EP2031330A2 - Device for radiating a substrate with UV-rays - Google Patents

Abstract

The device has an ultraviolet (UV) lamp (9) and a reflector arranged in a housing (2) having an outlet (20) and inlet (22) for a cooling gas, where UV rays are directly or indirectly discharged at an UV transparent plate (10) of the housing. A conveying wing (17), a blower (21) and a cooling channel (23) cools the lamp by a cooling fluid. The lamp has movable closures (12, 13) that are provided with motors (14-16), where the closures are rotatable around a longitudinal axis of the lamp along a rotation path by the motors. A part of the closures is provided with the wing for the cooling gas.

Description

The invention relates to a device according to the preamble of claim 1.

Such a device is made of numerous documents, such as EP-0985 121 , known. This device has proven relatively good in many applications. However, on several occasions you want a safer irradiation result, but also more intensive cooling and - last but not least - a more compact design.

It is also known from the US-A-5,094,010 to carry out the cooling by means of two cooling fluids, namely by means of cooling gas and by means of a cooling liquid. In this case, liquid channels are relatively close to the reflector of the lamp and do the main work of cooling, whereas the air is guided parallel to the longitudinal axis of the lamp at a distance from this through the housing. Thus, an interaction of the two cooling systems to a synergistic effect is practically impossible.

The present invention has the object of providing a device of the type mentioned in such a way that, if possible, safer or more efficient irradiation result, but above all a more intense cooling and - not least - also allows a more compact design. This is achieved according to the invention by the characterizing features of claim 1.

In a first inventive step it was recognized that a particularly effective cooling is achieved when it is ensured that cooling air is formed in the region of the heat source to a cooling air flow, but there is often a movable shutter for controlling the irradiation time is used, but in turn prevented by its space requirement, there also accommodate conveyors for the cooling air. However, by taking the idea in a second step to provide the shutter with a drive and with the aid of which to rotate about the longitudinal axis of the UV lamp, for example a so-called medium-high-pressure mercury radiator along a rotational path, succeeds in any case very compact design. But in a third step, this idea led to the idea of this rotatable one Part could itself be used as a kind of centrifugal pump for the cooling air. Moreover. Since at least a part of the closure is provided with conveying wings for the cooling gas, he also fulfills the function of a fan for air distribution, which is very effective because of its structurally tight arrangement and therefore optimizes the cooling.

Here is a note made to the prior art. In order to maintain the fan function, a pivotable movement of the shutter, such as the DE 26 23 020 , the US-A-3,930,318 the EP-B1-0 985 121 or the EDP B1-0 891 525 clearly does not show. A rotation, as provided for by the invention, is not sufficient even if it does not allow the attachment of conveying wings, as in the EP-B1-0 830 217 or the GB-2 388 652 the case is. Finally, it should also be noted that the invention works only by the interaction of all features, because with conveyor wings anyway no radiator blades or other projections (yes have no promotional function) meant when they are not sitting on a rotatable closure.

According to a development of the invention, it is provided that the closure has two closure wings rotating in opposite directions of rotation so that the opening of the closure results in the course of the rotation of the two closure wings. This opposite movement leads to an advantageous opening of the shutter in the manner of a diaphragm, namely with a symmetrical movement of an optical, extending through the outlet side of the housing axis.

If the closure between each at least a portion of the conveying wings each has a radially outwardly leading opening, the centrifugal force generated by the wings is exploited to produce an even more intense gas stream for cooling. For, in the context of this invention, when referring to a "cooling gas", it will generally be air, although the use of other gases, such as an inert gas, e.g. Nitrogen, should not be excluded in the invention.

It is advantageous if a flow divider arrangement is provided which subdivides the cooling gas flow generated by the rotating shutter into at least two flow sections, one of which can be supplied by this arrangement of the UV lamp, whereas a further section can preferably be supplied to a wall cooled by a cooling fluid , This latter, preferred feature may additionally or alternatively be replaced by another feature, namely that of the other Section of the cooling gas flow in a cycle back or discharged to the outside. In any case, there is a mixing of the cold and the heated air, which avoids overheating of the same as well as the parts coming into contact with it or allows cooling of exhaust air or circulating air.

The invention also relates to a lamp according to claims 11 and 12, which is of particular importance for the device according to the invention, although it can also be used for other purposes. It has been found that the measurement of the temperature in other places is subject to great fluctuations, whereby any control or regulation is inefficient. This disadvantage is eliminated in the inventive lamp.

Furthermore, the invention relates to a control method according to claim 13, which takes into account that changed surface properties of a system to be cooled changes the absorption or reflection behavior of the components. This is one of these, in itself of the above device also independent but there above all applicable with good success, invention underlying insight. It has been shown that in a merely predetermined (instead of in each case predetermined) temperature by IR absorption (which is the integrative effect of temperature-dependent systems and regulations) on the relevant components, the amount of air in an undesirable manner and thus increases the UV lamp is massively supercooled. This can reduce the efficiency and lifetime of the system. By the method according to the invention, however, the predetermined temperature value is adapted according to a predetermined curve, which results in an increased efficiency and a longer service life.

Fig. 1

einen Querschnitt durch die erfindungsgemässe Vorrichtung, wozu die

Fig. 2

ein vergrössertes Detail veranschaulicht;

Fig. 3

ist eine Ansicht des Röhrenendes einer erfindungsgemäss eingesetzten Lampe; und

Fig. 4

veranschaulicht die der Kühlregelung nach Fig. 1 aufgeprägte Leistungskurve.

Further details of the invention will become apparent with reference to the following description of a schematically illustrated in the drawing, preferred embodiment. Show it:

Fig. 1

a cross section through the inventive device, including the

Fig. 2

an enlarged detail illustrates;

Fig. 3

is a view of the tube end of a lamp used in the invention; and

Fig. 4

illustrates the cooling control after Fig. 1 impressed power curve.

According to Fig. 1 runs, essentially endless, conveyor belt 1 below a lamp housing 2 over and driven by a merely schematically indicated drive roller 3, which in the illustration of Fig. 1 For example, by means of a pressure device 4 against the conveyor belt 1, pressed against a stationary roller 5 and driven by a drive motor 6. Of course, the drive of the conveyor belt can be modified in any known manner. To promote a substrate to be irradiated and a turntable, especially with intermittent drive, such as a drive with Maltese Cross or with stepper motor could be used. Other known possibilities of linear or round promotion are possible within the scope of the invention.

The conveyor belt 1 transports articles to be treated by means of UV radiation. In the presentation of the Fig. 1 For example, a sheet-like sheet 11 printed or provided with an adhesive to be cured by UV ray is shown, but it may also include corresponding articles, blister packs, plastic articles, painted articles or the like. be.

The inside of the wall of the housing 2 preferably, preferably by a cooling medium, such as cooling water, flowed through cooling fins 7. In this case, the housing 2 is advantageously made up of at least two housing parts 2a, 2b which are connected to one another via flanges 8 or in some other way, so that they can surround a UV tube 9 located as far as possible in the interior. At the bottom is the light exit side of the housing, where a UV-transparent plate 10 is used, which prevents the entry of dust into the housing 2 from the outside as possible, while also preventing cooling air losses to the outside. This plate 10 can have an optical coating, such as an IR-absorbing coating and / or an anti-reflection coating at least for the wavelength of the lamp.

This "envelope", which is not conventional in UV lamps 9, through the housing 2 or its parts 2a, 2b over more than 180 °, is due to the fact that it advantageously forms a guide surrounding the lamp for a cooling gas flow. If a cooling gas flow is mentioned here, then the cooling gas will generally be air, but for some applications, another gas may also be expedient, for example an inert gas, such as nitrogen (N ₂ ).

The UV lamp 9 is preferably inserted in the direction of the longitudinal axis in the housing 2, so that it occupies a central position therein. According to Fig. 2 For example, an approximately hexagonal support T is provided, which the lamp 9 and the - according to the following description - so functionally connected parts 12, 13, 17, 19, 24 receives and stores, and the schematically illustrated dovetail guides S in the housing 2 can be inserted is. Of course, any other guide S can be used, which extends in each case in the direction of the longitudinal axis of the UV lamp 9 and parallel thereto. Since according to a preferred embodiment, the reflector 24 may be water-cooled, it may be advantageous if the carrier T is made so small that with him only the lamp 9 is inserted, whereas the reflector 24 is fixedly mounted in the housing 2.

It is clear that the lamp 9 produces not only UV rays but also heat, which must be kept within limits, otherwise the danger of early destruction of the tube 9 is given. On the other hand, it is often desirable that the UV radiation from the housing 2 exits only when under the housing 2, a substrate to be irradiated 11 is underneath. For this purpose, a closure, so called in the industry as a "shutter" means is provided which covers the light of the lamp 9 in its closed position after the window 10 toward, in the open position, however, releases. This closure is in the execution after Fig. 1 of two wings 12, 13 are formed, which rotate in the preferred embodiment in the opposite direction of rotation around the longitudinal axis of the housing 2. This is not absolutely necessary in the context of the invention, but embodiments are conceivable in which, for example, only one rotating closure vane 12 is provided, which extends over a larger or smaller angle as required. If rotation or rotation is mentioned here, then this does not necessarily have to be done with uniform speed, but could also be carried out intermittently or at different speeds. The drive of the two shutter blades 12 and 13 is effected by a motor 14, which supplies the rotary drive in one direction, via a hollow shaft 16 shown in the other direction via a dash-dotted lines indicated shaft 15. Again, the nature of the drive is not critical, because it may be a single motor 14, which drives the two shafts 15, 16 via a gear in opposite directions, but it can also each of the shafts 15, 16 has its own , suitably with the other synchronized, own engine.

As in Fig. 1 is indicated, at least a portion of the closure is provided with conveying wings 17 for the cooling gas, advantageously carries at least the closure member 12 over its entire circumference such wings. These wings 17 can between each other baggy closed and only against the UV lamp 9 to open (also an opening radially outward would be possible) have intermediate spaces, but it is preferred if the closure between at least a portion of the conveying wings 17 each one of radially inward radially outwardly leading opening 17 '(FIG. Fig. 2 ), because so does the centrifugal force similar to a fan blade in a more favorable manner in the sense of generating an air flow. This air flow is indicated by the arrow [1]. In this case, the air flow [1] passes in an annular space 2c past the cooled ribs 7 of the outer housing shells 2a, 2b, so that an even more intensive cooling results.

When the air flow [1] reaches the lower position [1 '] and then rises again, it comes into the area of two gas or air switches, namely an outer air switch 18 and then into the region of an inner air switch 19. These switches 18, 19 have the function of a flow divider, the counter-flow of the flow nose 18 a portion of the air flow in the circumferential direction again the air flow [1], whereas another part via a pipe extension 20 discharged to the outside, for example by means of a suction fan 21 is sucked. This results in a mixing of the cold and the heated air, which avoids overheating of the same and coming into contact with their parts or allows cooling of exhaust air or circulating air.

It is advantageous if the air diverter 18 has cooling channels 23 through which a liquid cooling medium flows in its interior, although it would also be conceivable to use an evaporable cooling medium for the purpose of cooling, as used for example in refrigerators. In any case, it is ensured that even the gas flowing in via a supply pipe 22 is effectively cooled. And also from the switch 18 to the air flow [1] zurückgelenkte section of the flow.

Instead of a suction fan, of course, a pressure fan may be connected to a supply port 22 at the supply side, although this will not be generally preferred because of the danger of the supply of dust particles. It is also understood that, if appropriate, only the first or only the second air switch 18 or 19 can be provided or that the flow division can be designed in a different manner. It would also be conceivable to feed the cooling gas flow tangentially (as shown), but to discharge it in the axial direction of the lamp 9 and vice versa.

The second air switch 19 divides the air flow again and generates an inner, secondary air flow [2], which passes directly to the UV lamp 9 and flows around it. It is advantageous if this further, radially inwardly guided or secondary section [2] of the air flow to a cooled by a cooling liquid 23 wall 24 can be fed, which - as can be seen - divided into two parts in this embodiment. This ensures that, on the one hand, the air (or the gas) efficiently dissipates the heat produced by the UV lamp 9, without the need for a complex construction, while this air flow itself transfers the heat to the cooling liquid 23. Due to the fact that the two wings 12, 13 of the closure rotate in the opposite direction, a sufficient opening is again and again created, through which this secondary air flow, driven by the centrifugal force produced by the wings 17, also flows outwards again and optionally via the connection piece 20 can be withdrawn. This wall 24 is expediently designed as a reflector at the same time, which directs the UV light emitted by the lamp 9 upwards against the window 10.

This opening of the two closure parts 12, 13 (in itself it would also be conceivable to provide more than two closure wings, as it would also be conceivable to equip the closure wing 13 with conveying wings 17) should of course - to ensure uninterrupted transport of the parts 11 to be irradiated and they do not have to promote intermittently - done so that the open position of the shutter wings 12, 13 is synchronized with the position of the substrate 11 to be irradiated below the window 10. For this purpose, a sensor arrangement 25 (only schematically indicated) is advantageously provided, which detects the presence of a part 11, such as a sheet or film to be dried, below the window 10 and then regulates the motors 6 and 14 via a synchronization circuit 26 synchronized. The sensor assembly 25 may be of a type known per se, so that it need not be shown and described in detail.

It is known per se to regulate the power (and that means, at approximately constant voltage: the current) of a lamp as a function of the temperature. Usually, a temperature sensor is arranged on a lamp reflector or in the exhaust air flow, but for various reasons, such as air turbulence, etc., the temperature detected only with rough approximation. If, how Fig. 3 illustrated, a thermal sensor 27 in the lamp housing 9 '(ie directly in the glass of the lamp 9) housed, in particular melted, then it is ensured that its measurement regardless of is random environmental temperature changes. It is particularly expedient here, when a temperature measuring cable 28 from a point in the end lying on the tubular housing tube neck or socket 9 ", for example via a terminal 33, its output, which latter also has a power supply cable 34. A thus formed lamp is here, and especially for the careful adjustment of the temperature of the UV lamp 9, particularly favorable, but can also regardless of the formation of the shutter 12, 13 with fan blades 17 apply wherever an accurate lamp temperature measurement is desired or necessary.

Another important embodiment is the type of cooling control, but which is also applicable regardless of whether a closure 12, 13 is equipped with fan blades 17 or not. It has already been stated above that the regulation to constant temperature is known per se by regulation of the power supply as a function of a temperature measurement. Of course, such power regulation results in fluctuating power within the control range, which may involve both the risk of overheating and the risk of over-cooling. So if now the temperature signal according to Fig. 1 is passed over the already mentioned temperature measuring cable 28 to a control unit 29, which then regulates the power supply via an actuator 30, so you go to the mentioned risks. To counter this, you can (and you have so far) make a Luftmengendrosselung (via a motorized flap or a correspondingly controlled fan). However, it is well known that altered surface properties change the absorption or reflection behavior of the components. In such a cooled radiation head, the amount of air can be regulated to a higher level by IR absorption on the relevant components and thus the mass of the UV tube (which is less subject to such a change in absorption) can be massively undercooled. It loses efficiency and durability.

It is therefore necessary to eliminate these adverse side effects. For this purpose, it is provided in the context of the invention that the control unit 29, a power curve 31 with juxtaposition of flow of the cooling fluid (see. Fig. 4 ) is assigned to a temperature-dependent value, in particular the power supplied to the UV lamp P, and that according to this power curve 31, the volume flow of the cooling fluid and / or its temperature is regulated. If the signal of the sensor 27 is supplied to the control circuit 29 via the line 28 in this embodiment, this is advantageous for the control, but not absolutely necessary, because the power curve 31 itself already includes the assignment of a temperature-dependent Value (namely, the power P), so that a control by means of this power curve 31 would be possible without the zoomed over the cable 28 signal. On the other hand, it may be appropriate to supply the control circuit 29 via a line, not shown, a signal corresponding to the power supplied to the lamp 9 (which in turn determines the temperature of the lamp). This power signal can either be dependent on the position of an adjusting device for the power (ie a pure control in the open circuit), or it is a power meter or a current sensor (the voltage is indeed substantially constant) provided, the output signal to a control can be used in a closed loop.

In the present case the Fig. 1 For example, the volume flow of the blower 21 driven by a motor 32 is regulated, which is also preferable because it allows a faster response control. However, it would be additionally or alternatively also conceivable to regulate cooling of the air supplied via the connecting piece 22. However, such temperature changes have a relatively long control time constant, which is why this type of control is less preferred.

The assignment of the power curve 31 can be solved constructively in various ways, for example by the control unit 29 has a program memory with this curve 31 or by training a software for the control unit (eg an electronic processor) with a corresponding algorithm. It is in Fig. 4 the power curve 31 is shown substantially as rising at a predetermined angle straight line, because in general the relationship between power and cooling demand will be linear. However, other forms of the curve are also conceivable, in particular if additional influencing variables are to be taken into account, or if the relationship to components to be controlled would be approximately logarithmic or exponential. In any case, however, a predetermined dependence of the volume flow of the supplied power will result, regardless of other factors, such as the change of surfaces or the absorption change to components of the housing or the like. is.

Of course, it is within the scope of the invention quite possible to separate the two functions of the control unit 29 from each other and make the control in two stages, one of which regulates the power of the lamp and the second - based on the lamp power - the cooling, was it by changing the volume flow, be it (alternatively or additionally) by changing the cooling temperature. Another possibility for the regulation would be that although the motor 32 with relatively constant, high power is operated, but instead of the motor 32, a recirculation bypassing the fan 21 return valve for returning the cooling gas flow from the outlet of the blower is opened more or less at its entrance, although such a solution will generally be less preferred.

Also, the control unit 29 may also have the same drive for the motor 32, which includes, for example, a frequency converter or a drive for a DC motor 32. Also, additionally or alternatively, the flow rate of the cooling water flow 23 could be regulated, in particular for keeping the temperature constant.

All motors 6, 14, possibly also 32, may preferably be synchronous motors or also stepper motors. Furthermore, it was mentioned above that a temperature control has a relatively large control time constant; this can be counteracted by placing in the measuring line, e.g. in the measuring cable 28, a differentiating stage, if necessary with a subsequent, a threshold determining stage installed so that deviations can be detected faster.

In the context of the invention numerous variants are possible; Thus, the closure 12 may have a peripheral wall without openings between the conveying wings 17.

Claims (11)

Device for irradiating a substrate by means of UV rays, with a UV lamp (9) and associated reflector (24), which are arranged in a housing (2) that UV rays directly or indirectly on an outlet side (10) the housing (2) and with a cooling device (17, 21, 23) for cooling the UV lamp (9), in particular using two cooling fluids ([1], [2], 23), wherein the housing (2 ) has at least one inlet (22) for a cooling gas forced to flow by a conveyor (21) and at least one outlet (20) therefor so that cooling gas can be passed through the housing (2), characterized in that a) the UV lamp (9) is associated with a movable closure (12, 13); that b) the closure (12, 13) provided with a drive (14-16) and with the aid of which is rotatable about the longitudinal axis of the UV lamp (9) along a rotational path, and that c) at least part of the closure (12, 13) is provided with conveying wings (17) for the cooling gas. Device according to claim 1, characterized in that the rotating shutter (12, 13) carries the conveying wings (17) on the side facing the UV lamp (9). Apparatus according to claim 1 or 2, characterized in that the closure (12, 13) has two in opposite directions of rotation rotating closure vanes (12 or 13), so that the opening of the closure (12, 13) in the course of rotation of the two closure wings (12 or 13) results. Device according to one of the preceding claims, characterized in that the closure (12, 13) between at least a portion of the conveying wings (17) each have a radially inwardly to radially outwardly leading opening (17 ') (Fig. 2). Device according to one of the preceding claims, characterized in that a flow divider arrangement (18, 19) is provided, which divides the cooling gas flow generated by the rotating shutter (12, 13) into at least two flow sections ([1], [2]), of which one ([2]) of this arrangement (18, 19) of the UV lamp (9), whereas a further section ([1]) can preferably be fed to a wall (18) cooled by a cooling liquid. Apparatus according to claim 5, characterized in that in the interior of the rotational path of the closure (12, 13) at least one of a cooling liquid (23) cooled wall part (24) is provided. Device according to one of the preceding claims, characterized in that the housing (2) surrounds the UV lamp (9) over more than 180 °, expediently consists of at least two mutually connectable housing parts (2a, 2b), and so the lamp (9) forms surrounding guide for at least a part ([1]) of the cooling gas flow. Device according to one of the preceding claims, characterized in that a, in particular band-like, conveyor (1) for individual substrates to be irradiated (11) is provided, and in that this conveyor (1) via a synchronization arrangement (26) with the rotatable shutter (12 , 13) is synchronized so that it is only opened when there is a substrate (11) to be irradiated under the UV lamp (9). Device according to one of the preceding claims, characterized in that the housing (2) at least partially surrounds the rotational path of the closure (12, 13), so that an approximately annular space (2c) is formed therebetween. Apparatus according to claim 9, characterized in that the housing (2) consists of at least two fastened to each other housing parts (2a, 2b). Apparatus according to claim 9 or 10, characterized in that the housing (2) in the direction of the longitudinal axis of the UV lamp (9) or parallel thereto extending guide (S) for the insertion of a lamp (9), preferably together rotatable closure (12, 13), supporting unit (T).

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