent years, signals having different frequencies have been input to a semiconductor device, which is a controller for displaying an image such as an image on a display device such as a display, as a signal for displaying on the display device. For example, in an in-vehicle video system, signals of different frequencies are input from various devices such as a camera (monitor) such as a back camera for smooth parking and a car navigation function linked with a smartphone.

In such a video display system, EMI (Electro Magnetic Interference) is reduced. For example, Reference 1 describes a technique of using a PLL with a frequency diffusion function for a system clock in order to reduce EMI. Has been done.

Japanese Unexamined Patent Publication No. 2003-150143

In an in-vehicle video system as described above, a signal input from a back camera, a device, or the like is subjected to predetermined image processing via a processing unit such as a CPU provided outside the system and then displayed on a display means. May cause you to. In this case, a digital signal that has been image-processed by a processing unit such as a CPU provided externally is input to the in-vehicle video display system.

In this way, various signals are input to the video display system, but in the conventional video display system, a signal that is not subjected to frequency diffusion processing may be output to the display means. For example, in the technique described in Patent Document 1, an analog image signal is output to an image display unit without performing frequency diffusion processing.

Therefore, there is a problem that the EMI cannot be sufficiently reduced.

The present invention has been proposed to solve the above-mentioned problems, and provides a semiconductor device, an image display system, and a signal processing method capable of reducing EMI regardless of the type of input signal. The purpose.

In order to achieve the above object, the semiconductor device of the present disclosure responds to the first input unit into which the video signal is input , the video signal converted into digital data, and the decoded video signal and the video signal. A decoder that outputs a decoder clock, a second input unit into which a data signal and a data clock corresponding to the data signal are input, a video signal, a decoder clock corresponding to the video signal, the data signal, and the data signal. A selector that selects either one of the data clocks according to the above as the first data signal and the first clock signal corresponding to the first data signal, and frequency diffusion with respect to the first clock signal selected by the selector. A first processing unit that performs processing, a scaling unit that scales the first data signal selected by the selector according to a display unit provided outside the own device, and a scaling unit before the scaling unit performs scaling. The first data signal or the first output unit that outputs the first data signal after scaling after the scaling unit has performed scaling, and the first data signal output from the first output unit or after the scaling. A third input unit to which a second data signal and a second clock signal are input, which is generated by performing predetermined image processing on the first data signal by an image processing unit provided outside the own device. , The second processing unit that performs frequency diffusion processing on the second clock signal input via the third input unit, the enable signal input unit into which the enable signal is input, and the frequency by the first processing unit. The second output unit that outputs the clock signal of either the first clock signal subjected to the diffusion processing or the second clock signal subjected to the frequency diffusion processing by the second processing unit according to the enable signal. And.

The video display system of the present disclosure includes an image processing unit that performs image processing, a semiconductor device of the present disclosure , and a display unit that displays an image according to an output signal output from the semiconductor device.

The signal processing method of the present disclosure includes a step of inputting a video signal to the first input unit and a decoder that converts the video signal into digital data and decodes the video signal and a decoder corresponding to the video signal. A step of outputting a clock, a step of inputting a data signal and a data clock corresponding to the data signal to the second input unit, a video signal and a decoder clock corresponding to the video signal, the data signal and the data. One of the data clocks corresponding to the signals is selected by the selector as the first data signal and the first clock signal corresponding to the first data signal, and the first clock signal selected by the selector. On the other hand, a step of scaling the first data signal selected by the selector by the first processing unit that performs frequency diffusion processing and the scaling unit according to a display unit provided outside the own device, and the scaling. The step of outputting the first data signal before the unit scales or the first data signal after scaling after the scaling unit performs the scaling from the first output unit and the output from the first output unit. A second data signal and a second clock generated by performing predetermined image processing on the first data signal or the first data signal after scaling by an image processing unit provided outside the own device. A step of inputting a signal to the third input unit, a step of performing frequency spreading processing by the second processing unit on the second clock signal input via the third input unit, and an enable signal. , The process of being input to the enable signal input unit, the first clock signal subjected to frequency spreading processing by the first processing unit, and the second clock signal subjected to frequency spreading processing by the second processing unit. A step of outputting one of the clock signals from the second output unit according to the enable signal is provided.

According to the present invention, there is an effect that EMI is reduced regardless of the type of input signal.

It is a block diagram for demonstrating the outline about the input of various signals to the image display system in the vehicle equipped with the image display system of this embodiment. It is a block diagram which shows the structure of an example of the image display system of this embodiment. It is a flow chart which shows an example of the flow in which the enable signal is input to the semiconductor device of a video display system in the vehicle of this embodiment. It is a flow chart which shows an example of the flow of the operation which outputs the input video signal and data signal to the display as an output signal in the video display system of this embodiment. FIG. 5 is an explanatory diagram showing a signal path when the enable signal is type A (when the video signal directly input from the back camera is output to the display) in the video display system of the present embodiment. In the video display system of the present embodiment, the description showing the signal path of the enable signal of type B (when the video signal input from any camera is image-processed by the main processor and then output to the display). It is a figure. It is explanatory drawing which showed the signal path of the enable signal of type B (when the video signal input from any camera is image-processed by the main processor and then output to the display) in the conventional video display system. ..

Hereinafter, the present embodiment will be described in detail with reference to the drawings.

In the present embodiment, a case where the present invention is applied to a video display system that displays a video signal captured by an in-vehicle camera on a display unit will be described. Further, in the present embodiment, as a specific example, when the vehicle backs up (more specifically, when the back gear is engaged), the image from the back camera is displayed on the display at high speed to the driver of the vehicle. A video display system having a function of displaying the image will be described.

FIG. 1 shows a block diagram for explaining an outline of an example of inputting various signals to the video display system in a vehicle equipped with the video display system of the present embodiment.

The vehicle 90 is provided with a back camera 72, a front camera 74, and other cameras 76. The camera provided in the vehicle 90 is not particularly limited and is arbitrary, and at least a camera capable of photographing the rear of the vehicle 90 may be provided. For example, the in-vehicle camera may be an around view monitor. In the following, when the back camera 72, the front camera 74, and the other cameras 76 are collectively referred to, they are collectively referred to as an “in-vehicle camera”.

The back camera 72, the front camera 74, and the other camera 76 are arbitrarily activated, and may be activated according to the activation of the vehicle 90, or may be activated according to an instruction from the user (driver). In the present embodiment, as described above, since the back camera 72 has a function of displaying the image from the back camera at high speed when the vehicle backs up, the back camera 72 starts the vehicle 90 or the back gear 70. It is preferable to start in conjunction with.

The selection unit 80 has a function of outputting a video signal selected from the video signals output from the back camera 72, the front camera 74, and the other camera 76 according to predetermined conditions to the video display system 10. In the vehicle 90 of the present embodiment, the selection unit 80 is interlocked with the back gear 70. When the back gear 70 is engaged, the selection unit 80 selects the video signal of the back camera 72 and outputs it to the video display system 10.

The enable signal generation unit 82 has a function of generating and outputting an enable signal for controlling a path (signal selection) in the semiconductor device 12 of the video display system 10. In the vehicle 90 of the present embodiment, the enable signal generation unit 82 is interlocked with the back gear 70. When the back gear is engaged, the enable signal generation unit 82 outputs an enable signal (type A: described in detail later) for selecting a video signal input from the back camera 72 and outputting it to the display to the video display system 10. ..

Further, a data signal is input to the video display system 10 from the mobile terminal 78 owned by the user via HDMI (registered trademark) (High-Definition Multimedia Interface: not shown). Although the data signal output from the mobile terminal 78 includes a video signal, it is referred to as a “data signal” in the present embodiment in order to distinguish it from the video signal output from the in-vehicle camera.

Examples of the mobile terminal 78 include smartphones and tablets. The mobile terminal 78 is not limited to the mobile terminal 78, and may be a car navigation system, a DVD player, a communication device, a network device, or the like. In the present embodiment, a case where a smartphone (hereinafter referred to as “smartphone”) is used as a specific example of the mobile terminal 78 will be described.

Next, the configuration of the video display system 10 of the present embodiment will be described. FIG. 2 shows an example of a schematic configuration of the video display system 10 of the present embodiment. The video display system 10 of the present embodiment includes a semiconductor device 12, a main processor 14, and a display 16. The display 16 is an example of a display unit.

The main processor 14 of the present embodiment is configured as a SoC (System-on-a-Chip) and has a function of performing predetermined image processing. Examples of the predetermined image processing include image processing in which a menu screen, map information, characters, and the like are combined with the input video signal and data signal. Further, the main processor 14 of the present embodiment has a function of performing scaling according to the display 16. Therefore, the digital data signal output from the main processor 14 is scaled to the size of the display 16. The image-processed digital data signal and data clock are output from the main processor 14 to the semiconductor device 12.

The semiconductor device 12 includes a video decoder 20, a selector 23, a scaling unit 24, a PLL with frequency diffusion function (hereinafter referred to as SSCPLL) 26, a selector 28, a memory 30, SSCPLL 32, a selector 34, an image adjustment unit 36, and a drawing function unit 38. A display I / F 40, an input unit 42, an input unit 44, an input unit 46, an input unit 48, an output unit 50, an output unit 52, and an output unit 54 are provided. SSCPLL26 is an example of the first processing unit, SSCPLL32 is an example of the second processing unit, the selector 34 is an example of the selection unit, the input unit 44 is an example of the first input unit, and the register 46 is the second. The input unit 42 is an example of the input unit, the input unit 42 is an example of the third input unit, the output unit 50 is an example of the first output unit, and the output unit 54 is an example of the second output unit.

An enable signal is input to the input unit 48. The input enable signal is output to the selector 23, the selector 28, the selector 34, and the drawing function unit 38, and functions as a control signal for controlling the operation of each unit. The enable signal controls whether the selector 23 selects a video signal or a data signal.

Further, the enable signal controls whether the selector 28 selects the clock output from the SSCPLL 26 or the clock output from the SSCPLL 32. Further, the enable signal controls whether the selector 34 selects the signal output from the scaling unit 24 or the digital signal output from the memory 30. In other words, the selector 28 and the selector 34 select and output either a signal input from the main processor 14 or a signal that does not pass through the main processor 14 (directly input).

The enable signal of this embodiment has the following four types (types) according to the control in each unit.

Type A is a case where the selector 23 selects a video signal and the selector 28 selects a directly input clock.

Type B is a case where the selector 23 selects a video signal and the selector 28 selects a clock input from the main processor 14.

Type C is a case where the selector 23 selects a data signal and the selector 28 selects a directly input clock.

Type D is a case where the selector 23 selects a data signal and the selector 28 selects a clock input from the main processor 14.

The video signal output from the vehicle-mounted camera is input to the input unit 44. The video signal input to the input unit 44 is output to the video decoder 20. The video decoder 20 has a decoding function for converting a video signal into digital data. The video decoder 20 outputs the decoded video signal and the decoder clock to the selector 23.

The data signal and data clock output from the mobile terminal 78 (smartphone) are input to the input unit 46. The data signal input to the input unit 46 is output to the selector 23.

The selector 23 has a function of selecting a signal according to the enable signal and outputting it to the scaling unit 24 and the SSCPLL26. In this embodiment, a multiplexer is used as the selector 23, the selector 28, and the selector 34 as a specific example.

Specifically, when the enable signal is of type A or type B, the selector 23 selects the video signal output from the video decoder 20 and outputs it to the scaling unit 24 and the output unit 50. Further, the selector 23 selects the decoder clock output from the video decoder 20 and outputs it to the SSCPLL 26. On the other hand, when the enable signals are of type C and type D, the selector 23 selects the data signal input from the smartphone and outputs it to the scaling unit 24 and the output unit 50. Further, the selector 23 selects the data clock input from the smartphone and outputs it to the SSCPLL 26.

The SSCPLL 26 has a function of generating a display clock to be output to the display from the decoder clock output from the video decoder 20 and the data clock input from the smartphone. Further, the SSCPLL26 of the present embodiment spreads the spectrum of the output clock by applying a slight modulation to the frequency of the decoder clock output from the video decoder 20 and the data clock input from the smartphone, and the EMI peak. It has a function to reduce the value. The display clock generated by frequency diffusion by SSCPLL26 is output to the selector 28.

The SSCPLL26 includes a register for storing a value corresponding to each frequency of various input signals, selects a register corresponding to the various input signals, and uses the value stored in the register for a frequency. Perform diffusion processing. The method of selecting the register is not limited and is arbitrary. For example, the register may be selected according to the enable signal, or may be selected in conjunction with the selector 23. The SSCPLL26 may be configured as a hardware resource or may be configured as software.

The scaling unit 24 has a function of scaling (enlarging and reducing according to the size of the display area) according to the size of the display 16. The video signal or data signal scaled by the scaling unit 24 is output to the selector 34 and the output unit 50.

From the output unit 50, either the signal output from the selector 23 or the signal output from the scaling unit 24 is output. Which one is output may be determined in advance according to the function of the main processor 14, for example, or may be a signal selected according to a control signal input from the outside. In the present embodiment, since the main processor 14 has a scaling function, the output unit 50 outputs a signal (video signal or data signal) before scaling output from the selector 23. When the main processor 14 does not have the scaling function, the signal (video signal or data signal) output from the scaling unit 24 may be output from the output unit 50. The signal (video signal or data signal) output from the output unit 50 is input to the main processor 14 via the outside of the semiconductor device 12.

A data signal and a clock are input to the input unit 42 from the main processor 14. The data signal input to the input unit 42 is output to the memory 30. Further, the clock input to the input unit 42 is output to the SSCPLL32.

In the semiconductor device 12 of the present embodiment, the clock input from the main processor 14 is not used as it is as the display clock, but is replaced with the display clock generated by the SSCPLL32. The memory 30 has a function of storing the data input from the main processor 14 in order to absorb the difference in frequency caused by the clock change. The data signal output from the memory 30 is output to the selector 34.

The SSCPLL 32 is the same as the SSCPLL 26 described above, and has a function of reducing the EMI by performing frequency diffusion processing on the frequency of the clock input from the main processor 14. The display clock output from the SSCPLL 32 is output to the selector 28.

As described above, the selector 28 has a function of selecting either the display clock output from the SSCPLL 26 or the display clock output from the SSCPLL 32 and outputting the display clock to the image adjustment unit 36 and the output unit 54 according to the enable signal. Have. The display clock output from the selector 28 is output to the display 16 via the output unit 54.

As described above, the selector 34 selects either the video signal or data signal output from the scaling unit 24 or the data signal output from the memory 30 as an output signal according to the enable signal, and the image adjustment unit 34. It has a function to output to 36.

The image adjusting unit 36 has a function of adjusting the image quality such as the brightness and hue of the image displayed on the display 16 based on the output signal.

The drawing function unit 38 has a function of performing a predetermined drawing process on the image displayed on the display 16 based on the output signal according to the enable signal. Specifically, when the vehicle 90 has a back gear, the drawing function unit 38 of the present embodiment performs drawing processing on an output signal based on a video signal directly input from the back camera 72, and in other cases. Does not perform drawing processing on the output signal. Therefore, when the enable signal is type A, the output signal input from the image adjustment unit 36 is output after drawing processing. On the other hand, when the enable signals are types B to D, the output signal input from the image adjustment unit 36 is output as it is.

When the image based on the video signal directly input from the back camera 72, that is, the video captured by the back camera 72 is displayed on the display 16 as it is, it may be difficult for the user (driver) to recognize the position and state of the vehicle 90. is there. Therefore, in the present embodiment, when displaying an image based on the video signal directly input from the back camera 72 on the display 16, a guideline and characters for calling attention are displayed together with the video. Therefore, the drawing function unit 38 performs drawing processing such as adding a guideline and characters to call attention. The drawing process performed by the drawing function unit 38 is a simpler process than the image processing performed by the main processor 14. Therefore, the drawing function unit 38 may be configured by software, or may be configured by hardware resources in a simple configuration that does not require a CPU or the like.

Next, the operation of the video display system 10 of the present embodiment will be described. As described above, the semiconductor device 12 of the video display system 10 of the present embodiment operates in response to the enable signal. That is, in the semiconductor device 12, the path through which various signals flow is determined according to the enable signal.

First, in the vehicle 90, the flow in which the enable signal is input to the semiconductor device 12 of the video display system 10 will be described. FIG. 3 shows a flow chart showing an example of the flow in which the enable signal is input to the semiconductor device 12 of the video display system 10. The operation shown in FIG. 3 is started, for example, when the vehicle 90 is started.

When the back gear 70 is activated (Y in step S100), the enable signal generation unit 82 generates a type A enable signal in conjunction with the activation of the back gear 70, and the generated enable signal is input to the semiconductor device 12. (Step S102).

On the other hand, when the back gear 70 is not activated (N in step S100), one of the type B to type D enable signals is generated and generated by the enable signal generation unit 82 according to a predetermined condition. The enable signal is input to the semiconductor device 12 (step S104).

In the present embodiment, the type A enable signal is input to the semiconductor device 12 only when the back gear 70 is activated, but the type A enable signal is also input to the semiconductor device 12 in other cases. It may be done. For example, when displaying the input video signal or data signal on the display 16 at a higher speed, or when displaying the video signal or data signal on the display 16 without performing image processing on the main processor 14, type A It is preferable that the enable signal of is input to the semiconductor device 12.

The generation of the enable signal and the input of the generated enable signal to the semiconductor device 12 of the video display system 10 are repeated (N in step S106), and predetermined conditions such as stopping the start of the vehicle 90 are satisfied. When the condition is satisfied, the process ends (Y in step S106).

Next, in the video display system 10, the flow of the operation of outputting the input video signal and data signal to the display 16 as an output signal will be described. FIG. 4 shows a flow chart showing an example of an operation flow in which the input video signal and data signal are output to the display 16 as output signals. The operation shown in FIG. 4 is started, for example, when the video display system 10 or the semiconductor device 12 is activated. The activation of the video display system 10 (semiconductor device 12) may be linked with the activation of the vehicle 90, or may be activated in response to a user's instruction from a car navigation system or the like. In the semiconductor device 12 of the present embodiment, when the back gear 70 is engaged, the image of the back camera 72 is displayed on the display 16 at a higher speed, so that the semiconductor device 12 is linked with the activation of the vehicle 90 or the activation of the back camera 72. Is preferable, and at least it is preferable to start in conjunction with the back gear 70.

The video signal input to the video display system 10 via the input unit 44 is decoded by the video decoder 20, and the decoded video signal and the decoder clock are input to the selector 23. Further, the data signal and the data clock input via the input unit 44 are input to the selector 23.

When the enable signal is input to the input unit 48, the selector 23 selects either the video signal and the decoder clock, or the data signal and the data clock according to the type of the enable signal, and outputs the data signal to the scaling unit 24 and the SSCPLL26. (Step S200).

In the video display system 10 of the present embodiment, the selector 23 outputs the selected image signal or data signal to both the scaling unit 24 and the output unit 50 regardless of the type of the enable signal. When the enable signal is type A or type C, the video signal or data signal output to the scaling unit 24 becomes the output signal. When the enable signal is type B or type D, the video signal or data signal output to the output unit 50 becomes the output signal. Each case will be described in detail with reference to the drawings illustrating the path through which the signal flows.

FIG. 5 shows an explanatory diagram showing a signal path when the enable signal is type A (when the video signal directly input from the back camera 72 is output to the display 16). When the enable signal is type A, the output signal corresponding to the video signal output to the scaling unit 24 and the decoder clock output to the SSCPLL 26 are output to the display 16.

The scaling unit 24 scales the input video signal according to the size of the display 16 to generate an output signal, and outputs the output signal to the selector 34 (step (S202). Further, the SSCPL26 26 is the input decoder. After performing frequency spreading processing corresponding to the frequency on the clock, it is output to the selector 28 (step S202).

The selector 28 selects the clock output from the SSCPLL 26 as the display clock (step S210), and outputs the selected display clock to the display 16 via the image adjustment unit 36 and the output unit 54. Further, the selector 34 selects the video signal output from the scaling unit 24 as an output signal and outputs it to the image adjustment unit 36 (step S210).

The image adjustment unit 36 performs image adjustment processing on the input output signal (video signal) and outputs it to the drawing function unit 38 (step S212).

Since the enable signal is type A (Y in step S214), the drawing function unit 38 performs drawing processing (step S216), and displays the output signal (video signal) that has undergone drawing processing on the display I / F 40 and the output unit 52. Is output to the display 16 via (step S218).

As described above, in the case of type A, the video signal of the back camera 72 is input to the display 16 as an output signal via the output unit 52. Further, the display clock frequency-spread processed by the SSCPLL 26 is input to the display 16 via the output unit 54.

When the enable signal is type C, the data signal and data clock input from the smartphone via the input unit 46 are selected by the selector 23, and the drawing function unit 38 does not perform drawing processing (N in step S214, N, (Proceed to step S218), which is different from the case of type A. Other signal paths in the case of type C are the same as in type A. The data signal of the smartphone is input to the display 16 as an output signal via the output unit 52. Further, the display clock frequency-spread processed by the SSCPLL 26 is input to the display 16 via the output unit 54.

On the other hand, when the enable signals are type B and type D, the data signal output to the output unit 50 is input to the main processor 14.

FIG. 6 is an explanatory diagram showing a signal path of the enable signal of type B (when the video signal input from any of the in-vehicle cameras is image-processed by the main processor 14 and then output to the display 16). Shown.

The output unit 50 outputs the signal selected by the selector 23 to the main processor 14 (step S204). In the case of type B, the video signal is output to the main processor 14. The main processor 14 performs predetermined image processing and scaling on the input video signal to generate a data signal. The data signal and clock generated by the main processor 14 are input to the semiconductor device 12 via the input unit 42 (step S206). At this time, the clock input to the semiconductor device 12 is in a state where the frequency is not spread.

A data signal is input to and stored in the memory 30. A clock is input to the SSCPLL 32, and frequency diffusion processing is performed (step S208). A data signal is output to the selector 34 from the memory 30, and a display clock is output to the selector 28 from the SSCPLL32.

The selector 28 selects the clock output from the SSCPLL 32 as the display clock (step S210), and outputs the selected display clock to the display 16 via the image adjustment unit 36 and the output unit 54. Further, the selector 34 selects the signal (video signal) output from the memory 30 as an output signal and outputs it to the image adjustment unit 36 (step S210).

The image adjustment unit 36 performs image adjustment processing on the input output signal (video signal) and outputs it to the drawing function unit 38 (step S212).

When the enable signal is type B, unlike the case of type A, the drawing function unit 38 does not perform drawing processing (N in step S214, proceeds to step S218). In the semiconductor device 12, the signal (video signal) input to the drawing function unit 38 is directly output to the display 16 via the display I / F 40 and the output unit 52 (step S218).

As described above, in the case of type B, the signal (video signal) input from the main processor 14 is input to the display 16 as an output signal via the output unit 52. Further, a display clock frequency-spreading processed by the SSCPLL 32 is input to the display 16 via the output unit 54.

The case where the enable signal is type D is different from the case of type B in that the data signal and the data clock input from the smartphone via the input unit 46 are selected by the selector 23. Other signal paths in the case of type D are the same as in type B. A signal (data signal) input from the main processor 14 is input to the display 16 as an output signal via the output unit 52. Further, a display clock frequency-spreading processed by the SSCPL L32 is input to the display 16 via the output unit 54.

The above processing operation for displaying an image based on the input video signal and data signal on the display 16 is repeated (N in step S220), for example, a predetermined condition such as when the start of the vehicle 90 is stopped. Is satisfied (Y in step S220).

As described above, the video display system 10 of the present embodiment includes the memory 30 and the SSCPLL32. A video signal is input to the semiconductor device 12 from an in-vehicle camera via an input unit 44, and a data signal and a data clock are input from a mobile terminal 78 such as a smartphone via the input unit 46. Further, a data signal and a clock are input to the semiconductor device 12 from the main processor 14 via the input unit 42. The semiconductor device 12 transmits the video signal input via the input unit 44 and the output signal corresponding to the decoder clock, or the data signal input via the input unit 46 and the output signal corresponding to the data clock to the main processor 14. When the data is output to the display 16 without passing through the above, the display clock subjected to the frequency diffusion processing by the SSCPLL 26 is output to the display 16 via the output unit 54. On the other hand, when the semiconductor device 12 outputs the data signal input from the main processor 14 and the output signal corresponding to the clock to the display 16 via the input unit 42, the semiconductor device 12 outputs the display clock subjected to the frequency diffusion processing by the SSCPLL 32. It is output to the display 16 via the unit 54.

In the semiconductor device 112 of the conventional video display system 100 shown in FIG. 7, the data signal input from the main processor 14 is directly input to the image adjusting unit 36 via the selector 34, and the image is adjusted by the image adjusting unit 36. The output signal was output to the display 16. Further, the clock input from the main processor 14 was directly output to the display 16 as a display clock via the selector 28 and the output unit 54. That is, in the conventional semiconductor device 112, the display clock on which the frequency diffusion processing is not performed is output to the display 16. Therefore, when the data signal and the clock input from the main processor 14 are output to the display 16, there is a problem that the EMI is not reduced.

On the other hand, as described above, in the semiconductor device 12 of the video display system 10 of the present embodiment, which of the input unit 42, the input unit 44, and the input unit 46 is the signal (video signal or data signal) input from? Regardless of this, the display clock that has undergone frequency diffusion processing is output to the display 16. Therefore, in the video display system 10 of the present embodiment, the EMI can be reduced regardless of the type of the input signal. Further, in the video display system 10 of the present embodiment, the EMI can be appropriately reduced for input signals having different frequencies.

Further, in the video display system 10 of the present embodiment, when the video signal directly input from the back camera 72 is output to the display 16 (when the enable signal is type A), the video signal is directly input without going through the main processor 14. The output signal generated by the generated video signal is output to the display 16. Further, in this case, the drawing function unit 38 performs drawing processing on the output signal, and in other cases, the drawing function unit 38 does not perform drawing processing. Therefore, in the image display system 10 of the present embodiment, when the image captured by the back camera 72 is displayed on the display 16, the image can be displayed at high speed, and information such as guidelines is displayed instead of the image as it is captured. It can be displayed to the user (driver).

In the above embodiment, the case where the enable signal generated outside the video display system 10 is input to the semiconductor device 12 has been described, but the enable signal is not limited to the outside of the video display system 10 but is internally. It may be generated. For example, depending on the operation of the main processor 14, it may be generated by the main processor 14 or another generation unit inside the video display system 10 and input to the semiconductor device 12 via the input unit 48.

Further, in the above embodiment, when the selector 34 selects the video signal input from the scaling unit 24, the drawing function unit 38 performs the drawing process, but the drawing process is not limited to this. For example, the selector 34 is the scaling unit 24. Since the image processing of the data signal input from is not performed by the main processor 14, the drawing function unit 38 may also perform drawing processing on the data signal. At least, when the selector 34 selects the video signal input from the scaling unit 24, it is preferable that the drawing function unit 38 performs the drawing process.

Further, in the above embodiment, the case where the back gear 70 is activated as the case where the video signal from the back camera 72 directly input without passing through the main processor 14 is output to the display 16 has been described, but the present invention is limited to this. Not done. For example, it may be linked to the activation of the vehicle 90 or the activation of the back camera 72, or may be instructed by the user.

Further, the type and number of video signals and data signals input to the semiconductor device 12 are not limited to the above-described embodiment, and are arbitrary. Similarly, the number of input units to which these signals are input is not limited to the above embodiment, and is arbitrary.

Further, in the above embodiment, the case where the video display system 10 is applied to the video display system for displaying the video of the vehicle-mounted camera has been described, but the present invention is not limited to this, and may be applied to, for example, a door phone in a general-purpose security system. ..

Further, the configuration, operation, and the like of the video display system 10, the semiconductor device 12, and the vehicle 90 described in each of the other embodiments described above are examples, and can be changed according to the situation within a range that does not deviate from the gist of the present invention. Needless to say, there is.

10 Video display system 12 Semiconductor device 14 Main processor 16 Display 24 Scaling unit 26 SSCPLL
30 memory 32 SSCPLL
38 Drawing function unit 42, 44, 46 Input unit 50, 52 Output unit 70 Back gear 72 Back camera 90 Vehicle

Claims (7)

The first input section where the video signal is input and
A decoder that converts the video signal into digital data and outputs the decoded video signal and a decoder clock corresponding to the video signal.
A second input unit into which a data signal and a data clock corresponding to the data signal are input, and
Either one of the video signal and the decoder clock corresponding to the video signal and the data signal and the data clock corresponding to the data signal is used as the first data signal and the first clock signal corresponding to the first data signal. Selector to select and
A first processing unit that performs frequency diffusion processing on the first clock signal selected by the selector , and
A scaling unit that scales the first data signal selected by the selector according to a display unit provided outside the own device, and a scaling unit.
A first output unit that outputs the first data signal before the scaling unit performs scaling, or a first data signal after scaling after the scaling unit performs scaling.
The first data signal output from the first output unit or the first data signal after scaling is generated by performing predetermined image processing by an image processing unit provided outside the own device. A third input unit to which the second data signal and the second clock signal are input, and
A second processing unit that performs frequency diffusion processing on the second clock signal input via the third input unit, and
The enable signal input section where the enable signal is input and the enable signal input section
The clock signal of either the first clock signal subjected to the frequency diffusion processing by the first processing unit or the second clock signal subjected to the frequency diffusion processing by the second processing unit is subjected to the enable signal. 2nd output section to output
Semiconductor device equipped with. A selection unit that selects the first data signal after scaling or the second data signal as an output signal according to the enable signal.
When the output signal selected by the selection unit is the first data signal after scaling, a drawing function unit that performs drawing processing on the output signal and a drawing function unit.
With more
When the output signal selected by the selection unit is the first data signal after scaling, the second output unit is subjected to frequency diffusion processing by the first processing unit as one of the clock signals. When one clock signal is output and the output signal selected by the selection unit is the second data signal, the second clock is frequency-spread processed by the second processing unit as one of the clock signals. The semiconductor device according to claim 1, which outputs a signal. When the output signal selected by the selection unit is the second data signal, the drawing function unit does not perform the drawing process.
The semiconductor device according to claim 2. The video signal selected by the selector is a video signal of an in-vehicle camera.
The enable signal is a signal output from the vehicle in conjunction with a predetermined operation of the vehicle on which the vehicle-mounted camera is mounted.
The semiconductor device according to any one of claims 1 to 3 . The in-vehicle camera is a back camera.
The video signal selected by the selector is a video signal that images the rear of the vehicle on which the in-vehicle camera is mounted.
The predetermined operation is when the back gear of the vehicle is engaged.
The semiconductor device according to claim 4 . An image processing unit that performs image processing and
The semiconductor device according to any one of claims 2 to 5 .
A display unit that displays an image corresponding to an output signal output from the semiconductor device, and a display unit.
Video display system equipped with. The process in which the video signal is input to the first input unit,
A process of converting the video signal into digital data by a decoder and outputting the decoded video signal and a decoder clock corresponding to the video signal.
A process in which a data signal and a data clock corresponding to the data signal are input to the second input unit, and
Either one of the video signal and the decoder clock corresponding to the video signal and the data signal and the data clock corresponding to the data signal is the first data signal and the first clock corresponding to the first data signal by the selector. The process selected as the signal and
A first processing unit that performs frequency diffusion processing on the first clock signal selected by the selector , and
A step of scaling the first data signal selected by the selector by the scaling unit according to a display unit provided outside the own device.
A step of outputting the first data signal before the scaling unit performs scaling or the first data signal after scaling after the scaling unit performs scaling from the first output unit.
The first data signal output from the first output unit or the first data signal after scaling is generated by performing predetermined image processing by an image processing unit provided outside the own device. The process in which the second data signal and the second clock signal are input to the third input unit, and
A step of performing frequency diffusion processing by the second processing unit on the second clock signal input via the third input unit, and
The process in which the enable signal is input to the enable signal input section and
The clock signal of either the first clock signal subjected to the frequency diffusion processing by the first processing unit or the second clock signal subjected to the frequency diffusion processing by the second processing unit is used as the enable signal. Depending on the process of outputting from the second output unit,
Signal processing method with.