DE19929319A1 - Ink jet printer for producing photographic prints, has edge detection sensor, controller for applying digital mask to printed image to prevent printing onto vacuum support, drier, and spool - Google Patents

Abstract

The printer has a paper supply roller (12), a rear side printer (26) between a first transport roller (16) and a measurement roller (18), a perforator (26'), a deflector (27) between the first and a second measurement roller (20), a vacuum drum (70), a vacuum paper support (31'), a color ink jet print head (36), a perforation and edge detecting image sensor (46). The printer has a controller (54) for applying a digital mask to a printed image to prevent printing onto the vacuum support, a drier (48) and a paper spool (58).

Description

The invention relates to an ink jet printer for the production of photos prints, especially on an inkjet printer for printing digital photos graphic images.

Digital photographic images offer significant advantages over conventional ones photographic images insofar as they are using digital computer and data communication nication technologies manipulated, stored, retrieved and transmitted can be. Digital photographic images can either be scanned on conventional photographic film of recorded photographic images or directly are generated by digital cameras that work with solid-state image sensors. Today, paper prints of digital photographic color images are produced using thermo printers, electrographic printers, scanners for exposing conventional silver halide photo papers and inkjet printers.

Most amateur photos nowadays are made using optical Printer and photographic paper manufactured. However, it has been found that in amateur photography making prints of the benefits of digital Image processing would benefit because the digital images are in terms of a verbes correct correction of color balance and exposure can be processed digitally and you can add text or special effects to them through digital manipulation or can combine them with other images. In doing so, they are based on silver halide film scanned images to generate digital color images, the digital Color images processed to correct the color balance and exposure, and then The images are printed using a digital color printer. The only ones  digital printers currently available on the market for producing photo prints genes in amateur photography all work with a scanning light beam with which conventional silver halide photo paper is exposed. Developing the belich Photographic paper is still used on these digital printers the path of chemical wet development. Handling and disposal of the However, photographic processing chemicals are expensive and take up space for example in the form of rents must also be paid. There is therefore a Need for a digital printer to produce photo prints, which with the chemical wet development of photographic paper related problems and Avoids costs.

Among the competing technologies, i. H. Thermal printing, electrography and tin is the use of thermal printing due to the printing speed and the material costs, the electrography due to the equipment costs and complexity limited. As a result, inkjet printing technology is the best solution represents an improvement over the silver halide pressure at the digita len production of photo prints in amateur photography.

The use of inkjet printers for the production of paper prints from digital photographic images are known. Lower resolution images will appear on Desktop inkjet color printers with a resolution in the range of 300 to 1200 dpi manufactured. Graphic inks are used to produce large format color images jet printer on; see for example the published European patent application EP 0 710 561 A2 and the published PCT application WO 97/28003. If it also seems likely that the high-resolution color ink jet printing will become the preferred technique for making photo prints the use of the currently available inkjet printers because of their throughput speed very limited. There is therefore a need for an ink jet Printer for the production of photo prints with high resolution and high throughput.

An ink jet printer for making photo prints includes a paper pre advice roll to take up a roll of printing paper, a first conveyor roller to take up one paper web coming from the paper supply roll and one in one Distance to the first conveyor roller arranged first measuring roller, which is a first plan position of the paper web defined. There is a back printer and a punch  for printing on the back of the paper web or for attaching marking Punch holes in the paper between the first conveyor roller and the measuring roller arranges. After the first measuring roller, a second measuring roller and is arranged, and defines a vacuum drum arranged at a distance from the second measuring roller a second flat position of the paper web. Between the first and the second measurement roller is arranged a deflection device, and between the second measuring roller and a vacuum paper support is provided for the vacuum drum. Above the Vacuum paper support is a color Ink jet printhead arranged to print an image on the paper web. On Image sensor arranged in front of the ink jet print head detects the punch holes and the edges of the paper web transported under the printhead. One on control responsive to the image sensor generates the edges of the paper web representing digital mask and puts it on a digitally printed one Image, which controls overprinting on the vacuum paper support. After the vacuum drum, a paper dryer is placed, and the paper skirt ner is a paper take-up spool for receiving the paper web with the pictures printed on it. In one embodiment of the invention, the Paper dryer a meander with an air roller, by means of which the paper is so is transported through the inner turns that the paper surfaces are not be touched.

The inkjet printer according to the invention offers the following advantages: roller and the vacuum drum ensure precise paper feeding. By the deflection devices arranged before and after the printing station are avoided that the paper punching device and / or the shrinking of the paper in the Drying station can affect the printing process. When executing form of the invention, in which the paper dryer comprises a meander, can because the long paper transport path in the drying section with a very high printhead Throughput can be worked.

The invention is based on an Ausfüh shown in the drawing example explained in more detail.

Show it:  

Figure 1 is a schematic representation of the ink jet printer according to the invention for producing photographic prints.

Fig. 2 is a schematic representation from which the position of a lead section and the images printed on the paper web in the printer can be seen;

Fig. 3 is a schematic representation of the image sensor used in the ink jet printer according to the invention;

Fig. 4 is a perspective view of an air knife used in the paper dryer of the present invention;

5 is a perspective view of the vacuum-type paper tray under the printer according to an alternative embodiment of the invention.

Fig. 6 is a perspective view of a used in an alternative embodiment of the invention edge-trimming device;

Fig. 7 is a perspective view of a movable print head according to a further alternative embodiment of the invention;

Fig. 8 is a partially broken perspective view of the vacuum paper pad used according to the Invention; and

Fig. 9 is a perspective view of the vacuum drum used in connection with the inventive ink jet printer.

In Fig. 1, an ink jet printer according to the invention, generally designated 10 , for printing photographic images has a paper supply roll 12 for feeding a paper web 14 of photographic inkjet printing paper. The photographic ink jet printing paper consists for example of 10 cm wide white paper with a weight of 200 to 300 g / m ² , which is specially surface-treated in a known manner for the absorption of ink by the ink jet printer. The paper web 14 is fed to a first pair of conveyor rollers 16 .

A arranged at a distance from the first pair of conveyor rollers 16 pair of driven measuring rollers 18 defines a flat position 21 of the paper web 14th Between the conveyor and the driven measuring rollers 16 and 18 are a back printer 26 for printing on the back of the paper web 14 with information and a punching device 26 'for making punch holes 14 "for separating the deductions and / or punch holes 14 ' for the provided separation of the orders. the back printer 26 may, for example, a single-color ink jet print head composed of low resolution, uses fast-drying ink. Alternatively, a dot matrix printer may be used as back printer 26 may be provided. the reverse side printer 26 prints specified information, such as order and image field number on the back of the paper web 14. The punching device 26 'for punching holes for the separation of the prints / orders is of the type known in photographic printers and serves to determine the position between the individual images and the end of an order for example, by displaying de r Separation point between two images is punched a hole near one edge of the web and to indicate the end of an order holes are punched near both edges of the web 14 .

At a distance from the first driven measuring roller 18 , a second set of driven measuring rollers 20 is arranged, and between the driven measuring rollers 18 and 20 , a deflection device 27 is provided. The deflection device 27 forms a free hanging paper loop, the lower edge for controlling the size of the free hanging loop is detected in a known manner by a sensor (not shown) in the deflection device 27 .

A vacuum drum 70 defines a second flatness 21 'of the paper web between the driven measuring roller 18 and the vacuum drum 70 . A vacuum paper support 31 'is provided under the second flat position 21 ' of the paper web 14 , which supports the web 14 of the photographic ink jet printing paper during its movement through the ink jet printer 10 by means of the driven measuring rollers 20 and the vacuum drum 70 . As can be seen in FIG. 8, the vacuum paper support 31 'comprises a plenum 950 which has a plurality of shallow depressions 952 in its upper surface. A plurality of holes 954 leading into the interior of plenum 950 are provided at the bottom of each of the shallow recesses 952 . An outlet opening 956 is connected to an air pump (blower), not shown, and serves to produce a part of the vacuum in the plenum 950 . A partition 958 to compensate for the negative air pressure at the holes 954 is provided inside the ple num 950 . The paper support surface of the vacuum paper support 31 'is designed to be low-friction and consists, for example, of polished, hardened and coated with a Teflon layer aluminum, so that the paper web 14 can be easily pulled over the vacuum paper support while the vacuum part flat the paper holds. The vacuum drum 70 serves to keep the web 14 under its predetermined tension during its transport through the printer by means of the driven measuring rollers 20 .

As can be seen from FIG. 9, the vacuum drum 70 consists of a hollow metal tube which is provided with a plurality of circumferential shallow depressions 72 . At the bottom of each of the depressions 70 are a plurality of holes 74 leading into the interior of the vacuum drum 70 . An outlet opening 76 is connected to an air pump (blower), not shown, and serves to apply a partial vacuum to the vacuum drum 70 . A bearing 78 is provided on each end face of the vacuum drum 70 so that the drum can be rotated in a known manner by means of a drive (not shown) in order to keep the paper web 14 under tension. On the inside of the vacuum drum 70 , a plate 79 made of metal is arranged so that the vacuum is only applied to the part of the vacuum drum 70 which is in contact with the paper web 14 . The paper web is held against the outside of the vacuum drum 70 by the portion of vacuum applied through the holes 74 and the drum is rotated to transport the paper.

Above the paper support 31 'is a full-width, high-resolution color ink jet print head 36 is arranged, by means of which a photographic color image is printed on the paper web 14 , while this is from the driven measuring rollers 20 and the vacuum drum 70 under the Printhead is transported through. The full-width ink jet printhead 36 is, for example, a printhead of the type described in US-A-5,812,162. Preferably, the printhead is a little wider than the paper web 14 (e.g. 12 cm wide) and has a print resolution of 1200 dpi. The preferred ink jet printhead 36 includes a plurality of printhead elements 38 , 40 , 42 , 44 , each of which is supplied with ink of a different color, for example cyan, magenta, yellow and black. The inkjet printhead can print at a transport speed of 5 cm per second or about 1000 copies per hour.

In front of the inkjet print head 36 is an image sensor 46 , e.g. B. a linear CCD image sensor arranged, which detects the edges of the paper web 14 when it is transported by the driven measuring rollers 20 and the vacuum drum 70 under the print head 36 . In one embodiment, image sensor 46 detects a line that is as wide as inkjet printhead 36 (ie slightly wider than paper web 14 ) and has a resolution of, for example, 2700 pixels. In Fig. 3 an example of a suitable linear image sensor array is illustrated. The image sensor 46 has a housing 500 , an objective 502 for focusing an image of the paper and the conveyor belt on an image sensor module 504 and a light source 506 for exposing the paper on the conveyor belt. A suitable image sensor module 504 is the ILX533K linear CCD color image sensor sold by Sony Corporation. An example of such an arrangement is described in published PCT application 96/38370. According to an alternative embodiment, the image sensor 46 comprises a pair of edge sensors, ie one for each edge of the paper. The edge sensors can be shorter versions of the CCD image sensor described above arranged on the edges of the paper web 14 .

Referring again to FIG. 1, the paper dryer 48 includes a through a second vacuum drum 80, a bearing roller 82 and a pair of non-contact web guides 84 and 86 meander formed. The web guides 84 , 86 are designed as solid shoes with a plurality of holes. Air is continuously blown through the holes in the web guides 84 and 86 at a flow rate sufficient to keep the freshly printed surface of the paper web 14 out of contact with the surface of the web guides, thereby preventing ink from wiping and drying the fresh printed image is supported.

A plurality of air doctor blades 50 are arranged above the paper web 14 in the paper dryer 48 and dry the freshly printed images before they reach the conveyor rollers 28 '. In Fig. 4 it can be seen that the air doctor blades 50 each have a plenum 52 with an air inlet 51 for heated compressed air, an air outlet opening 53 and a partition 55 for equalizing the air pressure along the air outlet opening 53 . Because of the relatively long paper transport path in the meander of the paper dryer 48 , very high printing speeds can be achieved, and at the same time there is sufficient time for the prints to dry in the printer. The paper dryer 48 is followed by a conveyor roller 28 ', and the För derwalze 28 ' is followed by a paper take-up spool 58 for receiving the printed web 14th

In order to control the operation of printer 10 , which is discussed below, the various components of the printer are connected to control electronics 54 with a digital processor, for example a microcomputer. The control electronics 54 receives, from an input unit, for example a film scanning station or a (not shown) digital image processing station, digital image data, print data for the back and instructions for the print job. Before printing, a rear side print is applied to the rear side of the first image to be printed by the rear side printer 26 and a punching hole is punched out by the punching device 26 'for the separation of the orders. The paper is then transported the length of a print in the deflection device 27 , and the punching device 26 'punches out a punch hole for the separation of the prints. The further transport animals, printing the back with job information and punching out punch holes for the separation of the prints takes place at a speed which ensures that the deflection device 27 is always supplied with paper.

When the deflection device 27 is full, the control electronics 54 causes the driven measuring roller 20 to transport the paper further until the image sensor 46 detects the first punch hole for the separation of the prints. Then the printing of the image is started while the driven measuring roller 20 continuously transports the paper web 14 at a predetermined speed and under the print head 36 . Alternatively, special sensors with known LED / photodetector units for detecting the punch holes for separating the prints can also be used to detect the punch holes for separating the orders and the deductions in the web 14 . In the meantime, the back printer 26 continues to print the back information on the web 14 , and the marker die 26 'continues to punch holes for the separation of the prints in the web 14 as required to keep the diverter filled .

In Fig. 2, which shows part of the printed paper web 14 , a first punch hole 14 'is made in the web for the separation of the jobs after the lead section L of the tape. The punch hole 14 'for separating the jobs includes holes on both edges of the paper web 14 . There follows a first printed image P1 and then a punch hole 14 "for the separation of the prints in only one of the edges. The second image P2 and another punch hole 14 " for the separation of the prints follows. At the end of the customer order, a further punch hole 14 'is punched for the separation of the orders into the paper web, and the next order is then printed.

During the printing process, the image sensor 46 detects the edges of the paper web 14 before it passes the area under the print head 36 . The image of the paper web 14 is processed by the control electronics 54 , the edges of the paper web are detected, and a print mask is generated which has the same width as the paper web 14th The print mask is then added to the digital image data, and the control electronics 54 feed the digital image data to the inkjet print head 36 so that it prints the image precisely up to the edge of the paper web 14 . In this way, overprinting of the inkjet print head 36 onto the paper support 31 ′ at the edges of the paper web 14 is prevented. In the case of prints with an edge, the mask is evenly made somewhat narrower than the paper web 14 , as a result of which the print is properly aligned on the paper web 14 .

In an alternative embodiment of the invention shown in FIG. 5, the paper support 31 'is provided with collecting grooves 37 for excess ink. The left edge of the paper web 14 is aligned with the left catch groove by means of a pair of paper alignment elements 37 '. So only a collecting groove 37 is provided on the left side, since all paper widths are aligned with this groove. On the other side of the paper, a catch groove 37 is provided for each paper size that the printer can work with. The collecting grooves 37 are about 2 mm wide and can be equipped with an absorbent material, such as felt, for receiving the excess ink. In this embodiment, the image sensor 46 only needs to detect the right edge of the paper web 14 , since the position of the left edge is always fixed. The vacuum paper support 31 'is also provided with holes 37 ", by means of which the edge of the paper web is kept flat when the wider paper web is used in the printer. The control electronics 54 generate a print mask that is slightly wider on both sides of the paper (by about 1 mm), and the resulting excess printing ink is collected in the collecting grooves 37 .

According to a further alternative embodiment of the invention, the paper web 14 is wider than the finished print, and both edges (z. B. 1 mm per edge) are trimmed by an edge trimming device arranged after the paper feed rollers 28 '. For example, in FIG. 6, the edge trimmer includes a pair of rotary knives 850 and 852 for trimming the edges of paper web 14 . In this embodiment, the ink jet printhead is controlled to remain slightly (e.g., 0.5 mm) within the edges of the paper web during printing, thereby preventing overprinting on the paper support 31 ', but at the same time being perfect after the edges have been trimmed rimless deduction is made.

In a further alternative embodiment of the invention shown in FIG. 7, the high-resolution ink jet print head 36 , which extends over the entire printing width, can be moved back and forth in the direction of arrow A over the vacuum paper support 31 ', the vacuum paper support being at least as long such as the movement distance of the ink jet print head 36 plus the width of the print head. The inkjet print head 36 and the image sensor 46 are received on a print head carriage 936 . The print head carriage 936 can be moved back and forth on guide rails 935 in the direction of movement of the paper web 14 . The printer is equipped with a sensor 937 for the position of the print head carriage, which delivers a signal when the carriage 936 is in its starting position shown in FIG. 7. The carriage 936 can also be equipped with an actuating device 939 , for example a piezoelectric actuating device, by means of which the ink jet print head 36 can be moved by an amount in the order of the nozzle spacing of the ink jet print head in a direction perpendicular to the direction of the arrow A. .

In operation, printhead carriage 936 is initially in its leftmost position, as shown in FIG. 7. During the transport of the paper through the driven measuring rollers 20, the image sensor 46 detects the punch holes for the separation of the prints. When the image sensor 46 (or a special punch hole sensor) detects a punch hole for the separation of the prints, the control electronics 54 transports the paper web 14 under the print head 36 by a predetermined amount and then stops it. First, the print head carriage is moved from left to right over the paper, as shown in FIG. 7, so that the image sensor 46 can capture an image of the edges of the paper web 14 and determine the punched hole 17 "for the separation of the prints. The control electronics 54 processes the image of the paper web 14 , detects the edges of the paper web and generates a print mask identical to the paper web 14. The print mask is then added to the digital image data, and the control electronics 54 feeds the digital image data to the ink jet print head 36 , which carries the image prints on the paper web 14 while the printhead 36 is moved back to its starting position by means of the printhead carriage 936. In this way, overprinting of the inkjet printhead 36 onto the paper support 31 'is avoided and a perfect borderless print is produced.

With some combinations of ink and paper compositions and ink droplet spacing, adjacent ink droplets emitted by the ink jet printhead cannot be printed at the same time as they would otherwise converge. Therefore, according to an alternative mode of operation of the movable ink jet print head according to FIG. 7, in a first pass it initially prints only with every second nozzle of the ink jet print head. Then, the ink jet print head 36 performs a second print pass, printing with the nozzles that were not used in the first pass. This gave the ink droplets applied during the first pass some time to react with the paper before the second pass, which improves the resolution of the print.

According to a further operating mode of the moving ink jet print head of FIG. 7 is carried, a first pressure passage, after which the ink jet print head 36 moved by the amount of a fraction (for example, half) the distance between the ink jet nozzles of the print head laterally be by means of the actuating element 939 and a second pressure passage running becomes. This mode can be used to effectively double the print head resolution. Alternatively, however, it can also serve to compensate for non-functional, for example blocked or misaligned, nozzles of the printhead.

It goes without saying that the other methods for controlling overprinting, for example the collecting grooves 37 for excess ink according to FIG. 5 and the trimming of the edges of the paper web 14 shown in FIG. 6 after printing also in connection with that in FIG. 7 illustrated embodiment of the invention can be set.

Parts list

10th

Inkjet printer

12th

Paper supply roll

14

Paper web

14

'' Punch hole for separation of orders

14

"Punch hole for separation of the prints

16

first conveyor rollers

17th

"Punch hole

18th

first measuring rollers

20th

second measuring rollers

21

first flatness of the paper web

21

'' second flat position of the paper web

26

Back printer

26

'' Punch hole for end of order

27

Deflection device

27

'' Deflection device

28

'' second conveyor rollers

31

'' Vacuum paper pad

36

Inkjet printhead

37

Collection grooves for excess ink

37

'' Paper alignment elements

37

"Holes

38

Printhead element

40

Printhead element

42

Printhead element

44

Printhead element

46

Image sensor

48

Paper dryer

50

Air knife

51

Air intake

52

plenum

53

Air outlet opening

54

Control electronics

55

partition wall

58

Paper take-up reel

70

Vacuum drum

72

Indentations

74

Holes

76

Outlet opening

78

camp

79

plate

80

Vacuum drum

82

Bearing roller

84

Web guide

86

Web guide

500

casing

502

lens

504

Image sensor module

506

Light source

850

Rotary knife

852

Rotary knife

935

Guide rails

936

Carriage for the inkjet printhead

937

Slider position sensor

939

Actuator

950

plenum

952

deepening

954

hole

956

Outlet opening

958

partition wall

Claims (8)

1. Inkjet printer ( 10 ) for the production of photo prints, characterized by

• a) a paper supply roll ( 12 ) for receiving a roll of printing paper,
• b) a first conveyor roller ( 16 ) for receiving a paper web ( 14 ) coming from the paper supply roll ( 12 ),
• c) a first measuring roller ( 18 ) which is arranged at a distance from the first conveyor roller ( 16 ) and which defines a first flat position ( 21 ) of the paper web ( 14 ),
• d) one between the first conveyor roller ( 16 ) and the measuring roller ( 18 ) arranged rear side printer ( 26 ) for printing on the back of the paper web ( 14 ),
• e) a paper punching device ( 26 ') arranged between the rear side printer ( 26 ) and the first measuring roller ( 18 ) for making punching holes ( 14 ', 14 ") in the paper,
• f) a second measuring roller ( 20 ) connected downstream of the first measuring roller ( 18 ),
• g) a deflection device ( 27 ) arranged between the first ( 18 ) and the second measuring roller ( 20 ),
• h) a vacuum drum ( 70 ) which is arranged at a distance from the second measuring roller ( 20 ) and defines a second flat position ( 21 ') of the paper web ( 14 ),
• i) a vacuum paper support ( 31 ') provided between the second measuring roller ( 20 ) and the vacuum drum ( 70 ),
• j) a color ink jet print head ( 36 ) arranged over the vacuum paper support ( 31 ') and extending over the entire printing width for printing an image on the paper web ( 14 ),
• k) a front of the ink jet print head (36) arranged image sensor (46) for detecting the punched holes (14 ', 14 ") and the edges of the transported under the print head (36) through the paper web (14),
• l) a controller ( 54 ) responsive to the image sensor ( 46 ) for generating a digital mask representing the edges of the paper web ( 14 ) and applying the digital mask to a currently printed digital image, thereby overprinting on the vacuum paper support ( 31 ' ) is mastered,
• m) one of the vacuum drum ( 70 ) downstream paper dryer ( 48 ) and
• n) a paper take-up spool ( 58 ) connected downstream of the paper dryer ( 48 ) for receiving the paper web with the printed images thereon.

2. Inkjet printer according to claim 1, characterized in that the paper dryer ( 48 ) one of the first vacuum drum ( 70 ) downstream second vacuum drum ( 80 ), a deflection device ( 27 ') for forming a paper loop between the first and the second vacuum drum ( 70 , 80 ) and an air knife ( 50 ) which directs a flow of heated air onto the paper in the deflection device. 3. Inkjet printer according to claim 2, characterized in that the paper dryer ( 48 ) further comprises a meander ( 84 , 86 ) with an air roller, by means of which the paper web ( 14 ) is guided around the inner turns such that the printed surface of the Paper is not touched. 4. Ink jet printer according to claim 1, characterized in that the back side printer ( 26 ) comprises an ink jet print head. 5. Inkjet printer according to claim 1, characterized in that the image sensor (46) is a linear CCD line sensor. 6. Inkjet printer according to claim 1, characterized in that the vacuum paper support ( 31 ') further has collecting grooves ( 37 ) for excess ink, that the image sensor ( 46 ) is a simple edge sensor and that the controller ( 54 ) the print head ( 36 ) controls so that it prints slightly beyond the edges of the paper. 7. Inkjet printer according to claim 1, characterized in that further an edge trimming device ( 850 , 852 ) is provided for trimming the two edges of the paper after the paper dryer ( 48 ) and that the control ( 54 ) the print head ( 36 ) so controls that it prints until just before the edges, the unprinted area of the paper web ( 14 ) from the trimming device ( 850 , 852 ) being cut off. 8. Inkjet printer according to claim 1, characterized in that a printhead carriage ( 936 ) arranged above the first vacuum paper support ( 31 ') is provided, the inkjet printhead ( 36 ) and the image sensor ( 46 ) extending over the entire printing width the print head carriage ( 936 ) are mounted and the print head carriage ( 936 ) can move in a direction parallel to the paper transport direction over the paper web ( 14 , 14 ') located on the vacuum paper support ( 31 '), the carriage ( 936 ) also being able to move a sensor ( 937 ) which indicates when the carriage ( 936 ) is in its starting position.