# Patent

## Title
System and method for deactivating a first device from a second device

## Abstract

A signaling circuit may be implemented with a connection comprised of signal lines having predefined signals and/or functions. The predefined signals and/or functions may be defined by an individual entity or standards organization. The signaling circuit transmits information in addition to the predefined signals and/or functions. The information may be transmitted from a second device, such as a visual display screen, to a first device, such as a computing device, using at least one signal line in the connection. The information may include information about the state or status of the second device. The signaling circuit may, for example, place the first device in a reduced power state by generating a signal transition on at least one of the signal lines when a switch associated with the second device is asserted.

## Background
BACKGROUND
1. Technical Field
The present invention relates to electronic devices, and more particularly to techniques for transmitting information concerning a second electronic device to a first electronic device. Still more particularly, the present invention relates to a system and method for deactivating a first device from a second device.
2. Description of the Prior Art
Modern electronic devices, such as computing systems, strive to offer a variety of features to users. Some of these features are standard features known and used in a particular industry, while others are unique and differentiate a particular product or manufacturer from its competitors. One example of a feature that is offered in some computing systems is the ability to turn off, or place in a reduced power state, a first device from a second device. For example, turning off a display screen may also turn off a computing device, such as a laptop or desktop computer, connected to that display screen.
Another feature that may be offered in some computing systems is the ability to have multiple display screens connected to a computing device. The display screens may be connected to the computing device using one or more connection techniques. For example, the connection means may be unique to a manufacturer. Other connection techniques may include connectors or ports having predefined functions. The predefined functions may be defined by an individual manufacturer or designer, or by a standards organization. A government, administrative department, technical, or industry group are examples of standards organizations that may define the functions and/or signals that create a particular standard.
One limitation with using a connection comprised of signals having predefined functions is that additional features not defined in the standard may be lost. A manufacturer may not be able to implement any additional features since there may not be any free, or unused, signal lines available in the connection. Thus, features that a user may expect with a particular product and/or manufacturer may be lost when a system uses a connection technique having predefined functions.
SUMMARY
A signaling circuit may be implemented with a connection comprised of signal lines having predefined functions. The predefined functions may be defined by an individual manufacturer or designer, or by a standards organization. The signaling circuit transmits information in addition to the predefined functions. The information may be transmitted from a second device, such as a visual display screen, to a first device, such as a computing device, using at least one signal line in the connection. The information may include information about the state or status of the second device.
In an exemplary embodiment of the present invention, the signaling circuit may place the first device in a reduced power state when a switch associated with the second device is asserted. The signaling circuit may generate a signal transition on one or more signal lines having a range of signal values for a particular output state. For example, a high output state may be defined to be within a range of 2.4 volts to 5.5 volts. This range may be subdivided in order to signal the first device.
In an exemplary embodiment of the present invention, a voltage level at or near 3 volts may indicate the signal line is to be used for its predefined function only, while a voltage level at or near 5 volts may transmit information about the state of the switch in addition to the predefined function. Thus, the signaling circuit may utilize the one or more signal lines for their predefined functions and, at the same time, transmit information to the first device.



BRIEF DESCRIPTION OF THE DRAWINGS
The novel features believed characteristic of the invention are set forth in the appended claims. The invention itself, however, as well as a preferred mode of use, and further objects and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawings, wherein:
FIG. 1 is a block diagram illustrating a first embodiment of a system that may be used to implement the present invention;
FIG. 2 is a block diagram depicting a second embodiment of a system that may be used to implement the present invention;
FIG. 3a illustrates an exemplary system as shown in FIG. 1;
FIG. 3b depicts an exemplary system 200 as shown in FIG. 2;
FIG. 4 is a block diagram illustrating an exemplary signaling circuit according to the present invention;
FIG. 5 is a block diagram depicting an alternate exemplary signaling circuit according to the present invention;
FIG. 6(a)–6(b) are circuit diagrams of an exemplary signaling circuit according to the present invention;
FIG. 7 is a timing diagram for certain signals in the exemplary signaling circuit of FIG. 6; and
FIG. 8 is a flowchart illustrating an exemplary method for signaling a first device from a second device according to the present invention.



DETAILED DESCRIPTION
To facilitate an understanding of the present invention, it is described hereinafter in the context of a specific embodiment. In particular, reference is made to the implementation of the invention in a computing system utilizing a connection or port having predefined signals and/or functions. The computing system includes a computing device connected to a visual display screen through a Digital Visual Interface (DVI) connection or port. It will be appreciated, however, that the practical applications of the invention are not limited to this particular embodiment. Rather, the invention can be employed to signal other information in other types of electronic devices and systems, including, but not limited to, broadcast systems, network structures, and electronic devices that utilize one or more connections or ports having signal lines with predefined functions.
With reference now to the figures and in particular with reference to FIG. 1, a block diagram illustrates a first embodiment of a system that may be used to implement the present invention. System 100 may include, but is not limited to, a second device 102 electronically connected to a first device 104 via connection 106. In an exemplary embodiment, the second device may be implemented as a visual display screen and the first device may be implemented as a computing device. Connection 106 may include signal lines having predefined signals and/or functions. The predefined signals and/or functions may be defined by an individual manufacturer or designer, or by a standards organization. In this exemplary embodiment, connection 106 may be implemented as a Digital Visual Interface (DVI) connection. In alternate embodiments, system 100 may be implemented using various components and configurations in addition to, or instead of, those discussed in conjunction with the FIG. 1 embodiment.
FIG. 2 is a block diagram depicting a second embodiment of a system that may be used to implement the present invention. System 200 may include, but is not limited to, an adapter 202 electronically connected to a second device 204 and to a first device 104. In the FIG. 2 embodiment, the second device may be implemented as a visual display screen and the first device may be implemented as a computing device. In alternate embodiments, system 200 may be implemented using various components and configurations in addition to, or instead of, those discussed in conjunction with the FIG. 2 embodiment.
Referring now to FIG. 3a, an exemplary system from FIG. 1 is shown. System 100 may include, but is not limited to, a visual display screen 102 electronically connected to a computing device 104 via connection 106. Visual display screen 102 may be implemented as a digital display, such as a Liquid Crystal Display (LCD) or plasma display. Alternatively, visual display screen 102 may be implemented as an analog display, such as a cathode-ray-tube (CRT) display. Computing device 104 may be implemented as a portable or desktop computer. And connection 106 may be implemented as a Digital Visual Interface (DVI) connection. In alternate embodiments, system 100 may be implemented using various components and configurations in addition to, or instead of, those discussed in conjunction with the FIG. 3a embodiment.
FIG. 3b depicts an exemplary system 200 as shown in FIG. 2. System 200 may include, but is not limited to, an adapter 202 electronically connected to a visual display screen 204 and to a computing device 104. Visual display screen 204 may be implemented as a digital or analog display screen. Computing device 104 may be implemented as a portable or desktop computer. Adapter 202 may be implemented as a DVI adapter, such as the DVI to ADC Adapter sold by Apple Computer®. In alternate embodiments, system 200 may be implemented using various components and configurations in addition to, or instead of, those discussed in conjunction with the FIG. 3b embodiment.
Referring now to FIG. 4, a block diagram illustrates an exemplary signaling circuit according to the present invention. Second device 102 may include, but is not limited to, a secondary signal generation 400, a primary signal generation 402, and a switch 408. First device 104 may include, but is not limited to, a secondary signal detection 404 and a system detect and enable 406. In alternate embodiments, first and second devices may be implemented using various components and configurations in addition to, or instead of, those discussed in conjunction with the FIG. 4 embodiment.
In this exemplary embodiment, secondary signal generation 400 may perform similarly to that of a two-state power supply, in that second signal generation 400 may generate two signal levels. A first signal level may be generated when the signal lines in connection 106 are being used for their predefined functions only. A second signal level may be generated when at least one signal line is used for signaling first device 104. In the FIG. 4 embodiment, the second signal level may be generated in order to deactivate first device 104.
Secondary signal generation 400 may generate or alter a signal when switch 408 is depressed or asserted. In this exemplary embodiment, switch 408 may be pressed or asserted in order to deactivate first device 104. The second device 102 may or may not respond to the assertion of switch 408. In this exemplary embodiment, asserting switch 408 may also deactivate second device 102. The term “deactivate” is defined herein as a reduced power state, including, but not limited to, a sleep state and an off (i.e., no power) state. At least one predefined signal line in connection 106 may then be utilized to transmit this information to first device 104 in order to deactivate first device 104.
Secondary signal detection 404 may be used to detect the different signal levels generated by secondary signal generation 400. When a signal level indicates switch 408 has been asserted, secondary signal detection 404 generates a signal that may cause system detect and enable 406 to initiate deactivation of first device 104. System detect and enable 406 may also be used to detect the presence of secondary signal generation 400. If secondary signal generation 400 is not present in the system, the system detect and enable 406 may then disable secondary signal detection 404.
FIG. 5 is a block diagram depicting an alternate exemplary signaling circuit according to the present invention. Adapter 202 may include, but is not limited to, secondary signal generation 400 and primary signal generation 402. Second device 204 may include, but is not limited to, switch 408. And first device 104 may include, but is not limited to, secondary signal detection 404 and system detect and enable 406. The various components in adapter 202, second device 204, and first device 104, may operate in a manner similar to the components described with reference to FIG. 4. However, in alternate embodiments, adapter, first device, and second device may be implemented using various components and configurations in addition to, or instead of, those discussed in conjunction with the FIG. 5 embodiment.
Referring now to FIG. 6(a)–6(b), circuit diagrams of an exemplary signaling circuit according to the present invention are shown. The FIG. 6 example is presented for purposes of illustration, and in alternate embodiments, the present invention may utilize various components and component values other than those discussed in conjunction with the FIG. 6 embodiment. The operation of the exemplary signaling circuit will be described in conjunction with the timing diagram in FIG. 7.
Initially, system detect and enable 406 may determine whether secondary signal generation 400 is present in the system. If secondary signal generation 400 is present, a signal DDC—+5V and a signal DDC_ON in primary signal generation 402 may be in a high state (see FIG. 7). When DDC_ON is in a high state, transistor Q6 in primary signal generation 402 may be turned on, thereby connecting primary signal generation 402 to secondary signal generation 400. In particular, transistor Q6 connects resistor R9 to a signal V_HPD in secondary signal generation 400. In this exemplary embodiment, the V_HPD signal may be used to signal, including deactivate, first device 104.
The Digital Visual Interface (DVI) specification defines a high level output for the V_HPD signal to be within a range of 2.4 volts to 5.5 volts. This range may be subdivided in the FIG. 6 embodiment in order to signal first device 104. In particular, the V_HPD signal may have a high voltage level at or near 3 volts or 5 volts, both of which comply with the DVI specification. The voltage level of V_HPD may be controlled by the PWR_SW_IN* signal and resistors R6, R7, and R8 in secondary signal generation 400. When the system is operating in a non-signaling mode, the signal PWR_SW_IN* may be set at a high state, and the reference divider for a voltage regulator (U1 and Q1) is comprised of resistors R6 and R8. The ratio of resistors R6 and R8 may set voltage regulator U1/Q1 to regulate the V_HPD signal at or near 3 volts. But when information is to be signaled to first device 104, such as when a switch associated with the second device is depressed or asserted, the signal PWR_SW_IN* may transition to a low state (point 700 in FIG. 7) and the ratio of resistors R6, R7, and R8 may adjust the level of the V_HPD signal at or near 5 volts (point 702 in FIG. 7).
When the V_HPD signal transitions to or near 5 volts, a signal DVI_HPD may also transition from 3 volts to approximately 5 volts (point 704). The DVI_HPD signal may be transmitted to first device 104 by at least one signal line in the DVI connection. The transition of the DVI_HPD signal to approximately 5 volts may be detected by secondary signal detection 404 in first device 104. In particular, the input V+into comparator U2 may transition to an increased voltage level, such as 2.5 volts, causing the output of comparator U2 to transition to a high state (points 706 and 708 in FIG. 7). This, in turn, may activate transistor Q13 in system detect and enable 406. When transistor Q13 is turned on, a signal PWR_SW_OUT* may transition to a low state (point 710 in FIG. 7). In this exemplary embodiment, the transition of signal PWR_SW_OUT* to a low state may initiate deactivation of first device 104.
When PWR_SW_IN* transitions back to a high state, the signals V_HPD, DVI_HPD, and V+may transition to lower voltage states (points 712, 714, 716, and 718 in FIG. 7). In the FIG. 6 embodiment, V_HPD and DVI_HPD may transition back to approximately 3 volts, and V+transitions to approximately 1.5 volts. In response, the signal COMP_OUT may then transition to a low state (point 720), causing the signal PWR_SW_OUT* to return to a high state (point 722 in FIG. 7). Thus, the signaling circuit in the present invention may utilize a signal output range in a manner that allows the signaling circuit to simultaneously use one or more signal lines for their predefined functions and transmit information to the first device.
FIG. 8 is a flowchart illustrating an exemplary method for signaling a first device from a second device according to the present invention. The FIG. 8 example is presented for purposes of illustration, and in alternate embodiments, the present invention may utilize various steps and sequences other than those discussed in conjunction with the FIG. 8 embodiment.
Initially a determination may be made as to whether or not first device 104 is turned on or off, as shown in block 800. If first device 104 is turned on, the process may pass to blocks 802 and 804 where the presence of second device 102 may be acknowledged and the device type determined. In this exemplary embodiment, determining the device type includes the detection of secondary signal generation 400.
A determination may then be made as to whether or not the second device 104 is the correct type (block 806). If it is the correct type, the secondary signal generation 400 may be connected electronically to secondary signal detection 406, as shown in block 808. A determination may then be made as to whether or not a switch associated with the second device has been depressed or asserted. In the exemplary embodiment of FIG. 6, asserting the switch causes the PWR_SW_IN* to transition to low state and the signal V_HPD to increase from approximately 3 volts to approximately 5 volts, thereby signaling the first device 104 that the switch has been asserted.
If the switch has been asserted, the process may continue at block 812 where the secondary signal detection may be activated in order to initiate deactivation of the first device. In the FIG. 6 embodiment, the secondary signal detection may be activated by increasing the voltage level of signal V+, which causes the output of the comparator U2 to transition to a high state. When the output of comparator U2 is high, the transistor Q13 may be activated and the signal PWR_SW_OUT* may transition to a low state. This transition may initiate the deactivation of first device 104.
Next, a determination may be made as to whether or not the first device 104 has been deactivated. This step is shown in block 814. If not, the process may return to block 810 and repeat until first device 104 is deactivated. When first device 104 is deactivated, the process may end.
Thus, the present invention provides a mechanism for signaling a first device from a second device using at least one predefined signal line in a connection between the two electronic devices. While the invention has been particularly shown and described with reference to an exemplary embodiment, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention. For example, the present invention has been described with reference to deactivating the first device from the second device when a switch associated with the second device is asserted. The invention, however, is not limited to this function. The present invention may be used to signal any information along with the predefined functions of the connection. For example, the state or status of a particular device or a system may be transmitted to another device using the techniques of the present invention. Additionally, actions or functions other than asserting a switch may be used to signal information to the first device.

## Claims

1. A method for signaling a first device from a second device using a connection comprised of signal lines with predefined functions, the method comprising:
connecting electronically a first circuit in the second device with a second circuit in the first device using the connection comprised of signal lines with predefined functions, wherein the first circuit generates a signal representing information to be transmitted to the second circuit and the information is not defined in the predefined functions associated with the connection; and
transmitting the signal to the second circuit in the first device a signal line in the connection, wherein the signal line is used simultaneously to transmit the information and one or more predefined functions assigned to the signal line.

2. The method of claim 1, further comprising the step of detecting the presence of the first circuit in the second device.

3. The method of claim 2, wherein the first device is comprised of a computing device and the second device is comprised of a visual display screen.

4. The method of claim 3, wherein the information to be transmitted to the second circuit includes information regarding the state of a switch associated with the visual display screen in order to deactivate the computing device.

5. The method of claim 1, wherein the first device is comprised of a computing device and the second device is comprised of an adapter.

6. A system for signaling a first device from a second device using a connection comprised of signal lines with predefined functions, the system comprising:
means for connecting electronically a first circuit in the second device with a second circuit in the first device using the connection comprised of signal lines with predefined functions, wherein the first circuit generates a signal representing information to be transmitted to the second circuit and the information is not defined in the predefined functions associated with the connection; and
means for transmitting the signal to the second circuit in the first device using a signal line in the connection, wherein the signal line is used simultaneously to transmit the information and one or more predefined functions assigned to the signal line.

7. The system of claim 6, further comprising means for detecting the presence of the first circuit in the second device.

8. The system of claim 7, wherein the first device is comprised of a computing device and the second device is comprised of a visual display screen.

9. The system of claim 8, wherein the information to be transmitted to the second circuit includes information regarding the state of a switch associated with the visual display screen, wherein the information is used to initiate deactivation of the computing device.

10. The system of claim 7, wherein the first device is comprised of a computing device and the second device is comprised of an adapter.

11. The system of claim 10, wherein the information to be transmitted to the second circuit includes information regarding the state of a switch associated with a visual display screen connected to the adapter, wherein the information is used to initiate deactivation of the computing device.

12. A signaling circuit for signaling a first device from a second device using a connection comprised of signal lines with predefined functions, the signaling circuit comprising:
a secondary signal generation circuit in the second device for generating a signal transition on a signal line in the connection, wherein the signal transition is not defined in the predefined functions associated with the connection and is simultaneously transmitted with one or more predefined functions;
a secondary signal detection circuit connected electronically to the secondary signal generation circuit using the connection, wherein the secondary signal detection circuit detects the signal transition on the signal line in the connection; and
a system enable circuit in the first device connected electronically to the secondary signal detection circuit, wherein the system enable circuit signals the first device in response to the secondary signal detection circuit detecting the signal transition.

13. The signaling circuit of claim 12, further comprising a detector circuit in the first device for detecting the presence of the secondary signal generation circuit.

14. The signaling circuit of claim 12, wherein the first device is comprised of a computing device and the second device is comprised of a visual display screen.

15. The signaling circuit of claim 14, wherein the secondary signal generation circuit generates the signal when a switch associated with the visual display screen is asserted, and wherein the signal initiates deactivation of the computing device.

16. The signaling circuit of claim 12, wherein the first device is comprised of a computing device and the second device is comprised of an adapter.

17. The signaling circuit of claim 16, wherein the secondary signal generation circuit generates the signal when a switch associated with a visual display screen connected to the adapter is asserted, and wherein the signal initiates deactivation of the computing device.

18. A first device for deactivating a second device connected electronically to the first device through a connection comprised of signal lines having predefined functions, comprising:
a signal generation circuit for generating a signal transition on a signal line in the connection, wherein the signal transition is not defined in the predefined functions and the signal transition initiates deactivation of the second device and the signal transition is transmitted to the second device on the signal line in the connection simultaneously with one or more predefined functions.

19. The first device of claim 18, wherein the first device is comprised of a visual display screen.

20. The first device of claim 19, wherein the signal generation circuit generates the signal transition on the signal line when a switch associated with the visual display screen is asserted.

21. The first device of claim 18, wherein the first device is comprised of an adapter.

22. The first device of claim 21, wherein the signal generation circuit generates the signal transition on the signal line when a switch associated with a visual display screen connected to the adapter is asserted.