WO1999021356A1

WO1999021356A1 - Viewing distance sensor and method

Info

Publication number: WO1999021356A1
Application number: PCT/US1998/022187
Authority: WO
Inventors: Salah U. Din
Original assignee: Gateway 2000, Inc.
Priority date: 1997-10-22
Filing date: 1998-10-21
Publication date: 1999-04-29
Also published as: AU1106599A

Abstract

A video monitor includes circuitry for sensing a viewer's distance from the display screen. The circuitry compares this distance with predetermined optimum viewing distance and indicates to the viewer whether they should move closer, farther away, or that they are within the optimum viewing distance. The indicator may be a single light emitting diode (LED) which is on or a particular color when the viewer is at the optimal viewing distance and is off or a different color when the viewer is not at the optimal viewing distance. The indicator may also consist of a pattern of two or more LEDs, a graduated light bar having one or more colors to indicate different viewer positions, or a text message or visual indicator incorporated in the display itself. The viewer has the option to disable the distance indicator.

Description

VIEWING DISTANCE SENSOR AND METHOD

Field of the Invention The present invention relates in general to methods and apparatus for monitoring a viewing environment, and particularly to monitoring the distance of a viewer from an electronic display.

Background of the Invention Video display terminals (VDTs) are being used more and more in today's electronic world. The term 'video display terminal' is a generic term intended to include the wide array of electronic display monitors, such as televisions and monitors attached to computers. They have found their ways into public places such as airports, many different rooms in homes and most offices around the world. They are used for many hours on end, playing video games, surfing the internet and doing work. Each of these VDTs have an optimal viewing distance. Optimum viewing distances have been identified for different viewing environments, (see, for example, "Computers and Vision: Simple Measures Can Ease Eyestrain", Safety+Health 40-43, July 1994) but viewers are not always aware of the optimal viewing distance for the particular viewing environment in which they happen to find themselves.

Viewers may be moving between a variety of viewing environments. It is difficult to remember which viewing distance may be optimal. For example, an optimal viewing distance for a television may be substantially different from an optimal viewing distance for a computer terminal. Human visual acuity, the ability to discern detail, varies from 0.5 to 5.0 minutes of arc. In conventional television displays, 1.7 minutes of arc of visual acuity is considered an average. For example, with 525 lines of broadcast and a visual acuity of 1.7 the viewing ratio (the ratio of viewing distance to picture height) can be as great as 4.4. A viewing ratio minimum of 4 is usually assumed for broadcast systems (such as those displayed on television sets), and the optimal ratio is between 5 and 8. For high-definition television (HDTV) the ratio is closer to 3, for desktop computer displays, the ratio is between 1 and 2 and in laptop computer displays, the ratio is 1. What is needed is a way for a user to identify the optimal viewing environment associated with the VDT they are viewing. There is also a need for a way to inform viewers of the recommended viewing environment for each of the variety of VDTs manufactured.

Summary of the Invention A sensor for detecting the location of a viewer is incorporated in the front of a video display terminal (VDT) and is coupled to a display indicator which shows whether the viewer is within an optimal viewing range for the particular VDT. Maintaining a proper viewing distance can help the viewer achieve optimal use of the VDT in the manner designed by a manufacturer. In various embodiments, the VDT is a computer monitor or a television.

According to one embodiment of the present invention, circuitry associated with the sensor compares the detected distance with a pre-determined optimum distance and indicates to the viewer whether they are within the predetermined optimum viewing distance. In one implementation a series of lights coupled to the VDT are illuminated according to the estimated distance - green for within the safe viewing zone, yellow for near the perimeter of the safe viewing zone, and red for outside the safe viewing zone. In another implementation the appropriate color is displayed in a window on the VDT screen which stays on the screen for a desired time following the last significant movement of the viewer. According to one embodiment the viewer has the option of disabling the safe viewing distance indicator.

Description of the Drawings Figure 1 is a block diagram illustrating a display device constructed in accordance with the present invention. Figure 2 is a block diagram of circuitry for determining viewing distance according to one embodiment of the present invention.

Figure 3 is a logic flow diagram showing the process steps followed by one embodiment of the present invention.

Figure 4 is a perspective drawing of a video display terminal according to one embodiment of the present invention. Detailed Description of the Preferred Embodiments 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 embodiments in which the invention may be practiced. These embodiments are described in detail sufficient to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that structural, logical and electrical changes may be made without departing from the spirit and scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims.

A video display terminal, such as a television or computer VGA or SVGA monitor is shown generally at 110 in Figure 1. Sony Corporation 15" (CPD15F23) and 17" (CPD17F23) monitors may be equipped with distance estimating circuitry 210 to provide viewing distance estimating capability and comparison to optimum viewing distance as further described herein. The display also comprises a cathode ray tube (CRT) 112 having a deflection yoke 114 which contains at least three color guns for red, green and blue colors from which all colors may be obtained. The display further comprises a video circuit board 116 for providing analog RGB signals directly to the deflection yoke 114 for controlling the color guns to provide images on CRT 112. The video board 116 receives a video in signal 118 from an external source, such as a computer or set top box, or from a tuner which receives broadcast unencrypted video signals, and may be included within a common television in further embodiments. The video board 116 also provides information back to such external devices on power-on, such as refresh rates, resolution settings and other data to enable the external devices to communicate appropriately with the display.

The video in signal 118 comprises analog RGB signals as well as horizontal and vertical synchronization signals which are all provided to a multiplexor 120 residing on an on-screen display (OSD) circuit 122. A second source of video signals is provided in the form of a read only memory (ROM) 124, which holds data for producing OSD menus. ROM 124, included in the OSD circuit 122, is coupled to signal generator 126 which generates digital representations of RGB signals. The RGB signals from signal generator 126 are provided to a digital to analog converter 130, which converts them to analog RGB signals which are in turn provided to the multiplexor 120, which has the ability to superimpose the various video inputs it receives, or selectively provide one of the video signals to the deflection yoke 114 of the CRT 112.

Multiplexor 120 is controlled by microprocessor 140, which in turn is controlled by a user operating user controls 142. User controls 142 in one embodiment comprise power-on switch and other standard brightness and contrast type controls for adjusting the display device. In one embodiment, the user controls comprise a remote control device along with reception circuitry which may operate in the IR, RF, or other suitable frequency range. Other elements, common to display devices, include a power supply 150 coupled to a source of power, such as household current, or in some embodiments a battery. In one embodiment, distance estimating circuitry 210 is coupled to microprocessor 140. It is activated each time a user powers on monitor 110 to calculate the distance a viewer is from the video display terminal 110. The viewer is able to selectively control operating parameters of circuitry 210, including deactivating and reactivating it, through on-screen menu options accessed through user controls 142. In another implementation the viewer may toggle circuitry 210 on and off through pressing a button or selecting a particular on-screen option using user controls 142.

An indicator 160, for indicating to the user whether they are within a safe viewing distance, is optionally included in monitor 110 in one embodiment of the present invention. According to one implementation, indicator 160 is a single light emitting diode (LED) which is illuminated when the viewer is within the optimal viewing distance. In a second implementation indicator 160 comprises two LEDs, a green one which is illuminated when the viewer is within the optimal viewing distance and a red one which is illuminated when the viewer is too close. In yet another embodiment indicator 160 comprises a slide bar-type display, having red, amber and green segments. If the user is too close the red segment is illuminated. As the user moves away and approaches the optimal viewing distance indicator 160 illuminates the amber segment. When the user is within the optimal viewing distance the green segment is illuminated.

As shown in Figure 2, according to one embodiment of the present invention circuitry 210 includes microprocessor 216 coupled to a transceiver 213 comprising a transmitter 212 and a receiver 214. Circuitry 210 also comprises a memory 218, which according to one embodiment, comprises an electrically erasable programmable read-only memory (EEPROM). Transceiver 213 comprises an infra-red (IR) transceiver. Those skilled in the art will recognize that other types of memory devices and optical, ultrasonic, ultra-violet, radar and other forms of signal transceivers which sense distance of objects based on the time period for a reflected pulse to be received can be employed without exceeding the scope of the present invention.

Signal transceivers or sensors of different types have been employed in conventional systems for indicating the location of various objects. For example, U.S. Patent No. 5,280,622, issued to Tino and entitled "Combined Light Beam and Ultrasonic Transducer Safety Sensing System", describes a system wherein ultrasonic transducers are used to determine the position of an object which intrudes into a robot's work space. As another example, U.S. Patent No. 5,004,997, issued to Shisgal et al. and entitled "Parking Aid Device" describes an electronic device for guiding a motorist when parking a vehicle in a parking bay. While these systems employ ultrasonic technology to estimate distance, other conventional systems employ optical triangulation for estimating distances (see, for example, Kenneth J. Kaufmann, "Position-Sensitive Detectors Develop into High-Tech Tailors", Photonics Spectra 167-174, May 1997).

According to one implementation an optimum viewing distance is identified for monitor 110. Those skilled in the art will recognize that this distance will potentially be different for different types of monitors, and may be different for the same monitor if it is to be used for different purposes. The identified optimum viewing distance is, in one embodiment, held in memory

218, either as a single value or a value range (that is defined including any value between a defined maximum and minimum value). Human visual acuity, the ability to discern detail, varies from 0.5 to 5.0 minutes of arc. In conventional television displays, 1.7 minutes of arc of visual acuity is considered an average. For example, with 525 lines of broadcast and a visual acuity of 1.7 the viewing ratio (the ratio of viewing distance to picture height) can be as great as 4.4. A viewing ratio minimum of 4 is usually assumed for broadcast systems (such as those displayed on television sets), and the optimal ratio is between 5 and 8. For high-definition television (HDTV) the ratio is closer to 3, for desktop computer displays, the ratio is between 1 and 2 and in laptop computer displays, the ratio is 1. According to one embodiment the optimum viewing distance is set by the monitor manufacturer and is not modifiable. In another embodiment the optimum viewing distance is set by the user through manipulation of user controls 142, while in yet another embodiment the optimum viewing distance is set through commands and data issued by an external source and received via signal input 118.

Figure 3 is a logic flow diagram showing the process steps followed by one embodiment of the present invention. At block 310 transmitter 212 transmits a signal or pulse in the direction toward a normal viewer, and at block 315 receiver 214 receives the reflected signal. Using the time it took the signal to travel from transmitter 212 to the viewer and back to receiver 214, at block

320 logic encoded in processor 216 calculates the viewer's distance from monitor 110. At block 325 processor 216 compares the calculated distance with the optimum viewing distance held in memory 218. The result is then displayed at block 330 using indicator 160 or an on-screen display so the viewer will know whether they are within a safe viewer distance of monitor 110.

According to one embodiment circuitry 210 includes clock device 217. In this embodiment, processor 216 uses clock device 217 to periodically trigger a process cycle as described previously. This enables circuitry 210 to update the indicator displayed to the user to reflect any change in the viewer's position. In one embodiment the sample period is one second, while in another it is sub- second. If there is no change in viewer position, the indicator 160 may not provide an indication of position to the viewer if desired. A buffer of a plurality of previous viewer distances is maintained in memory 218 to enable this comparison.

As shown in Figure 4, in one embodiment of the present invention circuitry 210 is positioned such that it transmits and receives signals from the front of monitor 110. Those skilled in the art will recognize that transmitter 212 and receiver 214 may be positioned anywhere on monitor 110 such that they transmit and receive signals to and from a viewer positioned in front of monitor 110. In one embodiment the position of transceiver 213 is a function of the anticipated viewing environment. For example, where one viewer is expected to sit relatively close to and directly in front of monitor 110, transceiver 213 may be positioned near the center of the bottom of face of monitor 110 as shown in Figure 4 in order to better ensure accurate distance measurement. If, for example, the monitor is to be used for television viewing, transceiver 213 may be placed differently in order to better sense the one or more viewers which will be at a greater distance and potentially wider angles from the front of monitor 110. In a further embodiment, the transceiver 213 is mounted on a gimbal assembly and can be pointed in a desired direction.

In another embodiment an indication of the viewer's position relative to the optimal viewing distance is displayed on the monitor screen as indicated at indicator 460. The display may be symbolic or descriptive text. As shown at 460, the indicator comprises a series of a plurality of red, amber and green stripes which are displayed based on the distance of the viewer. Red stripes are displayed if the user is too close, amber stripes represent close but adequate, while green stripes are displayed if the user is near the optimal viewing range. The number of stripes in each color range may vary from 1 to several, such as four, with each stripe corresponding to a distance in range based on the number of stripes. For example, if an optimal distance ranges from two feet to three feet, and there are four green stripes, each green stripe will represent about three inches of viewer distance, with the first green stripe representing a viewer distance of between three feet, and three feet, three inches. Display information for the stripes may be stored in ROM 124 and addressed by one of the microprocessors. Those skilled in the art will recognize that a wide variety of indicator formats and display techniques may be used without exceeding the scope of the present invention. It is to be understood that the above description is intended to be illustrative, and not restrictive. For instance, the distance circuitry 210 may always be on, and the distance indicator 160 or 460 only turned on when the viewer moves a significant distance, such as outside of an optimal viewing range, or a sufficient distance to trigger a change in the number of stripes in indicator 460 that are displayed. The distance indicators may also comprise two ranges, too close, and just right, as represented by red and green colors respectively. Even one indicator could be provided just to indicate when a viewer is within the optimal viewing range. Audio indications may also be used, including standard alarms or verbal cues. Further, microprocessor 140 may provide the functions of microprocessor 216, eliminating the need for multiple processors. Similarly, memory 218 and clock 217 may be replaced by circuitry normally found in the VDT. It should also be noted that the distribution of function between software, firmware and hardware may be modified as desired by the designer without departing from the scope of the invention. Many other embodiments will be apparent to those skilled in the art upon reviewing the above description. The scope of the invention should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.

Claims

What is claimed is:

1. A method for indicating viewing distance from a video monitor, comprising the steps of: determining a distance of a viewer from the video monitor; and providing an indication of the viewing distance.

2. A method for indicating viewing distance from a video monitor, comprising the steps of: determining a distance of a viewer from the video monitor; comparing the actual viewing distance to a predetermined viewing distance; and providing an indication of the viewing distance relative to the predetermined viewing distance.

3. The method of claim 2, wherein the step of providing an indication further comprises the step of presenting an indicator to a viewer when the viewer is within an optimum viewing distance.

4. The method of claim 3, wherein the step of providing an indication comprises illuminating a first light emitting diode.

5. The method of claim 3, wherein the step of providing an indication comprises displaying text on the video monitor.

6. The method of claim 2, and further comprising the step of updating the indication when the viewer moves.

7. The method of claim 2 wherein the distance of the viewer is determined at the end of consecutive time periods.

8. The method of claim 2 wherein the indication is provided when the actual distance value has significantly changed from a previous actual distance value.

9. A method for indicating viewing distance from a video monitor, comprising the steps of: determining a distance of a viewer from the video monitor; comparing the actual viewing distance to a predetermined optimum viewing distance; and providing an indication of the viewing distance relative to the predetermined viewing distance by illuminating a first segment of an indicator when the viewer is too close to video monitor, illuminating a second segment of the indicator when the viewer is near the edge of the optimum viewing distance, and illuminating a third segment of the indicator when the viewer is within the optimum viewing distance.

10. A method for indicating viewing distance from a video monitor, comprising the steps of: identifying an optimum viewing distance value; transmitting a pulse from the video monitor toward a viewer; receiving a reflection of the pulse from the viewer; calculating an actual distance value of the user from the video monitor as a function of the transmitted pulse and reflected pulse; comparing the distance value to the optimum viewing distance value; and providing a visual indication of the relative values of the optimum viewing distance and the actual distance.

11. A video monitor, comprising: circuitry for determining an actual viewing distance of a viewer in front of the video monitor; circuitry for comparing the actual viewer distance to an optimum viewing distance; and an indicator for representing the actual viewer distance relative to the optimum viewing distance.

12. The video monitor of claim 11 , and further comprising a memory that stores the optimum viewing distance.

13. The video monitor of claim 11 , wherein the circuitry for determining the actual viewing distance comprises an infrared transceiver.

14. The video monitor of claim 11 , wherein the circuitry for determining the actual viewing distance comprises an ultrasonic transceiver.

15. The video monitor of claim 11 , wherein the indicator comprises an optical transceiver.

16. The video monitor of claim 11 , further comprising a display screen, wherein the indicator comprises information displayed on the display screen.

17. The video monitor of claim 16, wherein the indicator comprises a text message displayed in the window.

18. The video monitor of claim 11 , wherein the indicator comprises a light bar having a plurality of stripes, wherein each stripe is separately illuminated.

19. A video monitor, comprising: circuitry for determining an actual viewing distance of a viewer in front of the video monitor; circuitry for comparing the actual viewer distance to an optimum viewing distance; an indicator for representing the actual viewer distance relative to the optimum viewing distance; and circuitry for causing the indicator on a periodic basis.

20. A video monitor, comprising: means for determining an actual viewing distance of a viewer in front of the video monitor; means for comparing the actual viewer distance to an optimum viewing distance; and means for representing the actual viewer distance relative to the optimum viewing distance.