(12) United States Patent
`Shiga
`
`I IIIII IIIIIIII Ill lllll lllll lllll lllll lllll lllll lllll lllll 111111111111111111
`US006625738Bl
`
`(10) Patent No.:
`(45) Date of Patent:
`
`US 6,625,738 Bl
`Sep.23,2003
`
`(54) USB APPARATUS THAT TURNS ON
`COMPUTER POWER SUPPLY USING
`SIGNALS SUBSTANTIALLY LONGER THAN
`INFORMATION CONVEYING PULSE
`WIDTHS WHEN PREDETERMINED
`OPERATION IS PERFORMED ON INPUT
`DEVICE
`
`(75)
`
`Inventor: Sadakazu Shiga, Fukushima-ken (JP)
`
`(73) Assignee: Alps Electric Co., Ltd., Tokyo (JP)
`
`( *) Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by O days.
`
`(21) Appl. No.: 09/454,621
`
`(22) Filed:
`
`Dec. 6, 1999
`
`(30)
`
`Foreign Application Priority Data
`
`Dec. 15, 1998
`
`(JP) ........................................... 10-355710
`
`Int. Cl.7 .................................................. G06F 1/26
`(51)
`(52) U.S. Cl. .......................................... 713/310; 710/67
`(58) Field of Search ................................. 713/310, 323,
`713/324; 710/67
`
`(56)
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`5,249,298 A * 9/1993 Bolan et al. ................ 713/340
`5,553,296 A * 9/1996 Forrest et al.
`.............. 713/321
`5,590,343 A * 12/1996 Bolan et al. ................ 713/300
`5,767,844 A * 6/1998 Stoye ......................... 345/212
`5,799,196 A * 8/1998 Flannery ..................... 713/320
`6,092,207 A * 7/2000 Kolinski et al.
`............ 713/323
`
`6,202,161 Bl * 3/2001 Wang ......................... 713/310
`6,205,502 Bl * 3/2001 Endo et al. ................. 710/100
`6,237,100 Bl * 5/2001 Cromer et al. .............. 713/300
`
`FOREIGN PATENT DOCUMENTS
`
`JP
`
`10-312235
`
`11/1998
`
`* cited by examiner
`
`Primary Examiner-Thomas Lee
`Assistant Examiner-Albert Wang
`(74) Attorney, Agent, or Firm-Brinks
`Liane
`
`(57)
`
`ABSTRACT
`
`Hofer Gilson &
`
`An apparatus for turning on a computer power supply in
`which when an input operation of a predetermined key is
`carried out, predetermined H signals are output to a first
`signal line and a second signal line of a USE chip provided
`in a keyboard. Since this signal combination is not a USE
`standard signal combination, they can be distinguished from
`ordinary data signals. Since a wake-up device which has
`received these signals outputs predetermined start-up signals
`to a main power supply, the main power supply can be
`turned on. When the main power supply is turned on,
`connections of a first relay contact and a second relay
`contact of a switching device switch are switched, whereby
`first signal lines and second signals between the host com(cid:173)
`puter and a keyboard are connected together, making it
`possible to carry out communication using the signals. By
`virtue of this structure, it is possible to start up the host
`computer whose main power supply is in an off state by
`operating the keyboard.
`
`81 Claims, 1 Drawing Sheet
`
`GND
`
`V
`
`6
`
`E
`
`Vee
`
`2
`
`;
`
`E V
`
`D+1---:r--...---3--'
`D-t---r---+---,1----;>--c-=,---rr-0
`
`9
`
`11
`
`12
`
`Vee
`D+
`0-
`GND
`
`.-----<l1E
`
`+
`POWER
`SUPPLY
`_rt_
`Sai--------,8-c--t
`
`GND
`
`5
`
`SA
`
`

`

`i,-
`~
`~
`~
`(It
`N
`O'I
`O'I
`rJ'J.
`e
`
`8
`C
`N
`~
`N
`~ '?
`'JJ.
`
`~
`
`~ = .....
`~ .....
`~
`•
`r:JJ.
`d •
`
`GND
`0-
`D+
`Vee
`
`12
`
`11
`
`9
`
`I
`
`I
`
`• •
`
`I
`
`I
`
`4
`'. .
`,_ --:--
`'2,
`: ~...__4C
`
`,
`I
`:
`:
`
`D-
`D+
`Vee
`
`1a
`
`02
`
`482
`
`V
`I~~
`
`E
`
`E
`
`I E V
`
`FIGURE 1
`
`~6
`
`V
`
`I
`
`I-------------~ -i-~
`J;
`GND D·
`0
`L Vee
`1
`
`-------·--------------------------'
`' ' '
`' ' I
`···-3
`
`I
`I
`
`I
`
`I
`I
`
`Sc
`
`........
`
`f
`
`3A3 3A 3A 1
`
`'
`: _IL T
`.;.e-
`V
`:
`:
`
`-.,-
`SA---u GND
`
`Sa
`
`5--t SUPPLY
`POWER
`
`+
`
`

`

`1
`USB APPARATUS THAT TURNS ON
`COMPUTER POWER SUPPLY USING
`SIGNALS SUBSTANTIALLY LONGER THAN
`INFORMATION CONVEYING PULSE
`WIDTHS WHEN PREDETERMINED
`OPERATION IS PERFORMED ON INPUT
`DEVICE
`
`BACKGROUND OF THE INVENTION
`
`US 6,625,738 Bl
`
`2
`computer is in an on state. Therefore, when the main power
`supply is in an off state, the host computer cannot be started
`with the above-described software.
`There has been a demand for adding value to such
`5 computers connected with the USE interface by providing a
`function that the USE does not have, that is, by providing a
`key called a power-on key, which allows the host computer
`to be started by a key input operation at a keyboard.
`
`1. Field of the Invention
`The present invention relates to a power-on function of,
`for example, a host computer including a universal serial bus
`(USE) interface, and more particularly to an apparatus for
`turning on a computer power supply, which is constructed so
`as to start up the host computer as a result of an operation
`of an input device, such as a keyboard, when a main power
`supply of the host computer is in an off state.
`2. Description of the Related Art
`In conventional computers, pieces of software are built in
`as resident programs in order to prevent wasteful energy
`consumption and to increase the efficiency with which
`energy is saved when the host computer is not used for a
`long time.
`In executing the resident program, when an input opera(cid:173)
`tion is not performed within a predetermined period of time
`from the most recent operation that has been performed at
`the input device, such as a keyboard, an operation which
`changes an electrical power mode of the host computer to a
`suspend mode is carried out. In the suspend mode, the clock
`speed of a central processing unit (CPU) is reduced, a drive
`motor of a hard disk or a floppy disk is stopped, and a
`display is turned off, so that the amount of electrical current
`supplied to the host computer for consumption is such that 35
`the host computer is set in a low electrical power state.
`When the host computer is set in the suspend mode, and
`the input device, such as a keyboard, is operated, the host
`computer receives information that the input device has been
`operated. This information is received in the form of a
`start-up signal. When this start-up signal is input to the host
`computer, the clock speed of the CPU returns to its original
`speed, the hard disk or the floppy disk drive motor is started
`again, and the display is turned on again. Accordingly, the
`host computer is restored to the state prior to the suspend
`mode state.
`Personal computer peripheral interfaces that have been
`primarily used for a long time are serial ports (RS232-C) and
`Centronics parallel ports. However, these types of peripheral 50
`interfaces have the following problems. The first problem is
`that the transfer speed limit is low. The second problem is
`that a larger number of ports need to be used when con(cid:173)
`necting a plurality of devices because only one device can be
`connected to one port. The third problem is that separate 55
`ports need to be provided for connecting a keyboard, a
`mouse, a display, etc., so that various connectors get
`crowded on the back side of the personal computers.
`To overcome the above-described problems, there has
`been proposed the USE, which allows various peripheral 60
`devices to be connected to only one connector as a result of
`integrating these interfaces. The USE has been rapidly
`attracting attention as a standard peripheral interface of the
`next generation.
`However, in the above-described conventional
`computers, the suspend and restore functions are provided
`on the assumption that the main power supply of the host
`
`10
`
`SUMMARY OF THE INVENTION
`Accordingly, it is an object of the present invention to
`provide an apparatus for turning on a computer power
`supply, which is constructed so as to start up a host computer
`including a USE interface by turning on a main power
`15 supply as a result of operating an input device when a switch
`of the main power supply of the host computer is in an off
`state.
`To overcome the above-described conventional problems,
`according to a basic form of the present invention, there is
`20 provided an apparatus for turning on a computer power
`supply, comprising a host computer; an input device con(cid:173)
`nected to the host computer through an interface; a main
`power supply for starting up the host computer; and a
`sub-power supply for applying electrical power to the input
`25 device when the main power supply is in an off state;
`wherein the host computer comprises wake-up means for
`turning on the main power supply to start up the host
`computer as a result of a predetermined operation performed
`at the input device when the main power supply is in an off
`30 state.
`According to the present invention, when the switch of the
`main power supply of the host computer is in an off state,
`and a keyboard, for example, is operated, the main power
`supply is turned on to start up the host computer.
`To make this operation possible, the sub-power supply
`(which is a battery) of the host computer supplies electrical
`power to the input device, such as a keyboard, through the
`interface. Therefore, when the main power supply of the host
`40 computer is in an off state, the electrical power level of the
`host computer is set low (which is also the case when the
`host computer is set in its ordinary suspend mode).
`When the predetermined operation is performed at the
`input device, the main power supply is turned on. Here, the
`45 operation may be performed on a special-purpose power-on
`key on the keyboard or on any combination of a plurality of
`keys. The operation may also be performed on a switch of,
`for example, a mouse for a predetermined time or a prede(cid:173)
`termined number of times.
`In another form of the present invention, an apparatus for
`turning on a computer power supply may further comprise
`switching means disposed at the interface, wherein when the
`main power supply is in an on state, the switching means
`connects a signal line of the host computer and a signal line
`of the input device, and wherein when the main power
`supply is in an off state, the switching means switches
`connections so that the wake-up means and the signal line of
`the input device are connected together; and
`wherein when the main power supply is in the off state,
`and a predetermined operation is performed at the input
`device, a start-up signal generated by the wake-up means is
`applied to the main power supply to turn on the main power
`supply, whereby the switching means switches connections
`so that the signal line of the host computer and the signal line
`65 of the input device are connected together.
`The switching means may be, for example, a relay or a
`logic circuit.
`
`

`

`US 6,625,738 Bl
`
`3
`In this case, when the main power supply is in an off state,
`the wake-up means and the input means, such as a keyboard,
`are connected together. When, for example, a predetermined
`key on the keyboard is operated, the main power supply is
`turned on by the wake-up means to start up the host
`computer, and the signal line of the host computer and the
`signal line of the input device are connected together.
`Therefore, after the host computer has been started, a signal
`indicating that the input operation has been performed at the
`keyboard can be transmitted to the host computer.
`In still another form of the present invention, when an 10
`apparatus for turning on a computer power supply comprises
`a host computer, an input device connected to the host
`computer through an interface, a main power supply for
`starting up the host computer, and a sub-power supply for
`applying electrical power to the input device when the main 15
`power supply is in an off state, and when the host computer
`comprises wake-up means, the interface may comprise four
`signal lines, that is, a universal serial bus standard power
`supply line, a first signal line, a second signal line, and a
`ground line. In addition, the wake-up means may comprise
`first comparing means for detecting whether or not a value 20
`of the first signal line is equal to or greater than a predeter(cid:173)
`mined standard value, second comparing means for, detect(cid:173)
`ing whether or not a value of the second signal line is equal
`to or greater than the predetermined standard value, and an
`AND circuit for determining a logical OR between the first 25
`comparing means and the second comparing means, with the
`main power supply being turned on when the logical OR
`reaches a predetermined value.
`In still another form of the present invention, when the
`interface comprises four signal lines, that is, a universal 30
`serial bus standard power supply line, a first signal line, a
`second signal line, and a ground line, and when the wake-up
`means comprises first comparing means, second comparing
`means, and an AND circuit, the predetermined operation
`may be performed at the input device in order to output H 35
`signals of a predetermined pulse width to both the first signal
`line and the second signal line, after which the H signals
`with a predetermined pulse width equal to or greater than the
`predetermined pulse width are output from the AND circuit
`to turn on the power supply.
`The communication mode in which both of the first signal
`line and the second signal line are in an H state result from
`a combination that does not exist in ordinary USE standard
`operation modes. Therefore, when the wake-up means is
`constructed so that it starts up when H signals are applied to
`both of these lines, there is no obstacle to carrying out 45
`ordinary communications using the USE interface. When
`the communication mode is switched at the USE interface,
`the first signal line and the second signal line may both be
`instantaneously set in the H state. When the duration in
`which the first signal line and the second signal line are in 50
`the H state becomes equal to or greater than a predetermined
`time period (more specifically, a time period which is longer
`than a USE standard signal transfer rate), and an attempt is
`made to start up the wake-up means, it is possible to prevent
`confusion with the case where communication modes are 55
`switched by the USE interface.
`With the first signal line and the second signal line being
`set in the H state when the main power supply is on and input
`from the input device is temporarily stopped, the main
`power supply can be turned off by setting both the first signal
`line and the second signal line in an L state for a predeter(cid:173)
`mined period of time as a result of carrying out the prede(cid:173)
`termined operation at the input device.
`BRIEF DESCRIPTION OF THE DRAWING
`FIG. 1 is a structural view of an embodiment of the 65
`apparatus for turning on a computer power supply in accor(cid:173)
`dance with the present invention.
`
`40
`
`5
`
`60
`
`4
`DESCRIPTION OF THE PREFERRED
`EMBODIMENT
`A description will now be given of the present invention
`with reference to the drawing.
`FIG. 1 is a structural view of an embodiment of the
`apparatus for turning on a computer power supply in accor(cid:173)
`dance with the present invention.
`Referring to FIG. 1, a host computer 1 and a keyboard 11
`(which is an example of an input device) are disposed on the
`left and right sides of line 1-1, respectively.
`In the interior of the host 1 of FIG. 1 are provided a
`universal serial bus (USE) chip 2 of large-scale integration
`for a USE interface; a wake-up means 3; a switching means
`4; a main power supply 5; and a sub-power supply 6. The
`USE chip 2 includes a power supply input terminal Vee, a
`ground terminal GND, a first signal line D+, and a second
`signal line D-, which correspond to those in a USE interface
`specification. FIG. 1 shows only the terminals that are
`particularly important for the USE interface, so that the rest
`of the terminals of the USE chip 2 are not shown. In FIG.
`1, an output voltage generated between a +terminal and a
`GND terminal of the main power supply 5 is expressed as E,
`and an output voltage generated between an OUT terminal
`and a GND terminal of the sub-power supply 6 is expressed
`as V. The power supply input terminal Vee of the USE chip
`2 is connected to the +terminal of the main power supply 5,
`while the GND terminal thereof is grounded to a ground
`line. The USE chip 2 is thus driven when electrical power is
`applied thereto from the main power supply 5. It is con(cid:173)
`nected to a central processing unit (CPU) in the host
`computer 1 by a local bus, and controlled by the CPU.
`The wake-up means 3 comprises a first comparing means
`3Aand a second comparing means 3B, both of which are, for
`example, OP amplifiers. A first input terminal 3Al of the
`first comparing means 3A and a first input terminal 3Bl of
`the second comparing means 3B are grounded through
`respective predetermined resistors. A standard voltage 7 (for
`example, 1.5 volts) is applied to a second input terminal 3A2
`of the first comparing means 3A and to a second input
`terminal 3B2 of the second comparing means 3B. An output
`terminal 3A3 of the first comparing means 3A is connected
`to an input terminal Sa of an AND circuit 8 and an output
`terminal 3B3 of the second comparing means 3B is con(cid:173)
`nected to an input terminal Sb of the AND circuit 8. An
`output terminal Sc of the AND circuit 8 is connected to a
`power-on terminal Sa of the main power supply 5. A USE
`chip 12 is provided in the keyboard 11. It is controlled by,
`for example, an 8-bit microcomputer (not shown), which is
`a controlling means (or a signal-generating means) provided
`in, for example, the keyboard 11. The USE chip 2 provided
`in the host computer 1 and the USE chip 12 provided in the
`keyboard 11 are connected together through a USE cable 9.
`The switching means 4 is, for example, a relay, and is
`provided between a connector terminal la, provided for the
`USE cable 9, and the USE chip 2 of the host computer 1.
`The switching means 4 of FIG. 1 includes a first relay
`contact 4A and a second relay contact 4B. The first relay
`contact 4A includes two connecting terminals 4Al and 4A2
`provided at the host computer 1 side, and one connecting
`terminal 4A3 provided at the keyboard 11 side. Similarly,
`the second relay contact 4B includes two connecting termi(cid:173)
`nals 4Bl and 4B2 provided at the host computer 1 side, and
`one connecting terminal 4B3 provided at the keyboard 11
`side.
`The connecting terminal 4Al of the first relay contact 4A
`is connected to the input terminal 3Al of the first comparing
`
`

`

`US 6,625,738 Bl
`
`5
`means 3A, and the connecting terminal 4El of the second
`relay contact 4E is connected to the input terminal 3El of
`the second comparing means 3E. The connecting terminal
`4A2 of the first relay contact 4A is connected to the first
`signal line D+ of the USE chip 2, and the connecting
`terminal 4E2 of the second relay contact 4E is connected to
`the second signal line D- of the USE chip 2. Through the
`connecting connector terminal la and the USE cable 9, the
`connecting terminal 4A3 of the first relay contact 4A and the
`connecting terminal 4E3 of the second relay contact 4E are
`connected to a first signal line D+ and a second signal line
`D- of the USE chip 12 in the keyboard 11, respectively. The
`switching means 4 also includes a relay actuator 4C actuated
`when electrical power is supplied thereto from the main
`electrical power 5. The first and the second relay contacts 4A
`and 4E can be simultaneously actuated and switched by the
`relay actuator 4C of the switching means 4.
`The main power supply 5 includes a power supply switch
`SA When the switch SA is switched on by a person or when
`a predetermined signal is input to the power-on terminal Sa,
`electrical power is supplied to the interior of the host
`computer 1.
`The sub-power supply 6 is, for example, a battery, and
`supplies electrical power to the first and the second com(cid:173)
`paring means 3A and 3E of the wake-up means 3 and the
`AND circuit 8. Outputs of the main power supply 5 and the
`sub-power supply 6 are connected to diodes Dl and D2 in
`an OR connection. They are also connected to a power
`supply input terminal Vee of the USE chip 12 in the
`keyboard 11 through the connector terminal la and the USE
`cable 9. In other words, at least one of the main power
`supply 5 and the sub-power supply 6 supplies electrical
`power to the keyboard 11. A GND terminal of the keyboard
`11 is grounded to a ground line at the host computer 1 side
`through the connector terminal la and the USE cable 9.
`Table 1 shows the USE standard signal line states when
`the host computer 1 is set in the suspend mode.
`
`TABLE 1
`
`Low Speed
`
`Full Speed
`
`Unconnected
`
`D+
`0-
`
`L(Hi-Z)
`H(Hi-Z)
`
`H
`L(Hi-Z)
`
`L(Hi-Z)
`L(Hi-Z)
`
`As shown in Table 1, according to the USE standards,
`there are three signal line state modes. They are a lower
`speed mode (hereinafter referred to as "LS mode") or a first
`mode; a full speed mode (hereinafter referred to as "FS
`mode") or a second mode; and an unconnected mode or a
`third mode. In the LS mode, the data transfer speed is 1.5 M
`bits/s. In the FS mode, the data transfer speed is 12 M bits/s.
`In the unconnected mode, the USE cable 9 is in an uncon(cid:173)
`nected state.
`When the host computer 1 is set in the suspend mode, first
`signal line D+ and second signal line D- in the LS mode are
`in an L (Hi-Z or high-impedance) state and in an H (high
`level) state, respectively. In the FS mode, they are in the H
`state and in the L (Hi-Z) state, respectively. In the uncon(cid:173)
`nected mode, they are both in the L (Hi-Z) state. The state
`in which both of these first and the second signal lines D+
`and D- are in the H state is not a USE standard state.
`A description will now be given of the operation of the
`apparatus for turning on a computer power supply, which
`has the above-described structure.
`When the power supply switch SA of the main power
`supply 5 is set in an off state, electrical power supply from
`
`5
`
`6
`the main power supply 5 is stopped. In this case, an
`operating system (OS) of the host computer 1 is not turned
`on. Therefore, the operation of the USE chip 2 is stopped.
`Since actuating electrical current is not supplied to the
`relay actuator 4C of the switching means 4, the connecting
`terminals 4Al and 4A3 of the first relay contact 4A are
`connected, and the connecting terminals 4El and 4E3 of the
`second relay contact 4E are also connected. Therefore, the
`first signal lines D+ of the host computer 1 and the keyboard
`10 11 are not connected to each other, and the second signal
`lines D- of the host computer 1 and the keyboard 11 are not
`connected to each other. The first signal line D+ and the
`second signal line D- of the keyboard 11 are connected to
`the first input terminals 3Al and 3El of the wake-up means
`15 3, respectively. The first signal line D+ and the second signal
`line D- of the host computer 1 are pulled down due to a
`predetermined resistance of 15 kQ as a result of the USE
`standards. When the first signal lines D+ of the host com(cid:173)
`puter 1 and the keyboard 11 are not connected to each other,
`20 and the second signal lines D- of the host computer 1 and
`the keyboard 11 are not connected to each other, the first
`signal line D+ and the second signal line D- at the host
`computer 1 side are set in the L level.
`From the sub-power supply 6, the output voltage V is
`25 applied to the wake-up means 3. In this case, the amount of
`electrical current supplied to the wake-up means 3 is equal
`to or greater than 500 µA, and the mode is set in a low
`electrical power mode lust as in the case where the host
`computer 1 is set in the suspend mode. The output voltage
`30 V from the sub-power supply 6 is also applied to the
`keyboard 11 through the diode D2, the connector terminal
`la, the USE cable 9 and the power supply input terminal
`Vee of the USE chip 12.
`35 When the power-on key on the keyboard 11 is operated,
`or when a plurality of keys on the keyboard 11 are operated
`at the same time, predetermined signals are output towards
`the host computer 1 through the first signal line D+ and the
`second signal line D- of the USE chip 12 in the keyboard
`11. These predetermined signals are generated by the afore-
`mentioned 8-bit microcontroller (not shown), which is a
`controlling means (or signal-generating means) at the key(cid:173)
`board 11 side. The first signal line D+ and the second signal
`line D- are in a fourth mode in which both signal lines D+
`and D- are in the H state. The pulse width and the pulse
`voltage of the predetermined signals are, for example, 50 ms
`and 3 volts, respectively.
`The fourth mode of first signal line D+ and second signal
`line D- in which both of them are in the H level state is not
`50 shown in Table 1 because it is not a USE standard mode.
`Taking into account that the data transfer speed of the USE
`is measured in nanoseconds (nsec), it can be said that a pulse
`width of 50 ms is very large. Therefore, even when fourth
`mode signals (H level signals with a pulse width of 50 ms)
`55 are set as signals that are not USE standard signals, and then
`transmitted to first signal line D+ and second signal line D-,
`they can be easily distinguished from USE standard data
`signals.
`When such fourth mode signals are transmitted from the
`60 keyboard 11, they are input to the USE cable 9, the con(cid:173)
`nector terminal la, and the first input terminal 3Al of the
`first comparing means 3A and the first input terminal 3El of
`the second comparing means 3E of the wake-up means 3
`through the first relay contact 4A and the second relay
`65 contact 4E of the switching means 4, respectively. In other
`words, the fourth mode signals are input to the first input
`terminal 3Al of the first comparing means 3A and the first
`
`40
`
`45
`
`

`

`US 6,625,738 Bl
`
`8
`
`15
`
`20
`
`7
`input terminal 3El of the second comparing means 3E. The
`first and the second comparing means 3A and 3E make a
`comparison between the voltages of the fourth mode signals
`and the standard voltage 7 (1.5 volts). Only when the fourth
`mode signals have a voltage greater than the standard 5
`voltage 7 are the H signals output from the output terminals
`3A3 and 3E3. In other words, the first and the second
`comparing means 3A and 3E act as comparators.
`When the H signals are output from the output terminal
`3A3 of the first comparing means 3A and the output terminal 10
`3E3 of the second comparing means 3E at the same time, the
`AND circuit 8 which has received these signals also outputs
`the H signals with the pulse width of 50 msec. When the H
`signals are input to the power-on terminal Sa of the main
`power supply 5, the main power supply 5 is turned on.
`When the main power supply 5 is turned on, electrical
`power is applied to the host computer 1, the USE chip 2, the
`relay actuator 4C of the switching means 4, etc. When a
`predetermined amount of actuating electrical current is
`supplied from the main power supply 5 to the relay actuator
`4C of the switching means 4, the connecting terminals 4A2
`and 4A3 of the first relay contact 4A are connected together,
`and the connecting terminals 4E2 and 4E3 of the second
`relay contact 4E are connected together. Therefore, the first
`signal lines D+ of the host computer 1 and the keyboard 11,
`and the second lines D- of the host computer 1 and the
`keyboard 11 are connected together, making it possible to
`allow transmission of signals between the host computer 1
`and the keyboard 11.
`Since the operating system existing as a resident program
`in the host computer 1 is started up as a result of supplying
`electrical power to the host computer 1, the host computer
`1 is started in order to set an environment that allows an
`input operation to be performed at the keyboard 11.
`The power supply turn-on apparatus of the present inven(cid:173)
`tion can be powered down when the keyboard 11 is not
`operated for a long time.
`For example, when communication is not carried out from
`the keyboard 11 to the host computer 1, application of H 40
`(high level) signals is continued from the aforementioned
`8-bit microcomputer (which is a controlling means or a
`signal-generating means disposed at the keyboard 11 side) to
`the first signal line D+ and the second signal line D- of the
`USE chip 2 of the host computer 1 through the USE chip 12. 45
`When a predetermined key on the keyboard 11 is operated,
`L signals are output from the 8-bit microcomputer to first
`signal line D+ and second signal line D- for, for example,
`25 msec. When the L signals are applied to the USE chip 2,
`the USE chip 2 is put in a state that is identical to the
`pull-down state that occurs when the keyboard 11 is not
`connected. This state of the USE chip 2 is detected at the
`host computer 1 side, and the main power supply is turned
`off.
`As can be understood from the foregoing description,
`when the main power supply of the host computer is turned
`off, that is, when it is in the power-off state, and the input
`device, such as a keyboard, is operated, the host computer
`can be started.
`It is possible to add value to a computer by allowing a host
`computer to be started by making use of a combination of
`signals that are not USE standard signals at the USE
`interface.
`What is claimed is:
`1. An apparatus for turning on a computer power supply,
`comprising:
`
`a host computer;
`an input device connected to the host computer through an
`interface, the interface supplying data and power to the
`input device;
`a main power supply to supply power to the host com(cid:173)
`puter; and
`a sub-power supply to supply power to the input device
`when the main power supply is in an off state;
`wherein the host computer comprises wake-up means for
`turning on the main power supply to power the host
`computer as a result of a predetermined operation
`performed at the input device when the main power
`supply is in the off state,
`wherein the apparatus further comprises switching means
`disposed at the interface, wherein when the main power
`supply is in an on state, the switching means connects
`a signal line of the host computer and a signal line of
`the input device, and wherein when the main power
`supply is in the off state, the switching means switches
`connection so that the wake-up means and the signal
`line of the input device are connected together; and
`wherein when the main power supply is in the off state,
`and the predetermined operation is performed at the
`input device, a start-up signal generated by the wake-up
`means is applied to the main power supply to turn on
`the main power supply, whereby the switching means
`switches connections so that the signal line of the host
`computer and the signal line of the input device are
`connected together,
`wherein the interface comprises four signal lines: a uni-
`versal serial bus standard power supply line, a first
`signal line, a second signal line, and a ground line; and
`wherein the wake-up means comprises first comparing
`means for detecting whether a value of the first signal
`line is at least a predetermined standard value, second
`comparing means for detecting whether a value of the
`second signal line is at least the predetermined standard
`value, and an AND circuit logically ANDing the first
`comparing means and the second comparing means,
`with the main power supply being turned on when an
`output of the AND circuit reaches a predetermined
`value, and
`wherein when the predetermined operation is performed
`at the input device, H signals of a first predetermined
`pulse width are output to both the first signal line and
`the second signal line, after which the H signals with a
`second predetermined pulse width of at least the first
`predetermined pulse width are output from the AND
`circuit to turn on the main power supply.
`2. An apparatus for turning on a computer power supply
`50 according to claim 1, wherein the first predetermined pulse
`width is substantially greater than a standard pulse width for
`signals transmitted between the host computer and input
`device through the interface when the host computer is the
`main power supply is turned on.
`3. An apparatus for turning on a computer power supply
`according to claim 1, wherein the predetermined operation
`consists of performing a plurality of individual operations at
`the input device.
`4. An apparatus for turning on a computer power supply
`60 according to claim 1, wherein the input device is a keyboard
`and the predetermined operation consists of activating a
`plurality of different keys on the keyboard.
`5. An apparatus for turning on a computer power supply
`according to claim 1, wherein the predetermined operation
`65 consists of performing a single operation at the input device.
`6. An app