English:
[0001] Modern operating systems provide a comprehensive approach to system and device power management. Timer-based features may be used to provide power savings. For example, if user activity is absent for more than what the IT idle timer policy is, the system starts saving power by going into lower power states. The power saving starts when the IT policy threshold is reached.
[0002] Figure 1 is a diagram illustrating a computing device with presence detection capabilities according to one example.
[0003] Figure 2 is a block diagram illustrating elements of the computing device shown in Figure 1 according to one example.
[0004] Figures 3A-3C are diagrams illustrating example presence sensor configurations.
[0005] Figure 4 is a flow diagram illustrating a method for detecting user presence according to one example.
[0006] In the following detailed description, reference is made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration specific examples in which the disclosure may be practiced. It is to be understood that other examples may be utilized and structural or logical changes may be made without departing from the scope of the present disclosure. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present disclosure is defined by the appended claims. It is to be understood that features of the various examples described herein may be combined, in part or whole, with each other, unless specifically noted otherwise.
[0007] Timer-based locks for displays have privacy issues and may waste host system resources. Most information technology (IT) policies set the idle timer to the 10-20 minutes range. If user activity is absent for more than what the IT idle timer policy is, the system starts saving power by going into lower power states. The power saving starts when the IT policy threshold is reached. In cases where the user comes back to the normal activity right after the IT idle threshold is reached, the savings is minimal. This approach of relying on IT defined policies may work when the user is idle for an extended period, but this approach is flawed as the device may still be wasting power during the first period where the IT threshold timer is not reached. Also, IT policies asking users to not leave the display open and unattended are difficult to enforce.
[0008] Some examples disclosed herein are directed to using presence sensors to detect the presence of a user to control a display's backlight, and to initiate user authentication (e.g., login/logout) on a host computing device. In some examples, a time of flight (ToF) sensor determines the distance of the user from the display. Some examples use multiple ToF sensors. In other examples, another type of sensor that is capable of measuring the distance of the user from the display may be used. When the sensor or sensors detect that the user has just approached the display, a user authentication process (e.g., login process) is automatically triggered. When the sensor or sensors detect that the user has moved away from the display, the brightness of the display is either immediately or progressively reduced to a dark or off state. Using ToF sensors to automate the screen dimming and initiate logoff and login automatically enhances productivity, increases power savings, and increases the life of the display backlight.
[0009] Figure 1 is a diagram illustrating a computing device 104 with presence detection capabilities according to one example. In the illustrated example, a presence sensor 106 is positioned on, or in close proximity to, a display 105 of the computing device 104. The sensor 106 may be connected to the computing device 104 via USB or directly to the device 104 using a sensor hub. In some examples, the presence sensor 106 includes a ToF sensor or another type of sensor that determines the distance 101 of a user 102 from the display 105. In some examples, the presence sensor 106 also generates a Boolean value that indicates whether the user 102 is currently present or not present within a range and a field of view (FOV) of the sensor 106. The presence sensor 106 may be a multi-zone ToF sensor that includes an array (e.g., 2x2, 3x3, 4x4, or user defined) of zones, and that determines separate distance values for each individual zone. In some examples, an on-screen display (OSD) menu may be used in display 105 to disable and enable the presence detection feature, and to select options for the presence detection feature.
[0010] Figure 2 is a block diagram illustrating elements of the computing device 104 shown in Figure 1 according to one example. Computing device 104 includes at least one processor 202, a memory 204, input devices 220, output devices 222, display 105, and presence sensor 106. In the illustrated example, processor 202, memory 204, input devices 220, output devices 222, display 105, and presence sensor 106 are communicatively coupled to each other through communication link 218. The presence sensor 106 can be embedded within the frame of the display 105, mounted along at least one of the edges of the display 105, or mounted in a suitable location in the room in which the display 105 is located.
[0011] Input devices 220 include a keyboard, mouse, data ports, and/or other suitable devices for inputting information into device 104. Output devices 222 include speakers, data ports, and/or other suitable devices for outputting information from device 104.
[0012] Processor 202 includes a Central Processing Unit (CPU) or another suitable processor. In one example, memory 204 stores machine readable instructions executed by processor 202 for operating device 104. Memory 204 includes any suitable combination of volatile and/or non-volatile memory, such as combinations of Random Access Memory (RAM), Read-Only Memory (ROM), flash memory, and/or other suitable memory. These are examples of non-transitory computer readable storage media. The memory 204 is non- transitory in the sense that it does not encompass a transitory signal but instead is made up of at least one memory component to store machine executable instructions for performing techniques described herein.
[0013] Memory 204 stores sensor data processing module 206, user authentication module 208, and display control module 210. Processor 202 executes instructions of modules 206, 208, and 210 to perform the techniques described herein. It is noted that some or all of the functionality of modules 206, 208, and 210 may be implemented using cloud computing resources.
[0014] In examples that use multiple ToF sensors 106, the individual ToF sensors may be enumerated separately, and each sensor 106 reports a presence detection Boolean value and a distance value to the computing device 104 at a predefined time interval. In one example, the Boolean values and distance values are provided to the sensor data processing module 206 for processing. For the examples that use multiple ToF sensors 106, the sensor data processing module 206 may assume that the user 102 is present as long as the presence detection Boolean value of at least one of the sensors 106 indicates that the user 102 is present, and may assume that the user 102 is no longer present when the presence detection Boolean value of all of the sensors 106 indicate that the user 102 is not present. For examples that use a single ToF sensor 106, the sensor data processing module 206 may assume that the user 102 is present as long as the presence detection Boolean value of the single sensor 106 indicates that the user 102 is present, and may assume that the user 102 is no longer present when the presence detection Boolean value of the single sensor 106 indicates that the user is not present.
[0015] Even in cases in which the presence detection Boolean value from the sensor 106 indicates that the user 102 is present, the sensor data processing module 206 may conclude that the user 102 is not present based on the distance data. The sensor data processing module 206 compares the distance data received from the sensor 106 to a presence distance threshold value. If a received distance value is less than the threshold value, the module 206 may assume that the user 102 is present. If the received distance value is greater than the threshold value, the module 206 may assume that the user 102 is not present. In some examples, the presence distance threshold value may be defined by the user 102 (e.g., via the OSD menu of display 105).
[0017] For a user leaving scenario, the response may be user defined (e.g., via the OSD menu of display 105) to cause the brightness of the display 105 to either immediately or progressively be reduced to a dark or off state. For the immediate case, the sensor 106 will detect the lack of presence of the user 102 and will report this information to the sensor data processing module 206. The sensor data processing module 206 then informs the display control module 210 of the lack of user presence. In response, the display control module 210 causes the display 105 to go dark immediately. The display control module 210 also generates a lock signal that causes the computing device 104 to be locked (i.e., locked such that user authentication will be subsequently triggered to unlock the device 104), and causes the computing device 104 to enter a low power state.
[0018] For the progressive case according to some examples, the brightness of the display 105 is reduced in stages. In a first stage, after the user 102 has been absent for more than a first period of time (e.g., 10 seconds), the display control module 210 reduces the display brightness by 30% from the last user settings (note that a user setting may already be at reduced level). In a second stage, after the user 102 has been absent for more than a second period of time (e.g., 20 seconds total), the display control module 210 reduces the display brightness another 20%. If the user 102 returns to the computing device 104 (before the third stage) and is sensed as being present, the display control module 210 gradually increases the display brightness in increments (e.g., increments of 5% per quarter second), without further authentication, until the full brightness level is restored.
[0019] In a third stage, after the user 102 has been absent for a third period of time (e.g., X seconds, where X is an integer greater than 20), the display control module 210 progressively reduces the display brightness another X% until a maximum reduction in display brightness has been achieved. At this time, a lock signal is generated by the display control module 210 to lock the computing device 104. If the user 102 comes back before the maximum brightness reduction has been reached and is sensed as being present, the display control module 210 gradually increases the display brightness in increments (e.g., increments of 5% per quarter second), without further authentication, until the full brightness level is restored. If the user 102 does not come back before the maximum brightness reduction has been reached and the device 104 has been locked, resumption of user presence at this point triggers the authentication process.
[0020] In some examples, computing device 104 uses multiple distance thresholds, and varies the rate of dimming of the display 105 based on the multiple thresholds. For example, if the user 102 is sensed as being beyond a first distance threshold, which is the shortest distance threshold, display control module 210 may dim the display 105 at a first rate, which may be the slowest rate of dimming. If the user 102 is sensed as being beyond a second distance threshold, which is a longer distance than the first distance threshold, the display control module 210 may dim the display 105 at a second rate, which may be faster than the first rate. If the user 102 is sensed as no longer being present (e.g., the user 102 is sensed as being beyond the presence distance threshold, which is a longer distance than the second distance threshold), the display control module 210 may dim the display 105 at a third rate, which may be faster than the second rate.
[0021] In some examples, the distance thresholds may vary based on the lateral position of the user 102 with respect to the display 105. For example, the distance thresholds for positions on the left and ride sides of the display 105 may be the same, but may be different than the distance threshold for positions near the center of the display 105. In one example, display control module 210 may dim the display 105 when the user 102 is just beyond the edge of the display 105, but may use a higher distance threshold when the user 102 is positioned near the center of the display 105. Also, each different position (e.g., left, center, right) with respect to the display 105 may have multiple distance thresholds, and the distance thresholds and dimming rates may vary for the various positions.
[0022] In some examples, computing device 104 generates an audible and/or visual warning signal when the user 102 is detected as being too close to the display of the computing device 104. In particular, if sensor data processing module 206 determines that a distance value provided by sensor 106 is less than a threshold value (e.g., 50 mm), module 206 causes the display 105 and/or at least one of the output devices 222 to generate the warning signal. This feature provides protection for the user's eyes, which could be damaged by prolonged exposure at close range. The sensor data processing module 206 may also keep track of the length of time that the user 102 has been present in front of the display 105, and cause an audible and/or visual warning signal to be generated when this time exceeds a predetermined threshold.
[0023] In some examples, the sensor data processing module 206 causes the distance values received from sensor 106 to be displayed on the display 105. This displayed information may be used, for example, to assist a user in moving to an appropriate distance for facial recognition. In some examples, based on the distance values received from the sensor 106, the sensor data processing module 206 causes adjustments to be made to at least one of the input devices 220 and the output devices 222 (e.g., making adjustments to the speakers and microphone of the device 104 based on the sensed distance of the user 102). Such adjustments may include, for example, changing a mode of these devices, increasing the volume as the user 102 moves farther away from the device 104, and/or decreasing the volume as the user 102 moves closer to the device 104. In some examples, based on the distance values received from the sensor 106, the sensor data processing module 206 causes changes to the display characteristics of the display 105 (e.g., increasing the font size as the user 102 moves farther away from the display 105, and decreasing the font size as the user moves closer to the display 105). The sensor 106 may also be used to detect hand gestures (e.g., a tap gesture or a swipe gesture) made by the user 102, and the sensor data processing module 206 may cause an action to be performed based on the detected gesture.
[0024] In some examples, sensor 106 includes a lower power mode and a higher power mode. In the lower power mode, the sensor 106 uses less power and checks for the presence of the user 102 less frequently than in the higher power mode. In some examples, when the sensor 106 detects that the user 102 is present, the sensor 106 operates in the lower power mode, and when the sensor 106 detects that the user 102 is no longer present, the sensor 106 is automatically switched to the higher power mode to check for the presence of the user 102 more frequently.
[0025] Figures 3A-3C are diagrams illustrating example presence sensor configurations. As shown in Figure 3A, the display 105(1 ) includes a single presence sensor (e.g., ToF sensor) 106(1 ). The presence sensor 106(1 ) has a field of view (FOV) 302(1 ) of about 27 degrees. The center line of the FOV 302(1 ) is perpendicular or substantially perpendicular to the display 105(1 ). The user 102 is positioned at a distance 304(1 ) of about 60 cm from the display 105(1 ). The lateral length 306(1 ) of the FOV 302(1 ) at this distance (and correspondingly the lateral detectable range of the user 102) is about 29 cm. The lateral detectable range may be increased by using multiple presence sensors 106, as shown in Figures 3B and 3C.
[0026] As shown in Figure 3B, the display 105(2) includes two presence sensors (e.g., ToF sensors) 106(2) and 106(3), which are positioned a distance 310(1 ) of about 29 cm apart. The presence sensors 106(2) and 106(3) have a FOV 302(2) and a FOV 302(3), respectively, which are each about 27 degrees. The center lines of the FOVs 302(2) and 302(3) are perpendicular or substantially perpendicular to the display 105(2). The user 102 is positioned at a distance 304(2) of about 60 cm from the display 105(2). The lateral length 306(2) of the combined FOVs 302(2) and 302(3) at this distance (and correspondingly the lateral detectable range of the user 102) is about 58 cm. There is a dead zone 308(1 ) extending outward from the display 105(2) between the FOVs 302(2) and 302(3) of the two presence sensors 106(2) and 106(3), where presence of the user 102 is not detectable. The size of the dead zone may be reduced by adjusting the angle of the sensors 106, as shown in Figure 3C.
[0027] As shown in Figure 3C, the display 105(3) includes two presence sensors (e.g., ToF sensors) 106(4) and 106(5), which are positioned a distance 310(2) of about 10 cm apart. The presence sensors 106(4) and 106(5) have a FOV 302(4) and a FOV 302(5), respectively, which are each about 27 degrees. The center lines of the FOVs 302(4) and 302(5) are perpendicular or substantially perpendicular to the display 105(3). The user 102 is positioned at a distance 304(3) of about 60 cm from the display 105(3). The lateral length 306(3) of the combined FOVs 302(4) and 302(5) at this distance (and correspondingly the lateral detectable range of the user 102) is about 58 cm. There is a dead zone 308(2) extending outward from the display 105(3) between the FOVs 302(4) and 302(5) of the two presence sensors 106(4) and 106(5), where presence of the user 102 is not detectable. By reducing the distance 310 between the sensors
[0028] The use of multiple presence sensors 106 with distance detection helps the system to distinguish between a human and non-human objects (e.g., a chair or a coffee mug), and provides for a more accurate tracking of the user 102, including being able to determine a direction that the user 102 has moved away from the display 105 (e.g., whether the user has exited to the left of the display or to the right of the display). Some examples determine whether an object is moving based on the sensed distance of the object over time, which helps the system to distinguish between human and non-human objects.
[0029] One example is directed to a method for detecting user presence. Figure 4 is a flow diagram illustrating a method 400 for detecting user presence according to one example. In one example, computing device 104 (Figure 1 ) may perform method 400. At 402 in method 400, a sensor senses a distance of a user from a display of a computing device. At 404, the computing device compares the sensed distance to a threshold distance. At 406, the computing device determines whether the user is present at the display based at least in part on the comparison.
[0030] In some examples, method 400 may further include reporting, with the sensor, to the computing device, the sensed distance; and reporting, with the sensor, to the computing device, a Boolean value that indicates whether the user is present within a field of view of the sensor. Method 400 may further include causing an automatic reduction in brightness of the display when it is determined by the computing device that the user is not present at the display. The brightness of the display may be immediately reduced to a dark state when it is determined by the computing device that the user is not present at the display. The brightness of the display may be progressively reduced in stages to a dark state when it is determined by the computing device that the user is not present at the display.
[0032] Another example is directed to a system that includes a computing device including a display, and a sensor to sense a distance of a user from the display. The system further includes at least one processor in the computing device to: compare the sensed distance to a threshold distance; and determine whether the user is present at the display based at least in part on the comparison.
[0033] In some examples, the sensor may include a plurality of time of flight (ToF) sensors that each sense a distance of the user from the display. At least one of the ToF sensors may be a multi-zone ToF sensor that includes an array of zones and that determines a separate distance value for each of the zones. The sensor may include a lower power state and higher power state, and wherein the sensor checks for presence of the user more frequently in the higher power state than in the lower power state.
[0034] Yet another example is directed to a non-transitory computer-readable storage medium storing instructions that, when executed by at least one processor, cause the at least one processor to: receive, from a sensor, a distance value representing a distance of a user from a display of a computing device, and a Boolean value that indicates whether the user is present within a field of view of the sensor; and determine whether the user is present at the display based on the received distance value and the received Boolean value.
[0035] The non-transitory computer-readable storage medium may further store instructions that, when executed by the least one processor, cause the at least one processor to reduce brightness of the display when it is determined that the user is not present at the display.

中文:
[0001]现代操作系统为系统和设备功率管理提供了全面的方法。基于计时器的特征可以用于提供功率节省。例如,如果缺少用户活动的时间超过IT空闲计时器策略的时间,则系统提供进入低功率状态而开始节省功率。当达到IT策略阈值时,功率节省开始。
[0002]图1是示出根据一个示例的具有存在检测能力的计算设备的示图。
[0003]图2是示出根据一个示例的图1所示的计算设备的元件的框图。
[0004]图3A-图3C是示出示例性存在传感器配置的示图。
[0005]图4是示出根据一个示例的用于检测用户存在的方法的流程图。
[0006]在下面的详细描述中,参考形成其一部分的附图,并且在附图中通过图示的方式示出了可以实践本公开的特定示例。应当理解,可以利用其他示例,并且可以进行结构或逻辑上的改变,而不脱离本公开的范围。因此,以下详细描述不应被理解为限制性的,并且本公开的范围由所附权利要求限定。应当理解,除非另外特别指出,否则本文描述的各个示例的特征可以部分或全部彼此组合。
[0007]用于显示器的基于计时器的锁存在隐私问题,并且可能浪费主机系统资源。大多数信息技术(IT)策略将空闲计时器设置为10-20分钟范围。如果缺少用户活动超出了IT空闲计时器策略的范围,则系统通过进入较低功率状态而开始节省功率。当达到IT策略阈值时,功率节省开始。在用户在达到IT空闲阈值之后立即恢复正常活动的情况下,所述节省是极小的。当用户在较长时间内空闲时,依赖IT定义策略的该方法可能会起作用,但是该方法存在缺陷,因为在未达到IT阈值计时器的第一时间段期间,设备可能仍在浪费功率。而且,要求用户不使显示器打开且无人看管的IT策略难以执行。
[0008]本文公开的一些示例涉及使用存在传感器来检测用户的存在以控制显示器的背光,并在主机计算设备上发起用户认证(例如,登录/注销)。在一些示例中,飞行时间(ToF)传感器确定用户到显示器的距离。一些示例使用多个ToF传感器。在其他示例中,可以使用能够测量用户到显示器的距离的另一类型的传感器。当一个或多个传感器检测到用户刚刚接近显示器时,自动触发用户认证过程(例如,登录过程)。当一个或多个传感器检测到用户已离开显示器时,显示器的亮度立即或逐步降低为暗或关状态。通过使用ToF传感器自动使屏幕变暗并启动注销和登录,自动地提高了生产率,增大了功率节省,并延长了显示器背光灯的寿命。
[0009]图1是示出根据一个示例的具有存在检测能力的计算设备104的示图。在所示示例中,存在传感器106被定位在计算设备104的显示器105上或紧邻计算设备104的显示器105。传感器106可以经由USB连接到计算设备104,或者可以使用传感器集线器直接连接到设备104。在一些示例中,存在传感器106包括ToF传感器或另一类型的传感器,其确定用户102到显示器105的距离101。在一些示例中,存在传感器106还生成指示用户102当前是否存在于传感器106的范围和视场(FOV)内的布尔值。存在传感器106可以是多区域ToF传感器,其包括区域的阵列(例如2x2、3x3、4x4或用户定义的阵列),并确定每个个体区域的单独的距离值。在一些示例中,可以在显示器105中使用屏上显示(OSD)菜单来禁用和启用存在检测特征,并且选择用于存在检测特征的选项。
[0010]图2是示出根据一个示例的图1所示的计算设备104的元件的框图。计算设备104包括至少一个处理器202、存储器204、输入设备220、输出设备222、显示器105和存在传感器106。在所示的示例中,处理器202、存储器204、输入设备220、输出设备222、显示器105和存在传感器106通过通信链路218彼此通信地耦合。存在传感器106可以嵌入在显示器105的框架内,沿着显示器105的至少一个边缘安装,或者安装在显示器105所处的空间中的合适的位置中。
[0011]输入设备220包括键盘、鼠标、数据端口、和/或用于将信息输入到设备104中的其他合适的设备。输出设备222包括扬声器、数据端口、和/或用于从设备104输出信息的其他合适的设备。
[0012]处理器202包括中央处理单元(CPU)或另一合适的处理器。在一个示例中,存储器204存储由处理器202为操作设备104执行的机器可读指令。存储器204包括易失性和/或非易失性存储器的任何适当的组合,诸如随机存取存储器(RAM)、只读存储器(ROM)、闪存和/或其他合适的存储器的组合。这些是非暂态计算机可读存储介质的示例。存储器204在其不包含暂态信号的意义上是非暂态的,而是由至少一个存储器部件组成,以存储用于执行本文所述技术的机器可执行指令。
[0013]存储器204存储传感器数据处理模块206、用户认证模块208和显示器控制模块210。处理器202执行模块206、208和210的指令以执行本文所述的技术。注意,可以使用云计算资源来实施模块206、208和210的一些或全部功能。
[0014]在使用多个ToF传感器106的示例中,可以分别枚举各个ToF传感器,并且每个传感器106以预定义的时间间隔向计算设备104报告存在检测布尔值和距离值。在一个示例中,布尔值和距离值被提供给传感器数据处理模块206以进行处理。对于使用多个ToF传感器106的示例,只要传感器106中的至少一个的存在检测布尔值指示用户102存在,则传感器数据处理模块206可以假设用户102存在,并且当所有传感器106的存在检测布尔值指示用户102不存在时,可以假设用户102不再存在。对于使用单个ToF传感器106的示例,只要单个传感器106的存在检测布尔值指示用户102存在,则传感器数据处理模块206可以假设用户102存在,并且当单个传感器106的存在检测布尔值指示用户不存在时,可以假设用户102不再存在。
[0015]即使在来自传感器106的存在检测布尔值指示用户102存在的情况下,传感器数据处理模块206也可以基于距离数据得出用户102不存在的结论。传感器数据处理模块206将从传感器106接收的距离数据与存在距离阈值进行比较。如果接收到的距离值小于阈值,则模块206可以假设用户102存在。如果所接收的距离值大于阈值,则模块206可以假设用户102不存在。在一些示例中,存在距离阈值可以由用户102定义(例如,经由显示器105的OSD菜单)。
[0017]对于用户离开场景,响应可以是用户定义的(例如,经由显示器105的OSD菜单),以使显示器105的亮度立即或逐步减小为暗或关状态。对于立即减小的情况,传感器106将检测到用户102的不存在,并将该信息报告给传感器数据处理模块206。传感器数据处理模块206然后向显示器控制模块210通知用户不存在。作为响应,显示器控制模块210使显示器105立即变暗。显示器控制模块210还生成锁定信号,该锁定信号使计算设备104被锁定(即,被锁定使得随后将触发用户认证以解锁设备104),并使计算设备104进入低功率状态。
[0018]对于逐步情况,根据一些示例,显示器105的亮度被分阶段降低。在第一阶段,在用户102缺席超过第一时间段(例如10秒)之后,显示器控制模块210将显示器亮度从最后的用户设置降低30%(注意,用户设置可能已经是降低的水平)。在第二阶段中,在用户102缺席超过第二时间段(例如总计20秒)之后,显示器控制模块210将显示器亮度再降低20%。如果用户102返回到计算设备104(在第三阶段之前)并且被感测为存在,则显示器控制模块210以增量(例如,每四分之一秒5%的增量)逐渐增大显示器亮度,而不用进一步的认证,直到恢复完全亮度水平。
[0019]在第三阶段中,在用户102缺席达第三时间段(例如X秒,其中X是大于20的整数)之后,显示器控制模块210将显示器亮度逐步再降低X%,直到已经实现显示器亮度的最大降低。此时,显示器控制模块210生成锁定信号以锁定计算设备104。如果用户102在达到最大亮度降低之前返回并被感知为存在,则显示器控制模块210以增量(例如,每四分之一秒5%的增量)逐渐增大显示器亮度,而不用进一步的认证,直到恢复完全亮度水平。如果用户102在达到最大亮度降低之前没有返回并且设备104已经被锁定,则此时用户存在的重新开始将触发认证过程。
[0020]在一些示例中,计算设备104使用多个距离阈值,并且基于多个阈值来改变显示器105的调光速率。例如,如果用户102被感测为超过第一距离阈值,该第一距离阈值是最短的距离阈值,则显示器控制模块210可以以第一速率将显示器105调暗,该第一速率可以是最慢的调光速率。如果用户102被感测为超过第二距离阈值,该第二距离阈值是比第一距离阈值更长的距离,则显示器控制模块210可以以第二速率将显示器105调暗,该第二速率可以比第一速率快。如果感测到用户102不再存在(例如,感测到用户102超过存在距离阈值,存在距离阈值是比第二距离阈值更长的距离),则显示器控制模块210可以以第三速率将显示器105调暗,该第三速率可以比第二速率快。
[0021]在一些示例中,距离阈值可以基于用户102相对于显示器105的横向位置而变化。例如,针对显示器105的左侧和右侧上的位置的距离阈值可以相同,但可能不同于针对显示器105的中心附近的位置的距离阈值。在一个示例中,当用户102刚好超过显示器105的边缘时,显示器控制模块210可以将显示器105调暗,但可以使用当用户102位于显示器105的中心附近时的较高距离阈值。此外,相对于显示器105的每个不同位置(例如,左、中、右)可以具有多个距离阈值,并且该距离阈值和调光速率可能因各种位置而改变。
[0022]在一些示例中,当检测到用户102太靠近计算设备104的显示器时,计算设备104生成可听和/或视觉警告信号。特别地,如果传感器数据处理模块206确定由传感器106提供的距离值小于阈值(例如50mm),模块206使显示器105和/或输出设备222中的至少一个生成警告信号。该特征可以提供对用户的眼睛的保护,长时间在近距离曝光可能对眼睛造成损伤。传感器数据处理模块206还可以跟踪用户102已经存在于显示器105前面的时间长度,并且当该时间超过预定阈值时,使得生成可听和/或视觉警告信号。
[0023]在一些示例中,传感器数据处理模块206使从传感器106接收的距离值显示在显示器105上。例如,可以使用该显示的信息来辅助用户移动到适当的距离,以用于面部识别。在一些示例中,基于从传感器106接收的距离值,传感器数据处理模块206使得对输入设备220和输出设备222中的至少一个做出调整(例如,基于用户102的感测到的距离来对设备104的扬声器和麦克风进行调整)。这样的调整可以包括例如改变这些设备的模式,随着用户102移动远离设备104而增大音量,和/或随着用户102移动靠近设备104而减小音量。在一些示例中,基于从传感器106接收的距离值,传感器数据处理模块206引起对显示器105的显示特性的改变(例如,随着用户102移动远离显示器105而增大字体大小,并且随着用户移动靠近显示器105而减小字体大小)。传感器106还可以用于检测用户102所做出的手势(例如,轻击手势或轻扫手势),并且传感器数据处理模块206可以使得基于所检测到的手势来执行动作。
[0024]在一些示例中,传感器106包括较低功率模式和较高功率模式。在较低功率模式下,与在较高功率模式下相比,传感器106使用较少的功率,并且较不频繁地检查用户102的存在。在一些示例中,当传感器106检测到用户102存在时,传感器106以较低功率模式进行操作,并且当传感器106检测到用户102不再存在时,传感器106被自动切换至较高功率模式,以更频繁地检查用户102的存在。
[0025]图3A-3C是示出示例性存在传感器配置的示图。如图3A所示,显示器105(1)包括单个存在传感器(例如,ToF传感器)106(1)。存在传感器106(1)具有大约27度的视场(FOV)302(1)。FOV 302(1)的中心线垂直于或基本垂直于显示器105(1)。用户102被定位在距显示器105(1)约60cm的距离304(1)处。FOV 302(1)在该距离(以及相应地,用户102的横向可检测范围)处的横向长度306(1)约为29cm。如图3B和3C所示,可以通过使用多个存在传感器106来增加横向可检测范围。
[0026]如图3B所示,显示器105(2)包括两个存在传感器(例如ToF传感器)106(2)和106(3),它们被定位成相距约29cm的距离310(1)。存在传感器106(2)和106(3)分别具有FOV302(2)和FOV 302(3),它们均为大约27度。FOV 302(2)和302(3)的中心线垂直于或基本垂直于显示器105(2)。用户102被定位在距显示器105(2)约60cm的距离304(2)处。组合的FOV302(2)和302(3)在该距离(以及相应地,用户102的横向可检测范围)处的横向长度306(2)约为58cm。在两个存在传感器106(2)和106(3)的FOV 302(2)和302(3)之间,存在从显示器105(2)向外延伸的盲区308(1),其中,用户102的存在不可检测。如图3C所示,可以通过调节传感器106的角度来减小盲区的大小。
[0027]如图3C所示,显示器105(3)包括两个存在传感器(例如,ToF传感器)106(4)和106(5),它们被定位成相距约10cm的距离310(2)。存在传感器106(4)和106(5)分别具有FOV302(4)和FOV 302(5),它们均为约27度。FOV 302(4)和302(5)的中心线垂直于或基本垂直于显示器105(3)。用户102被定位在距显示器105(3)约60cm的距离304(3)处。组合的FOV302(4)和302(5)在该距离(以及相应地,用户102的横向可检测范围)处的横向长度306(3)约为58cm。在两个存在传感器106(4)和106(5)的FOV 302(4)和302(5)之间,存在从显示器105(3)向外延伸的盲区308(2),其中用户102的存在不可检测。如图3C所示,通过减小传感器106之间的距离310并使传感器106向外倾斜,与图3B所示的死区308(1)的尺寸相比,死区308(2)的尺寸减小,同时仍然提供相同的横向可检测范围。
[0028]具有距离检测的多个存在传感器106的使用帮助系统区分人和非人物体(例如,椅子或咖啡杯),并提供对用户102的更精确的跟踪,包括能够确定用户102已经远离显示器105移动的方向(例如,用户是否已经退出显示器的左侧或显示器的右侧)。一些示例基于随时间推移所感测到的物体的距离来确定物体是否正在移动,这有助于系统区分人和非人物体。
[0029]一个示例针对一种用于检测用户存在的方法。图4是示出根据一个示例的用于检测用户存在的方法400的流程图。在一个示例中,计算设备104(图1)可以执行方法400。在方法400中的402处,传感器感测用户距计算设备的显示器的距离。在404,计算设备将感测到的距离与阈值距离进行比较。在406,计算设备至少部分地基于比较来确定用户是否存在于显示器处。
[0030]在一些示例中,方法400还可以包括利用传感器向计算设备报告感测到的距离;以及利用传感器向计算设备报告布尔值,该布尔值指示用户是否在传感器的视场内。方法400还可以包括:当计算设备确定用户不存在于显示器处时,引起显示器的亮度的自动降低。当计算设备确定用户不存在于显示器处时,显示器的亮度可以立即降低到暗状态。当计算设备确定用户不存在于显示器处时,显示器的亮度可以分阶段逐步减小到暗状态。
[0032]另一个示例涉及一种系统,该系统包括:包括显示器的计算设备;以及感测用户到显示器的距离的传感器。该系统还包括计算设备中的至少一个处理器,以:将感测到的距离与阈值距离进行比较;以及至少部分地基于所述比较来确定用户是否存在于显示器处。
[0033]在一些示例中,传感器可以包括多个飞行时间(ToF)传感器,其各自感测用户距显示器的距离。ToF传感器中的至少一个可以是多区域ToF传感器,该多区域ToF传感器包括区域的阵列并且确定每个区域的单独的距离值。传感器可以包括较低功率状态和较高功率状态,并且其中,传感器在较高功率状态下比在较低功率状态下更频繁地检查用户的存在。
[0034]另一示例针对一种非暂态计算机可读存储介质,该存储介质存储指令,该指令在由至少一个处理器执行时使至少一个处理器:从传感器接收代表用户距计算设备的显示器的距离的距离值、以及指示该用户是否存在于传感器的视场内的布尔值;并且基于所接收的距离值和所接收的布尔值确定用户是否存在于显示器处。
[0035]非暂时性计算机可读存储介质还可以存储指令,所述指令在由至少一个处理器执行时使至少一个处理器:当确定用户不存在于显示器处时,降低显示器的亮度。