WO1992012476A1

WO1992012476A1 - Controlling an external device using a visual display screen

Info

Publication number: WO1992012476A1
Application number: PCT/GB1991/002301
Authority: WO
Inventors: Baback Asady
Original assignee: Even Computers Limited
Priority date: 1991-01-10
Filing date: 1991-12-20
Publication date: 1992-07-23
Also published as: AU9105591A; GB9100567D0

Abstract

A computer output arrangement comprises a computer (1) having a visual display screen (2), means for energising a pixel (5) of the display screen in accordance with the desired output signal, means (3) for detecting the resulting light output of the pixel and means (7) for generating the output signal in accordance with the detected light output. Such an arrangement finds particular application in controlling a multiplicity of external devices (9) from the computer.

Description

Description of Invention

"Controlling an external device using a visual display screen"

THIS INVENTION relates to a method and apparatus for generating an output signal from a computer having a visual display screen.

The number of external devices which can be controlled by a computer is governed by the number of output ports with which the computer is provided. Moreover, these ports are frequently hardware dedicated to the control of certain devices, such as printers, modems and loudspeakers. Since the majority of computers are also sequential, normally only one operation can be carried out at a time. For example, if a printing task is being performed, a modem transmission will not be possible until the printing has been completed. Although it is possible to achieve multitasking through switching between different tasks, the effectiveness of such a technique is severely impaired by the overheads and the time factors involved in operating in this manner.

The ability of computers to process data is however quite phenomenal and, with the ever-advancing technology in this field, data processing speeds are reaching ever greater heights. It is therefore a serious deficiency that, although computers are capable of such high speed processing performance, the physical constraints and the communication overheads involved in transmitting the data via the output ports limit the number of such ports and hence the number of external devices which can be controlled by the computer.

SUBSTITUTESHEET One familiar output port is the computer display screen, otherwise known as the monitor or visual display unit (VDϋ) , which is the visual interface between the computer and a human user. Normally, data entered by the user is displayed on the screen for verification and output results produced by the computer are displayed in human-readable form on the screen. Apart from this, the display screen, however, serves no other purpose.

It is an object of the present invention to facilitate and enhance the output of signals from a computer, particularly output signals for controlling external devices.

Accordingly, in one aspect, the invention provides a method of generating an output signal from a computer having a visual display screen, comprising energising a pixel of the display screen in accordance with the desired output signal, detecting the resulting light output of the pixel and generating the output signal in accordance with the detected light output.

The invention also provides a computer output arrangement comprising a computer having a visual display screen, means for energising a pixel of the display screen in accordance with the desired output signal, means for detecting the resulting light output of the pixel and means for generating the output signal in accordance with the detected light output.

In a further aspect, the invention provides an output coupling device for a computer having a visual display screen and means for energising a pixel of the display screen in accordance with the desired output signal, which coupling device comprises means for detecting the resulting light output of the pixel and means for generating the output signal in accordance with

SUBSTITUTESHEET the detected light output.

In order that the invention may be more readily understood, an embodiment thereof will now be described, by way of example, with reference to the accompanying drawing, in which the single figure schematically illustrates a computer output arrangement and output coupling device embodying the present invention.

Referring to the drawing, a computer output arrangement comprises a computer 1 having a display screen 2, light detecting and linking elements 3 each having an input end located adjacent the screen 2 in juxtaposition to a respective pixel 5 of the screen 2. An output end 6 of the light detecting and linking element 3 is connected to a controller 7 which has an ouput connection 8 to an external device 9 to be controlled by the computer.

In use of the illustrated arrangement, each controlled pixel 5 of the display screen 2 is energised by the computer 1 in accordance with a desired output signal. The resulting light output of the pixel 5 is detected by the associated light detecting and linking element 3 and a corresponding signal passed to the controller 7. A corresponding output signal is generated by the controller 7 and delivered via output connection 8 to the respective external device 9 to be controlled.

Assuming that the visual display unit is of the normal cathode ray construction, the pixels 5 of the screen 2 comprise small dots of phosphor which emit light when struck by a beam of electrons. The colour of the light emitted depends upon the physical properties of the phosphor and the intensity of the emitted light depends upon the energy of the electron- beam which is moved across the screen to create the video display. Depending

SUBSTITUTESHEET upon the image to be produced on the screen, the electron beam can be turned on and off as it scans line by line down the screen in a raster which commences at the top left hand corner of the screen and terminates at the bottom right hand corner of the screen. Each raster or frame constitutes only half of the picture to be displayed on the screen and successive frames are interlaced in order to form the complete picture on the screen. Normally, approximately 25 complete frames are displayed per second. Once energised, a pixel glows for a short while and then turns off. However, due to the persistence of vision in the human eye and the fast rate at which the screen display is refreshed, those pixels which are energised by the electron beam appear to remain on until they are turned off by the computer.

Accordingly, each pixel on the screen can be energised and deenergised quite accurately and efficiently, simply by turning the electron beam on or off as it passes the pixel. The pixel turns some of the energy imparted to it by the electron beam into light energy and normally the greater the energy of the electron beam, the greater the intensity of the light output of the pixel. The intensity of the beam can normally be adjusted by the computer, so that each pixel on the screen can be considered as a source of light energy which can be turned on or off at will, with the intensity of the emitted light also being easily controlled by the computer. Thus, if optical detectors or optical fibers, such as the light detecting and linking elements 3, are placed on the screen in- juxtaposition to respective pixels, then the resulting detected light signals can be used to drive external devices, such as device 9. Given the number of available pixels on the screen and the rate of which these can be turned on and off by the computer, the computer screen 2 can thus be turned into an output port capable of driving

SUBSTITUTESHEET a very large number of external devices 9 without any modification of the hardware or any limiting communication overheads. The signal produced can be of the digital type, with the pixel being switched between 0 light intensity and a predetermined light intensity, or could equally be an analogue signal produced by varying the intensity of the light emitted by the pixel over a range of light intensities.

Because a pixel 5 ceases to glow after the electron beam passes it^', the light energy received by a detector juxtaposed to the pixel, or an area of the screen encompassing the pixel, is momentarily terminated until the next time the beam reaches the pixel. In certain cases, this could be of advantage since, in some cases, in order to limit power consumption, the power to a circuit is interrupted at a fast rate while the device remains on because of transients which reduce its response to sudden changes, such as the rapid interruption of the power supply. An electronics example of such a circuit is the Chopper Transformer. Where the controlled circuitry would be sensitive to such rapid changes, a delay circuit may be incorporated to maintain the generated output signal until the electron beam again reaches the pixel concerned.

The frequency of the output signal can be varied by generating the output signal from a plurality of pixels and selecting the spacial separation of the pixels on the screen so as to provide the desired frequency. Thus, each pixel on the screen can only be struck by the electron beam at a predetermined frequency, but the time interval between signals from two pixels depends upon their relative positions on the raster scanned by the electron beam. Accordingly, by varying the distance between a plurality of light detecting elements associated with the same output signal, the frequency of

SUBSTITUTESHEET the output signal may be varied as desired. Signals of different amplitude and frequency may be produced simply by rearranging the light detecting elements on the screen.

Although this technique could be used to generate signals for driving many external devices, often the device has to confirm the receipt of the signal or feed back some other information to the computer. This information is conveyed to the computer through its input ports. The number of the input ports on a computer is limited and is much less than the number of possible output signals from the screen. This may seem at first sight to be a problem but it can be easily overcome.

The signals are generated as the electron beam scans across the screen from left to right producing a series of lines down the screen. Once it gets to the end of the scan line, there is a period (line flyback period) during which the beam is switched off and is returned to the beginning of the next scan line. Also when the beam reaches the bottom right-hand corner, there is relatively an even longer period (field flyback period) during which the beam is turned off and is returned to the top left- hand corner to begin the next frame. During these periods (line flyback and field flyback) no control signals are sent to the external device(s) and it is during these periods that the device(s) being controlled can send the necessary information back to the computer through the computer's parallel or sequential input port(s).

It is envisaged that the method and apparatus of the present invention will find diverse applications. Thus, the majority of signals in the electronic world are digital or analogue electrical signals or light signals and a method or apparatus embodying the present invention

SUBSTITUTESHEET enables all three types of signals to be produced easily and efficiently as computer output signals. Electronic components capable of changing light energy into electrical signals are both cheap and readily available.

In particular, it is envisaged that the invention will find particular application in the field of robotics, where a method and apparatus embodying the invention will enable a great many robots (or other tools) to be controlled almost simultaneously from the screen of the computer which would otherwise require an enormous number of outputs and be subject to considerable communications overheads.

In its application to electronics, a method or apparatus embodying the invention would, as previously mentioned, enable the production of the three main kinds of output signal. Furthermore, because the electron beam strikes a pixel of the display screen at regular intervals, the light signal emitted by the pixel has a predetermined frequency and, as mentioned previously, the frequency of a desired output signal may be varied by providing a plurality of detecting elements and varying their position on the display screen. This enables waveforms of different shapes to be produced from the screen. Also, since there are so many pixels available on the display screen, output signals to different devices may be interleaved by placing the detecting elements appropriately, thereby enabling many tasks to be carried out substantially simultaneously.

With the ever-advancing opto-electronics technology and fibre-optics entering the telecommuni¬ cations field, it is envisaged that signals for transmission could be produced on the display screen of a computer, thereby enabling telephone, telex and telecopier transmissions direct from the computer screen.

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Claims

CLAIMS :

1. A method of generating an output signal from a computer having a visual display screen, comprising energising a pixel of the display screen in accordance with the desired output signal, detecting the resulting light output of the pixel and generating the output signal in accordance with the detected light output.

2. A method according to claim 1, comprising energising the pixel between two discrete levels of light output intensity and generating a corresponding digital output signal.

3. A method according to claim 1, comprising energising the pixel over a range of light output intensities and generating a corresponding analogue output signal.

4. A method according to any one of claims 1 to 3, comprising energising a set of pixels in accordance with the desired output signal, detecting the resulting light output of each pixel of the set and generating the output signal in accordance with the detected light outputs of the set of pixels.

5. A method according to claim 4, comprising spatially separating the pixels of the set on the display screen to provide an output signal of preselected frequency.

6. A method according to any preceding claim, comprising energising a respective pixel or respective set of pixels in accordance with a plurality of desired output signals, detecting the resulting light output from each pixel or set of pixels and generating the respective output signals from the respective detected light

SUBSTITUTESHEET outputs .

7. A method according to any preceding claim, comprising controlling an external device in accordance with the or each output signal generated in accordance with the or each detected light output.

8. A computer output arrangement comprising a computer having a visual display screen, means for energising a pixel of the display screen in accordance with the desired output signal, means for detecting the resulting light output of the pixel and means for generating the output signal in accordance with the detected light output.

9. An output arrangement according to claim 8, wherein the energising means energises the pixel between two discrete levels of light output intensity and the generating means generates a corresponding digital output signal.

10. An output arrangement according to claim 8, wherein the energising means energises the pixel over a range of light output intensities and the generating means generates a corresponding analogue output signal.

11. An output arrangement according to any one of claims 8 to 10, wherein the energising means energises a set of pixels in accordance with the desired output signal, the detecting means detects the resulting light output of each pixel of the set and the generating means generates the output signal in accordance with the detected light outputs of the set of pixels.

12. An output arrangement according to claim 11, wherein the pixels of the set are spatially separated in the display screen so as to provide an output signal of preselected frequency.

13- An output arrangement according to any one of claims 8 to 12, wherein the energising means energises a respective pixel or respective set of pixels in accordance with a plurality of desired output signals, the detecting means detects the resulting light output from each pixel or set of pixels and the generating means generates the respective output signals from the respective detected light outputs.

14. An output arrangement according to any one of claims 8 to 13, comprising an external device connected to the generating means to receive the or a respective output signal of the generating means as a control signal.

15- An output coupling device for a computer having a visual display screen and means for energising a pixel of the display screen in accordance with the desired output signal, which coupling device comprises means for detecting the resulting light output of the pixel and means for generating the output signal in accordance with the detected light output.

16. A coupling device according to claim 15, wherein the detecting means detects two discrete levels of light output intensity from the pixel and the generating means generates a corresponding digital output signal.

17. A coupling device according to claim 15, wherein the detecting means detects a range of light output intensities and the generating means generates a corres¬ ponding analogue output signal.

18. A coupling device according to any one of claims 15 to 17, wherein the detecting means detects the light output of each pixel of a set of pixels and the generating means generates an output signal in accordance with the combined detected light outputs of the plurality of pixels.

19. A coupling device according to any one of claims 15 to 18, wherein the detecting means detects the light output of each of a plurality of pixels or the light output of each set of a plurality of sets of pixels and the generating_^ means generates respective output signals from the respective detected light outputs.

20. A coupling device according to any one of claims 15 to 19, wherein the detecting means comprises one or more light detectors connected to the generating means by respective transmission links.

21. A coupling device according to claim 20, wherein the transmission links comprise fibre-optics.

22. A coupling device according to any preceding claim, wherein the generating means comprises means for connection to an external device to be controlled by the output signal.

23. A method of generating an output signal from a computer having a visual display screen, substantially as hereinbefore described with reference to the accompanying drawing.

24. A computer output arrangement substantially as hereinbefore described with reference to the accompanying drawing.

25. An output coupling device for a computer substantially as hereinbefore described with reference to the accompanying drawing.

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26. Any novel feature or combination of features described herein .

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