JP5237228B2 - Electronic equipment and circuit boards - Google Patents

Description

  The present invention relates to an electronic device and a circuit board equipped with a VGA controller.

  Analog RGB has long been used for display output of PCs (Personal Computers) and has been widely used, so it is always supported by VGA (Video Graphics Array) controllers that control display output of PCs. Most of the display devices that can be connected to many notebook PCs are analog RGB.

  By the way, in recent years, in order to provide an IC at a low cost, the die size of the IC has been reduced. Specifically, IC manufacturers subdivided the processes executed in the IC in order to reduce the die size, and also in order to reduce the size and power consumption of the package for a small mobile PC. The functions that realize each process are narrowed down, and only the minimum necessary functions are installed. For example, a CPU (Central Processing Unit), a memory controller, and a VGA controller are integrated on one chip. Such ICs are inexpensive, but have limited functions that can be used, so some products may not be able to satisfy the specifications.

  A VGA controller for a PC is built in a chip set. In particular, in the case of a mobile PC, it is necessary and sufficient to have only an output for a main body LCD (Liquid Crystal Display) and an output for an external monitor. In general, LVDS (Low Voltage Differential Signaling) is used for the output for the LCD of the main body, and analog RGB is used for the output for the external monitor. In this case, the VGA controller built in the chip set supports only two ports of LVDS and analog RGB.

  By the way, the design of an electronic device having a VGA controller as described above may be changed. For example, it is a design change that allows the specification of the electronic device to be used in LVDS and LVDS with the same design as the mobile PC (VGA controller supports only two ports of LVDS and analog RGB only). In this case, the specification can be satisfied by mounting an IC for converting analog RGB to LVDS (see Patent Document 1).

  However, in order to realize the specifications including the case of using in LVDS and analog RGB and the case of using in LVDS and LVDS with the same equipment, an expensive switch IC is mounted and analog RGB and There is a problem in that it is necessary to switch between LVDS and mounting a switch IC requires power and space in the device.

  The present invention has been made in view of the above, and it is an object of the present invention to provide an electronic device and a circuit board that can satisfy a device specification and can support a plurality of display devices using an inexpensive chip set. Objective.

In order to solve the above-described problems and achieve the object, the present invention provides a generation circuit that generates a first display signal, displays various information based on the first display signal, and terminates the first display signal. A first connector to which a first display device having a resistor can be connected; a conversion circuit for converting the first display signal into a second display signal different from the first display signal; and the second display signal. The generation circuit is configured to connect a second connector to which a second display device that displays various types of information and does not have a termination resistance of the second display signal can be connected, the first connector, the conversion circuit, and the generation circuit. a first termination resistor mounted on the transmission side of the signal line for transferring said first display signal to said first connector and said conversion circuit from said varying of said signal lines The second and the termination resistance can be on or off while being mounted on the receiving side to connect the circuit, the connection of the second display device to the connection or the second connector of the first display device to the first connector When the recognition unit recognizes and the connection of the first display device to the first connector is recognized, the second termination resistor is turned off and the connection of the second display device to the second connector is recognized. And a circuit for turning on the second termination resistor.

The present invention also provides a first connector that displays various information based on the first display signal and is connectable to a first display device equipped with a termination resistance of the first display signal, and the first display signal. A conversion circuit for converting to a second display signal different from the first display signal can be connected to a second display device that displays various information based on the second display signal and does not have a termination resistance for the second display signal. A second connector, a signal for connecting the output source of the first display signal to the first connector and the conversion circuit, and transferring the first display signal from the output source to the first connector and the conversion circuit a first termination resistor mounted on the transmission side of the line, on-together is mounted on the receiving side to be connected to said conversion circuit of said signal line or off possible second A termination resistor, a recognition unit for recognizing the connection of the first display device to the first connector or the connection of the second display device to the second connector, and the first display device to the first connector. A circuit that turns off the second termination resistor when connection is recognized, and turns on the second termination resistor when connection of the second display device to the second connector is recognized. .

  The electronic device and the circuit board according to the present invention have an effect that a plurality of display devices can be supported by using an inexpensive chip set that satisfies the specifications of the device.

FIG. 1 is a block diagram showing a hardware configuration of an electronic device according to an embodiment of the present invention.

  Exemplary embodiments of an electronic apparatus and a circuit board according to the present invention will be explained below in detail with reference to the accompanying drawings.

  FIG. 1 is a block diagram showing a hardware configuration of an electronic device according to an embodiment of the present invention. The electronic device 100 according to the present embodiment is a personal computer, for example, and has a display function for displaying various information on LCDs (Liquid Crystal Displays) 1 to 3 (200, 300, 400). In the following description, the configuration of the circuit board related to the display function of the electronic device 100 will be described.

  A CPU (Central Processing Unit) 101 is a main part of the electronic device 100 and controls each part centrally. The CPU (Central Processing Unit) 101 controls a memory 102 (not shown), which will be described later, and a VGA (Display Function). Video Graphics Array) controller 103 is provided. Also connected to the CPU 101 are an I / O controller 104 that controls I / O to the electronic device 100, a memory 102 such as a RAM (Random Access Memory) that functions to rewrite various data, and the like.

  The I / O controller 104 includes a serial input / output (SIO) 105 that performs serial input / output, a read only memory (ROM) 106 that stores a BIOS and the like, and a peripheral component interconnect (PCI) that is an expansion bus. 107, an HDD (Hard Disk Drive) 108 which is an auxiliary storage device, and a USB (Universal Serial Bus) 109 for connecting external devices such as a mouse and a keyboard are connected.

  The VGA controller 103 generates analog RGB signals (first display signals) and LVDS signals, and includes analog RGB 103b and LVDSI / F 103a that output the generated analog RGB signals and LVDS signals.

  In addition, the electronic device 100 includes connectors 110, 111, and 112 to which the LCDs 1 to 3 (200, 300, and 400) are connected. The connector 110 is connected to the LCD 1 (200) that displays various information based on the LVDS signal generated by the VGA controller 103.

  The connector 111 (first connector) is a device that displays various types of information based on the analog RGB signal generated by the VGA controller 103, and the LCD 2 (300) on which the termination resistor (not shown) of the analog RGB signal is mounted. Connected. The LCD 2 (300) corresponds to the first display device of the present invention.

  The connector 112 (second connector) is a device that displays various information based on the LVDS signal converted by the RGB-LVDS conversion circuit described later, and is connected to the LCD 3 (400) that does not have a termination resistance for the LVDS signal. The The LCD 3 (400) corresponds to the second display device of the present invention.

  The user can display various information based on the analog RGB signal generated by the VGA controller 103 by connecting to either the connector 111 or the connector 112 with the LCD 2 (300) or the LCD 3 (400). it can.

  The RGB-LVDS conversion circuit 113 converts the analog RGB signal generated by the VGA controller 103 into an LVDS signal (second display signal) different from the analog RGB signal.

  The LVDS I / F line 114 is a signal line for connecting the LVDS / F 103 a that outputs an LVDS signal and the connector 110 with a cable and transferring the LVDS signal from the VGA controller 103 to the connector 110.

  The analog RGB I / F line 115 connects the analog RGB I / F 103b that outputs an analog RGB signal to the connector 111 and the RGB-LVDS conversion circuit 113 via a cable, and the connector 111 and the RGB-LVDS conversion circuit from the VGA controller 103. 113 is a signal line for transferring analog RGB signals to 113.

  A termination resistor 116 is mounted on the transmission side of the analog RGB I / F line 115. One termination resistor must be mounted on each of the transmission and reception sides. Therefore, a termination resistor 117 that can be turned on / off is mounted on the reception side of the analog RGB I / F line 115.

  Here, the reason why the termination resistor 117 mounted on the reception side of the analog RGB I / F line 115 can be turned on / off will be described.

  When the LCD 2 (300) is connected to the connector 111, the termination resistance on the receiving side of the analog RGB I / F line 115 is mounted in the LCD 2 (300). If both the termination resistor 116 and the termination resistor 117 are mounted on the analog RGB I / F line 115 even though the termination resistor is mounted in the LCD 2 (300), the analog RGB I / F line is installed. 115 termination resistors are mounted on the transmission side 115, and impedance matching cannot be achieved. Therefore, when the LCD 2 (300) is connected to the connector 111, it is necessary to turn off the termination resistor 117.

  On the other hand, when the LCD 3 (400) is connected to the connector 112, the termination resistance on the reception side of the analog RGC I / F line 115 is not mounted in the RGB-LVDS conversion circuit 114 (or LCD 3 (400)). Therefore, when the LCD 3 (400) is connected to the connector 112, it is necessary to turn on the termination resistor 117.

  Returning to FIG. 1, the insertion / removal recognition circuit 118 is connected to the GND and recognizes the connection of the cable of the LCD 2 (300) or the LCD 3 (400) to the connector 111 or the connector 112. The insertion / removal recognition circuit 118 outputs a RESET signal to the RGB-LVDS conversion circuit 114 when the cable of the LCD 2 (300) is connected to the connector 111. Thus, when the LCD 2 (300) is connected to the connector 111, the connector 3 (400) is not used, so the RGB-LVDS conversion circuit 114 is reset to reduce power consumption. When the insertion / removal recognition circuit 118 recognizes the connection of the cable of the LCD 2 (300) to the connector 111, it outputs Low to the termination ON / OFF circuit 119 and connects the cable of the LCD 3 (400) to the connector 112. When recognized, High is output to the termination ON / OFF circuit 119.

  Termination ON / OFF circuit 119 is an FET (Field Effect Transistor) connected to GND, and when Low is input from insertion / removal recognition circuit 118 (that is, connection of LCD 2 (300) to connector 111 is recognized). ), The termination resistor 117 is disconnected from the analog RGB I / F line 115, and the termination resistor 117 is turned off.

  On the other hand, when the termination resistance ON / OFF circuit 119 receives High from the insertion / removal recognition circuit 118 (that is, when the connection of the LCD 3 (400) to the connector 112 is recognized by the insertion / removal recognition circuit 118), the termination resistance 117 is detected. Is connected to the analog RGB I / F line 115 to turn on the termination resistor 117.

  As described above, according to electronic apparatus 100 according to the present embodiment, VGA controller 103 that generates an analog RGB signal and a device that displays various types of information based on the generated analog RGB signal, the analog RGB signal A connector 111 to which an LCD 2 (300) equipped with a termination resistor is connected, an RGB-LVDS conversion circuit 113 that converts a generated analog RGB signal into an LVDS signal, and various information are displayed based on the converted LVDS signal. And a connector 112 to which the LCD 3 (400) not equipped with the termination resistance of the LVDS signal is connected, and an analog RGB I for transferring the analog RGB signal from the VGA controller 103 to the connector 111 and the RGB-LVDS conversion circuit 113. / F line 15, a termination resistor 116 mounted on the transmission side of the analog RGB I / F line 115, a termination resistor 117 mounted on the reception side of the analog RGB I / F line 115, which can be turned on / off, and an LCD 2 connected to the connector 111. Specification including a case of using in LVDS and analog RGB and a case of using in LVDS and LVDS by providing a termination ON / OFF circuit 119 for turning off the termination resistor 117 when (300) is connected Can be achieved without mounting an expensive switch IC for switching between analog RGB and LVDS, so that the chip set that satisfies the specifications of the electronic device 100 and is inexpensive can be realized. Using a plurality of LCDs 1 to 3 ( 00,300,400) can be supported.

DESCRIPTION OF SYMBOLS 100 Electronic device 103 VGA controller 111,112 Connector 113 RGB-LVDS conversion circuit 115 Analog RGB I / F line 116,117 Termination resistance 118 Insertion / removal recognition circuit 119 Termination ON / OFF circuit 300 LCD2
400 LCD3

Japanese Patent Laid-Open No. 11-8865

Claims (4)

A generating circuit for generating a first display signal;
A first connector to which various information is displayed based on the first display signal and to which a first display device on which the termination resistance of the first display signal is mounted can be connected;
A conversion circuit for converting the first display signal into a second display signal different from the first display signal;
A second connector that can be connected to a second display device that displays various types of information based on the second display signal and that does not include the termination resistance of the second display signal;
A first termination mounted on a transmission side of a signal line for connecting the first connector and the conversion circuit and the generation circuit and transferring the first display signal from the generation circuit to the first connector and the conversion circuit. Resistance,
A second termination resistor mounted on a receiving side connected to the conversion circuit of the signal line and capable of being turned on or off;
A recognition unit for recognizing connection of the first display device to the first connector or connection of the second display device to the second connector;
When the connection of the first display device to the first connector is recognized, the second termination resistor is turned off, and when the connection of the second display device to the second connector is recognized, A circuit for turning on the second termination resistor;
With electronic equipment. Before SL circuit, when the connection of the first display device to the first connector is recognized, the second termination resistor separately from the signal line, to claim 1 for turning off the second termination resistor The electronic device described. A first connector to which various information is displayed based on the first display signal and to which a first display device on which the termination resistance of the first display signal is mounted can be connected;
A conversion circuit for converting the first display signal into a second display signal different from the first display signal;
A second connector that can be connected to a second display device that displays various types of information based on the second display signal and that does not include the termination resistance of the second display signal;
Mounted on the transmission side of the signal line for transferring said first display signal to the first said first connector from said output source connected output source of the display signal and a first connector and said conversion circuit and said conversion circuit A first termination resistor,
A second termination resistor mounted on a receiving side connected to the conversion circuit of the signal line and capable of being turned on or off;
A recognition unit for recognizing connection of the first display device to the first connector or connection of the second display device to the second connector;
When the connection of the first display device to the first connector is recognized, the second termination resistor is turned off, and when the connection of the second display device to the second connector is recognized, A circuit for turning on the second termination resistor;
Circuit board with. Before SL circuit, when the connection of the first display device to the first connector is recognized, the second termination resistor separately from the signal line, to claim 3, turning off the second termination resistor Circuit board as described.

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