Abstract:
A hand held measurement apparatus and method for in situ optical analysis of a specific display screen or viewing box and associated ambient light environment is disclosed. The apparatus uses a plurality of input collector optics and a plurality of optical filter/photodetectors as a device to separate the light output of an individual monitor screen, display screen, or viewing box and associated ambient light environment into key optical component intensities, the analysis of which are used to optimize the probability for a correct diagnosis by a qualified viewer/analyst. The optical signals are converted into digital electrical signals, processed, and compared to previously stored information of the specific viewing display and the viewing display environment in order to determine if the combination of viewing device and viewing environment is either GO (acceptable, in compliance) or NO GO (not acceptable, non-compliant) according to industry standards or approved procedures.

Description:
PRIORITY 
       [0001]    The present invention claims priority under 35 USC section 119 and based upon a provisional application with a Ser. No. 61/280,045 which was filed on Oct. 28, 2009 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    Embodiments of the present invention generally relate to a measurement apparatus and method for rapid verification of critical optical parameters of a specific monitor screen, display screen or viewing box and the ambient lighting of the associated viewing environment. 
         [0004]    The ability to make a correct early diagnosis, for example, of certain forms of cancer, may mean detection of very small, early-stage tumors. This makes subsequent successful remedial action much more likely, resulting in recovery and a potentially longer life for many victims. However, early diagnosis may depend upon a trained viewer&#39;s ability to identify subtle, even minute changes in shading in an x-ray image. 
         [0005]    Traditionally, viewing boxes, which include diffused sources of white light, have been used to back light an image on black and white film that was acquired by passing x-ray radiation through a body to expose film. A trained viewer then analyzes the exposed x-ray films as a means of diagnosis of tumors, etc. This was in part possible because of the large dynamic range of x-ray film. Critical viewing was often performed in a controlled, darkened environment to maximize the image contrast thereby virtually eliminating reflections of overhead lights, etc. from degrading the viewed image. 
         [0006]    More recently, x-ray images, displayed on high resolution, monochromatic cathode ray tube (CRT) screens and color computer monitor screens, are replacing lamp-based viewing boxes. These images are digital in nature, replacing the need for film and film archival, with digital archival and ease of electronic copy, transfer and storage. However, digital images lack the dynamic range of film, and often cannot be viewed in an environment with the lights totally off, for example, when portable x-ray machines are used. Also, since monitors are not as stable as lamp-based viewing boxes, due to degradation, etc., the quality of the displayed image may not be adequate to minimize misdiagnosis. 
         [0007]    Display and monitor manufacturers have attempted to mitigate the viewing device degradation issue by several methods: For example, by including an internal means to sample the light signal generated, or by including a built-in external monitoring device that is tethered to the monitor to aid in monitor calibration. The former method does not actually measure the light output from the point of view of the viewer, and the latter method is only available on a few monitor systems, and not appropriate for general use. Neither method accounts for the reduction in viewing screen contrast due to the ambient light issue. 
         [0008]    In addition, new more energy-efficient lighting technologies are emerging, for example Organic Light-Emitting Diodes (OLEDs) and High Brightness Light-Emitting Diodes (HB-LEDs), and are appropriate for displays, display backlighting and industrial lighting. These and other technologies rely on limiting the spectral emission to the visible spectrum, thereby reducing energy that is usually wasted as heat, for example, as in incandescent lamps. Also, the quality of the emitted light is often preferred to light emitted, for example, from fluorescent lamps. However, these low-energy technologies rely on narrowband spectral emission which further complicates the interaction of the light emitted from the display screen, the ambient lighting, and ability of a qualified viewer/analyst to make a correct diagnosis. Initially these new lamps will be more expensive than the lamps they replace, but lighting quality and full lifetime costs should prevail in industrial applications, especially those which are as critical as medical diagnosis. 
         [0009]    Standards have been written to quantify the minimum acceptable monitor optical parameters, such as light output intensity, monitor white point color, etc., and the ambient lighting requirements of the viewing surround. 
         [0010]    2. Description of Related Art 
         [0011]    These standards often require a calibration-traceable, precision optical instrument, such as a filter photometer, filter colorimeter, or spectrally-based variants, common in the art for the measurement of emissive sources such as computer monitor screens, and which also contain an optical input means for the measurement of reflective sources, such as the ambient light incident on computer monitor screens. Designed primarily for laboratory use by skilled users, these high quality variants are sufficiently accurate for monitor verification and alignment. However, they are both bulky and expensive, and thereby not suited for rapid and frequent use by operators in situ, nor are they optimized for a specific monitor screen and viewing situation. 
         [0012]    There are two general classes of optical instrument means used to measure the intensity and color of emissive sources such as monitors, displays, and viewing boxes: Those based on the photoelectric tristimulus method and those based on the photoelectric spectral analysis method. 
         [0013]    The photoelectric spectral analysis-based instruments for this application are generally called spectroradiometers or spectrocolorimeters. This method relies on an optical input means to acquire the optical signal, and uses either a dispersive element, and/or multiple or variable narrowband filters to divide the spectrum of the light signal emitted by the display monitor screen into narrow component bands of color. The light intensity levels of the spectral component colors are then converted to electronic signals by the photoelectric detecting device or devices, digitized, and processed by the computer/controller. Outputs are usually general purpose radiometric, photometric and colorimetric parameters, and are not optimized for a specific monitor screen and viewing situation or viewers. 
         [0014]    The strength of this technique is high accuracy, especially for structured light sources such color monitor screens and new narrow band, energy efficient ambient sources of light. The major deficits, besides the aforementioned bulkiness and expense of these devices, is their reduced sensitivity due to the low signal levels in the narrow spectral component bands, and their lack of ruggedness, requiring constant recalibration. 
         [0015]    Broadband optical filter/photodetector-based instruments are generally called photoelectric tristimulus colorimeters, because they divide the spectrum of the emitted light signal into much wider bands of color thereby mitigating the sensitivity issue, and are often filtered to approximate CIE tristimulus color-matching functions. 
         [0016]    A photoelectric tristimulus colorimeter is used to measure the color of the light emitted from a light source, such as a computer display screen. An emissive photoelectric colorimeter directs the light through input optics to three or four photodetectors. A primary filter (green, red or blue) is positioned in front of each photoelectric detecting device. Each primary filter conforms, as closely as possible, the spectral sensitivity of the photoelectric detecting device to a linear combination of the color-matching functions. A measuring device, which is connected to the photoelectric detecting devices, reads or measures the intensity of the respective primaries or tristimulus values in response to the incident light. Although it is theoretically possible to design primary filters exactly corresponding to an ideal, it is practically impossible to manufacture primary filters having transmission factors exactly corresponding to the ideal. This is because an error is inherent in measuring primary or tristimulus values of the color sample. This is a spectral mismatch error and is caused by differences between actual and theoretical transmission factors of the primary filters. 
         [0017]    Many past attempts have been made to overcome the inherent tristimulus spectral mismatch error with varying degrees of success, associated cost and complexity. 
       U.S. Patent Documents 
       [0000]    
       
         U.S. Pat. No. 6,819,306 November 2004 Cooper 
       
     
       CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0019]    The present application contains subject matter related to U.S. Pat. No. 6,819,306 by Ted J. Cooper entitled “Color correcting and ambient light responsive CRT system” which is incorporated by reference in its entirety. Mr. Cooper describes a display system including an optical sensor system as a light emitting color display system having an optical sensor system comprising: a plurality of photosensors directed towards and away from said light emitting color display system for respectively providing a plurality of display and ambient color outputs proportional to the light energy applied thereto respectively from and away from said light emitting color display system, each of said plurality of photosensors associated with a color of light respectively from and away from said light emitting color display system; a control system for controlling each color of light from said light emitting color display system; and a processing system connected to said plurality of photosensors and said control system, said processing system responsive to said plurality of display and ambient color outputs to compare said plurality of display and ambient color outputs over time with an initial plurality of display and ambient color outputs and including a mechanism for providing information to allow compensation for color differences respectively from and away from said light emitting color display system over time. 
         [0020]    None of the present art solutions address the ability to rapidly affirm that a specific viewing display device screen and viewing environment is acceptable or not acceptable by means of a GO or NO GO indication. 
       DESCRIPTION OF THE INVENTION 
       [0021]    The present invention includes various embodiments for a hand held measurement apparatus and method for in situ optical analysis of a specific display screen or viewing box and associated ambient light environment. 
         [0000]    1. One embodiment is the design of a portable, hand held solid-state optical light intensity and color-measuring apparatus that can be optimized for a specific monitor viewing screen and associated viewing environment for the rapid verification of monitor viewing environment performance per industry standards. The solid-state optical light intensity and color-measuring device includes both a plurality of input optics and a plurality of broadband and/or narrow bandpass optical colorant filters and light detector channels that are selected to optimize the performance of a specific monitor viewing screen and viewing environment. The colorants comprise optical filters and light passes through the filters to cause the light detectors to produce an output electrical signal proportional to the input light signal. The output of all the detectors can be combined by the included processor to approximate the spectral responses of one or more CIE-like color-matching functions, and/or used to more accurately assess the narrow-band nature of the incoming structured light signal. The internal microcontroller software module determines the resulting GO/NO GO status by being in a first predetermined state or a second predetermined state and displays the result and predicts when probable non-compliance may occur.
 
2. A second embodiment is the design of a closed-loop automated or semi-automated test method for said viewing screen verification and/or monitor self-calibration/alignment including the said optical measurement apparatus from the first embodiment with an external computer and application-specific software test modules. The said optical measurement apparatus is either affixed adjacent to the screen or mounted on a positioning device adjacent to the screen and placed at a specific location. An external computer is commanded to display a certain test pattern or light intensity level and the said optical measurement apparatus evaluates and/or records the measured results. The cycle is repeated until the test is completed.
 
3. A third embodiment is the design of added capability to the said optical measurement apparatus from the first embodiment, with a device to update, customize outputs or add optional software application modules remotely, e.g., via the internet, to insure ongoing compliance to future standards, etc., after initial purchase.
 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]    The foregoing objects, features and advantages of the invention will become more apparent from a reading of the following description in connection with the accompanying drawings, in which: 
           [0023]      FIG. 1  is a block diagram illustrating a measuring device; 
           [0024]      FIG. 2  is a perspective view of a Measuring Apparatus Housing with a partially cut away sectional view of light Collector A and a plurality Optical Filters and Photodetectors; 
           [0025]      FIG. 3  is a perspective view of a Measuring Apparatus with partially cut away sectional view of a light Collector B and a plurality Optical Filters and Photodetectors; 
           [0026]      FIG. 4  is a detailed block diagram of a Measuring Apparatus; 
           [0027]      FIG. 5  is a block diagram of a measuring apparatus and a remote computer; 
           [0028]      FIG. 6  is a detailed block diagram of circuitry of a measuring apparatus. 
       
    
    
     DETAILED DESCRIPTION 
       [0029]    Reference now should be made to the drawings. 
         [0030]    Referring more particularly to the drawings, a device  100  for measuring light L from a source  102   a  is illustrated in  FIG. 1 . As described in detail below, the measuring device  100  may be utilized for measuring light from a variety of luminance sources, such as sources like CRT, LED, LCD, Viewing box displays. According to a number of embodiments, the measuring device  100  is configured to measure light from a source in situ, that is, at the installation site of the source. One embodiment in which this feature is useful is where the measuring device  100  is configured to test the brightness of displays. Other embodiments will also be discussed below. 
         [0031]    According to a number of embodiments, the device  100  includes a measuring apparatus  104  and a luminance collector  106   a . The measuring apparatus  104  may include a detector  108   a , circuitry  110  for processing output signals from the detector  108   a , and an output  112  such as a display. With additional reference to  FIG. 2 , the collector  106   a  engages with the measuring apparatus  104  such that light L from the source  102   a  is incident on the detector  108   a , which incident light is indicated by L. In many embodiments, the collector  106   a  is configured to be releasable engageable with the measuring apparatus  104 , which will be discussed in more detail below. 
         [0032]    According to a number of embodiments, the device  100  includes a measuring apparatus  104  and an ambient integrator  106   b . The photometer  104  may include a detector  108   b , circuitry  110  for processing output signals from the detector  108   b , and an output  112  such as a display. With additional reference to  FIG. 2 , the collector  106   b  engages with the measuring apparatus  104  such that light L from the source  102   b  is incident on the detector  108   b , which ambient light is indicated by L′. In many embodiments, the collector  106   b  is configured to be releasable engageable with the measuring apparatus  104 , which will be discussed in more detail below. 
         [0033]    Referencing  FIG. 2 , the measuring device  100  may be configured to measure light from a plurality of light sources  102   a ,  102   b , . . .  102 N. As shown, each source  102  may have a predetermined configuration or a predetermined size that is different from the other sources. In these embodiments, the measuring device  100  may include a plurality of collectors  106   a ,  106   b , . . .  106 N each having a light collector that is configured to complement the configuration of a respective one of the sources  102 . In addition, each collector  106  may include engagement structure  126  that is configured to releasably engage with complementary engagement structure  128  disposed on the photometer  104 . Accordingly, in a number of embodiments, light from a plurality of sources  102  may be measured with a single measuring apparatus  104  and a plurality of interchangeable collectors  106 . 
         [0034]    Referencing  FIG. 2 , in a number of embodiments the photometer  104  may be a portable hand-held device including a body  134  and a head  136 , with the head being configured to receive the collector  106 . The body  134  may house the circuitry  110  and the output  112  (see  FIG. 1 ), and the head  136  may house the detector  108 . The head and body  134  and  136  may be connected by a swivel connector  137 . 
         [0035]    Referring to  FIG. 4 , a light collector is selected from a plurality of input optical light collectors  106   a ,  106   b  and depends upon the optical parameter being measured. For example measurement of viewing display screen parameters from Source A  102   a  requires imaging input optics light Collector A  106   a  per  FIG. 2 , while the measurement of ambient lighting Source B  102   b  requires a diffuse input optical light Collector B  106   b  per  FIG. 3 . Referring to  FIG. 2  or  3 , Housing  104  of the hand held Measuring Apparatus  100  is positioned adjacent to the viewing display screen Source A. 
         [0036]    Again referring to  FIG. 4 , the collected light signal La or Lb passes through one or more of the plurality of Optical Filter/Photodetector  108   a    108   b  channels simultaneously and is converted into parallel electrical signals, amplified by Autoranging Amplifier Circuit  146 , digitized by the Dual Slope A/D Converter  148 , processed and evaluated, by the integral Microprocessor  138  which may be connected to control switches  166  and stored in the internal memory per an application-specific software program module. The A/D converter  148  may be connected to a voltage regulator  158  for voltage regulation which may be connected to a power supply  154  which may be connected to a switch  160  to control the power. For rapid verification, said apparatus also includes software that contains the key optical viewing parameters and limits of acceptability and calibration data. The resultant plurality of Outputs  112  include measurement GO/NO GO status to indicate a first predetermined state (GO) or the second predetermined state (NO GO), the results of which is displayed on a Touchscreen Display  150  readout, and archival for future comparisons and/or ongoing monitoring to predict a potential out-of-tolerance status before occurrence also displayed on Touchscreen Display  150 . Output  112  data may also be sent to the host computer by hardwired or wireless interface Transmitter/Receiver  178  for further archival, transfer, automatic test, etc. 
         [0037]    The exact apparatus Optical Filter/Photodetector  108  elements are selected at the time of purchase from a list of candidates by the manufacturer to be the most optimal given the specific classes of monitor or viewing screen technology lighting signal La from Source A  102   a  and viewing environment lighting signal Lb from Source B  102   b  (monochrome or color CRTs, LCDs, LEDs, OLEDs, HB-LEDs, etc.) to be measured. The selection of optical filter elements is dependent upon the nature of the light signals La emitted by the display viewing screen, the ambient surround light signal Lb, and applicable industry standards and approved procedures. Optional software modules are anticipated to further customize Outputs  180  so as to maintain compliance with future industry standards. 
         [0038]    Light may be characterized by a number of parameters, including intensity and color. According to some of the embodiments, the detector  108   a    108   b  may provide an output that is indicative of at least one parameter of the light L, e.g., intensity. Referencing  FIGS. 1 and 4 , the circuitry  110  may include a processor  138  for processing the output of the detector  108 . Based on this processing, the display  112  may provide an indication of the parameter of the light L responsive to the output of the detector. For example, the display  112  may output a numeric indication of the value of the intensity. Alternatively, the display  112  may output an indication on whether the intensity meets a predetermined threshold. In addition to a visual display such as an LCD, the output  112  may provide an audio output. 
         [0039]    The measuring apparatus circuitry  110  may also include a converter  140 . In some of the embodiments, the detector output may be an analog signal, with the converter  140  digitizing the signal for the processor  138 . 
         [0040]    A number of embodiments of the measuring device  100  may include circuitry  110  as shown in  FIG. 4 . For example, the converter  140  may include an amplifier  146  connected to the detector  108  for amplifying the output signal therefrom. The converter  140  may include an analog-to-digital (A/D) converter  148  for converting the amplified signal to a digital signal for the processor  138 . As mentioned, the output  112  may include a display, such as a liquid crystal display (LCD)  150  with a driver circuit  152  for receiving output signals from the processor  138 . 
         [0041]    A power supply  154  may include a battery  156  connected to a voltage regulator  158  for supplying power to the other components of the circuitry  110 . An ON/OFF switch  160  may be provided for actuating the measurement of the light L. 
         [0042]    Any number of control switches  166  may also be provided for actuating additional functions. For example, based on the signal from the detector  108 , the processor  138  may be configured to estimate when the intensity of the light L from the source  102  falls below a threshold. As mentioned, the intensity and the critical parameters of the display over time. Accordingly, based on known degradation characteristics, for example, stored in a memory  167  (see  FIG. 4 , the processor  138  may compare the measured value of critical parameters of the display with the known characteristics to estimate when the intensity will fall below a certain level or threshold. The display  112  may then provide an indication of the same. 
         [0043]    According to a number of embodiments, the measuring device  100  may be configured to transmit data wireless to a remote location. More specifically, with further reference to  FIG. 4 , the measuring apparatus circuitry  110  may include a transmitter  178  in communication with the processor  138 . 
         [0044]    Accordingly, responsive to the signal received from the detector  108 , the transmitter  178  may wirelessly transmit a signal to a remote unit  180 , which signal is indicated by W. In some of the embodiments, the calibration circuit  142  may receive calibration signals from the remote unit  180  for calibrating the converter  140  depending upon the parameters of the source  103 . 
         [0045]    The remote unit  180  may include an electronic information device capable of receiving data wirelessly such as a personal digital assistant (PDA), a palm-top or lap-top computer, a cellular device, or a desk-top computer with a wireless modem. Although the drawings indicate one-way data transmission, the circuitry  110  may be configured to receive data wireless as well; i.e., in certain embodiments, the transmitter  178  may be configured as a transceiver  178 . 
         [0046]    In addition to determining the type of source based on parameters as discussed above, in other embodiments the measuring apparatus  100  may be configured to determine a particular individual source installed at a specific location. More particularly, with reference to  FIG. 1 , each source  102  to be measured may include an identifying marker  192  that includes information specific thereto, e.g., a barcode. Complementarily, the measuring device  100  may include a reader  194  for reading the data of the marker  192 . The reader  194  may be disposed on the collector  194  as shown. 
         [0047]    When the measurement of the light L is completed, data associated with the measurement and the source  102  may be sent to a remote computer  196  with a database  198 . Based on the received data, the computer  196  may look up in the data base specific information on the source  102 , for example, manufacturer name, warranty information, operating parameters, and so on. 
         [0048]    While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the invention to the particular forms disclosed.