Abstract:
A printer with an output image quality control function, comprising: a pattern storage portion for storing evaluation patterns to evaluate quality test items; a pattern output time storage portion for storing output times of the evaluation patterns to evaluate the quality test items; and a print control portion for determining a layout of an evaluation pattern coming into an output time on a recording material based on information of the pattern output time storage portion, and outputting the evaluation pattern from the pattern storage portion onto the recording material.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to a technical field of various printers such as a thermal recording system, a photo-thermographic system, etc., and particularly relates to printers in which quantitative control (quality control of images, which will be referred to as “QC” and especially “printer QC” as quality control of printer images) can be performed in the installation site.  
       BACKGROUND OF THE INVENTION  
       [0002]     Various diagnostic image acquisition systems using X-rays or the like have been heretofore used in the medical field. X-ray machines, CR (Computed Radiography) machines, CT (Computed tomography) machines, MRI (Magnetic Resonance Imaging) machines, etc. have been put to practical use.  
         [0003]     Medical image information acquired by these machines is reproduced as a hard copy on a recording material such as a film or the like by a printer, and used for medical diagnosis by experts.  
         [0004]     For such medical diagnosis based on an image, a monochrome (black and white) image is typically used, and a microscopic structure is observed through a difference of density in the image. Accordingly, the medical diagnosis image is required to have enough high sharpness. It is therefore necessary to perform printer QC such that a fixed quality can be always kept.  
         [0005]     In recent years, there has been a request to define managerial responsibility of medical equipment. From such a request, it has been required to grasp quality control by users, and the equipment has been required to be able to acquire its quality control data easily in the installation site.  
         [0006]     In the background art, here, the quality control data can be grasped through a print of evaluation patterns. Suitable time of testing differs from one quality control item to another. Evaluation patterns have to be outputted every suitable time of testing. However, periodical testing may be forgotten, or printing the evaluation patterns may be forgotten. Further, testing must be frequently carried out for some quality control items. There is also a problem that use of recording materials increases in accordance with the number of test items.  
         [0007]     As background arts, JP-A-2004-237533 and JP-A-2004-122443 are known.  
       SUMMARY OF THE INVENTION  
       [0008]     The present invention was developed in consideration of the aforementioned problems. An object of the invention is to provide a printer with an output image quality control function in which quality control data can be acquired easily and surely and the usage of recording materials can be suppressed.  
         [0009]     The aforementioned object of the invention is attained by the following configurations:  
         [0010]     (1) A printer with an output image quality control function, including a pattern storage portion for storing evaluation patterns to evaluate quality test items; a pattern output time storage portion for storing output times of the evaluation patterns to evaluate the quality test items; and a print control portion for determining a layout of an evaluation pattern coming into an output time on a recording material based on information of the pattern output time storage portion, and outputting the evaluation pattern from the pattern storage portion onto the recording material.  
         [0011]     (2) A printer according to the configuration (1), wherein the evaluation patterns outputted by the print control portion are recorded on a sheet of the recording material.  
         [0012]     Suitable evaluation patterns are printed thus in accordance with output times set for equality test items respectively. It is therefore possible to prevent forgetting to perform a periodical test or forgetting to print evaluation patterns. Thus, it is possible to prevent forgetting to acquire control data.  
         [0013]     Further, evaluation patterns to be outputted at one and the same time are aggregated on a sheet of the recording material. Thus, the number of sheets of the recording material to be used for test data can be reduced as compared with the case where evaluation patterns are recorded for each test item.  
         [0014]     According to the invention, it is possible to provide a printer with an output image quality control function in which patterns for quality test items showing quality control data can be acquired easily and surely and the usage of recording materials can be suppressed. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]      FIG. 1  is a schematic side view showing the configuration of a thermal recording printer with a measuring function according to an embodiment of the invention.  
         [0016]      FIG. 2  is a block diagram showing the schematic configuration of an image quality measuring function portion  24  with an outputted image quality control (QC) function according to the invention.  
         [0017]      FIG. 3  is a view showing patterns for use in density measuring.  
         [0018]      FIGS. 4A and 4B  are explanatory views showing a visual evaluation pattern in this embodiment.  
         [0019]      FIG. 5  is a flow chart for explaining the operation of the outputted image quality control (QC) function in this embodiment shown in  FIG. 2 . 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0020]     An embodiment of the invention will be described below in detail with reference to the accompanying drawings.  
         [0021]      FIG. 1  is a schematic side view showing the configuration of a thermal recording printer with a measuring function according to an embodiment of the present invention.  
         [0022]     A printer  10  shown in  FIG. 1  performs thermal image recording on a thermal recording material such as an optically transparent thermal recording film (hereinafter referred to as “film” simply) F having a predetermined size such as a half size. The printer  10  has a loading portion  12 , a conveyance portion  16 , a recording portion  20 , a tray  22  and an image quality measuring function portion  24 . The recording portion  20  has a print control portion for performing thermal image recording on the film F by means of a thermal head  18  and outputting evaluation patterns. The tray  22  receives the recorded film.  
         [0023]     The film F has a base made of transparent PET (polyethylene terephthalate) or the like. A thermal recording layer is formed on one side of the base. Predetermined units, for example, about 100 sheets of films F are stacked and received in a dedicated magazine  26 .  
         [0024]     This magazine  26  has a cover  28 . The magazine  26  is inserted into the printer  10  through an insertion hole formed in the printer  10 , and loaded in a predetermined position of the loading portion  12  by a known means using a guide, a stopper or the like.  
         [0025]     The conveyance portion  16  has a function to extract the film F from the magazine  26  loaded in the loading portion  12  and convey the extracted film F to the recording portion  20 . The conveyance portion  16  has a sheet feeding mechanism using a sucker  30  for sucking the film F, a conveyance roller pair  32 , a conveyance guide  34 , a cleaning roller pair  36 , a not-shown opening/closing mechanism, etc.  
         [0026]     First, description will be made about the outline of the fundamental operation of the printer  10  in the aforementioned configuration according to this embodiment.  
         [0027]     When an instruction to start recording is issued in the printer  10 , the aforementioned opening/closing mechanism opens the cover  28  of the magazine  26 , and the sucker  30  sucks a sheet of film F, extracts the sucked film F from the magazine  26 , and supplies the extracted film F to the conveyance roller pair  32 . The film F supplied to the conveyance roller pair  32  is guided by the conveyance guide  34  so as to be conveyed to the cleaning roller pair  36 . The film F is sent to the recording portion  20  while dust, grime or the like adhering to the recording surface of the film F is removed by the cleaning roller shown in the upper of  FIG. 1 .  
         [0028]     The recording portion  20  has a thermal head  18 , a platen roller  38 , a conveyance guide  40 , a discharge roller pair  44   a  and  44   b,  a head driving control portion  46 , a cooling fan (not shown) for the thermal head  18 , etc.  
         [0029]     The thermal head  18  is a known thermal head including a thermal head body and a heat sink fixed to the thermal head body. The thermal head body has a thermal storage layer (glaze layer), heating elements and a glaze. The heating elements are made of heating resistors and electrodes and arrayed in one direction (main scanning direction, which is a direction perpendicular to the paper of  FIG. 1 ). The glaze is made of a protective layer or the like. Each heating element of the thermal head  18  is driven to be, for example, pulse-modulated in according to a recorded image by a head driving control portion  46 .  
         [0030]     Here, evaluation patterns outputted by a QC (Quality Control) function which will be described later, such as test patterns for measuring sharpness, are recorded as a recorded image (or a part thereof) according to a predetermined recording system (as will be described later in detail).  
         [0031]     The platen roller  38  rotates the film F in a predetermined velocity while retaining the film F in a predetermined position. The film F is put between the platen roller  38  and the thermal head  18  (or its glaze). The platen roller  38  conveys the film F at a predetermined recording speed in a sub-scanning direction perpendicular to the main scanning direction.  
         [0032]     The film F conveyed through the cleaning roller pair  36  is put between the platen roller  38  and the thermal head  18  (glaze thereof) and conveyed in the sub-scanning direction in that state. Thus, the film F is scanned by the thermal head  18  (heating element array). In parallel to this conveyance, the head driving control portion  46  drives each heating element of the thermal head  18  in accordance with image data so as to heat each heating resistor. Thus, the film F is heated and colored correspondingly so that an image is recorded.  
         [0033]     The film F having the image recorded is conveyed by the discharge roller pair  44   a  and  44   b  and discharged to the tray  22  as a hard copy.  
         [0034]     The image quality measuring function portion  24  controls (checks) the quality of the image in the printer  10  by use of evaluation patterns for measuring the image quality, which patterns are recorded in the film F. The image quality measuring function portion  24  has an image quality measuring control portion  48  and an image quality measuring portion  50 .  
         [0035]     The image quality measuring control portion  48  outputs records of evaluation patterns for measuring image quality to the film F in accordance with at least the recording time of each item to be measured. Further in this embodiment, the image quality measuring control portion  48  sets the layout of the evaluation patterns on one sheet of film, and controls various processes in accordance with measurement of the evaluation patterns and results of the measurement. In these operations, if necessary, the image quality measuring control portion  48  gives an instruction to the head driving control portion  46  to record the aforementioned evaluation patterns by the means of the thermal head  18 , or to receive results of measurement of the recorded evaluation patterns and perform processes in accordance with the received results.  
         [0036]     The image quality measuring portion  50  measures the evaluation patterns recorded in the conveyed film F between the discharge roller pair  44   a  and  44   b,  for example, when QC about sharpness is performed. The image quality measuring portion  50  is constituted by a lighting source  50   a  and a two-dimensional photo-sensor  50   b.    
         [0037]     Here, since the optically transparent film F is a target for measurement, the image quality measuring portion  50  is designed to measure transmitted light. However, when the target for measurement is not optically transparent, it is a matter of course that the image quality measuring portion  50  is designed to measure so-called reflected light.  
         [0038]     In this measurement, the film F may be temporarily stopped in a predetermined position. This is effective in preventing focal misalignment caused by flipping due to the film F moving during the measurement. To this end, in the printer  10  according to this embodiment, a function to control driving of the discharge roller pair  44   a  and  44   b  disposed to hold the image quality measuring portion  50  therebetween is provided to temporarily stop and fix the film F in the measuring position.  
         [0039]      FIG. 2  is a block diagram showing the schematic configuration of the image quality measuring function portion  24  having a quality control (QC) function for an outputted image according to the present invention.  
         [0040]     As shown in  FIG. 2 , in the image quality measuring function portion  24  according to this embodiment, the image quality measuring control portion  48  which is the center of the image quality measuring function portion  24  and also serves as a pattern print control portion is connected to the head driving control portion  46  for outputting an automatic measuring evaluation pattern F 1  and a visual evaluation pattern F 2  which are evaluation patterns to test quality items of an image. Further, the image quality measuring portion  50 , a determination portion  52 , a memory  54 , an evaluation pattern storage portion  56  and a pattern output time storage portion  58  are connected to the image quality measuring control portion  48 . A display  62  for displaying image quality QC results or the like can be also connected to the image quality measuring control portion  48 . Further, the image quality measuring control portion  48  can be also connected to an external system or the like through a network  60  such as the Internet.  
         [0041]     The printer according to this embodiment is not limited especially, but preferably a medical printer for outputting a transparent monochrome film. Such a medical printer is preferably a dry printer needing no wet developing process. A preferred example of the medical printer includes a thermal recording apparatus using a thermal head or a heat mode laser, or a photosensitive heat coloring image recording apparatus using a photosensitive heat developing recording material or a photosensitive thermal recording material.  
         [0042]     Of the automatic measuring evaluation pattern F 1  for automatically measuring the image quality and the visual evaluation pattern F 2  for evaluating the image quality by human eyes, patterns of items in due output time are selected based on data in the pattern output time storage portion  58  as described previously. The selected patterns are determined as to their layout on the film F serving as a recording material by the quality measuring control portion  48  based on data prepared in the evaluation pattern storage portion  56  in advance. The determined layout is stored by the head driving control portion  46 .  
         [0043]     Here, examples of image quality measuring items to be recorded in the automatic measuring evaluation pattern F 1  and automatically measured may include density, format, sharpness, etc. At least one of these items of image quality is automatically measured. For example, a pattern to measure density at three points of high density, middle density and low density is used as a density measuring pattern.  
         [0044]     A visual SMPTE pattern or a practical clinical image such as a chest or knee X-ray photogram is used as the visual evaluation pattern F 2 . The SMPTE pattern is a pattern to examine strain, spatial resolution, contrast, artifact, etc. of an image. The practical clinical image is used for testing as to whether there appears a pseudo-contour or not or whether there is a problem as a diagnostic image or not.  
         [0045]     These image quality measuring items have their own proper measuring times respectively. Some items have to be measured everyday, and some items have to be measured at an interval of about half a year to a year. Data in the pattern output time storage portion  58  are used.  
         [0046]     It is preferable that the automatic measuring evaluation pattern F 1  and the visual evaluation pattern F 2  are recorded in one pattern sheet  71  as shown in  FIG. 3 . In this manner, both automatic measuring and visual evaluation can be carried out on one pattern sheet  71 . Thus, the loss of outputted film can be reduced so that testing can be performed effectively.  
         [0047]     As for the visual evaluation pattern F 2 , only one frame of an SMPTE pattern or a practical clinical image may be outputted to the single pattern sheet  71  as shown in  FIG. 4A . Alternatively, an SMPTE pattern and a plurality of practical clinical images may be outputted (as all-in-one output) to the single pattern sheet  71  as shown in  FIG. 4B .  
         [0048]     In the layout on the single pattern sheet  71 , images can be packed in the automatic measuring evaluation pattern F 1  and the visual evaluation pattern F 2 , and arranged in time series so as to be sorted by measuring time. Any other layout can be set and selected optionally.  
         [0049]     The image quality measuring portion  50  is a measuring means such as a densitometer as described previously. Measured data are sent to the determination portion  52 . The measured data and determination results in the determination portion  52  are recorded in the memory  54 .  
         [0050]     The visual input portion  53  is a portion for manually inputting results of visual evaluation performed on the visual evaluation pattern F 2  by human eyes. The visual evaluation results inputted by the visual input portion  53 , the aforementioned measured values, etc. are also stored in the memory  54 .  
         [0051]     When there is a failure in the image quality measuring portion  50  such as a built-in densitometer or when the image quality measuring portion  50  is not mounted, automatic measuring cannot be carried out in the printer  10 . In such a case, the automatic measuring evaluation pattern F 1  may be measured by an external measuring means outside the printer  10 , and values measured by the means may be inputted into the visual input portion  53 . Alternatively, the external measuring means may be connected to the printer  10  so that data can be inputted directly.  
         [0052]     The memory  54  stores the measured data (image quality data) automatically measured as described above or the determination results thereof, the image quality test results obtained by visual evaluation, etc. as QC data.  
         [0053]     The display  62  can display the QC data or the history of the QC data stored in the memory  54 . The display format is not limited especially. An example thereof includes a liquid crystal panel or the like.  
         [0054]     The printer  10  can be connected to another printer, a system including the printer, a printer QC system on the printer maker side, etc. through the network  60  so that the QC data etc. can be transmitted to the outside.  
         [0055]     The printer  10  can print the QC data from the head driving control portion  46  by itself.  
         [0056]     Further, the printer  10  preferably also includes a function to automatically calibrate the built-in image quality measuring portion  50  such as a built-in densitometer. The calibration method is not limited especially. An example thereof includes a method in which a test piece serving as reference is measured by the built-in measuring portion  50 , and test is performed by comparing a result of the measurement with a proper value.  
         [0057]     The operation of this embodiment will be described below.  
         [0058]      FIG. 5  is a flow chart for explaining the operation of the quality control (QC) function of an output image in this embodiment shown in  FIG. 2 .  
         [0059]     First, in the start of Step S 101 , as soon as the printer is powered on to start work, a QC program of the image quality measuring function portion  24  may be activated automatically. Alternatively, a user may select a QC menu to activate the QC program of the image quality measuring function portion  24 .  
         [0060]     Next in Step S 102 , evaluation pattern output time of each image quality measuring item is set as data of the pattern output time storage portion  58 . The data may be inputted as defaults in the printer manufacturing stage. Alternatively, the user may set the data uniquely.  
         [0061]     Step S 103  is effective in the configuration where the user can issue an instruction to output evaluation patterns desirably. When there is an instruction to output evaluation patterns, the routine of processing moves to Step S 104 . In Step S 104 , output items are specified by the input portion  53 , and the routine of processing moves to Step S 107 . In Step S 107 , the layout of the evaluation patterns on the recording material is determined by the image quality measuring control portion  48 . In Step S 108 , the evaluation patterns are outputted.  
         [0062]     When there is not any output instruction in Step S 103 , the routine of processing moves to Step S 105 , where the last pattern output of each image quality measuring item is compared with data in the pattern output time storage portion  58 , and it is determined whether the evaluation pattern output time of the item becomes due or not. Here, in this embodiment, this step is designed to execute the routine work till the output time becomes due. Generally, however, the printer is usually switched on whenever it is used. In this case, the step may be designed so that the routine of processing moves to Termination Step S 109  when it is concluded once in the determination that the output time does not become due.  
         [0063]     When it is concluded in Step S 105  that the evaluation pattern output time of one image quality measuring item becomes due, the routine of processing moves to Step S 106 . In Step S 106 , it is determined whether or not there are a plurality of measuring items whose evaluation pattern output times become due. When there are a plurality of measuring items, the routine of processing moves to Step S 107 . When there is one measuring item, the routine of processing moves to Step S 108 , where outputting the evaluation pattern of the item is started.  
         [0064]     In Step S 107 , evaluation patterns corresponding to the plurality of measuring items are read from the evaluation pattern storage portion  56 , and the layout on the film F serving as a recording material is set. After that, the routine of processing moves to Step S 108 , where outputting the evaluation patterns is started. In Step S 109 , outputting the evaluation patterns is terminated.  
         [0065]     In the aforementioned embodiment, evaluation patterns are outputted on the assumption that the printer is powered on. Even if the printer has not been used for a long time, there may occur a problem due to deterioration or nonuse of the printer. Therefore, a clock may be provided in a printer so that evaluation patterns of important items can be outputted forcibly regardless of the power state of the printer.  
         [0066]     Here, the automatic measuring evaluation pattern F 1  on the pattern sheet  71  is measured by the image quality measuring portion  50  built in the printer  10  before the pattern sheet  71  in which the evaluation pattern has been printed is sent to the outside of the printer  10 .  
         [0067]     When, for example, the image quality is measured about density, the automatic measuring test pattern F 1  is a density measuring pattern composed of three density patterns for high density, middle density and low density. The density patterns are measured by a built-in densitometer of the image quality measuring portion  50 . The density measuring is performed by scanning the pattern sheet  71  with the densitometer. The densitometer measures densities at three points of high, middle and low densities on the density measuring patterns. Data measured by the image quality measuring portion  50  are sent to the determination portion  52 .  
         [0068]     The determination portion  52  makes determination based on the measured values, and sends the measured data and determination results (QC data) to the memory  54 . For example, this determination is performed by comparing the measured values obtained by measuring the outputted density measuring patterns, with proper values of data stored in the memory  54  as density measuring patterns in advance.  
         [0069]     On the other hand, the pattern sheet  71  where the image quality has been measured automatically is sent to the tray  22  outside the printer  10 . The user visually examines the visual evaluation pattern F 2  recorded on the pattern sheet  71 , and inputs the result of the examination to the printer  10  through the visual input portion  53 . The inputted result of the examination is stored and saved in the memory  54 .  
         [0070]     The QC results are displayed on the display  62  automatically or in response to an instruction given through the input portion  53  by the user. At the same time, the QC data can be printed through the head driving control portion  46  by the printer itself.  
         [0071]     The aforementioned embodiment has been described on the case where the invention is applied to a thermal recording apparatus using a thermal head by way of example. The invention is not limited to this, but can be also applied to various other printers such as photo-thermography etc. Especially the invention is preferably applied to a medical printer where importance is attached to the quality control of image quality for the sake of proper diagnosis.  
         [0072]     Further, it is also preferable that the aforementioned results of image quality measurements are sent to and accumulated in a suitable database installed in a site different from the site where the printer is installed, via a network. In this case, it is possible to get ready for access from another apparatus connected to the network, such as a supervisory center, a work station, etc.  
         [0073]     As has been described above in detail, the printer with an output image quality control function according to the present invention grasps output times of evaluation patterns for image quality, and outputs the patterns to one sheet of recording material automatically. There is a conspicuous effect that it is possible to acquire quality control data easily and surely, and the usage of the recording material can be suppressed.  
         [0074]     This application is based on Japanese Patent application JP 2005-362071, filed Dec. 15, 2005, the entire content of which is hereby incorporated by reference, the same as if set forth at length.