EP1378367B1 - Thermal printing method - Google Patents
Thermal printing method Download PDFInfo
- Publication number
- EP1378367B1 EP1378367B1 EP20020100773 EP02100773A EP1378367B1 EP 1378367 B1 EP1378367 B1 EP 1378367B1 EP 20020100773 EP20020100773 EP 20020100773 EP 02100773 A EP02100773 A EP 02100773A EP 1378367 B1 EP1378367 B1 EP 1378367B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- recording material
- image
- area
- polygon
- transparent
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
- B41J11/00—Devices or arrangements of selective printing mechanisms, e.g. ink-jet printers or thermal printers, for supporting or handling copy material in sheet or web form
- B41J11/008—Controlling printhead for accurately positioning print image on printing material, e.g. with the intention to control the width of margins
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
- B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
- B41J2/315—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of heat to a heat sensitive printing or impression-transfer material
- B41J2/32—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of heat to a heat sensitive printing or impression-transfer material using thermal heads
Definitions
- the present invention relates to hard copy recording of medical images.
- An example of such an image acquisition system is a system based on temporary storage of the medical image such as a radiographic image on a photo-stimulable phosphor screen.
- a digital signal representation of the medical image is obtained by scanning a screen which has been exposed to a radiation image by means of stimulating radiation, detecting light emitted by the screen upon stimulation and converting the detected light into an electric signal representation.
- Another example of such an image acquisition system is a so-called direct radiography system wherein a radiation image is recorded by a two-dimensional array of radiation sensitive elements that, upon addressing, render a digital signal representation of the radiation image.
- a visible reproduction either in the form of a hard copy or a soft copy is generated from a digital medical image.
- the digital signal representation of the medical image is applied to a hard copy recorder such as a thermal printer.
- the hard copy is attached to a viewing box for visual inspection and examination by the radiologist.
- Hard copy images generated from a digital signal representation of an image commonly have a transparent boarder.
- This transparent boarder originates from the fact that hard copy recorders do often not print up to the outer edges of the recording material, i.a. because tolerances on the dimensions of the recording material, tolerances regarding transport and handling of the recording material in the printer etc. are taken into account.
- recording materials used for reproduction of medical images commonly have rounded angles. Since the addressable area on a recording material is commonly defined in terms of a rectangular which fits into the area of the recording material, the distance from the edge of the recording material that is left transparent is also determined by the presence of these rounded angles.
- a well known technique for avoiding the dazzling effect of the transparent boarders is the use of collimating curtains that are partially slided over the hard copy so to cover the transparent parts.
- collimating curtains are not applicable to cover the area where the images are juxtaposed.
- An alternative solution consists in providing an additional black boarder near to the transparent boarder in the boarder region of the image. The hard copies are then put in an overlapping position so that the transparent dazzling area of either of the films in the region between the two images is covered by the black boarder.
- Hard copy recording systems exist that do not require the transparent boarder and that thus inherently solve the above-described problem originating from transparent boarders.
- An example of such a hard copy recorder is a laser recorder. Such systems are capable of printing across the boarder of the hard copy material so that no transparent boarder is created.
- thermal printers do not have this ability.
- Thermal printing is a recording process wherein images are generated by applying image-wise modulated thermal energy to a recording material.
- the applied heat brings about a visible change of optical density in a thermo-sensitive imaging material.
- a particular interesting direct thermal recording material comprises a combination of an organic silver salt in combination with a reducing agent.
- a visible image may be created in such a material by applying image-wise modulated heat to the material which causes the silver ions to be developed into metallic silver.
- the thermal heat is applied to the recording material by means of a print head which consists of a linear array of resistor elements.
- the recording material and the print head are transported relative to each other.
- Electric pulses corresponding with a digital image representation are applied to a thermal print head.
- the resistor elements convert the electrical energy into heat which is transferred to the recording material and generates a chemical reaction resulting in development of a visible image.
- European patent application EP 1 170 140 A1 discloses a method of generating a hard copy of an image on a substantially rectangular heat sensitive recording material. Image pixels are printed within a substantially rectangular printing area.
- Figure 1 shows the components of the thermal printer that are relevant in the context of the present invention.
- the printer comprises a recording head 1 consisting of an array of juxtaposed resistor elements in a line-wise arrangement and associated electronic control and driver circuitry.
- a recording material 2, which may be in sheet or web form, and the recording head 1 are transported relative to each other.
- the recording material is secured to a driven rotatable drum 3 so that the recording material is advanced past the recording head 1.
- the recording material in this example comprises a support coated with a thermo-sensitive layer containing an organic silver salt.
- the organic silver salt When being heated by the elements of the recording head the organic silver salt is locally reduced to metallic silver thereby producing a density that is proportional to the amount of energy transferred to the recording material at a specific location.
- Energy is applied to each of the resistors under control of an electric signal.
- the amount of energy that is applied to an element of the recording head is controlled in accordance with the density to be reproduced by this element.
- the recording head of this thermal printer comprises 4992 individually energisable resistors (10) (at a resolution of 508 dots per inch).
- This number of resistors is subdivided into a plurality of groups of a number of individual resistors.
- the head comprises a plurality of shift registers (11) each providing data signal values for a group of resistor elements.
- each element of the latch registers is connected to a corresponding gating means (13).
- the output terminal of the gating means is connected to the electronic driver (14) of a resistor element of the recording head so that, under control of a strobe signal (15), the output of an element of the latch register can be gated to an individual element of the thermal recording head.
- digital values range from a value 0 to a value 8000.
- Minimal density is obtained when an element of the print head is energised by an amount of electric energy corresponding with the digital value 2000, maximum density is obtained when the print head is energised by an amount of energy corresponding with the value 8191.
- Values lower than 2000 result in transparency.
- the printer has stored a description of the printable area within the total area of the film.
- this printable area is defined within the area of the recording material as a polygon with a degree higher than 4 which approximates the area of the recording material. For each vertex of the polygon the (x,y) coordinates are stored.
- edges of the polygon are parallel to the edges of said recording material and the remaining edges approximate the shape of said rounded corners.
- An envelope imaginary rectangle can be drawn around this polygon.
- Figure 3 shows an example of the lay out of the printable area on a recording material, the edge (4) of this material having rounded corners.
- the printable area is defined by a polygon.
- the area resulting from subtraction of the polygon area from a rectangle comprising the horizontal and vertical edges is left transparent.
- the transparent border (7) situated at the thorax side of the mammography is kept as small as possible in order to be able to put a left and a right mammography close to each other on a viewing box.
- the printable area within the polygon comprises in addition to the diagnostic area (6) a black border (5).
Landscapes
- Electronic Switches (AREA)
- Heat Sensitive Colour Forming Recording (AREA)
- Record Information Processing For Printing (AREA)
- Dot-Matrix Printers And Others (AREA)
Description
- The present invention relates to hard copy recording of medical images.
- Nowadays several image acquisition systems exist that render medical images such as radiographic images in the form of digital signal representations.
- An example of such an image acquisition system is a system based on temporary storage of the medical image such as a radiographic image on a photo-stimulable phosphor screen.
A digital signal representation of the medical image is obtained by scanning a screen which has been exposed to a radiation image by means of stimulating radiation, detecting light emitted by the screen upon stimulation and converting the detected light into an electric signal representation. - Another example of such an image acquisition system is a so-called direct radiography system wherein a radiation image is recorded by a two-dimensional array of radiation sensitive elements that, upon addressing, render a digital signal representation of the radiation image.
- Still other examples such as tomography acquisition system etc. may be envisaged.
- For the purpose of diagnosis commonly a visible reproduction, either in the form of a hard copy or a soft copy is generated from a digital medical image.
- To that end the digital signal representation of the medical image is applied to a hard copy recorder such as a thermal printer.
- In case the diagnosis is performed on the hard copy image, the hard copy is attached to a viewing box for visual inspection and examination by the radiologist.
- Hard copy images generated from a digital signal representation of an image commonly have a transparent boarder.
This transparent boarder originates from the fact that hard copy recorders do often not print up to the outer edges of the recording material, i.a. because tolerances on the dimensions of the recording material, tolerances regarding transport and handling of the recording material in the printer etc. are taken into account. - Furthermore, recording materials used for reproduction of medical images commonly have rounded angles. Since the addressable area on a recording material is commonly defined in terms of a rectangular which fits into the area of the recording material, the distance from the edge of the recording material that is left transparent is also determined by the presence of these rounded angles.
- When an image having a transparent boarder is attached to a viewing box for examination by the radiologist the dazzling light originating from the presence of transparent boarders on the hard copy may negatively affect the viewing conditions. Care has thus to be taken to minimise this effect.
- A well known technique for avoiding the dazzling effect of the transparent boarders is the use of collimating curtains that are partially slided over the hard copy so to cover the transparent parts.
- However, in the field of mammography, it is common practice to compare images of left and right breast by putting these images side by side on a viewing box.
- In this case collimating curtains are not applicable to cover the area where the images are juxtaposed.
- An alternative solution consists in providing an additional black boarder near to the transparent boarder in the boarder region of the image. The hard copies are then put in an overlapping position so that the transparent dazzling area of either of the films in the region between the two images is covered by the black boarder.
- Hard copy recording systems exist that do not require the transparent boarder and that thus inherently solve the above-described problem originating from transparent boarders. An example of such a hard copy recorder is a laser recorder.
Such systems are capable of printing across the boarder of the hard copy material so that no transparent boarder is created. - However, thermal printers do not have this ability.
- Thermal printing is a recording process wherein images are generated by applying image-wise modulated thermal energy to a recording material. The applied heat brings about a visible change of optical density in a thermo-sensitive imaging material.
- A particular interesting direct thermal recording material comprises a combination of an organic silver salt in combination with a reducing agent. A visible image may be created in such a material by applying image-wise modulated heat to the material which causes the silver ions to be developed into metallic silver.
- The thermal heat is applied to the recording material by means of a print head which consists of a linear array of resistor elements. The recording material and the print head are transported relative to each other.
Electric pulses corresponding with a digital image representation are applied to a thermal print head. The resistor elements convert the electrical energy into heat which is transferred to the recording material and generates a chemical reaction resulting in development of a visible image. - In case of thermal printers printing across the border of the hard copy material in order to avoid the creation of transparent borders would result in melting of heat sensitive substance of the recording material at the border of the recording material.
This melted substance would soil the print head and its surroundings resulting in dirty prints. -
European patent application EP 1 170 140 A1 discloses a method of generating a hard copy of an image on a substantially rectangular heat sensitive recording material. Image pixels are printed within a substantially rectangular printing area. - It is an aspect of the present invention to provide a method of thermal printing hard copy images on a recording material with rounded angles whereby the dazzling effect originating from clear border surrounding the image area is minimized.
- The above-mentioned advantageous effects are realised by a method of generating a hard copy as set out in claim 1.
- Specific features for preferred embodiments of the invention are set out in the dependent claims.
- Further advantages and embodiments of the present invention will become apparent from the following description and drawings.
-
- Fig. 1 is a schematic illustration of a thermal printer,
- Fig. 2 is a scheme illustrating the data flow in a thermal printer,
- Fig. 3 illustrates the lay-out of the printable area on a recording material.
- Figure 1 shows the components of the thermal printer that are relevant in the context of the present invention.
- The printer comprises a recording head 1 consisting of an array of juxtaposed resistor elements in a line-wise arrangement and associated electronic control and driver circuitry.
- A
recording material 2, which may be in sheet or web form, and the recording head 1 are transported relative to each other. In the illustrated example the recording material is secured to a drivenrotatable drum 3 so that the recording material is advanced past the recording head 1. - The recording material in this example comprises a support coated with a thermo-sensitive layer containing an organic silver salt.
- When being heated by the elements of the recording head the organic silver salt is locally reduced to metallic silver thereby producing a density that is proportional to the amount of energy transferred to the recording material at a specific location.
- Energy is applied to each of the resistors under control of an electric signal. The amount of energy that is applied to an element of the recording head is controlled in accordance with the density to be reproduced by this element.
- An electronic scheme illustrating the composition of the recording head is shown in figure 2. The recording head of this thermal printer comprises 4992 individually energisable resistors (10) (at a resolution of 508 dots per inch).
- This number of resistors is subdivided into a plurality of groups of a number of individual resistors. The head comprises a plurality of shift registers (11) each providing data signal values for a group of resistor elements.
- The output of each of the registers is applied to a latch register (12).
- The output of each element of the latch registers is connected to a corresponding gating means (13).
- The output terminal of the gating means is connected to the electronic driver (14) of a resistor element of the recording head so that, under control of a strobe signal (15), the output of an element of the latch register can be gated to an individual element of the thermal recording head.
- In the present embodiment digital values range from a value 0 to a value 8000. Minimal density is obtained when an element of the print head is energised by an amount of electric energy corresponding with the digital value 2000, maximum density is obtained when the print head is energised by an amount of energy corresponding with the value 8191. Values lower than 2000 result in transparency.
- According to a specific implementation of the present invention for each film type and film dimension the printer has stored a description of the printable area within the total area of the film.
- In accordance with the present invention this printable area is defined within the area of the recording material as a polygon with a degree higher than 4 which approximates the area of the recording material. For each vertex of the polygon the (x,y) coordinates are stored.
- Preferably four edges of the polygon are parallel to the edges of said recording material and the remaining edges approximate the shape of said rounded corners.
- An envelope imaginary rectangle can be drawn around this polygon.
- For pixels within the area which originates from subtracting the area of the polygon from this rectangular area a digital value zero is applied to the print head resulting in a transparent area.
- Within the printable area density values corresponding with image data are printed.
- The higher the degree of the polygon, the better the rounded edges of the hard copy material will be approximated. However, an acceptable solution is already obtained by means of an octagon.
- Figure 3 shows an example of the lay out of the printable area on a recording material, the edge (4) of this material having rounded corners.
- The printable area is defined by a polygon.
- When printing a medical image, the area resulting from subtraction of the polygon area from a rectangle comprising the horizontal and vertical edges is left transparent.
- In case of mammographic images the transparent border (7) situated at the thorax side of the mammography is kept as small as possible in order to be able to put a left and a right mammography close to each other on a viewing box.
- In the embodiment shown the printable area within the polygon comprises in addition to the diagnostic area (6) a black border (5).
Claims (3)
- A method of generating a hard copy of an image on a substantially rectangular heat sensitive recording material by printing image pixels of said image in a printable area within the area of said recording material, characterised by printing said image in a printable area being defined by a polygon with a degree higher than 4 that approximates the area of the recording material with rounded corners and by leaving the area outside said polygon transparent.
- A method according to claim 1 wherein four edges of said polygon are parallel to the edges of said recording material and wherein remaining edges approximate the shape of said rounded corners.
- A method according to any of the preceding claims wherein said polygon is an octagon.
Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE2002623349 DE60223349T2 (en) | 2002-07-02 | 2002-07-02 | Thermal printing |
EP20020100773 EP1378367B1 (en) | 2002-07-02 | 2002-07-02 | Thermal printing method |
JP2003180768A JP2004034703A (en) | 2002-07-02 | 2003-06-25 | Thermal printing method |
US10/610,283 US6972781B2 (en) | 2002-07-02 | 2003-06-30 | Thermal printing method |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP20020100773 EP1378367B1 (en) | 2002-07-02 | 2002-07-02 | Thermal printing method |
Publications (2)
Publication Number | Publication Date |
---|---|
EP1378367A1 EP1378367A1 (en) | 2004-01-07 |
EP1378367B1 true EP1378367B1 (en) | 2007-11-07 |
Family
ID=29719762
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP20020100773 Expired - Fee Related EP1378367B1 (en) | 2002-07-02 | 2002-07-02 | Thermal printing method |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP1378367B1 (en) |
JP (1) | JP2004034703A (en) |
DE (1) | DE60223349T2 (en) |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6972781B2 (en) | 2002-07-02 | 2005-12-06 | Agfa Gevaert N.V. | Thermal printing method |
CN101386238B (en) * | 2003-10-15 | 2012-03-28 | 王子制纸株式会社 | Medical transparent thermal recording sheet |
WO2005037567A1 (en) * | 2003-10-15 | 2005-04-28 | Oji Paper Co., Ltd. | Thermal recording sheet and thermal recording sheet pack |
Family Cites Families (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0679523B1 (en) * | 1994-04-29 | 1997-10-01 | Agfa-Gevaert N.V. | Method for making prints by means of a thermal printer |
EP1170140B1 (en) * | 1996-11-28 | 2005-04-20 | Agfa-Gevaert | Thermal-sensitive film having a uniform peripheral margin |
-
2002
- 2002-07-02 EP EP20020100773 patent/EP1378367B1/en not_active Expired - Fee Related
- 2002-07-02 DE DE2002623349 patent/DE60223349T2/en not_active Expired - Fee Related
-
2003
- 2003-06-25 JP JP2003180768A patent/JP2004034703A/en active Pending
Also Published As
Publication number | Publication date |
---|---|
JP2004034703A (en) | 2004-02-05 |
DE60223349T2 (en) | 2008-08-28 |
EP1378367A1 (en) | 2004-01-07 |
DE60223349D1 (en) | 2007-12-20 |
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