LIGHT SOURCE AND METHOD FOR OPERATING A LIGHT SOURCE

Abstract

A light source comprises at least one light-emitting component, in particular a component emitting ultraviolet light and/or a semiconductor component, and a line system, through which a cooling fluid can flow in a flow direction, for controlling the temperature of the at least one light-emitting component, and also a first and a second cooling-fluid pressure sensor, which are arranged one after the other in the line system in the flow direction, and an electronics unit which is connected to the first and second cooling-fluid pressure sensors and configured to determine at least one diagnostic, control and/or regulating value on the basis of pressures captured by the first cooling-fluid pressure sensor and by the second cooling-fluid pressure sensor.

Claims

1. A light source comprising at least one light-emitting component, in particular a component emitting ultraviolet light and/or a semiconductor component, and a line system, through which a cooling fluid can flow in a flow direction, for controlling the temperature of the at least one light-emitting component, wherein a first and a second cooling-fluid pressure sensor, which are arranged one after the other in the line system in the flow direction; and an electronics unit which is connected to the first and second cooling-fluid pressure sensors and configured to determine at least one diagnostic, control and/or regulating value on the basis of pressures captured by the first cooling-fluid pressure sensor and by the second cooling-fluid pressure sensor.

2. The light source according to claim 1, wherein the cooling-fluid line system comprises a distributor block with a cooling-fluid inlet opening and a cooling-fluid return opening, wherein the distributor block comprises a first cavity and a further cavity, wherein the first cavity and the further cavity are fluidically connected to one another by means of at least one fluid path; wherein the first cooling-fluid pressure sensor is arranged in the first cavity and the second cooling-fluid pressure sensor is arranged in the second cavity, wherein in particular the first cooling-fluid pressure sensor is arranged at the cooling-fluid inlet opening and/or the second cooling-fluid pressure sensor is arranged at the cooling-fluid return opening, and/or wherein, in particular, the first pressure sensor is arranged at the end of the distributor block opposite the cooling-fluid inlet opening and/or the second pressure sensor is arranged at the end of the distributor block opposite the cooling-fluid return opening.

3. The light source according to claim 1, wherein the first cooling-fluid pressure sensor and/or the second cooling-fluid pressure sensor captures a pressure measurement value of the cooling fluid and provides a corresponding electrical pressure measurement signal to the electronics unit, wherein in particular the corresponding pressure measurement signal is realized as a preferably proportional current or voltage signal.

4. The light source according to claim 1, wherein the electronics unit has a flow control and/or regulation device which is configured to define a flow rate of the cooling fluid in the flow direction through the line system.

5. The light source according to claim 4, wherein the flow control and/or regulation device has a pump with a delivery rate for conveying the cooling fluid through the line system, wherein the flow control and/or regulation device is configured to adjust the delivery rate of the pump taking into account a desired temperature control of the light-emitting component for a lowest desired cooling-fluid flow rate, wherein in particular the flow control and/or regulation device is configured to adjust the lowest desired cooling-fluid flow rate as a function of a diagnostic, control and/or regulating value of the electronics unit.

6. The light source according to claim 1, wherein the electronics unit comprises at least one power electronics unit for adjusting the light output of the at least one light-emitting component, wherein in particular the electronics unit is configured to determine the at least one diagnostic, control and/or regulating value on the basis of the light output and/or wherein the flow control and/or regulation device is configured to define the flow rate of the cooling fluid through the line system on the basis of the light output.

7. A method for operating a light source, in particular according to claim 1, comprising at least one light-emitting component, wherein the temperature of the at least one light-emitting component is controlled by means of a cooling fluid, wherein the cooling fluid is conveyed through a line system, wherein at a first point in the line system, a first pressure of the cooling fluid is captured, at a second point in the line system, a second pressure of the cooling fluid is captured, and a diagnostic, control and/or regulating value is determined on the basis of the first pressure and the second pressure.

8. The method for operating a light source according to claim 7, wherein a flow rate of the cooling fluid in the flow direction through the line system is defined, wherein a lowest desired cooling-fluid flow rate is set, in particular taking into account a desired temperature control of the light-emitting component.

9. The method for operating a light source according to claim 7, wherein a diagnostic value, in particular an error message, is output when the first pressure and the second pressure are equal or substantially equal.

10. The method for operating a light source according to claim 7, wherein a diagnostic value, in particular a warning message, is output when a difference Δp) between the first pressure and the second pressure falls below a minimum threshold value and/or exceeds a maximum threshold value.

11. The method for operating a light source according to claim 7, wherein a light output of the at least one light-emitting component is set, wherein the diagnostic, control and/or regulating value is determined on the basis of the light output and/or wherein the flow rate is set on the basis of the light output.

Description

[0059] The invention is illustrated in more detail below by examples and drawings, wherein the examples and drawings do not limit the invention. Furthermore, unless otherwise indicated, the drawings are not true to scale. Preferred embodiments of the invention are given in the claims. Particular embodiments and aspects of the invention are described below with reference to the accompanying figures, in which are shown:

[0060] FIG. 1 an embodiment of a light source according to the invention;

[0061] FIG. 2 a perspective sectional view of an exemplary distributor block for a light source according to the invention; and

[0062] FIG. 3 a schematic diagram of a first and a second cooling-fluid pressure as a function of the flow rate.

[0063] FIG. 1 shows a schematic representation of a light source 1 according to the invention. The light source 1 comprises an electronics unit which is connected to a first cooling-fluid pressure sensor 21 and a second cooling-fluid pressure sensor 22. The light source 1 further comprises a distributor block 10 with a cooling-fluid inlet opening 121 and a cooling-fluid return opening 122. Light-emitting components 11, 13, 15 are fastened to the distributor block. The light source 1 comprises a power electronics unit 7 for adjusting the light output of the light-emitting components 11, 13 and 15.

[0064] The light source 1 comprises a line system 103 through which the cooling fluid is conveyed in a flow direction F. The cooling fluid is conveyed by means of a flow control and/or regulation device 5 through the line system 103, which can comprise a pump 51 and optionally also a restrictor and/or a valve 53, such as a control valve or a balancing valve.

[0065] The first pressure sensor 21 can be arranged at the cooling-fluid inlet opening 121 of the distributor block 10. The second cooling-fluid pressure sensor 22 can be arranged at the cooling-fluid return opening 122 of the distributor block. The distributor block 10 is designed as a housing for receiving the light-emitting semiconductor components 11, 13, 15.

[0066] FIG. 2 shows a schematic partial representation of a section of the distributor block of a light source 1 according to the invention according to FIG. 1. In FIG. 2, a carrier element 12 is shown that carries one of the light-emitting components 11. The light-emitting component 11 is realized as an ultraviolet light-emitting semiconductor component, more precisely: an LED module. FIG. 2 shows just one first carrier element 12 with a single light-emitting component 11. Referring to FIG. 1, it is clear that a light source 1 can comprise a plurality of light-emitting components 11, 13, 15, wherein in particular each light-emitting component 11, 12, 13 can be fastened to the distributor block 10 by means of one carrier element 12 each. The first light-emitting semiconductor component 11, which is an LED module 11, is soldered onto the first carrier element 12. The first carrier element 12 can be screwed onto the distributor block 10 with, for example, two countersunk screws as fastening means. The first light-emitting semiconductor component 11, the first carrier element 12 and the distributor block 10 overlay one another in the aforementioned order. The LED module 11 contains a substrate made of a ceramic material onto which a plurality of LED chips is mounted, in particular in chip-on-board technology. The LED module 11 is a UV LED module. 28 carrier elements with 12 with one LED module 11, 13, 15 each are, for example, mounted next to one another on the distributor block 10 in the longitudinal direction thereof.

[0067] According to another example not shown, 16 carrier elements 12, each of which has a longitudinal width of 1″ and carries one LED module 11, 13 or 15, can, for example, be mounted next to one another on the distributor block 10 in the longitudinal direction thereof. In this example, a desired flow rate of 16 L/min can be provided, wherein a pressure difference Δp of approximately 300 mbar is established between the first cooling-fluid pressure p1 (for example, 1.2 bar) measured at the first pressure sensor 21 and the second cooling-fluid pressure p2 (for example, 0.9 bar) measured at the second pressure sensor 22 (see FIG. 3). The diameter of the first channel 501 and/or of the second channel 502 can be 0.75 inches, for example. The diameter of the first branch channel 504 and/or of the second branch channel 506 can be 1.3 mm, for example.

[0068] The schematic cross-sectional representation shown in FIG. 2 of the distributor block 10 of a light source 1 according to the invention shows that the distributor block 10 contains a first cavity 501, which is designed as an inlet for the cooling fluid. The first cavity is formed as a first channel that passes through under each of the carrier elements 12. The distributor block 10 also contains a second cavity 502, which is designed as a return for the cooling fluid. The second cavity 502 is formed as a second channel which passes through under each of the carrier elements 12. A first fluid path 409 leads from the first cavity 501 to the second cavity 502. The cross-section of the first cavity 501 and the cross-section of the second cavity 502 are of equal size. In order to flow from the first cavity 501 to the second cavity 502, the cooling fluid must flow through one of the plurality of fluid paths 409 of the distributor block 10.

[0069] A fluid path 409 consists of three sections. The middle section is provided by the carrier body 12. The carrier body 12 comprises a plurality of heat-exchanger channels 403, which are formed below the light-emitting element 11 (or 13, 15) in the carrier body 13. A first branch channel 504 r leads from the first cavity 501 to the heat-exchanger channels 403. A further first branch channel (not shown), which leads from the first cavity 501 to the heat-exchanger channels 403 of the carrier element or carrier body 12, can also be provided in the distributor block 10. The first branch channel and optionally the further first branch channel form the first section of the fluid path 409.

[0070] From the second cavity 502, at least one second branch channel 506 leads to the heat-exchanger channels 403 of the carrier body 12. A further second branch channel (not shown in more detail) can lead from the second cavity 502 to the heat-exchanger channels 403. The at least one first branch channel 504 and the at least one second branch channel 506 are formed in the distributor block 10. The at least one first branch channel 504, the at least one second first branch channel 506 and the at least one heat-exchanger channel 403 together form the fluid paths 409.

[0071] The flow resistance or pressure loss between the first cooling-fluid pressure sensor 21 and the second cooling-fluid pressure sensor 22 is decisively determined by the hydraulic properties of the fluid path. The hydraulic properties of the fluid path 409 are decisively determined by the section with the smallest cross-section. The first section of the fluid path 409 is formed by the first branch channels 504; and the third section of the fluid path 409 is formed by the branch channels 506. The first branch channels 504 and the second branch channels 506 have substantially the same cross-section. The branch channels 504 and 506 decisively determine the hydraulic properties of the fluid path 409. The flow resistance or the pressure difference between the first cooling-fluid pressure sensor 21 the second cooling-fluid pressure sensor 22 is decisively determined by the flow resistance of the at least one first branch channel 504 and of the at least one second branch channel 506.

[0072] The heat-exchanger channels 403 in the carrier body 12 are bounded on the one hand by the carrier body 12 and on the other hand by an outer surface of the distributor block 10. A seal 16 is provided between the outer side of the distributor block 10 and the carrier body 12 in order to prevent a loss of cooling fluid. Alternatively, it is conceivable for the light-emitting components to be fastened directly to the distributor block 10 without a carrier body, the fluid path being realized in the distributor block 10 (not shown in detail). Alternatively, it is conceivable for heat-exchanger channels 403 to be formed in a carrier body 12 not bounded by a distributor block side. Such heat-exchanger channels would only be bounded by the carrier body 12 (not shown). The light-emitting components 11 can emit light to the surroundings through a protective window 14 which is held on the distributor block 10.

[0073] Starting from one end 101 of the distributor block 10, the light-emitting components 11, 13 and 15 can be divided into one or more proximal light-emitting components 11, one or more minute light-emitting components 13 and one or more distal light-emitting components 15. The various proximal (11), middle (13) and distal (15) light-emitting components can be adjusted independently of one another by means of the power electronics unit 7 of the electronics unit 3.

[0074] For example, when the light source 1 is used in a printer for different format widths, the light-emitting components can be dimmed and/or deactivated in part, in particular in a location-dependent manner. For example, for a small format, it is possible for only the proximal light-emitting components 11 to be activated and for the middle and distal light-emitting components 13, 15 to be deactivated or dimmed. It is clear that the subdivision made into proximal, middle and distal light-emitting components 11, 13 and 15 is purely by way of example. In particular, the power electronics unit 7 can adjust the light output of each individual light-emitting component 11, 13 and/or 15 of a light source 1 independently of one another.

[0075] The pump 51 can be operated at its maximum nominal pump output, and the flow rate f can be set with the valve 53 to a desired flow rate, for example with a balancing valve as described in DE 20 2013 001 744 U1. In this way, it is possible to set the flow rate f which is required to ensure, at a predetermined cooling-fluid input temperature, the required cooling power for the temperature control of the light-emitting components 11, 13, 15 during operation during their operation at their respective maximum nominal output.

[0076] FIG. 3 schematically shows a diagram of measurements of the first pressure p1 and measurement of the second pressure p2. Since the second pressure p2 is measured downstream of the first pressure p1 in the flow direction F in the line system 103, the second pressure p2 is lower than the first pressure p1 as a result of the flow resistance between the first measuring point the second point. The difference between the first pressure p1 and the second pressure p2 is the pressure difference Δp. It is clear that the distributor block 10 and/or, if appropriate, the line system 103 could be flowed through in the reverse direction in particular in the case of a different pump configuration (not shown).

[0077] According to the diagram shown in FIG. 3, the pressure can be given as a pressure value in bar or pascal. It is conceivable for a pressure measurement value to be used as the pressure, for example in the form of a voltage signal or of a current signal, which is generated by the first cooling-fluid pressure sensor 21 or the second cooling-fluid pressure sensor 22. The pressure measurement value, i.e., the current value or the voltage value, preferably corresponds proportionally to the respective pressure value p1 or p2.

[0078] As shown in FIG. 3, the pressure p1 or p2 [bar] within the line system 103 is dependent on the flow rate f [L/min] of the cooling fluid through the line system 103. The pressure difference between the first pressure sensor 21 second pressure sensor 22 can be determined approximately by a formula known to the person skilled in the art for determining a pressure change along a straight pipe.

[0079] The electronics unit 3 is configured to detect whether the first pressure p1 and second pressure p2 captured by the sensors 21, 22 can permit a conclusion as to whether the light source 1 is functioning correctly or is malfunctioning.

[0080] If the pressure difference Δp approaches 0, it can be assumed that the volumetric flow rate is likewise approaching 0; or, in other words, the temperature of the light-emitting components 11, 13 and 15 is not being properly controlled. In this case, the electronics unit 3 can initiate an emergency shutdown of the light source 1. In the event of an emergency shutdown of the light source 1, the power electronics unit 7 can in particular first be caused to switch off the light output of the light-emitting components 11, 13 and 15.

[0081] The electronics unit 3 can in particular be configured to generate a diagnostic value, such as a status message, depending on the presence of a smallest required pressure difference Δp, wherein the power electronics unit 7 is configured to then operate the at least one light source 1 exclusively when the electronics unit 3 reports the presence of the lowest required pressure difference Δp. The lowest required pressure difference can correspond, for example, to 50 mbar, 100 mbar, 500 mbar or 1 bar. Otherwise, it can be assumed that no or no adequate cooling-fluid flow f is present to operate the at least one light source 1 without damage.

[0082] In normal operation of the light source 1, the electronics unit 3 can carry out a regulation on the basis of the first pressure p1 and the second pressure p2 or on the basis of electrical pressure measurement values corresponding to the first pressure or second pressure. If, for example, the pressure difference Δp decreases, this can indicate a reduced flow rate so that the electronics unit 3 can adjust the flow rate f by means of the flow control and/or regulation device 5, wherein, for example, the delivery rate of the pump 51 can be increased and/or a valve 53 can be opened wider.

[0083] If, during operation of the light source 1, the difference of the Δp between the first pressure p1 and the second pressure p2 or electrical pressure measurement values corresponding thereto increases in particular unexpectedly, the electronics unit 3 can, by means of the control or regulation device, adjust the flow rate f and/or output a diagnostic value, in particular a warning and/or error message.

[0084] In the case of a rapid increase in the difference Δp (e.g., a change by at least 0.5 bar in less than one minute), this can indicate a leakage or a significant blockage of the line system 103, for example of the first or second channel 501 or 502. The electronics unit 3 can be configured to adjust the flow rate f by means of the control or regulation device in the event of a rapid increase in the difference Δp, by, for example, reducing the delivery rate of the pump 51 and/or reducing the opening width of the valve 53.

[0085] In the case of a creeping increase in the difference Δp (e.g., a change by at least 0.5 bar within a period of at least one hour), this can indicate a partial and/or progressive closure of the line system 103, in particular of at least one fluid path 409. In the case of a creeping increase in the difference Δp, it can be assumed that, at the same delivery rate of the pump 51, the flow rate f decreases while the flow resistance and the associated difference Δp increases. The electronics unit 3 can be configured to adjust the flow rate f by means of the control or regulation device in the event of an in particular creeping increase in the difference Δp, by, for example, increasing the delivery rate of the pump 51 and/or increasing the opening width of the valve 53.

[0086] The electronics unit 3 can take into account, for example, a highest permissible maximum threshold value and/or a lowest permissible minimum threshold value in order to detect whether the pressure difference Δp is within a permissible range between the lowest permissible minimum threshold value and the highest permissible maximum threshold value. If the pressure difference of Δp is outside this permissible range, the electronics unit 3 can be configured to output a corresponding diagnostic value, control value and/or regulating value. Due to the structure of the light source 1, each of the carrier elements 12 of the light source 1 can be cooled in the method with a cooling power of approximately 300 W by means of a water-glycol mixture as cooling fluid, which flows, for example, at approximately 5 bar or approximately 1.5 bar within a cooling circuit 103, so that the two carrier elements 12 lying furthest away from one another in the longitudinal direction show a temperature difference of at most 4K. As a result, all LED modules 11, 13, 15 of the light source can be operated at approximately the same efficiency. As a result, a homogeneous irradiation and thus a homogeneous curing of the printing ink over a large area is possible, for example.

REFERENCE SIGNS

[0087] 1 Light source [0088] 3 Electronics unit [0089] 5 Control and/or regulation device [0090] 7 Power electronics unit [0091] 10 Distributor block [0092] 11, 13, 15 Light-emitting component [0093] 12 Carrier body [0094] 14 Window [0095] 16 Seal [0096] 21 First pressure sensor [0097] 22 Second pressure sensor [0098] 51 Pump [0099] 53 Valve [0100] 103 Line system [0101] 121 Cooling-fluid inlet opening [0102] 122 Cooling-fluid return opening [0103] 403 Heat-exchanger channel [0104] 409 Fluid path [0105] 501 First cavity [0106] 502 Second cavity [0107] 504 First branch channel [0108] 506 Second branch channel [0109] f Flow rate [0110] F Flow direction [0111] p1 First pressure [0112] p2 Second pressure [0113] Δp Pressure difference