Abstract:
A handheld colour measurement device includes a housing in which an optoelectronic measurement unit is located which receives measurement light originating from a measurement object, converts it into corresponding electrical measurement signals and processes these measurement signals into preferably digital measurement data characterizing the colour of the measurement object. It further includes passive components required for the realization of different application functions, such as measurement windows and reference standards, which can be selectively positioned into the measurement beam path of the measurement unit. The passive components are positioned in a first housing block ( 100 ) and the opto-electronic measurement unit as a whole in a second housing block ( 200 ). The second housing block is adjustable into several defined application positions relative to the first housing block, in which application positions respectively one of the passive components is located in the measurement beam path of the opto-electronic measurement unit. This special division into two mutually relatively adjustable housing blocks allows an easy realization of a compact colour measurement device suitable for many application functions, which is distinguished by a particular user friendliness.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The invention relates to a handheld colour measurement device, especially a handheld spectrophotometer.  
         [0002]     Numerous variants of handheld colour measurement devices of the generic type are on the market. The best representatives are, for example, the devices “Eye-One” and “Spectro Eye” of the company Gretag-Macbeth AG, Regensdorf, Switzerland, as well as the devices “Pulse” of the company X-Rite Inc., Grandville, Mich. 49418, U.S.A. and “PrintFix Pro” of the company Datacolor, Lawrenceville, N.J. 08648, U.S.A.  
         [0003]     Handheld colour measurement devices of the type discussed herein can be based on any measurement technology. For example, they can be constructed as filter or spectral measurement devices, whereby the latter are the most universal, since as known all of the other parameters of interest in the practice (for example colour values, colour density values etc.) can be derived from the spectral measurement values. The above mentioned known devices are all spectral measurement devices.  
         [0004]     Handheld colour measurement devices can furthermore be constructed as autonomous devices or as measurement peripherals for use in connection with a controlling computer. Autonomous handheld colour measurement devices include all control and display structures required for the measurement operation as well as their own power supply and are furthermore additionally often also provided with an interface for communication with a computer, whereby both measurement data as well as control data can be exchanged with the computer. Handheld colour measurement devices designed as measurement peripherals generally have no inherent control and display structures and are like any other computer peripheral—controlled by the superior computer. For communication with a computer, modem handheld colour measurement devices are often provided with a so called USB-interface (Universal Serial Bus), through which in many cases the power supply is simultaneously achieved (from the connected computer). Such a measurement device concept is described, for example, in U.S. Pat. No. 6,590,648 (=EP 1067369 A1).  
         [0005]     Handheld colour measurement devices of the generic type can be used for many measurement applications depending on the construction and accessories. The classic base application function is the measurement on coloured substrates, typically a printed product. The handheld colour measurement device is thereby manually positioned on the substrate so that the desired measurement location is located in the field of view (capture region) of the measurement device. Many known handheld colour measurement devices are equipped with aiming aids which facilitate the correct positioning of the device for the user.  
         [0006]     A further classic application function is the serial measurement at a multitude of measurement locations on a substrate, typically a colour measurement strip. This application function is normally referred to as Scanning. The handheld colour measurement devices thereby manually guided across the measurement locations, whereby also mechanic guiding devices, for example tracks or the like, can be used.  
         [0007]     In a further application function, several known handheld colour measurement devices can also be used for the measurement on monitors. The handheld colour measurement device is thereby manually positioned on the monitor to be measured, whereby it either touches the monitor or is positioned at a small distance therefrom {preferably less than 20 cm). Furthermore, handheld colour measurement devices can in further applications also be used for the measurement of the ambient light or possibly for (remote) measurements on a projection surface which is illuminated, for example, by an electronic projector (beamer). These points are described, for example in EP 1150559 A1 and U.S. Pat. No. 6,590,648 (=EP 1067369 A1).  
         [0008]     A special case of application functions consists in the execution of calibration or reference measurements on white or possibly also coloured reference measurement objects (for example a white tile or reference colour surfaces). For example, the handheld colour measurement devices known for this purpose are equipped with incorporated reference measurement objects, which can be manually placed into the measurement beam path. Alternatively, some handheld colour measurement devices are equipped which external reference measurement objects as accessories on which the measurement device can be positioned as in the case of the normal measurement.  
         [0009]     Principally, all of the mentioned applications can be realized with most of the known handheld colour measurement devices. However, except for the basic application, more or less significant practical handling difficulties occur in many cases. Either special accessories are required for some applications or the orientation of the measurement device is not possible without auxiliary means or the specific application is overall only relatively laboriously realizable.  
       SUMMARY OF THE INVENTION  
       [0010]     A handheld colour measurement device of the generic type should be improved so that it is easily usable for all mentioned applications and without awkward handling and thereby does not need any accessories.  
         [0011]     The invention is characterized by an handheld colour measurement device with a housing in which an opto-electronic measurement unit is located which receives measurement light originating from a measurement object and converts it into corresponding electric measurement signals and processes the measurement signals into preferably digital measurement data characterizing the colour of the measurement object, and having passive components required for the realization of different application functions, which components can be selectively moved into the measurement beam path, characterized in that the passive components are positioned in a first housing block, that the opto-electronic measurement unit is located in a second housing block, and that the second housing block is adjustable relative to the first housing block to several, defined application positions in which application positions one of the passive components is respectively located in the measurement beam path of the opto-electronic measurement unit. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]     The invention is further discussed in the following by reference to the drawings. It is shown in:  
         [0013]      FIG. 1  an exemplary embodiment of the handheld colour measurement device in accordance with the invention in oblique view;  
         [0014]      FIG. 2  the handheld colour measurement device of  FIG. 1  with a removed outer housing portion;  
         [0015]      FIG. 3  the interior of the handheld colour measurement device of  FIG. 1 ;  
         [0016]      FIG. 4 a  plan view analogous to  FIG. 3 , whereby some functionally unimportant details are omitted;  
         [0017]      FIG. 5 a  Cross-section through the handheld colour measurement device in the plane V-V in  FIG. 1 , whereby only functionally essential details are illustrated;  
         [0018]      FIG. 6  an oblique view of the opto-electronic measurement arrangement of the handheld colour measurement device;  
         [0019]      FIGS. 7-8  two sketches for the illustration of an aiming device provided an the handheld colour measurement device;  
         [0020]      FIG. 9 a  schematic sectional illustration of the handheld colour measurement device for the illustration of the functioning in different applications;  
         [0021]      FIG. 10 a  schematic side view of the handheld colour measurement device with an integrated fastening hook;  
         [0022]      FIG. 11 a  handheld colour measurement device in the practical use during measurement on a monitor; and  
         [0023]      FIG. 12 a  highly simplified principal sketch of a second exemplary embodiment of the handheld colour measurement device in accordance with the invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0024]     As is shown in  FIG. 1 , the outer shape of the illustrated exemplary embodiment of the handheld colour measurement device in accordance with the invention is essentially a square cube with a rounded corner. In practical use, the handheld colour measurement device stands upright as shown in the Figures, the flat underside  101  thereby serving as supporting surface. The depth of the device (perpendicular to the square side surfaces) is significantly smaller compared to the length and height.  
         [0025]     An important aspect of the invention consists in a special division and structural combination of the individual functional components of the device. As illustrated in  FIGS. 2 and 3 , the handheld colour measurement device is divided into two device blocks  100  and  200  which can be moved, relative to one another, into different, defined positions. In the illustrated exemplary embodiment, the first device block  100  is of essentially circular shape and at the Same time forms the largest part of the device housing  1 . The second device block  200  is essentially drum shaped and supported in the first device block  100  for rotation about its axis A. The totality of all possible defined rotational positions which the second block  200  can take up within the first device block  100  is in the following referred to as use positions. As is apparent especially from FIGS.  3  to  5 , the second (in this exemplary embodiment inner) device block  200  includes the complete opto-electronic measurement unit  20  of the handheld colour measurement device. It includes all optical and electronic components which are required for the capture of the measurement light originating from the measurement object as well as its further conversion into corresponding measurement signals and for their processing into preferably digital measurement data. Individually they are, as shown especially clearly in the detailed illustration of  FIG. 6 , an input Jens  21 , a pickup head  22 , a spectrometer  23  with associated electronic  24  for the light converters included in the spectrometer  23  and a processing and control electronic  23  which is preferably built on a flexible and, for reasons of space savings, folded circuit board. For communication with an external computer, a USB-interface  26  is provided through which the Power supply is also carried out at the same time. For remission measurements on measurement objects which themselves do not illuminate, a light source  27  is further provided in the form of a white light emitting diode, which is also controlled by the processing electronic  25 . For gloss measurements (measurements of measurement light which is reflected in a specific direction by the measurement object), an addition optical sensor  29  ( FIG. 5 ) can be provided as generally known, opposite the light source  27 , as well as possibly a projection optic, which images the light source reflected on the surface to be measured into the optical sensor. Lenses, mirrors, diffractive elements or a shutter can be used, for example, as imaging elements.  
         [0026]     A sufficiently large opening  28  through which the measurement light from the measurement object enters into the interior of the second device block  200  and through which also the Illumination light of the light source  27  passes, is provided in the wall of the second device block  200  opposite the intake lens  21 .  
         [0027]     The opto-electronic measurement unit  20  is of conventional construction. A detailed description including its connection to an external Computer is found, for example, in US 2005/0052648 A1 (=EP 1507134 A1) and U.S. patent application Ser. No. 11/355,140 of Feb. 15, 2006 (=EP Patent Application No. 06001006 of Jan. 18, 2006). The content of these prior art documents is included in the present disclosure by reference. The person skilled in the art does therefore not require any further description in relation thereto.  
         [0028]     In the illustrated exemplary embodiment, the opto-electronic measurement unit  20  is constructed as a grating spectrophotometer. Of course, the opto-electronic measurement unit  20  can also be based on other technologies. Especially, the measurement unit  20  can be constructed as a colourimeter, which is based on three or more filters adapted to the visual perception. The spectrophotometer can furthermore be realized instead of with a grating with at least 3, but typically 6 to 16 filters, which are not specifically adapted to the visual perception. Finally, the measurement unit  20  can also be based on the principle of a single photo diode which is sequentially illuminated by several coloured light sources (for example LEDs). In all mentioned cases, the measurement unit can also be realized by distributed elements instead of in the form of a compact subsystem,  
         [0029]     The illustrated handheld colour measurement device is further constructed as a peripheral device for connection with an external computer, which means all functions are controlled by the external computer through the communication interface  26  (preferably a USB-interface) and the measurement data produced are transmitted to the computer, where they can be further processed. Of course, the handheld colour measurement device can also be constructed as an autonomous measurement device whereby the additionally required functional elements (control and display units, power supply) must be provided in the device itself.  
         [0030]     All passive components of the handheld colour measurement device are housed in the first (here outer) housing block  100 , which are necessary for the different applications of the measurement device. Essentially, those are various measurement windows  111 - 114  in the surrounding walls of the first housing block as well as a white reference standard  115  in the inner periphery of the first housing block and possibly also colour reference standards  116 , which are used for the adjustment or calibration of the device. This is schematically illustrated in  FIG. 9 . The handheld colour measurement device is in this example equipped for the applications “spot measurement” (usual measurement at a single measurement location on a substrate), “serial measurement” (automatic measurement at a series of measurement locations on a substrate), “monitor measurement”, “projector measurement”, “ambient light measurement”, “white reference measurement” and “colour reference measurement”.  
         [0031]     Each specific application is associated with a use position of the second housing block  200  relative to the first housing block  100 , in which use position the measurement opening  28  of the second housing block  200  is located in front of respectively one of the measurement windows  111 - 114  or the white reference standard  115  or the colour reference standards  116 . In  FIG. 9 , the measurement opening  28  is located, for example, in front of the measurement window  111  located in the flat base wall  101  of the first housing block. The selection of the different applications for the adjustment of the colour measurement device to the different applications is then carried out by corresponding (rotational) adjustment of the inner housing block  200  relative to the outer housing block  100  (see especially  FIG. 9 ).  
         [0032]     In order to facilitate this rotational adjustment, it is practical to shape one or both of the housing blocks so that they can be gripped well by the fingers of the user. This can be achieved, for example, by corresponding bulges, openings, recesses, etc. A bulgeshaped protrusion  201  of the second housing block  200  is apparent in  FIGS. 1, 2  and  10 .  
         [0033]     A main measurement window  111  is positioned in the flat base wall  101  of the first housing block  100  for the spot measurement, the most common application. Furthermore, a foldable sighting element  120  is located in the region of this main measurement window  111 . As shown in  FIGS. 7 and 8 , the sighting element  120  is reset into the base wall  101 . In order to position the handheld colour measurement device on the measurement point, the aiming aid  120  is folded out by Operation of a release button  121  (FIGS.  1  to  4 ) and positioned with its target opening  122  on the measurement spot. The measurement device is thereby held obliquely so that the user (eye symbol E) can look through the sighting element  120  onto the measurement spot. Subsequently, the measurement device is righted up and the aiming aid  120  is thereby again folded back into the base wall  101 . One proceeds analogously for serial measurements. As soon as the colour measurement device is positioned on the first measurement spot, a serial measurement process (“scan”) is initiated and the colour measurement device is thereby simultaneously moved manually along the line of measurement locations, generally a colour measurement strip. It is understood that this is only reasonably possible with measurement Fields of a sufficiently large surface. However, the scanning along a measurement strip is highly facilitated by the relatively small size of the supporting surface of the colour measurement device. This can be further supported by suitable markings in the housing block  100 . Furthermore, the sliding can be supported by corresponding elements in the base wall  101 . Such elements can be gliding dots, gliding strips, rollers, balls, wheels, etc.  
         [0034]     For measurements on a monitor, the outer housing block  100  is provided with an integrated hook  140  apparent from  FIGS. 10 and 11  by which the handheld colour measurement device can be suspended on the monitor M to be measured, as shown in  FIG. 11 . The measurement of the monitor is thereby carried out by way of the main window  111  in the flat base wall  101  of the first housing block  100 . The hook  140  is removably fastened to the first housing block  100  in a suitable manner and connected therewith by way of a short string, or chain, or a wire, or a rope  141 . Since the hook is a fixed component of the device, the so far common cumbersome mounting of an accessory for the fastening to the monitor is obviated. By mounting the handheld colour measurement device to the monitor by way of a hook, the use of a heavy counterweight is obviated.  
         [0035]     Alternatively, a monitor measurement window  112  can be provided for the measurement on a monitor. This window can also be located at the side of the housing. It is furthermore possible to integrate the monitor measurement window  112  into a projector measurement window  114  (see further below). The colour measurement device can thereby be simply positioned in front of the monitor to be measured and the so far common cumbersome mounting on the monitor by way of accessory parts is obviated. This application can be carried out in addition to or instead of the above mentioned measurement for which the device is hung on the monitor and is in contact with the monitor.  
         [0036]     An ambient light measurement window  113  is provided in the first housing block  100  for the ambient light measurement, which is about diagonally opposite, which means displaced by about 180°, of the main measurement window  111  at the upper side of the housing block  100 . A scatter disk  113   a  is preferably positioned in this measurement window  113 .  
         [0037]     Finally, a projector measurement window  114  is provided in the rounded part of the housing block  100  for the measurement on projector surfaces, which are illuminated, for example, by an electronic projector (beamer). It is of elongated shape and extends over an arc of about 60°. The measurement light originating from the projection surface to be measured can enter into the colour measurement device through this projector measurement window. The opto-electronic measurement device  20  can thereby be optimally aimed at the projection surface to be measured (elevation angle) without any additional means by rotational adjustment of the second housing block  200  (for example in discrete steps). The lower most part of the projection measurement window  114  can at the same time also form the already mentioned monitor measurement window  112 .  
         [0038]     Generally known detent means are provided to lock the second housing block  200  and thereby the opto-electronic measurement unit  20  in the respectively desired application positions. They can consist, for example, of cutouts  40  at the outer circumference of the second housing block  200  into which a cam  41  in the first housing block engages under spring bias. The cam  41  can thereby also function at the same time as position sensor and can deliver a corresponding position signal to the control electronic  25  which can then be used for the adjustment of the measurement sequences or evaluation of the measurement data required for the respective application function. Of course, the position of the second housing block can also be captured by way of another sensor which detects, for example, markings positioned on the circumferential wall of the second housing block, as symbolically illustrated in  FIG. 9 . The reaching of a defined use position or the snapping into the latter can be signaled to the user of the measurement device in suitable manner either acoustically or optically by way of the control electronic  25 .  
         [0039]     A further intuitive control of the adjusted use positions or functions can be achieved by pictograms which are placed on one housing block and by an index on the other housing block.  
         [0040]     The drum shaped outer shape of the second housing block  200 , which is here illustrated only as an example, has the advantage that in certain application positions, for example during the measurement of a white reference standard or the colour reference standards, all measurement windows  111 - 114  in the first housing block  100  are closed and the measurement device is thereby protected from infiltration of undesired light and dirt. A separate park position for the second housing block  200  can possibly also be provided for this protective function.  
         [0041]     It is possible that individual or all measurement applications are not carried out in internally separate use positions (measurement positions) but separate with the same measurement window. Especially, the functions individual measurement (“spot”) and serial measurement (“scan”), the functions individual measurement, serial measurement and monitor measurement can be carried out in one and the same measurement window. It is further possible to transport the light to be measured for individual or all measurement functions over a certain length and to redirect it by a certain angle, for example 90°. Individual or all measurement windows can thereby be brought into a position optimal for the measurement. Especially for the monitor measurement, the measurement device can be constructed such that it lies flat against the screen to be measured during the measurement. In the described exemplary embodiment, a wired interface  26  is provided for  30  communication within the external Computer. Of course, wireless or infrared interfaces can also be provided.  
         [0042]     For certain applications, namely for the measurement of ambient light, of monitors at a distance or of the reflection from a projector, it can be advantageous to equip the handheld colour measurement device with a tripod mount. This tripod mount is preferably threaded and is located at the housing block  100  preferably at the underside  101  of the device. Finally, it can also be advantageous to provide the colour measurement device with shock absorbing elements, for example foam elements, in order to insure the application even under rough environmental conditions.  
         [0043]     In the exemplary embodiment illustrated in FIGS.  1  to  11 , the second housing block  200  is rotationally adjustably supported in the first housing block  100 . Alternatively, the two housing blocks can also, for example, be movable linearly relative to one another, as is illustrated in the principle sketch of  FIG. 12 . The first housing block  100 ′ thereby forms a supporting base for the measurement device. In this variant embodiment, the mutual adjustability of the two housing blocks  100 ′ and  200 ′ can also be facilitated by corresponding construction of gripping means for the user. The measurement windows and control elements are correspondingly positioned differently than in the exemplary embodiment of FIGS.  1  to  11 .  
         [0044]     These and other variations upon and modifications to the described embodiments are provided for by the present invention, the scope of which is limited only by the following claims.