Abstract:
A device and method for adjustment of a work place illumination in computerized image presentation, a detection device being arranged to detect the current light and/or contrast values of at least one active presentation surface, that the detection device is connected to a control and adjustment device arranged to automatically adjust the work place illumination of the presentation surface depending on reference values determined in the control and adjustment device in relation to the current light and/or contrast value of the presentation surface.

Description:
TECHNICAL FIELD OF THE INVENTION  
       [0001]     The present invention relates to the field of image ergonomics in computerized work for display of images on a presentation surface, in particular in computer terminal work.  
       BACKGROUND OF THE INVENTION  
       [0002]     So-called workstations for computer terminal work are in general embraced by the description below but in particular medical applications with the purpose of making diagnoses based on anatomical images of focused objects.  
         [0003]     The diagnostic examination work of patient images from X-ray, MR (magnetic resonance imaging scanner) and ultrasound examinations requires great concentration and is more or less trying depending on prevailing circumstances regarding illumination and ergonomic functions with regard to strain and load.  
         [0004]     A large disadvantage upon analogous examination of X-ray film, which is transilluminated by a light field lying behind, has always been disturbing stray light outside the limits of the film, which is both tiring and makes the diagnosis of examined objects more difficult. It is true that this can be remedied by delimiting dimming curtains, which however require both concentration and time to manoeuvre and not the least depending on the occurring different film sizes.  
         [0005]     Another disadvantage of the analogous technique is the risk of underexposed and overexposed images, i.e., light and dark films, respectively.  
         [0006]     Upon change to digital examination by computerized display devices, the disturbing-light problem becomes negligible and too light or dark images are fixed by so-called image manipulation.  
         [0007]     The difference in light intensity between analogous negatoscopes and display devices is about factor 10, but counted in light transmission, the difference is negligible and occasionally the opposite.  
         [0008]     Therefore, it is not unusual that the user erroneously thinks that the sharpness and contrast of the details on the display device are improved by a weak surrounding illumination.  
         [0009]     Too low a light intensity of the surrounding illumination in relation to the display device may have the opposite effect and become tiring by generating so-called melatomia, i.e., sleep requirement. Upon trying to focus on adjacent papers having text, also the reading is made more difficult due to erroneous luminance ratio.  
         [0010]     The National Swedish Board of Health and Welfare is, for instance, of the opinion that good contrast for doing computer terminal work is at hand if the luminance ratios between adjacent surfaces in the working area, i.e., so-called infield, surround field and outer field of vision, should be of 5:3:1. The infield is within a radius of about 20 cm from the focus of the examiner, surround field within a radius of about 40-50 cm and outer field of vision beyond that.  
         [0011]     In conclusion, the following primary physiological factors are valid for the function of the eye and working capacity-decreasing results: At a large pupil, the depth of field of the eye decreases, thereby increasing requirements on correct viewing distance.  
         [0012]     Too weak light deteriorates the detail viewing in varying degree.  
         [0013]     From this, anybody realizes that the combination mentioned above considerably increases the risk of imperfectly made diagnoses, such as, e.g., undiscovered tumours or other symptoms being life-threatening or serious to the patient.  
         [0014]     The number of digital workstations varies with the size and extent of the examination unit. A smaller department comprises as a rule 4-8 workstations and a larger 20-30 workstations. Even if the workstations are distributed between various numbers of rooms, it is inevitable that a smaller or greater number of workstations are placed neighbouring each other for reasons of space or organisation. Thereby, upon image analysis and diagnostics, varying disturbances arise in concentration depending on the activity of the department and the amount of movable personnel and not the least incident light from windows, inappropriately placed general lighting, etc.  
         [0015]     It is true that the imaging technique of the computerized digital workstations offers many technical and ergonomic advantages in order to facilitate image processing, analysis and diagnosis in comparison with analogous technique. Unfortunately, in other respects the equipment is not adapted to existing wishes and ergonomic requirements with regard to vision, strain and workload.  
         [0016]     The shortcomings of the digital workstations in vision ergonomics are summarized according to the following:  
         [0017]     Measures are lacking for facilitating the light adaptation and contrast viewing of the eye at different viewing conditions.  
         [0018]     Screening off of the workstations from disturbing factors such as external illumination, incident glaring daylight via windows as well as activities from other personnel and equipment such as, e.g., other workstations, so-called large screen projectors, copying machines, automatic drink dispensers, etc., is inferior.  
       OBJECT OF THE INVENTION  
       [0019]     By the invention, the drawbacks mentioned above are solved by the fact that the device and the method ensures that surrounding light source(s) is(are) automatically adapted to requirements on luminance ratio in order to thereby optimise the depth of field and detail viewing of the eye.  
       SUMMARY OF THE INVENTION  
       [0020]     By the present invention such as the same is defined in the independent claims, the above-mentioned object is met. Suitable embodiments of the invention are defined in the dependent claims.  
         [0021]     As one embodiment, the invention comprises a workstation for computer terminal work provided with at least one sensor for measuring the light intensity of one or more display devices. In this connection, each display device may be connected to a sensor.  
         [0022]     Additional embodiments within the scope of the present invention are shown below.  
         [0023]     A device for automatically, linearly or progressively, stepwise or variably adapting the surrounding light sources of the workstation in relation to the light intensity of any display device within preset values for optimal or optional ranges in terms of luminance ratios.  
         [0024]     Upper, rear or several light sources ajapted for automatic light intensity.  
         [0025]     A device for measuring at least one light intensity of display devices in computerized workstations either externally by separate sensor or internally in the display device during scanning of the display image in CRT screens or during de-coding of a matrix of LCD (flat) screens for automatic adaptation of the light intensity of surrounding light sources to the light intensity of the display device within preset values for optimal or optional luminance ratio with a settable adjustment of limit values of the light source.  
         [0026]     Distance-adapted automatic adjustment of the light intensity in relation to alteration of the distance between the user and the light source.  
         [0027]     At least two integrated light sources for automatic or optional luminance ratio.  
         [0028]     That the device for adjustment of surrounding illumination is controlled by the display device used for the moment.  
         [0029]     That the display device used for the moment is recorded by means of the device that the user uses for the moments, e.g. the cursor&#39;s positioning by computer mouse.  
         [0030]     That a plurality of display devices may be connected to “one” common cursor.  
         [0031]     That above-mentioned light source is delimited to illuminate surfaces of surround and outer field of vision. That above-mentioned light source is delimited in the direct and indirect viewing direction of the user.  
         [0032]     That the user uses pre-programmed personal settings of light sources and the adjustment thereof.  
         [0033]     Fixed or movable screening off devices in order to delimit, e.g., external light sources and activities in progress by other personnel or equipment, which may affect intended conditions for the work result. That such a screening off device is movable in the horizontal plane.  
         [0034]     To subordinate a light source in the room, being external to the workstation, to the illumination function of the workstation.  
         [0035]     A so-called movement detector in order to detect if a user is within the working space of the invention in order to control internal and external functions having connection to the object of the invention.  
         [0036]     A device for temporary or permanent integration of external light sources for control and adjustment of light intensity as well as connection and disconnection.  
         [0037]     By the invention, the traditional terminal work may be substantially facilitated by supplementing functions that are important for ergonomic vision such as adapted illumination technique and delimitation of disturbing surrounding factors.  
         [0038]     By letting the light intensity of the focused viewing field of the eye controlling surrounding light intensities, a pleasant adaptation of secondary lighting conditions for the surround field and the outer field of vision to the primary infield of the user is attained. By means of this, dissimilarities between the current light intensity of the display device and the surrounding illumination are levelled out.  
         [0039]     The light intensity for the control by the display device of secondary lighting conditions of surrounding light sources may be read in various ways. In a device stand separate from the computer system, a light-sensitive sensor may, e.g., be placed adjacent to the concerned display device or at an arbitrarily distance but preferably focused to the display image.  
         [0040]     For workstations containing more than one display device, it is suitable to provide each display device with an individual light-reading. In order to, in that connection, facilitate the connection of the display device intended for the moment for light control, for instance the pointer (cursor) of the display device being used may activate the local reading.  
         [0041]     In order to adapt said mutual lighting conditions to occurring deviations between different users, the light intensities may be adjusted according to personal wishes either manually or automatically. Thereby, the difference between the light of the display device and that of the illumination may optionally be decreased or increased.  
         [0042]     The light intensity of the controlled surrounding illumination may be adjusted in respect of the absolute lowest and highest level of the light source, as well as in respect of the relative light intensity of the light source. This means that the limit values for occurring light source may optionally vary more or less within a low or within a high light intensity.  
         [0043]     In order not to limit the degrees of freedom of the work place illumination, the user may, as a nomial activity, connect the light intensity controlled by the display device and in disconnected position turn on, switch off or set the light intensity separately for the respective light source.  
         [0044]     In order to additionally facilitate the operation of the invention by the user, the above-mentioned options for individual setting of the controlled light intensities of the surrounding illuminations may be preset according to personal wishes. Said preset values may then be activated, e.g., via a control means intended for the purpose or upon so-called login into the workstation, i.e., when the user enters a code in order to use the current computer system.  
         [0045]     The light sources of the invention are dimmed both directly and indirectly in order to eliminate disturbing light surfaces in the surround field and outer field of vision of the user. Only necessary light surfaces will be illuminated, such as, e.g., the tabletop and delimited surfaces, by automatically or manually set light intensities.  
         [0046]     By using a remote movement detector already known in the art in order to turn on and switch off light sources, the light sources of the invention may be adjusted as well as also concerned external light sources.  
         [0047]     External light sources, which may be both directly and indirectly disturbing, may be delimited or screened off by fixed and/or movable screens. A direct disturbance may, e.g., consist of incident daylight in the eyes of the user through windows and indirect via reflections in the display device.  
         [0048]     Other disturbances, which may be screened off, are intermittent or permanent moving activities in the field of vision of the user.  
         [0049]     External light sources may then be controlled and adjusted by the control means of the invention by direct connection to existing permanent electric installation or via known wireless devices for, e.g., IR communication. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0050]     The invention will now be described in more detail by means of embodiment examples, reference being made to the accompanying drawings where,  
         [0051]      FIG. 1  shows a side view of a work place having a display device equipped with an external device according to the invention,  
         [0052]      FIG. 2  shows a side view of a work place having a display device equipped with an internal device according to the invention,  
         [0053]      FIG. 3  shows a work place comprising three display devices, one of which is equipped with an external device and two are equipped with an internal device according to the present invention,  
         [0054]      FIG. 4  shows a top view of the work place according to  FIG. 2 .  
     
    
     DESCRIPTION OF THE INVENTION  
       [0055]     A presentation surface P, in  FIG. 1  shown as a display device  8  on a monitor  10 , is active when the surface, seen by an observer  11 , shows an display image having determined values of the light properties of light intensity and luminance between different segments in the image. The light properties of the presentation surface are detected by an external detection device  12 , which either scans the display image in order to record maximum and minimum of said values or only detects a mean value of the detected surface. The detection device  12  is mounted at the upper edge of the front rim of the monitor and directed towards the display device  8  thereof. To the detection device  12 , a control and adjustment device  14  is connected, which in turn is connected to a work place illumination  16 . As is also seen in the figure, a movement detector  17  is connected to the work place illumination  16 , the detector being arranged to remotely detect a user&#39;s presence within the area of the work place and being arranged to control internal and external functions. To the control and adjustment device  14 , a redirection means  18  is connected, which upon manoeuvre via a hand wheel  20  provides a disconnection of the control and adjustment device  14  so that a direct manual control of the work place illumination  16  can be effected. The redirection means is provided with a resetting button  19 , which upon activation resets the system in automatic mode. The control and adjustment device  14  is programmable, the levels of the light intensity of the work place illumination in relation to the light properties of the display device being entered. The work place illumination  16  is furthermore provided with screening off devices  21  for direct light flux, on one hand towards the display device  8  and on the other hand towards the observer  11 . Furthermore, an angularly movable light reflector  22  is placed behind the monitor  10  in order to reflect place light in a non-disturbing way.  
         [0056]     According to a second embodiment, shown in  FIG. 2 , of the invention, for instance the centred light value of the display device  8  or the total mean value may be decoded by a device in the form of an internal detection device  30  integrated with the computer system. For so-called CRT screens having picture tubes of the cathode ray type, the scanning of the display image by the ray may be read and for so-called flat screens of LCD type having liquid crystals, the dot matrix may be decoded in the X and Y directions.  
         [0057]     A detailed description of the technique for the internal decoding of the display device becomes too extensive and is therefore limited to a simple principle. The decoding method assumes that the detection device  30  is integrated with the internal image control of the monitor and the external equipment in the form of the control and adjustment device  14  and the work place illumination  16 . In correspondence to what has been shown with regard to the embodiment according to  FIG. 1 , a redirection means  18  is connected, which upon manoeuvre via a hand wheel  20  provides a disconnection of the control and adjustment device  14 . The redirection means is provided with a resetting button  19 , which upon activation resets the system in automatic mode.  
         [0058]     The structure of the display is based on display elements, so-called pixels, oriented as co-ordinates in the X and Y directions. The position and light intensity of the display elements are voltage dependent and are essentially generated by the computer&#39;s so-called graphics card, which in turn is controlled by the computer&#39;s drivers via the CPU unit (Central Processing Unit), which contains the computer&#39;s primary software. By means of the above-described functions and conditions, the exact position and light intensity of the display elements, either in grey-scale or colour scale, may be controlled by the program and the requisite electronics. The invention according to this embodiment is arranged to conversely and simultaneously externally forward this display image information related to an arbitrary part of the image area, in order to be processed in a way corresponding to the case of effecting the detection of the lighting conditions of the display device from outside.  
         [0059]      FIG. 3  shows a work place having three monitors and thus three display devices,  31 ,  32 ,  33 , each one of which is connected to a detection device each, the middle display device of which is provided with an external device while the other two are provided with internal devices. The signals from respective detection device are collected in a master-slave unit  35 , to which also the cursor signal of each monitor is connected, while that one of the screens&#39; cursor controls which is being active for the moment defines master for the adjustment of the work place illumination. Should a plurality of cursor controls be active simultaneously, master is defined by a mutual hierarchy between the screens. Other screens will constitute slaves. The master-slave unit is connected to a control and adjustment device  14 , which in turn is connected to a work place illumination  16 . To the control and adjustment device  14 , a redirection means  18  is correspondingly connected, which upon manoeuvre via a hand wheel  20  provides a disconnection of the control and adjustment device  14  so that a direct manual control of the work place illumination  16  may be effected. The redirection means  18  is provided with a resetting button  19 , which upon activation resets the system in automatic mode. Behind the monitors, a screen wall  37  is located in order to, on one hand, screen off the work place, and on the other hand reflect light in a suitable way.  
         [0060]      FIG. 4  shows a top view of the work place according to  FIG. 3 , the location of the monitors having been made angled so that the observer  11  should be able to study a plurality of images simultaneously and as ergonomically advantageously as possible. Also monitor table  41  and worktable  43  are formed bent for the best ergonomics. In order to additionally screen off the work place from disturbance sources, the table  43  is provided with a left and a right screen wall  44 ,  45  as complement to the screen wall  37 .  
         [0061]     The work places shown in the figures are furthermore associated with a login operation, which identifies the current user. In this connection, the login results in that user data is retrieved from a database so that the user in question always begins to work having his/her own settings. Of course, new settings after the end of the working period may be stored for coming working sessions. Also the choice of a plurality of individual settings may be made.