JPH1185338A - Switching device, branching device, and peripheral equipment system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the operability by automatically supplying and interrupting necessary power based on the on/off state of power in a connected peripheral equipment and eliminating the need of the time and labor for executing the power supply operation of a branching device in accordance with the power supply situation of the peripheral equipment. SOLUTION: A switching device 12a forming a channel between a host unit and plural peripheral equipment inputs a power state signal showing a power state whether the power of unit connected to the line of a peripheral equipment- side is turned on or off through connectors 19a and 19b and power state signal lines 27a and 27b. When the power state is turned-on state, relays 23-26 are turned on and power is supplied to the device. The power state signal showing the supply state of power in the device is outputted to a host unit-side line from a power circuit 21 through a connector 18.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a switching device and a branching device for connecting a plurality of peripheral devices to one host device, and a peripheral device system using them. More specifically, for example, the present invention relates to a switching device and a peripheral device system for enabling connection between a host computer having one printer interface and a plurality of printers. Further, the present invention relates to a branching device suitable for configuring a display system for connecting and displaying a plurality of display devices to one host device and a peripheral device system using the same.

[0002]

2. Description of the Related Art Generally, a printer switching device as shown in FIG. 1 is known. This is to switch one of the two printers 4a and 4b by switching a switch 3 provided on the switching device 2 to enable printing / printing. Also, as shown in FIG. 2, by connecting this switching device serially, a plurality of printers 4 can be connected.
It is also possible to configure so that one printer is selected from a to 4c. FIG. 3 shows a configuration in which one of the printers 4a to 4e is selected by using more switching devices 2a to 2d.

As described above, when the number of connected printers increases and the number of switching devices increases, the total length of the connection cables between the switching devices increases, and the load as viewed from the host computer 1 increases. For this reason, a circuit or the like for shaping the signal waveform is required in each switching device. Since the waveform shaping circuits and the like require electric power to operate, the switching device has a power supply and power switches 5a to 5d for turning the power on / off (FIG. 3).

In a display system in which a plurality of displays are connected to one host device, as shown in FIG. 9, the displays 100, 120, and 120 are connected via branch-type connectors 202, 203, and 204. 130 is connected.

[0005]

However, in the configuration shown in FIG. 3 described above, in order to perform printing / printing using the printer 4d, all the power switches 5a to 5d of the switching devices 2a to 2d are turned on. These tasks had to be borne by the user.

When the printers 4a and 4b are used but the printers 4c to 4e are not used, the power switches 5a of the switching devices 2a and 2b are used.
Although the switch 5b needs to be turned on, the power switches 5c and 5d of the switching devices 2c and 2d need not be turned on. From the viewpoint of power consumption, these switching devices 2c,
2d is preferably off. The combination of the operation states of the power switches 5a to 5d is also borne by the user.

[0007] Furthermore, since the switching device with the power switch on and the switching device with the power switch off are mixed, it is easy to forget to turn off the power switch.

Further, in the above-described display system including a branch-type connector for distributing and supplying image data from a host device to a plurality of displays, the number of display devices and branch-type connectors constituting the system increases. In addition, power-on and power-off operations performed every time the system is started up and shut down are increased, and a burden is imposed on the user.

The present invention has been made in view of the above-mentioned problems, and has been made in consideration of turning on a power supply of a connected peripheral device.
An object of the present invention is to provide a branching device that automatically supplies and shuts off necessary power based on an off state, and a peripheral device system using the same.

Further, the present invention provides a branching device capable of controlling power supply to a peripheral device instructed by a host device to be automatically supplied, and a peripheral device using the branching device. An object is to provide an equipment system.

[0011]

A switching device according to the present invention for achieving the above object has the following arrangement. That is, a switching device that forms a communication path between a host device and a plurality of peripheral devices, and inputs a signal indicating a power state of whether a device connected to a line on the peripheral device side is on or off. Input means, when the signal indicates that the power supply state is on, supply means for supplying power to the apparatus, and supply state of power supply by the supply means to the line on the host device side as the power supply state of the apparatus Output means for outputting.

According to another aspect of the present invention, there is provided a peripheral device system having a host device, a plurality of peripheral devices, and a plurality of switching devices for forming a communication path therebetween. A first output unit that outputs a signal indicating a power state of whether the power of the plurality of peripheral devices is on or off, and a line on the peripheral device side in each of the plurality of switching devices. Input means for inputting a signal indicating a power state of a device being turned on or off; supply means for supplying power to the switching device when the signal indicates that the power state is on; Output means for outputting the state of power supply by the means as a power supply state of the switching device to a line on the host device side.

According to another aspect of the present invention, there is provided a branching device for forming a communication path between a host device and a plurality of peripheral devices, wherein the holding device holds a set identification number. Detecting means for detecting identification information output from the host device; and determining whether to supply power based on the identification information detected by the detecting means and the identification number held by the holding means. And a control unit that controls power supply to peripheral devices connected to the branching device based on a result of the determination by the determining unit.

Further, a peripheral device system according to another configuration of the present invention is a peripheral device system having a host device, a plurality of peripheral devices, and a plurality of branch devices forming a communication path therebetween. In each of the branching devices, holding means for holding the same identification number as the identification number set for the connected peripheral device, detection means for detecting the identification information output from the host device, detection by the detection means Determining means for determining whether to supply power based on the received identification information and the identification number held by the holding means, and a power supply for the connected peripheral device based on a determination result by the determining means. Control means for controlling the supply.

[0015]

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

[First Embodiment] FIG. 4 is a block diagram showing a configuration of a printer switching system according to a first embodiment. In FIG. 4, reference numeral 11 denotes a host computer;
Reference numerals a and 12b denote switching devices, and reference numerals 14a to 14c denote printers. 16a, 16b and 17 are cables for connecting the host computer and the switching device, between the switching device and the switching device, and between the switching device and the printer, respectively.

Here, the interface specification between the devices is assumed to be a general Centronics interface as a printer interface. Therefore, the cables 16a, 16b, and 17 have strobe signal lines, data bus signal lines, acknowledge signal lines, busy signal lines,
And ground lines (both not shown). In the present embodiment, the cables 16a, 16b, and 17 further include a power state signal line indicating whether the power is on or off. Here, it is assumed that the power supply status signal line outputs an “H” level when the corresponding device is turned on, and outputs an “L” level when the corresponding device is turned off.

The cable 17 is connected to a printer (14a to 14a).
As seen from the c) side, the strobe signal line and the data bus signal line are inputs, and the acknowledge signal line and the busy signal line are outputs. The power status signal line is an output, and indicates the power status of the printers 14a to 14d. The cable 16a is viewed from the switching device 12a side,
b indicates that the strobe signal line and the data bus signal line are inputs and the acknowledge signal line and the busy signal line are outputs when viewed from the switching device 12b side. The power status signal line is an output, and indicates the power status of the switching device on the side closer to the printer.

FIG. 5 is a block diagram showing the configuration of the switching device according to the first embodiment. In FIG. 5, reference numeral 18 denotes a connector, which is connected to the host computer 11 or a preceding-stage switching device (a switching device on the host computer side). Reference numerals 19a and 19b denote connectors, which are connected to a printer or a subsequent switching device (a switching device on the printer side). Reference numeral 20 denotes a selector circuit which makes any one of a connection between the connector 18 and the connector 19a or a connection between the connector 18 and the connector 19b effective as a data communication path. Details will be described later with reference to FIG. Note that which of the connectors 8 and 19a or between the connectors 8 and 19b is effective is determined by the switch 1
3 is set by the user.

FIG. 6 is a diagram showing a configuration example of the selector circuit. In the figure, reference numeral 20a outputs the input signal as it is when the select signal is "H", and outputs the select signal "L".
Is a three-state buffer which is in a high impedance state at the time of. Reference numeral 20b denotes a three-state buffer which outputs the input signal as it is when the select signal is "L" and enters a high impedance state when the select signal is "H". Therefore, depending on whether the select signal from the switch 13 is “H” or “L”, the path of each signal of the strobe signal line, the data bus, the acknowledge signal, and the busy signal is “between the connector 18 and the connector 19a” or “the connector 18 Between the connectors 19b ”.

Reference numeral 21 denotes a power supply circuit, which generates 5 V required by the selector circuit 20 when 100 V AC is applied to the power supply line 22. Reference numerals 23, 24, 25, and 26 denote relays that conduct or insulate between input and output depending on the potential of the control terminal. Here, it is assumed that each of the relays 23, 24, 25, and 26 is in a conductive state when the control terminal is "H" and is in an insulated state when the control terminal is "L". The relays 23, 24, 25, and 26 perform power ON / OFF control, which is one of the features of the present embodiment.

Reference numerals 27a and 27b denote power supply status signal lines, which indicate the power supply status of the printer or the switching device connected to the connectors 19a and 19b. Power supply status signal line 27
“a” is connected to the control terminals of the relays 23 and 25, and the power supply status signal line 17b is connected to the control terminals of the relays 14 and 16. When the power supply of the printer or the switching device connected to the connector 19a is ON, the power supply state signal line 27a is at the "H" level. As a result, the relay 23 and the relay 25 become conductive, and the AC 100
V is applied to the power supply line 22 through the relay 23 and the relay 25. Thus, the power supply circuit 21 operates, and the 5 V power is supplied to the selector circuit 20 to start the operation. In other words, the power supply of the present switching device is turned on and the operation starts. Similarly, when the power of the printer or the switching device connected to the connector 19b is ON, the relay 24
It is also clear that the switching device starts to operate through the relay 26.

Reference numeral 29 denotes a power supply state signal line.
The DC power supply 5V output from the power supply circuit 21 is output to the connector 18 as it is, and is connected to the switching device at the preceding stage connected to the connector 18. Needless to say, the power supply state signal line 19 is at the “H” level when the power supply is on,
At the time of F, it is at the “L” level.

With the configuration described above, for example, when the printer 14b shown in FIG. 4 is turned on, the switching device 12b operates, and the power supply state signal output from the switching device 12b becomes "H" level. As a result, the switching device 12a operates regardless of the power supply state of the printer 14a, and printing / printing from the host computer 11 to the printer 14b becomes possible. Similarly, when the printer 14c is turned on, the switching devices 12a and 12b operate, and printing / printing from the host computer 11 to the printer 14c is enabled. Further, the printer 14b and the printer 14c
Is turned on at the same time, printing / printing from the host computer 11 to the printer 14b or the printer 14c is performed.
It is clear that printing is possible.

Further, in any of the above cases, the printer 1
If the power supply of the switch 4a is ON, the switching device 12a is operating, so that printing / printing on the printer 14a is possible. Also, the printer 14a is ON and the printer 14b is O
When the FF and the printer 14c are OFF, the printer 14
Since "a" is ON, the switching device 12a operates, and printing / printing on the printer 14a becomes possible. At this time,
Since both the printer 14b and the printer 14c are OFF, the switching device 12b does not operate, and power consumption can be reduced.

[Second Embodiment] Next, a second embodiment will be described. FIG. 7 is a diagram illustrating a printer system according to the second embodiment. In FIG. 7, the switching device 32a,
32b is substantially the same as FIG. 4 except that one of the three printers or switching devices can be selected. However, the power status signal lines of the cables 16a, 16b, and 17 output an "H" level when the corresponding device is turned on, and enter a high impedance state when the corresponding device is turned off.

FIG. 8 is a block diagram showing a configuration example of a switching device according to the second embodiment. Here, the selector circuit 40 is configured to select one from three printers, and has a different configuration from the selector circuit 20 (FIG. 6) of the first embodiment. The detailed description is omitted here because it can be configured by technology.

Since the power supply status signal line 47 is at "H" level when the power supply is ON and is in a high impedance state when the power supply is OFF, three power supply status signal lines 47 are connected here, and the power supply signal line 47 is further pulled down by the resistor 50. To form a wired OR, and are connected to control terminals of the relays 51, 43 and 44. Therefore, the voltage levels of the control terminals of the relays 43, 44, 51 are determined by the connectors 19a to 19c.
If all the power supplies of the printer or the switching device connected to are turned off, the level becomes "L" level.

Reference numeral 49 denotes a power supply status signal line.
5 V output from the power supply circuit 41 is output to the connector 18 through the relay 51 and is connected to the switching device at the preceding stage connected to the connector 18. The control terminal of the relay 51 is a relay 4 for controlling ON / OFF of the power supply.
Since the same signal lines as those of the power supply lines 3 and 44 are connected, the power supply state signal line 49 is at “H” level when the power is on,
It becomes a high impedance state at the time of.

With the configuration described above, when at least one of the printers 14b, 14c, and 14e in FIG. 7 is turned on, the switching device 32b operates, and the power supply state signal line output from the switching device 32b is set to "H". "
Level. As a result, the switching device 32a operates regardless of the power status of the printers 14a and 14d, and the host computer 11
b or the printer 14c or the printer 14e
Printing / printing on Also, the printer 14a,
Alternatively, if the power of the printer 14d is ON, the switching device 32a is operating, so that printing / printing on the printer 14a is possible.

When the printer 14a is ON, the printer 1
4d is OFF and the printers 14b, 14c and 14e are all OFF, the printer 14a
N, the switching device 32a operates, and the printer 14
Printing / printing on a becomes possible. Further, at this time, since all of the printers 14b, 14c, and 14e are OFF, the switching device 32b does not operate and power consumption can be suppressed.

When the printer 14a is off, the printer 14d is on, and the printers 14b, 14c, and 14e are all off, the printer 14d is turned off.
N, the switching device 32a operates, and the printer 14
It is possible to print / print on a. Further, at this time, since all of the printers 14b, 14c, and 14e are OFF, the switching device 32b does not operate and power consumption can be suppressed.

Further, when the printer 14a is ON, the printer 1
When 4d is ON and the printers 14b, 14c and 14e are OFF, since the printer 14a or 14d is ON, the switching device 32a operates and printing / printing on the printer 14a or 14d is possible. Further, at this time, since all of the printers 14b, 14c, and 14e are OFF, the switching device 32b does not operate and power consumption can be suppressed.

As described above, according to the first and second embodiments, the power of the necessary switching device can be automatically turned on in accordance with the power-on state of the connected printer. Furthermore, the power of the switching device that does not need to be turned on is not turned on, and the power consumption is reduced. Further, the switching device whose power is ON is automatically turned OFF when the power ON is not required.

[Third Embodiment] Next, a third embodiment will be described.

FIG. 9 is an overall configuration diagram of a display system for connecting and displaying a plurality of display devices. In FIG. 9, branch type connectors 202, 203, and 204 connect the respective displays 100, 120, and 130 connected thereto to a host computer, and perform power control of the respective displays. The detailed description of the display system in FIG. 9 will be described later.

FIG. 10 is a block diagram showing a configuration relating to power supply control of the separator device according to the third embodiment. The serial / parallel converter 301 receives an ID signal and an AHDL signal sent from a host computer serving as an image source via a communication I / F cable 210. The ID signal is a signal for determining and selecting a display device on which image data following the ID signal is to be displayed. Also, A
The HDL signal is a signal notifying the start of transfer of image data. The serial / parallel converter 301 synchronizes with the AHDL signal and converts the ID signal into a serial signal.

As will be described in detail later, as shown in FIGS. 15 and 16, an ID signal and an address are transmitted from the host onto the data bus in synchronization with the rise of the AHDL signal. Therefore, by latching the data on the data bus at the falling edge of the AHDL signal, the ID signal and the address can be read. The serial / parallel converter 301 used in the third embodiment takes out only the ID signal therein and sends it to one input of the comparator 304.

On the other hand, the set value of the DIP switch 302 for setting the ID of each device
It is sent to the other input of the comparator 304. Therefore, the ID signal in the image data sent from the host computer and the ID value set by the DIP switch 302 are input to the comparator 304, and the comparison result is sent to the power supply device 305. Become. When the two ID values match, the comparator 304 turns off the power supply.
Generate N signal.

The power ON signal thus generated is sent to the power supply device 305, and the power supply device 305
The power supply is started by receiving the signal. The power supply device 305 starts power supply to each unit and each device other than the power control unit (each unit of the branch device main body and a display device connected to the branch device).

FIG. 11 is a timing chart for explaining the timing of the power control process according to the first embodiment. As mentioned above or as shown in the figure,
The ID signal is latched by latching the signal on the data bus at the falling edge of the AHDL signal, and is converted into a serial signal by the S / P converter. The comparator 304 determines the ID value set in the DIP switch 302 and the S / P converter 3
The power supply signal is turned on when the ID values obtained through the “01” are compared with each other.

It is to be noted that, according to a control signal input from the outside,
A power supply device capable of controlling ON / OFF of its output is well-known and will not be described.

As will be described later in detail, when a reflective ferroelectric liquid crystal without a backlight is employed as a display device, the supply of main power can be controlled by a power supply device.

The overall configuration of a display system according to a third embodiment for connecting and displaying a plurality of display devices will be described below.

FIG. 12 is a diagram showing the inside of a branch type connector according to the third embodiment. In FIG. 12, reference numeral 324 denotes the power control unit described with reference to FIG. Also, 321
Is a connector to which the cable 210 to be connected to the host or the preceding branch type connector is connected, 322 is a connector to which the cable 210 to be connected to the subsequent branch type connector is connected, and 323 is connected to the display 100. Cable 205
Is a connector to be connected.

The signal SOUT output from the connector 321 to the preceding branch type connector or the host is
SOU from the subsequent-stage branch-type connector input from S2
It is the logical product of T and the signal SOUT from the display input from the connector 323. When the power of the subsequent branch-type connector or the display is cut off, or when the signal of the signal SO to be disconnected from the latter-stage branch-type connector or the display is inputted.
When the UT is in a disconnected state, these signals SOUT are high.
It is pulled up in the branch type connector so that

Similarly, the BUSY signal output from the connector 321 to the preceding branch type connector or the host is transmitted from the connector 322 to the B branch signal from the subsequent branch type connector.
This is the logical product of the USY signal and the BUSY signal from the display input from the connector 323. When the power supply of the subsequent branch-type connector or display is cut off, or when the BUSY signal to be input is disconnected due to disconnection with the subsequent branch-type connector or display, and these input BUs are disconnected.
The SY signal is pulled up in the branching connector to be H.

FIG. 13 is a block diagram showing the internal configuration of the display according to the third embodiment. 101 is the cable 21
0 is a connector to be connected, 105 is a liquid crystal display element using ferroelectric liquid crystal, 102 is a drive controller that receives display data and controls the liquid crystal display element 105, 106 is a backlight including a lighting circuit and a lamp, and 104 is a liquid crystal. A power supply unit for supplying power to the display element 105 and the backlight 106; 107, a temperature sensor for detecting a temperature near the liquid crystal display element 105; 103, a drive controller 102
And a display controller that controls the power supply unit 104 and performs serial communication with the host 1 to control the entire display.

Reference numeral 108 denotes the display units 100, 120, 1
An ID setting unit for setting a unit ID for distinguishing the 30s. It should be noted that the same ID value as the ID number set in the ID setting unit 108 is set in the above-described branch type connector. In the present embodiment, ID = 1h is displayed on the display 100,
ID = 2h is displayed on the display 200, and ID is displayed on the display 300.
= 3h is set in the ID setting means 108.

The liquid crystal display element 105 is a display panel using a ferroelectric liquid crystal as a liquid crystal.
The liquid crystal material used for displaying 280 × 1024 pixels is, for example, a mixture mainly composed of a biphenyl type and a phenylpyrimidine type. The phase transition temperature of the liquid crystal material is Cryst → (−10 ° C.) → Sm → (63 ° C.) → SmA
→ (72 ° C.) → Ch → (91 ° C.) → Iso.

The display element 10 using a ferroelectric liquid crystal
In No. 5, the optimum driving condition changes depending on the temperature. FIG. 14 is a diagram for explaining the relationship between driving conditions and temperature of the ferroelectric liquid crystal display element. The driving conditions in the present embodiment include a driving voltage (Vop) which is a voltage of a driving waveform applied to the liquid crystal, and a horizontal scanning time (1) which is a time for driving one driving line.
H). As shown in FIG. 14, the optimal driving conditions are:
It changes so that the product of Vop and 1H becomes smaller as the temperature becomes higher. The display controller 103 includes the liquid crystal display element 10
The optimum driving conditions are selected according to the temperature near 5, and one horizontal scanning time (1H) is set in the driving controller 102 and Vop is set in the power supply unit 104. The drive controller 102 adjusts the time of 1H and requests display data at a timing corresponding to the time.
5 is supplied to a driver circuit (not shown). Further, the power supply unit 104 generates a liquid crystal driving voltage corresponding to Vop, and supplies this to the driver circuit of the liquid crystal display element 105.

FIG. 15 is a diagram showing the transfer timing of image data sent from the host device to the display device via the branch type connector. For simplicity, FIG. 15 focuses on the host computer 201 and the display device 100 for explanation.

The signal PDi (i = 0-15) is image data, and image data for one scanning line is transmitted with a scanning line address in synchronization with the transfer clock FCLK. A
HDL is a signal indicating whether the content of the signal PDi (i = 0-15) is image data or a scanning line address. Signal B
USY is a signal indicating whether or not the display side can receive image data. Drive controller 102 of display 100
Sending L to the BUSY signal is a data transfer request. That is, when the BUSY signal is lowered to L on the display device 100 and a transfer request for image data is output, the host computer 201 sets AHDL for one clock of FCLK.
Is raised to H, and in synchronization with this, the scan line address is transmitted,
Subsequently, image data for one scanning line is transferred.

FIG. 16 is a diagram showing the structure of image data to be transferred. As described above, a 12-bit scanning line address is transmitted at the head, and then 1280 × 4 bit image data (D0 to D5119) is transferred. A unit ID (UnitID, UnitID,
U3 to U0). The unit ID is data indicating which display unit receives and displays the image data for one scanning line.

Next, the operation from the time when the power of the display device 100 is turned on to the time when driving is started will be described.
17 and the flowcharts of FIGS. 23 to 25 showing the control procedure of FIG.

FIG. 17 is a flowchart showing the overall operation of the display controller 103. When the power of the display 100 is turned on, the display controller 103 performs necessary initialization for itself, the drive controller 102, the power supply unit 104, and the like (step S101), and outputs the signal PW
Wait for ON to drop to L (step S102). The signal PWON is a signal notifying that the power supply of the host computer 201 is turned on, the preparation for the transfer of the image data is completed, and that the connected display unit can perform the display operation. When detecting PWON = L, the display controller 103 determines an operation mode (master mode, slave mode) according to an operation selection procedure described later (step S103), and turns on a liquid crystal power supply including the backlight 106 (step S104). ).

Next, in the case of the master mode, information about the type of the host and the display is exchanged with the host 1 by serial communication (steps S105 and S10).
6). This series of communication is called initial communication.

There are two types of serial communication protocols. FIGS. 18 and 19 are diagrams for explaining the first protocol in the third embodiment. 20 and FIG.
1 and FIG. 22 are diagrams for explaining the second protocol.

In the first protocol, a command is sent from a host computer (hereinafter, also simply referred to as a host) to a display, and the display returns a status (FIG. 18). The command is always issued by the host and the next command is not issued until the corresponding status is received. Also, the display retains the last status issued until it receives the next valid command. Thus, when the host cannot receive the status due to a communication error, a command (Request Stat
us) makes it possible to retransmit the status (FIG. 19).

In the second protocol, the display is an Attention
To request communication, the host responds
Request the contents of Attention (Attention Information),
The display responds to this (status), and the host responds with Atte
A command (Clear Attention) for clearing the ntion is issued, and the display issues an acknowledgment status to complete the communication (FIG. 20).

When the host receives Attention, it clears it.
Until the Attention is cleared by the Attention command (this period is called the Attention state), a command that requests the contents of Attention (Request Attention Informat
ion), a command to clear Attention (Clear Attent
ion), a command to request the retained status (Reque
Commands other than st Status) are not issued. These three commands are called specific commands. On the display, the status for the specific command is not held, but the status immediately before is kept. The display is Attention
If a command other than a specific command is received before issuing the Attention clear command from the host (in the Attention state) after issuing the command, the status transmission is suspended, and after the Attention is cleared, the status is suspended. The status is issued (FIG. 21).

The case where the display receives a command other than the specific command during the Attention state occurs when the host issues the command and the display issues the Attention almost simultaneously (FIG. 21).

If the Attention cannot be received normally on the host side due to a communication error, the host originally expects the status for the issued command, and requests a retransmission of the status (Request Stat).
us) is issued (FIG. 22). On the other hand, Atte
An error status (No Status) is issued because the received command is suspended and the status immediately before it is not retained, and the command is held. This allows the host to determine that the data that could not be received normally is an Attention, and a command (R
equest AttentionInformation) (Figure 2)
2). If the host suddenly receives a status while not issuing a command, the host will follow this flow
est Status ”and“ Request Attention Information ”.

The mode selection in step S103 in FIG. 17 is performed by using the operation of the host when this unexpected status is received to confirm the presence of another display device already communicating with the host. Select master mode or slave mode. That is, of the plurality of displays connected to the host, only one display performs serial communication with the host, and the other displays do not perform serial communication. The host exchanges information with a display performing serial communication, transfers image data suitable for this, and all displays receive this image data. The operation mode of the display device that performs serial communication with the host is called a master mode, and the operation mode of the display device that does not perform serial communication is called a slave mode.

FIG. 23 is a flowchart showing the mode selection operation. First, it is checked whether there is any command issued by the host to another display. If any command is received, there is another display that is already communicating with the host, so that it is determined that the slave mode is not performed after that (steps S201, S202, and S202).
210). In this example, the SIN signal is monitored for 200 ms, and the slave mode is set if the SIN signal is detected.

If no command (SIN input) is received, status 0h (OK) is issued next, and it is confirmed whether there is any command to be received again (step S2).
03, S204, S205). The host issues a "Request Status" command for the unexpected status.

If there is another display that is already communicating with the host, the other device that is communicating with the display will display its “Requ
"No Status" in response to the "est Status" command,
Further, the host issues a “Request Attention Information” command. Therefore, step S20
"Request Status" for the status issued in step 3
Is detected as a SIN input, followed by a “Request
If "Attention Information" is detected as the SIN input, there is another display device in communication, and the display device is set to the slave mode (step S20).
7, S208, S210). That is, 0h is set to SOUT.
"Request Status" is detected in step S205 within 200 ms after the
Within 0 ms, “Request Atte
ntion Information "is detected, the process proceeds to step S21.
Proceeding to 0, the slave mode is set.

On the other hand, if no command is received after the "Request Status" command, no display unit is communicating with the host, and it is determined that the display unit is in the master mode for communication thereafter (step S209).

After outputting 0h to SOUT, 20
If the SIN signal is not detected during 0 mS, 0h output to SOUT is repeated the number of times specified in step S206. If the SIN is never detected even after the specified number of retries, an error is notified because there is something more than the connection or the like.

Returning to FIG. After the operation mode is selected by the mode selection, if the mode is the master mode, initial communication with the host is performed (steps S105 and S105).
106). Then, as long as the signal PWON is at L, the reception of image data for each line and the driving of the liquid crystal display element (one-line driving) are repeated (steps S107 and S108).
Further, in the case of the master mode, the serial communication process is also repeated (step S109).

When the signal PWON becomes H, it indicates that the display is instructed by the host to stop the display or the power supply of the host is cut off. The drive is immediately stopped, the backlight is turned off, the liquid crystal power supply is cut off, and other operations are terminated. Processing is performed (steps S110, S111). When the power supply of the display unit is cut off, a series of end processing is started by an interrupt signal from the power supply unit 104, and the processing ends during the output holding time of the power supply unit 104. Although not shown, after the termination process is performed, and after a certain period of time, the power of the display is continuously turned off.
In the case of N, the operation of the display controller 103 returns to the top of FIG. 17, and waits until PWON becomes L again after initialization.

FIG. 24 is a flowchart showing the operation of one-line driving according to the third embodiment. One-line driving is an operation in which image data for one horizontal scanning line of a liquid crystal display element is received from a host, transferred to the display element, and driven. First, when the operation mode is the master mode, B is used to request the host for image data for one horizontal scanning line.
USY is set to L (steps S301 and S302). As described with reference to FIG. 15, the transfer of the image data is started by the signal AH.
It can be detected by H of DL. When the scanning address and the unit ID are received together with H of the signal AHDL, the signal BUSY is changed to H.
(Steps S303 to S305). If the received unit ID matches the ID set in the ID setting unit 108, or if the received unit ID is 0h specifying all the display devices, the image data is received (steps S306 and S307). . Then, the image data is transferred to a driver circuit (not shown) of the display element 105 while measuring the timing with the display element 105, and the driving of one scanning line is instructed (step S308).

The received unit ID is the ID setting means 1
If the ID does not match the ID set to 08,
If it is not h, the image data is not transferred to the display element 105 and the driving start instruction for one scanning line is not issued.
Although the signal BUSY is not raised or lowered in the slave mode, this will be described later.

FIG. 25 is a flowchart showing the operation of the communication process. In the communication process, when the operation mode is the master mode and a command has been received (steps S401 and S402), a process is performed according to the instruction of the received command, and the status is transmitted (steps S403 and S404). .

Further, regardless of the operation mode, the temperature near the liquid crystal display element 105 is detected by the temperature sensor 107 at regular time intervals, and optimal driving conditions are selected according to FIG.
1H time to drive controller 102, power supply unit 1
04 is set to Vop (steps S405, S40)
6). This operation is called a temperature compensation operation.

Next, operations in two operation modes, a master mode and a slave mode, will be described. First, the power of the display 100 is turned on, and then the power of the host is turned on. At this point, it is assumed that the power of the displays 200 and 300 is still off.

FIG. 26 is a diagram showing the operation from the power-on of the display 100, to which the power is turned on before the other displays 120, 130, to the start of driving. As described with reference to the flowchart of FIG. 17, when the display device 100 detects L of PWON, the display device 100 checks whether there is communication from the host 201 to another display device based on the signal SIN, and then outputs the status 0h as the signal SOUT. On the other hand, the command “Re
quest Status "is received, but no subsequent command is received, and it is determined that there is no other display already communicating with the host. Therefore, the display 100 changes the operation mode to the master mode. Then, initial communication with the host 201 is started.

That is, the fact that the preparation on the display side has been completed is indicated by Atte.
ntion (Unit Ready Attention) to inform the host, and the host inquires about the contents of this attention (Reque
st Attention Information), Clear Attention (Clear Attention). Next, the host notifies the display type of the host (Send Host Code). The display returns an acknowledged status if the host is connectable, and an error status if the host is not connectable. Next, the host requests a display unit type (Request Unit Code).
In addition, after the host inquires necessary information to the display and sends necessary information to the display, the host issues an instruction to start a data request (Unit Start). The display returns the status, lowers the BUSY, and requests image data transfer. When the display unit receives image data for one scanning line with a scanning line address, it starts driving the corresponding scanning line while comparing the unit ID with the ID set in the ID setting unit 108.

In FIG. 26, drv indicates driving of the scanning line specified by the scanning line address. Tw0 in FIG. 26 is a drive suspension period. When the operation mode is the master mode,
A pause is inserted every time the drive is started. Pause time tw
The setting of 0 will be described later in detail.

On the other hand, FIG.
FIG. 11 is a diagram for explaining the operation from the time when the power of the display unit 120 is turned on to the time when driving is started after communication with the display device 01 and the driving is started. When the power of the display device 200 is turned on and the initialization is completed, the signal PWON is already at L, and the image data has been transferred. The display 200 monitors the signal SIN, and immediately determines the operation mode as the slave mode upon receiving a command transmitted from the host to another display. When the command is not received, a status 0h is output to the signal SOUT. In this case,
A command Reques from the host for this signal SOUT
t Status and the command Request AttentionInformation are received, and it is determined that the host is communicating with another display. Thus, the display 120 determines the operation mode as the slave mode.

The display set to the slave operation does not perform serial communication with the host. The display 120 indicates the signal B
Wait for image data transfer without lowering USY
Rises, receives image data for one scanning line with a scanning line address, and sets the unit ID to the ID setting unit 108.
The driving of the corresponding scanning line is started while comparing with the ID set in. Also, the transfer timing of image data is delayed,
When the driving of the immediately preceding scanning line has been completed, the driving is started while waiting for the transfer of image data while the driving is stopped. Drv in FIG. 27 represents the driving of the scanning line specified by the scanning line address.

Further, when the power of the display 130 is turned on after the display 120, the same operation as the display 120 is performed, and the display operation is performed in the slave mode.

Next, the display 1 operating in the master mode
00 and indicators 120 and 13 operating in slave mode
Data transfer of 0 and drive timing will be described with reference to FIG. In the figure, BUSY1 and drv1
Represents a signal BUSY output from the display device 100 and the driving timing of the scanning line. BUSY2 and drv2 are the signal BUSY output from the display 120 and the driving timing of the scanning line. The dashed line of BUSY2 indicates that the display 120 operating in the slave mode is BUSY in one-line driving operation.
This shows the timing of waiting for the signal AHDL without outputting L to Y. BUSY3 and drv3 are the signal BUSY output from the display unit 130 and the drive timing of the scanning line.

When the host 201 receives L of the signal BUSY1, it changes the signal AHDL to H and sends out image data with a scanning line address. This signal AHDL and P
Di (i = 0-15) is also transferred to the displays 120 and 130 in common. Upon receiving the image data, the display unit 100 starts driving the corresponding scanning line after the pause time described above, and makes a next data request at a timing corresponding to the 1H time. That is, the display 100 requests data with a cycle of “1H + pause time tw0”.

The pause time tw0 is set to a time for absorbing a difference of 1H that changes due to self-heating at the environmental temperature where the display 100 is placed. In FIG. 14 showing the optimal driving conditions of the liquid crystal display element 105, the display device 100 is at room temperature 2
1H when the power is turned on in a 5 ° C environment is about 130μ.
s. If driving for display is continued in this environment, self-heating of the liquid crystal display element 105 itself and the backlight 10
6, the temperature of the liquid crystal display element 105 rises to about 3
Saturates at 5 ° C. Therefore, 1H which is the optimum driving condition is about 1
00 μs. The pause time tw0 is 1H of the display 200 or 300 when the power of the other display 200 or 300 is turned on while the display 100 is in a temperature saturated state and driven at the shortest 1H. Is chosen to be equal to

On the other hand, in the display 120, for example, in FIG. 28, 1H 'longer than the 1H time of the display 100 is selected as the optimum driving condition. The display 100 is started to be driven first, and after the internal temperature has sufficiently increased, the display 12
This corresponds to the case where the power supply of 0 is turned on. Also in this case, if the connected indicators are in the same room, the following relationship is substantially maintained.

1H ′ ≦ 1H + tw0 In the display 120 operating in the slave mode, the signal BUSY output from the display 100 operating in the master mode
Receiving the image data transmitted in a form corresponding to L of 1;
The driving drv2 of the corresponding scanning line is started, and a next data request is waited for at a timing corresponding to its own 1H.
The standby of the image data occurs every 1H ′. Since the transfer cycle of the image data is “1H + pause time” of the display 100, the drive pause of the time tw1 indicated by tw1 = 1H + tw0-1H ′ occurs. The transferred image data is not lost.

Similarly, for the display 130, 1H, which is the same as that of the display 100, is selected as the optimum driving condition, for example. This corresponds to the case where the power of the display 130 is turned on almost continuously to the display 100. Similarly, the display unit 130 receives the image data transmitted in response to L of the signal BUSY1 output from the display unit 100 operating in the master mode, and starts driving drv3 of the corresponding scanning line.
The next data request is made at a timing corresponding to its own 1H. Although the data request is a 1H 'cycle, the transfer cycle of the image data is "1H + tw0" of the display 100, so that the data reception is delayed by the same pause time tw0 as the next display 100, and the drive is also suspended for the same time. Is generated.

As described above, the apparatus according to the third embodiment has communication means other than the transfer of image data, and the display which communicates with the host transmits the image data prior to the start of display on the display. By having means for appropriately selecting an operation mode using communication means other than the above, and also, only one display communicates according to the selected operation mode and a pause time appropriately selected for driving one scanning line. In the operation mode of inserting a single line, or by not performing communication with other multiple displays according to the selected operation mode, multiple displays can be connected to a single line cable without providing additional circuits such as new memories other than inside the host. It becomes possible to connect the two display units and display simultaneously.

The insertion of the pause time slightly lowers the frame rate of the displayed image as compared with the case where the display is connected to the host alone. For example, as already explained 25
When the temperature of the liquid crystal display element is saturated in an environment of 1 ° C., 1H can be driven at about 100 μs and the frame frequency is 9.8 Hz.
μs, and the frame frequency is 7.5 Hz. However, in the display device of the present embodiment using the ferroelectric liquid crystal as the liquid crystal of the liquid crystal element, once writing ON or OFF to one pixel is performed, the ferroelectric liquid crystal maintains the state even when the applied voltage is removed. Utilizing the characteristics of the liquid crystal (memory characteristics), it is possible to use the method without giving a problem to the image quality by using a technique such as preferentially rewriting the changed area of the displayed image (partial rewriting technology). It is.

The branch type connector of the display system as described above has a power control unit 324, and the unit ID transmitted from the host is the DIP switch 302 (FIG. 10).
When the ID value coincides with the ID value set in the step, power is supplied to the display device. Therefore, first, one display is set to the master mode by setting the unit ID of the display to be driven in the master mode and transferring the display data. Thereafter, by transmitting image data to other display devices (by setting the unit ID of the other display device), the display devices are sequentially turned on.

The termination of the power supply from the branch type connector may be performed by the comparator 304 monitoring the PWON signal of the host. That is, when the PWON signal becomes H, the supply of power from the branch-type connector ends. In this case, the power supply is shut off after delaying by a time necessary for the display device to perform an end process or the like (step S111 (FIG. 17)).

In the display system of the above embodiment,
When the unit ID is 0h, it indicates designation of all display devices. Therefore, the comparator 304 may be configured to output a power-on signal when the input ID signal is either equal to the ID value set by the DIP switch 302 or is 0h. .

Further, in the above display system, a power ON signal (output of the comparator 304) is output from the branching type connector to the display, and this is used to turn on and off the backlight of the display. Is also good.

When a reflective ferroelectric liquid crystal display is used as the display, the power supply may be stopped when the DIP switch 302 and the input ID signal do not match. good.

That is, according to the third embodiment, in a multi-display system in which a plurality of display devices having unique IDs are connected on a communication I / F cable, image data for each display device is transmitted. The power consumption can be reduced by supplying a necessary portion of power only during a period in which the communication I / F cable exists.

In particular, as a display device, a reflection type FLCD
In such a case, the power supply of the display device itself can be cut off, and a great reduction in power consumption can be realized.

The power supply cutoff by the branch type connector may be executed when the set ID signal is not received for a predetermined time or more. By doing so, a function similar to auto power off can be realized.

The present invention can be applied to a system including a plurality of devices (for example, a host computer, an interface device, a reader, and a printer).

Further, an object of the present invention is to provide a storage medium storing a program code of software for realizing the functions of the above-described embodiments to a system or an apparatus, and to provide a computer (or CPU) of the system or the apparatus.
And MPU) read and execute the program code stored in the storage medium.

In this case, the program code itself read from the storage medium implements the functions of the above-described embodiment, and the storage medium storing the program code constitutes the present invention.

Examples of a storage medium for supplying the program code include a floppy disk, hard disk, optical disk, magneto-optical disk, CD-ROM, and CD.
-R, a magnetic tape, a nonvolatile memory card, a ROM, or the like can be used.

When the computer executes the readout program code, not only the functions of the above-described embodiment are realized, but also the OS (Operating System) running on the computer based on the instruction of the program code. ) May perform some or all of the actual processing, and the processing may realize the functions of the above-described embodiments.

Further, after the program code read from the storage medium is written into a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, based on the instruction of the program code, It goes without saying that the CPU included in the function expansion board or the function expansion unit performs part or all of the actual processing, and the processing realizes the functions of the above-described embodiments.

[0105]

As described above, according to the present invention,
The necessary power supply and cutoff are automatically performed based on the on / off state of the power supply of the connected peripheral device, so that the branch device power-on operation is performed according to the power-on status of the peripheral device. This eliminates the need for labor and improves operability.

Further, according to the present invention, the power is automatically supplied to the peripheral device specified by the host device, so that the operation of turning on the power to the peripheral device to be used becomes unnecessary. Operability is improved.

[0107]

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration example of a printer switching system.

FIG. 2 is a block diagram illustrating a configuration example of a printer switching system.

FIG. 3 is a block diagram illustrating a configuration example of a printer switching system.

FIG. 4 is a block diagram illustrating a configuration example of a printer switching system according to the first embodiment.

FIG. 5 is a block diagram illustrating a configuration of a switching device according to the first embodiment.

FIG. 6 is a diagram illustrating a configuration example of a selector circuit.

FIG. 7 is a diagram illustrating a printer system according to a second embodiment.

FIG. 8 is a block diagram illustrating a configuration example of a switching device according to a second embodiment.

FIG. 9 is an overall configuration diagram of a display system for connecting and displaying a plurality of display devices.

FIG. 10 is a block diagram illustrating a configuration related to power supply control of a separator device according to a third embodiment.

FIG. 11 is a timing chart illustrating the timing of a power supply control process according to the first embodiment.

FIG. 12 is a diagram showing the inside of a branch type connector according to a third embodiment.

FIG. 13 is a block diagram illustrating an internal configuration of a display according to a third embodiment.

FIG. 14 is a diagram illustrating a relationship between driving conditions and temperature of a ferroelectric liquid crystal display element.

FIG. 15 is a diagram illustrating a transfer timing of image data sent from the host device to the display device via the branch-type connector.

FIG. 16 is a diagram showing a configuration of image data to be transferred.

FIG. 17 is a flowchart illustrating an overall operation of the display controller 103.

FIG. 18 is a diagram illustrating a first communication protocol according to the third embodiment.

FIG. 19 is a diagram illustrating a first communication protocol according to the third embodiment.

FIG. 20 is a diagram illustrating a second communication protocol according to the third embodiment.

FIG. 21 is a diagram illustrating a second communication protocol according to the third embodiment.

FIG. 22 is a diagram illustrating a second communication protocol according to the third embodiment.

FIG. 23 is a flowchart showing a mode selection operation.

FIG. 24 is a flowchart illustrating an operation of one-line driving according to the third embodiment.

FIG. 25 is a flowchart illustrating an operation of a communication process.

FIG. 26 is a diagram showing an operation from the power-on of the display 100 to which power is turned on before the other displays 120 and 130 to the start of driving.

FIG. 27 is a diagram illustrating an operation up to the start of driving when another display is turned on after a certain display starts driving.

FIG. 28 is a diagram showing data transfer and drive timings of a display operating in a master mode and a display operating in a slave mode.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Eiichi Matsuzaki, 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Nobuharu Ichihashi 3-30-2, Shimomaruko, Ota-ku, Tokyo Within Non Corporation (72) Inventor Morimoto Hajime 3-30-2 Shimomaruko, Ota-ku, Tokyo Within Canon Corporation (72) Inventor Takashi Yamamoto 3-30-2 Shimomaruko, Ota-ku, Tokyo Within Canon Corporation

Claims (16)

[Claims] 1. A switching device for forming a communication path between a host device and a plurality of peripheral devices, wherein the signal indicates a power state of whether a device connected to a line on the peripheral device side is on or off. Input means for inputting, and when the signal indicates that the power state is on,
A switching device comprising: a supply unit that supplies power to the device; and an output unit that outputs a power supply state of the supply unit to a line on a host device side as a power supply state of the device. 2. The apparatus according to claim 1, further comprising a line on one host device side and a plurality of peripheral device side lines, wherein said supply means includes a power supply for any one of the devices connected to said plurality of peripheral device side lines. The switching device according to claim 1, wherein when the state is on, power is supplied to the device. 3. The apparatus according to claim 1, further comprising a switching unit configured to switch a signal input from a line on the host device side to be output to any one of the selected lines on the peripheral device side. 3. The switching device according to 2. 4. The power supply status signal according to claim 1, wherein the power supply status signal is represented by a high level and a low level of a voltage supplied by a power supply of a device connected to the peripheral device side line. Item 1. The switching device according to Item 1. 5. The power supply state according to claim 1, wherein the signal indicating the power supply state indicates the power supply state by a high level state and a high impedance state of a power supply of a device connected to the peripheral device side line. The switching device according to claim 1. 6. A peripheral device system comprising a host device, a plurality of peripheral devices, and a plurality of switching devices forming a communication path therebetween, wherein each of the plurality of peripheral devices has its own power supply. A first output unit that outputs a signal indicating a power state of on or off; and a power state of whether a power supply of a device connected to a line on a peripheral device side is on or off in each of the plurality of switching devices. Input means for inputting a signal to indicate, when the signal indicates that the power supply state is on,
A peripheral device system comprising: a supply unit that supplies power to the switching device; and an output unit that outputs a power supply state of the switching device to a line on a host device side as a power supply state of the switching device. . 7. The peripheral device system according to claim 6, wherein the peripheral device is a printer device. 8. A branching device for forming a communication path between a host device and a plurality of peripheral devices, comprising: holding means for holding a set identification number; and detecting identification information output from the host device. Detecting means for determining whether or not to supply power based on the identification information detected by the detecting means and the identification number held by the holding means; and And control means for controlling power supply of peripheral devices connected to the branch device. 9. The determination means compares the identification information detected by the detection means with the identification number held by the holding means, and determines that power supply is to be performed if the identification numbers match. The branching device according to claim 8, wherein 10. The branching device according to claim 8, wherein the control unit supplies necessary power to the peripheral device when the determination unit determines to supply power. 11. The control device according to claim 8, wherein the control unit outputs a signal for instructing the peripheral device to turn on power when the determination unit determines that power is to be supplied. Branching device. 12. The control unit according to claim 1, wherein when the identification information detected by said detection unit and the identification number held by said holding unit do not match, at least a part of the supplied power is cut off. The branching device according to claim 8, characterized in that: 13. The control unit according to claim 8, wherein when the identification number held by the holding unit is not detected for a predetermined time, at least a part of the supplied power is cut off. The branching device according to item 1. 14. A peripheral device system comprising a host device, a plurality of peripheral devices, and a plurality of branch devices forming a communication path therebetween, wherein the peripheral devices are connected in each of the plurality of branch devices. Holding means for holding the same identification number as the identification number set in, detecting means for detecting identification information output from the host device, identification information detected by the detecting means and held by the holding means Determining means for determining whether to supply power based on the identification number, and control means for controlling power supply to the connected peripheral device based on a determination result by the determining means. And peripheral equipment system. 15. The device according to claim 14, wherein the peripheral device is a ferroelectric liquid crystal display, and the control unit controls power supply to a drive circuit of the ferroelectric liquid crystal display. Peripheral equipment system. 16. The liquid crystal display according to claim 14, wherein the peripheral device is a reflective ferroelectric liquid crystal display, and the control unit controls power supply to the entire ferroelectric liquid crystal display. Peripheral system as described.