EP2093067B1 - Printer with an exposure head - Google Patents

Description

The invention relates to a printer, in particular a serial printer, with an exposure head for the exposure of printed images with light-curing ink.

Serial printers or line printers are printers that print characters one after the other within a single line. They are inexpensive to manufacture, reliable in operation and small in size, so that they are suitable as Auftischgeräte. Printers of this type are widely used as type printers, dot matrix printers or as ink printers. If light-curing ink is used in an ink printer, then an exposure head guided on a carriage is required in addition to the print head, which exposes and cures the printed image after printing with high radiation intensity.

To achieve high radiation intensities it is known in sheet-fed offset printing machines to use exposure heads with mercury vapor lamps, which reach temperatures of about 900 ° C during operation. However, such exposure heads are not suitable for use in tabletop devices because of their large dimensions of and installed large electrical power. The derivation of the resulting heat, which is often in the kilowatt range, would lead to insurmountable difficulties in table-top devices. In some cases, liquid-cooled exposure heads are used in sheetfed offset presses that require refrigeration units whose dimensions alone far exceed those of a tabletop device.

Even with large plotter systems that produce several lines of a printed image simultaneously with several print heads on a carriage, the use of exposure heads is known. They are cooled with air and are not suitable for tabletop devices because of their large dimensions of and their large electrical power loss. Their powerful fans generate noise that far exceeds the allowable noise levels of office desk desks. This noise passes directly to the environment without being damped, since the large plotter systems are equipped without a housing. When mounting a housing there is a risk that the heat energy accumulates in the housing and causes thermal damage. In addition, the exposure heads with their reflectors used for the beamline are designed ineffective for the requirements of a serial printer, since they use long stretched tube-like lamps.

The US 2002/0101491 A1 shows an arrangement with an exposure head, reflectors and an exposure head housing, wherein a blower unit is connected via at least one air duct with the exposure head, the air duct opens into a cooling air space between the reflectors and the side walls of the exposure head housing and in the exposure head housing a lamp with at least one lamp socket to Attachment in the exposure head and with a luminous body is arranged.

From the FR 2 234 966 A an exposure head is known in which a lamp is at least partially surrounded by reflectors is arranged, wherein elliptical and planar reflectors are provided which the radiation emitted by the lamp lead to a printable with light-curing ink printable plane.

It is an object of the present invention to disclose a printer having an exposure head for curing light-curing ink, which is suitable as a table-top device for office applications.

The object is achieved by the subject matter of claim 1. Advantageous embodiments of the invention are specified in the dependent claims.

The printer according to the invention has an exposure head for exposure of printed images with an exposure head housing, in which a lamp is at least partially surrounded by reflectors emitted during operation radiation, which is passed through the reflectors on a light-curing ink printable image plane. In order for such printers to be used as tabletop printers, it is important that the radiation emitted by the lamp to the image plane be sufficiently intense to cure the ink and that the heat loss emitted by the lamp of the exposure head be integrated into a desktop printer Cooler from the exposure head and from the printer, for example, can be discharged into the environment.

The lamp is mounted in the exposure head housing via at least one lamp socket, the lamp socket protruding into the air guide channel. As a result, the lamp holder is effectively cooled in the air stream and the heat dissipation on effectively reduces the exposure head housing. This air guide is particularly important when using a mercury vapor lamp with operating temperatures of about 900 ° C, to prevent the exposure head housing is thermally damaged.

Further advantages are achieved by an arrangement of elliptical reflectors and planar reflectors in the exposure head housing.

Because the combination of the geometrically different reflectors a much larger portion of the radiation emitted by the lamp in all directions radiation is directed to the image plane alone by elliptical reflectors.This can be done on the one hand, that the flat reflectors on opposite side walls of the exposure head housing and arranged are formed as cross reflectors. As a result, in particular the edge region, which is typically formed with a lower radiation intensity with respect to the center region, is irradiated more intensely by the printing image plane.

In this case, the reflection surfaces of the cross reflectors are inclined relative to the main beam direction of the lamp, that the focused beam area is reinforced at the edge in the print line direction by the reflected image of the lamp in the focal plane.

In order to increase the edge area of the illuminated print image section, it is advantageously provided that the cross reflectors, viewed from the lamp in the direction of the print image plane, run apart like a funnel. By enlarging the illuminated print image section, the residence time required to cure the ink is reduced. Therefore, the printing speed of the printer can be increased. To increase the radiation intensity, it is also possible that the planar reflectors are arranged on the opposite side of the lamp to the printing image plane and are designed as reflector elements. By means of these reflector elements, the radiation emitted by the lamp in the direction opposite to the printing image plane is directed onto the printing image plane. In this way, in addition to the increase of the radiation intensity on the print image plane is achieved that the heating of the exposure head housing is reduced by the radiation of the lamp.

According to another embodiment of the invention, it is preferred that the reflector elements extend in the transverse direction of the lamp, starting from the elliptical reflectors and / or cross-reflectors. Furthermore, it is preferred that the lamp is positioned in a first focal point of the elliptical reflectors. Finally, it is preferred that the elliptical reflectors, the lamp and the printing image plane are arranged relative to one another such that a second focal point of the elliptical reflectors is in the region of the printing image plane.

According to another preferred embodiment of the invention is a printer with an exposure head for exposure of printed images and a Exposure head housing provided in which a reflector is at least partially surrounded lamp is arranged, which emits radiation during operation, which is passed through the reflectors on a light-curing ink printable image plane. In this printer, the invention provides that a fan unit is connected via at least one air duct with the exposure head, wherein the air duct opens into a cooling air space between the reflectors and the side walls of the exposure head housing. As a result of this construction, the luminous element of the lamp is located in an interior space insulated from the reflectors. As a result, an optimal operating state of the lamp is achieved, which has a positive effect on the life. In addition, intensive cooling of the lighting head is achieved in the smallest space.

For discharging heated air or the heat loss from the exposure head connected to the exposure head exhaust duct is provided with an input and output port. Appropriately, it is provided that the inlet opening of the exhaust duct between the side walls of the Exposure head housing and the reflectors is arranged. A particularly advantageous embodiment of the invention provides that in the printer housing a blow-out for discharging heated exhaust air is provided, which is preferably arranged corresponding to the outlet opening of the air duct of the exposure head housing. This ensures that the loss heat produced in the exposure head housing by its lamp in its operation can be transported via a cooling medium such as air, for example, into the environment.

The invention will be explained in more detail below with reference to an embodiment with reference to the drawing.

Fig.1

ein Ausführungsbeispiel des Belichtungskopfes in perspektivischer Ansicht,

Fig. 2

eine perspektivische Ansicht auf die Lichtaustrittsseite des Belichtungskopfes,

Fig. 3

einen Querschnitt durch den Belichtungskopf mit seiner Strahlenführung und seiner Kühlluftführung,

Fig. 3A

einen projizierten Querschnitt des Belichtungskopfes der Fig.3,

Fig. 4

einen Querschnitt durch den Belichtungskopf mit der Kühlluftführung und einem Teil der reflektierten Strahlung, und

Fig. 4A

den Ellipsenträger in 2 Ansichten.

Show it

Fig.1

an embodiment of the exposure head in perspective view,

Fig. 2

a perspective view of the light exit side of the exposure head,

Fig. 3

a cross section through the exposure head with its beam guidance and its cooling air flow,

Fig. 3A

a projected cross section of the exposure head of Figure 3 .

Fig. 4

a cross section through the exposure head with the cooling air duct and a portion of the reflected radiation, and

Fig. 4A

the ellipse carrier in 2 views.

The invention relates to a printer, preferably a serial printer with a printer housing, in which an exposure head is mounted. The exposure head is the essential component of the invention. Therefore, the figures show only the exposure head and not the printer.

According to the perspective view Fig.1 The exposure head comprises an exposure head housing with elbows (1, 2). On the angle pieces (1, 2) a printed circuit board (3) with plug (4) and designed as a fan unit fan (10) with filter (5) are placed. Side of the two angle pieces (1, 2) identical exhaust air ducts (6, 7) are mounted, the removable segments (8, 9) have. By mutual removal of the segments (8, 9) in the exhaust air ducts (6, 7) arise output openings through which heated in the exposure head exhaust air (44) can be selectively blown on one side from the exposure head housing.
At least one of these outlet openings is in fluid communication with a correspondingly provided in the printer housing discharge opening to convey the heated exhaust air from the printer, eg. In the environment.
In the printer housing are mounted as a guide means for the exposure head and a printer head with light-curing ink carriage or rails over which the exposure head and the printer head during the printing process of the printer, controlled by a drive, traversing between two lateral end positions is moved. In order to achieve a good sound attenuation by the printer housing and still be able to dissipate the heated exhaust air, the printer housing has only one exhaust opening. The discharge opening of the printer housing and the outlet opening the exhaust duct (6, 7) are arranged to each other such that the openings are in flow connection in an end position of the exposure head. In this position, the exposure head is briefly stopped during printing and the heated exhaust air is blown out of the printer housing.

According to the perspective view of the light exit side of the exposure head in Fig. 2 the exposure head additionally contains elliptical reflectors (11, 12) and cross reflectors (13, 14). The light exit opening is covered by a glass pane (15), which is secured by the spring elements (16, 17) lying in the beam shadow.
A lamp (18) of the exposure head is not shown in this view.

According to Fig. 3 and Fig. 3A the exposure head housing is essentially formed by the two identical angle pieces (1, 2), which are firmly connected to each other. In the space formed by the angle pieces (1, 2), two ellipse carriers (20, 21) are inserted at a distance (19), each containing two elliptical recesses (22, 23).
In these recesses (22, 23), the elliptical reflectors (11, 12) are inserted from the light exit side. Since the recesses (22, 23) are only slightly wider than the thickness of the elliptical reflectors (11, 12), these have after mounting the exact calculated geometric shape on its reflector surface. For mounting and power supply are designated at 24 and 25 angled inner lobes of the angle pieces (1, 2) on both sides lamp sockets (26, 27) attached.

Above the lamp (18) is a protective shield (28) which shields the scattered radiation of the lamp (18) towards the top and in addition the two inner tabs (24, 25) of the angle pieces (1, 2) against forces of socket springs (29, 30) stabilized.
Above the angle pieces (1, 2), the printed circuit board (3) with the plug (4) for the electrical supply of the exposure head is provided, which is covered by the fan (10) with the upstream air filter (5).
The light exit opening of the exposure head is covered with the glass pane (15) against contamination and damage. The glass pane (15) is held by spring elements (16, 17), which are engaged in the radiation shadow behind an angled bend (31, 32) of the elliptical reflectors (1, 2). As a result, annealing of the spring elements in the direct beam path is avoided.
The cooling air flow in the exposure head is three-dimensional and is shown for one side by the dashed line (44). On the other hand, the cooling air duct is mirror-inverted.

According to Fig. 4 and Fig. 4A the lamp (18) emits light uniformly on all sides on its cylindrical jacket. It is arranged in a first focal point (34) of the elliptical reflectors (11, 12). In a second focal point (35) is a printing image plane (40) of the printer.
Above the lamp (18), the cross reflectors (13, 14) have a region (36, 37) formed as reflector elements. This is inclined to the main beam axis (38) in such a way that the reflected radiation (49) is largely radiated past the luminous element (39) of the lamp (18) in order not to unnecessarily heat it and to reflect it Use radiation (49) in addition to the exposure of the image plane (40).

The light radiated radially by the luminous element (39) of the lamp (18) is focused by the elliptical reflectors (11, 12) in a region (45) of the printing image plane (40) and thus by a direct comparison with the direct radiation of the lamp (18) Multiple amplified.

According to Figure 3 For example, this region (45) with a higher irradiance in the direction of the longitudinal axis of the lamp (18) is only as long as the luminous element (39) of the lamp (18).
To be able to cure the printed image with the highest possible printing speed, the longest possible exposure zone with a corresponding exposure intensity in the printing image plane (40) in the printing direction is advantageous. To achieve this, the cross reflectors (13, 14) are inclined obliquely to the main beam direction (38) of the lamp (18) to the extent that the reflected images (46) of the filament (39) through the cross reflectors (13, 14 ) are respectively imaged on the printing image plane (40) following the area (45) produced by the elliptical reflectors (11, 12) with high light intensity. This results in a zone (45, 46) of high radiation density, which extends over the entire light exit width of the exposure head. In order to accelerate the curing process of the ink after printing and to prevent the print image from bleeding, the image plane is only 1 to 2 mm away from the illumination head.

The exposure head and the fan unit are connected to each other via an air duct, which along the Guided by 44 dashed line. The air duct is guided past the luminous element (39) of the lamp (18), with the lamp socket (26, 27) protruding into the air duct. This opens into a cooling air space (48) between the reflectors (11, 12, 13, 14) and the side walls of the exposure head housing and is in communication with the exhaust air duct (7, 8) in flow connection.

LIST OF REFERENCE NUMBERS

elbows

1

elbows

2

circuit board

3

plug

4

filter

5

exhaust duct

6

exhaust duct

7

Removable segment

8th

Removable segment

9

fan

10

Elliptical reflector

11

Elliptical reflector

12

cross reflector

13

cross reflector

14

pane

15

leaf spring

16

leaf spring

17

lamp

18

distance

19

ellipse carrier

20

ellipse carrier

21

Elliptical recess

22

Elliptical recess

23

Angled inner flap

24

Angled inner flap

25

lamp socket

26

lamp socket

27

shield

28

Spring in lamp socket

29

Spring in lamp socket

30

Angling the cross reflectors

31

Angling the cross reflectors

32

focus

34

Second focal point

35

reflector element

36

reflector element

37

Main beam direction of the lamp

38

illuminant

39

Print image plane

40

lamp axis

41

lamp base

42

lamp base

43

cooling air

44

High radiation density area

45

Reflected illustration of the filament

46

Reflector interior

47

Cooling air space

48

Part of the reflected radiation

49

Anchor-like recess in the protective shield

50

Claims (13)

1. A printer comprising an imaging head for imaging printed images, reflectors (11, 12, 13, 14, 36, 37) and an imaging head housing, wherein
   a blower unit is connected to the imaging head by way of at least one air duct,
   the air duct leads to a cooling air space (48) between the reflectors (11, 12, 13, 14, 36, 37) and the sidewalls of the imaging head housing, and in the imaging head housing a lamp (18) is arranged that comprises a luminary (39) and at least one lamp socket (26, 27) by way of which the lamp (18) is affixed in the imaging head housing,
   characterised in that
   the luminary (39) is arranged in an interior space that is isolated by means of the reflectors (11, 12, 13, 14, 36, 37), and the lamp socket (26, 27) projects into the air duct.
2. The printer according to claim 1, characterised in that an air outlet duct (6, 7) comprising an inlet opening and outlet opening for removing heated air is connected to the imaging head.
3. The printer according to claim 2, characterised in that the inlet opening of the air outlet duct (6, 7) is provided between the sidewalls of the imaging head housing and the reflectors (11, 12, 13, 14, 36, 37).
4. The printer according to claim 3, characterised in that a printer housing is provided, and in the printer housing a discharge opening for removing heated air is provided, which discharge opening is arranged so as to correspond to the outlet opening.
5. The printer according to claim 4, characterised in that, in the printer housing, guidance means for traversing movements of the imaging head are provided, wherein the outlet opening of the air outlet duct (6, 7) to the discharge opening of the printer housing is arranged so as to correspond to a position of the imaging head.
6. The printer according to any one of the preceding claims, characterised in that the lamp (18) is at least in part encompassed by the reflectors (11, 12, 13, 14, 36, 37), the lamp (18) in operation emits radiation which by means of the reflectors (11, 12, 13, 14, 36, 37) is guided to a printable image plane (40) comprising light-curable ink, and elliptic reflectors (11, 12) and planar reflectors (13, 14, 36, 37) are installed in the imaging head housing
7. The printer according to claim 6, characterised in that the planar reflectors are arranged on opposite sidewalls of the imaging head housing and are designed as cross reflectors (13, 14).
8. The printer according to claim 7, characterised in that the cross reflectors (13, 14) extend from the lamp (18) in the direction of the printed image plane (40) so as to be inclined towards each other.
9. The printer according to claim 7 or 8, characterised in that the cross reflectors (13, 14) extend apart from each other in a funnel-shaped manner when viewed from the lamp (18) in the direction of the printed image plane (40).
10. The printer according to any one of claims 7 to 9, characterised in that the cross reflectors (13, 14) extend so as to be symmetrical to each other relative to a plane positioned perpendicularly on the printed image plane (40).
11. The printer according to any one of claims 6 to 10, characterised in that planar reflector elements (26, 37) are arranged on the side of the lamp (18), which side is opposite the printed image plane (40).
12. The printer according to any one of claims 1 to 11, characterised in that the lamp (18) is designed as a mercury vapour lamp comprising a tubular geometry.
13. The printer according to one of claims 11 or 12, characterised in that the planar reflector elements (36, 37) are arranged so as to be inclined in cross direction of the lamp (18).

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