Abstract:
A personal computer that enters sleep mode to conserve electrical energy is responsive to a proximity detector and a proximity timer. As long as a user is near the computer, as determined by the proximity detector, the computer is controlled by an activity timer, and enters sleep mode upon being idle for a predetermined period of time. When the proximity detector determines that the user has left the computer unattended, the proximity detector starts the proximity timer. When the proximity timer expires, the computer enters sleep mode. Because the proximity timer operates only when the user has left the computer unattended, the proximity timer may be set to expire earlier than the activity timer. Consequently, the computer may enter sleep mode earlier than would otherwise be possible, and thereby consumes less energy.

Description:
FIELD OF THE INVENTION 
   The present invention is related to the field of personal computers, and more specifically to a method and apparatus for reducing the electrical energy consumed by an unattended personal computer. 
   BACKGROUND 
   Personal computers have become so widely accepted that they now constitute a significant draw on the national power grid. For example, the computers in a large office building may consume more energy than the building&#39;s heating or lighting systems. As a result, attention has been directed toward improving personal computers so that they consume less energy. For example, a personal computer may have a reduced-power mode often called a “sleep mode.” 
   When the computer is idle for a predetermined period of time, as indicated by a control signal generated in the absence of activity from its keyboard, mouse, or other input device, the computer enters the sleep mode. When a user subsequently interacts with the computer, for example by moving the mouse, the computer awakens from the sleep mode and returns to its normal, full-power state of operation. Sleep mode is described in more detail in the following U.S. Pat. No. 6,268,845 to Pariza; U.S. Pat. No. 6,016,548 to Nakamura; U.S. Pat. No. 5,987,613 to Busch; and U.S. Pat. No. 5,721,935 to DeSchepper. 
   The need to awaken a personal computer from sleep mode can be an inconvenience to the user of the computer, as the computer may take a relatively long time to make the transition from asleep to awake. This can be especially annoying when the computer enters sleep mode when the user pauses only briefly for thought or conversation. 
   Consequently, a user of a personal computer often configures the personal computer to enter sleep mode only after it has been idle for a considerable time. For example, a personal computer may routinely continue to operate in full-power mode for twenty minutes or more after the user has left the office and therefore left the computer unattended. Thus, the desire for convenience may at times be fundamentally at odds with the need to conserve energy. 
   Battery powered personal computers, such as laptop computers, personal digital assistants, electronic notebooks, and the like may also have sleep modes. The purpose of having a sleep mode in a battery-powered device is to delay for as long as possible the need to recharge or replace the device&#39;s battery. Nevertheless, the same conflict between conservation and convenience applies also to personal computers that are powered by batteries, as battery-powered devices should enter sleep mode at the earliest convenient opportunity, in order to conserve battery life, and yet not inconvenience the user by entering sleep mode at an inopportune time. 
   As a result of the fundamental conflict between the desire to conserve energy and the desire not to inconvenience the user of a personal computer, there is a need to improve the operation of sleep mode for personal computers, so that a computer may enter sleep mode at the earliest convenient moment, and yet not needlessly inconvenience its user. 
   SUMMARY 
   The present invention improves the operation of a personal computer that has a sleep mode, by enabling the computer to enter the sleep mode at the earliest convenient time once it is left unattended by its user. The sleep mode may be a full state sleep mode as described in the aforementioned U.S. Pat. No. 6,268,845 to Pariza; U.S. Pat. No. 6,016,548 to Nakamura; U.S. Pat. No. 5,987,613 to Busch; and U.S. Pat. No. 5,721,935 to DeSchepper; or may be a new sleep mode according to the present invention wherein selected individual components of the computer enter a power-saving sleep mode but the computer otherwise stays in a full-power state. This kind of sleep mode is called here “component sleep mode.” For example, a display may enter component sleep mode, wherein the display sleeps but the other components of the computer continue in full-power mode. This is called here a “display sleep mode.” Other component sleep modes may be defined accordingly for other components. For example, part of a CPU may enter a sleep mode, which may be called processor sleep mode. As a convenience, however, the general term “sleep mode” is used herein to encompass full state sleep mode, component sleep mode, display sleep mode, processor sleep mode, and other component sleep modes that may be defined for other components. 
   A personal computer improved by the present invention includes a proximity detector, a proximity timer, an activity detector, and an activity timer. As long as the user is near the personal computer, as determined by the proximity detector, the computer may be controlled by the activity detector and activity timer, which put the computer into sleep mode after the computer has been idle for a predetermined period of time. When the proximity detector determines that the user is away from the computer and therefore has left the computer unattended, the proximity detector starts the proximity timer. Upon expiration of the proximity timer, the computer is put into sleep mode. Because the proximity timer operates only when the user has left the computer unattended, the proximity timer may be set to expire well ahead of the activity timer. As a result, the computer may enter the sleep mode at the earliest convenient time when left unattended, and thereby consume less electrical energy, and yet not inconvenience a user who remains with the computer but pauses midstream to think. 
   These and other aspects of the present invention will be more fully appreciated when considered in the light of the following detailed description and drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a block diagram showing a personal computer that includes proximity detector, a proximity timer, a proximity timer threshold, an activity detector, an activity timer, an activity timer threshold, controlling logic, and a wireless key carried by a user of the personal computer. 
       FIG. 2  shows the wireless key of  FIG. 1  attached to a security badge that identifies the user. 
       FIG. 3  is a flowchart that shows aspects of the operation of the logic of  FIG. 1  according to the present invention. 
       FIG. 4  is a flowchart that shows further aspects of the operation of the logic of  FIG. 1  according to the present invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The present invention conserves electrical energy by putting a personal computer into a power-reduced sleep mode when a proximity detector determines that the computer has been left unattended. 
     FIG. 1  shows aspects of the structure of an exemplary embodiment of the present invention. In  FIG. 1  there is a personal computer  110 , which may be powered by the electric mains or which may be powered by a battery. The personal computer  110  may be a traditional desk-top personal computer, a laptop computer, an Internet appliance, a specialized workstation, a personal digital assistant, an electronic organizer or notebook, a server and the like. 
   As shown in  FIG. 1 , the personal computer  110  includes a proximity detector  120 , a proximity timer  130 , a proximity timer threshold  135 , an activity detector  140 , an activity timer  150 , an activity timer threshold  155 , and logic  160  for controlling the operation of the proximity detector  120 , proximity timer  130 , proximity timer threshold  135 , activity detector  140 , activity timer  150 , and activity timer threshold  155 . The personal computer  110  may also include a display  180 , which may be any kind of display or monitor suitable for use with the personal computer  110 , such as a cathode-ray-tube display, a flat panel LCD display, a plasma display, and the like. 
   The proximity detector  120  determines whether a user  100  of the personal computer  110  is near the personal computer  110  or away from the personal computer  110 . When describing the present invention, the term “near” means that the user  100  is sufficiently close to the personal computer  110  to be reasonably presumed to be able to operate the personal computer  110  conveniently, for example the user  100  is within an office, cubicle, or room that also contains the personal computer  110 , or within a distance of roughly ten feet of the personal computer  110 . When the user  100  is not near the personal computer  110 , the user is “away” from the personal computer  110 , and the personal computer  110  is “unattended.” 
   As shown in  FIG. 1 , the user  100  carries or otherwise has immediate possession of a wireless key  170 . According to various embodiments of the invention, the wireless key  170  may include a key receiver component, a key transmitter component that emits a limited-range electromagnetic signal, a key transceiver component, which may operate according to the Bluetooth standard or which may include a passive transponder that delays and returns an electromagnetic signal emitted by the proximity detector  120 , or any combination or subset of these components. 
   The transmitter component of the wireless key  170  may emit the limited-range electromagnetic signal continuously, intermittently, or in response to a poll or prompt. The limited-range electromagnetic signal may be unmodulated, or the limited-range electromagnetic signal may be modulated to carry intelligence that bears a serial number or other attribute that identifies a particular user  100  who is presumed to have possession of the wireless key  170 . Range of the electromagnetic signal may be controlled by limiting the power of the key transmitter component, or by limiting the sensitivity of a receiver that receives the limited-range electromagnetic signal. 
   In one embodiment of the invention, the proximity detector  120  includes a receiver component that is responsive to the limited-range electromagnetic signal emitted by the wireless key  170 . When the receiver component of the proximity detector  120  fails to detect the limited-range electromagnetic signal emitted by the wireless key  170 , the proximity detector  120  concludes that the user  100  is away from the personal computer  110 . In this embodiment, the wireless key  170  may include a transmitter component and lack a receiver component. 
   In another embodiment of the invention, the proximity detector  120  includes a polling transceiver that polls the wireless key  170 . When the user  100  is near the personal computer  110 , the wireless key  170  carried by the user  100  detects the poll by the proximity detector  120  and responds thereto, and the proximity detector  120  detects the response from the wireless key  170 . When the user  100  is away from the personal computer  110 , the wireless key  170  carried by the user  100  fails to detect the poll and consequently fails to respond thereto, or the proximity detector  120  fails to detect the response by the wireless key  170 . 
   In another embodiment of the invention, the wireless key  170  is included in an identification badge  200  of the type assigned to an employee, with the expectation that the employee will wear the identification badge  200  when using the personal computer  110 . An exemplary structure of this embodiment is shown in  FIG. 2 . According to this embodiment, the limited range electromagnetic signal emitted by the wireless key  170  may be modulated to convey a serial number  210  that is associated with the badge  200  and thereby associated with the user  100 . The proximity detector  120  may determine whether the user  100  is near the personal computer  100  by taking into account not only detection of an electromagnetic signal emitted by the wireless key  170 , but also reception of the particular serial number  210 . Thus the proximity detector may discriminate between any user with a wireless key and a particular user  100  with a particular wireless key  170 . 
   When the wireless key  170  is included in an identification badge  200  and powered by a battery, power from the battery to the wireless key  170  may be switched on when the user  100  presents the identification badge  200  to a security system in order to enter a secure facility. Power may be switched off according to a timer (for example, nine hours after it is switched on) or when the user  100  presents the identification badge  200  to the security system in order to leave the secure facility. 
   In yet another embodiment of the invention, the wireless key  170  may be included in a cellular telephone or similar wireless communication device such as a personal digital assistant (PDA) carried by the user  100 . Here, the term “cellular telephone” is used as a convenience to describe all such personal devices equipped for wireless communication. In this embodiment, the proximity detector  120  detects electromagnetic signals emitted by the cellular telephone that includes the wireless key  170 . These signals may be coincidental to the operation of the proximity detector  120 , for example the periodic transmission of registration messages that identify the cellular telephone to a base station, or the signals may be emitted specifically for use by the proximity detector  120 , for example messages that are transmitted by a Bluetooth transceiver included in the cellular telephone. When the proximity detector  120  detects such signals, the user  100  is judged to be near the personal computer  110 . When the proximity detector  120  does not detect such signals, the user  100  is judged to be away from the personal computer  110 . 
   As shown in  FIG. 1  and mentioned above, the personal computer  110  may also include a proximity timer  130 , a proximity timer threshold  135 , an activity detector  140 , an activity timer  150 , and an activity timer threshold  155 . As explained below, the proximity timer  130  may be started when the proximity detector  120  determines that the user  100  is away from the personal computer  110 . The proximity timer threshold  135  specifies a particular value for the proximity timer  130 . When the proximity timer  130  reaches the proximity timer threshold  135 , which threshold may have an exemplary value of one minute, the personal computer  110  is consequently put into sleep mode. The logic  160  may compare the value of the proximity counter  130  to the value of the proximity counter threshold  135 , and generate a control signal or proximity signal when the value of the proximity counter  130  exceeds the value of the proximity counter threshold  135 . 
   The activity detector  140  monitors inputs to the personal computer  110  to determine when the personal computer  110  is active or idle. For example, the activity detector  140  may monitor keyboard or mouse activity. As explained below, the activity timer  150  may be started when the activity detector  140  determines that the personal computer  110  is idle (although not necessarily unattended). The activity timer threshold  155  specifies a particular value for the activity timer  150 . When the activity timer  150  reaches the activity timer threshold  155 , the personal computer  110  is consequently put into sleep mode. 
   Operations of the proximity detector  120 , the proximity timer  130 , the proximity timer threshold  135 , the activity detector  140 , the activity timer  150 , and the activity timer threshold  155  are controlled by the logic  160 . The logic  160  may include instructions executed by a programmable processor, which processor may also be used for other purposes by the personal computer  110 . Although  FIG. 1  shows the proximity detector  120 , the proximity timer  130 , the proximity timer threshold  135 , the activity detector  140 , the activity timer  150 , and the activity timer threshold  155  as elements separate from the logic  160  for descriptive convenience, these elements in whole or in part may be included within the logic  160 . 
     FIG. 3  is a flowchart that shows aspects of the operation of the logic  160  according to the present invention. To initialize the operation, the proximity timer  130  is reset to zero and started (step  300 ). The proximity detector  120  determines whether the user  100  is near the personal computer  110  or away (step  310 ). When the user  100  is determined to be near the personal computer  110 , the proximity timer  130  is reset to zero, and the process is begun again (step  300 ). Otherwise, (i.e., the user  100  is away from the personal computer  110 ), the value of the proximity timer  130  is compared with the value of the proximity timer threshold  135  (step  320 ). If the value of the proximity timer  130  exceeds the value of the proximity timer threshold  135 , the personal computer  110  is put into sleep mode (step  330 ). Otherwise (i.e., the value of the proximity timer  130  does not exceed the value of the proximity timer threshold  135 ), the process returns to the point where the proximity detector  120  determines whether the user  100  is near the personal computer  110  (step  310 ), and the process continues as just described. 
   The sleep mode may be a full-state sleep mode as described in the aforementioned U.S. Pat. No. 6,268,845 to Pariza; U.S. Pat. No. 6,016,548 to Nakamura; U.S. Pat. No. 5,987,613 to Busch; and U.S. Pat. No. 5,721,935 to DeSchepper; or may be a new sleep mode according to the present invention wherein selected individual components of the computer  110  enter a power-saving state but the computer  110  otherwise stays in a full-power state. This kind of sleep mode is called here “component sleep mode.” For example, the display  180  may enter component sleep mode, wherein the display  180  sleeps but the other components of the computer  110  continue in full-power mode. This is called here a “display sleep mode.” Other component sleep modes may be defined accordingly for other components. For example, part of the CPU or logic  160  may enter a sleep mode, which may be called processor sleep mode. As a convenience, however, the general term “sleep mode” is used to encompass full-state sleep mode, component sleep mode, display sleep mode, processor sleep mode, and other component sleep modes that may be defined for other components. The personal computer  110  may be configured to provide a particular kind of sleep mode, or may enable the user  100  to choose a particular kind of sleep mode by selecting an option from a list of available sleep modes. For example, the user  100  may be shown a list that includes full state sleep mode, display sleep mode, and processor sleep mode, from which he or she would choose. 
     FIG. 4  is a flowchart that shows further aspects of the operation of the logic  160  according to the present invention. To initialize the operation, the proximity timer  130  and the activity timer  150  are reset to zero and started (step  400 ). The activity detector  140  determines whether the personal computer  110  is active (more precisely, has been active since the last check for activity) (step  405 ). If the personal computer  110  is active, the process returns to the point where the proximity timer  130  and the activity timer  150  are reset to zero and restarted (step  400 ), and the process continues as just described. 
   Otherwise (i.e., the personal computer  110  is idle), the proximity detector  120  determines whether the user  100  is near the personal computer  110  or away (step  410 ). If the user  100  is near the personal computer  110 , the proximity timer  130  is reset (step  415 ), and the value of the activity timer  150  is compared with the value of the activity timer threshold  155  (step  420 ). 
   If the value of the activity timer  150  does not exceed the value of the activity timer threshold  155 , the process returns to the point where the activity detector  140  determines whether the personal computer  110  is active (step  405 ), and continues as described above. If the value of the activity timer  150  exceeds the value of the activity timer threshold  155 , the personal computer  110  is put into sleep mode (step  425 ). 
   While the personal computer  110  is in sleep mode, the activity detector  140  awaits activity (step  430 ). Activity may be detected when the user  100  manipulates an input of the personal computer  110 , or when the user  100  momentarily closes a switch that has the specific purpose of awakening the personal computer  110  from sleep mode. When activity is detected, the personal computer  110  awakens from sleep mode (step  435 ). The process then returns to the point where the proximity timer  130  and the activity timer  150  are reset to zero and started (step  400 ), and continues as described above. 
   Otherwise (i.e., the personal computer  110  is idle and the user  100  is away from the personal computer  110 , which is the negative branch following step  410  of  FIG. 4 ), the value of the proximity timer  130  is compared with the value of the proximity timer threshold  135  (step  440 ). If the value of the proximity timer  130  does not exceed the value of the proximity timer threshold  135 , the process returns to the point where the value of the activity timer  150  is compared with the value of the activity timer threshold  155  (step  420 ), and continues from this point as described above. If the value of the proximity timer  130  exceeds the value of the proximity timer threshold  135 , the personal computer  110  is put into the sleep mode (step  425 ), and the process continues from this point as described above. 
   From the foregoing description, those skilled in the art will recognize that the present invention conserves electrical energy be enabling a personal computer to enter a sleep mode at the earliest convenient moment once the computer is left unattended. The foregoing description is illustrative rather than limiting, however, and the present invention is limited only by the following claims.