CONTROL CIRCUIT FOR CONTROLLING A UV LIGHT SOURCE

Abstract

A control circuit for controlling a UV light source configured to emit UV light into a purifying chamber of a device for purifying a fluid, the control circuit comprising a driver configured to provide the UV light source with a drive current; a fluid flow sensor configured to determine whether a flow of a fluid through the purifying chamber is present and generate a flow signal indicative thereof; a light sensor configured to measure radiant flux of light emitted from the UV light source and to generate a radiant flux signal comprising data pertaining to the measured radiant flux; a memory comprising a reference radiant flux; and a processor configured to: activate the UV light source upon the flow signal being indicative of presence of flow of fluid through the purifying chamber, during the UV light source being active: determine the drive current for the driver based on the measured radiant flux comprised in the radiant flux signal and the reference radiant flux.

Claims

1. A control circuit for controlling a UV light source configured to emit UV light into a purifying chamber of a device for purifying a fluid, the control circuit comprising: a driver configured to provide the UV light source with a drive current; a fluid flow sensor configured to determine whether a flow of a fluid through the purifying chamber is present and generate a flow signal indicative thereof; a light sensor configured to measure radiant flux of light emitted from the UV light source before the light emitted from the UV light source (204) has entered the purifying chamber and to generate a radiant flux signal comprising data pertaining to the measured radiant flux; a memory comprising a reference radiant flux; and a processor configured to: upon the flow signal being indicative of presence of flow of fluid through the purifying chamber, activate the UV light source, during the UV light source being activated due to presence of flow of fluid through the purifying chamber, determine the drive current for the driver based on the measured radiant flux comprised in the radiant flux signal and the reference radiant flux; and upon the flow signal being indicative of non-presence of flow of fluid through the purifying chamber, instruct the driver to apply a drive current below a threshold to the UV-light source, wherein the threshold is set so that the radiant flux of UV-light emitted from the UV light source is ≤5% of a maximum radiant flux of UV-light emitted from the UV light source.

2. The control circuit according to claim 1, wherein the processor is configured to determine the drive current for the driver by determining a degradation of the UV-light source based on the measured radiant flux comprised in the radiant flux signal and the reference radiant flux, and determine the drive current for the driver based on the degradation of the UV-light source.

3. (canceled)

4. The control circuit (100) according to claim 1, wherein the processor is configured to: determine a time period of non-presence of flow of fluid through the purifying chamber, and upon a length of the time period of non-presence of flow of fluid through the purifying chamber is above a threshold, activate the UV light source.

5. The control circuit according to claim 1, wherein the fluid flow sensor is further configured to measure a flow rate of a fluid flowing through the purifying chamber, wherein the flow signal comprises data pertaining to the measured flow rate, and wherein the processor is further configured to determine the drive current for the driver based on the measured flow rate comprised in the flow signal.

6. The control circuit according to claim 1, wherein the light sensor is configured to measure UV-C light radiant flux and wherein the reference radiant flux is a UV-C light reference radiant flux.

7. The control circuit according to claim 1, wherein the UV light source comprises one or more UV LEDs.

8. The control circuit according to claim 7, further comprising a temperature sensor configured to measure a temperature of a UV LED and generate a temperature signal, wherein the processor is configured to, upon the temperature signal being indicative that the temperature of the LED is above a predetermined temperature threshold, generate a LED overheat signal.

9. The control circuit according to claim 1, wherein the processor is configured to, upon the radiant flux signal being indicative that the measured radiant flux is below a predetermined radiant flux threshold, generate a UV light source failure signal.

10. The control circuit according to claim 9, wherein the predetermined radiant flux threshold is a factory set threshold.

11. A device for purifying a fluid, the device comprising: a purifying chamber having a fluid inlet and a fluid outlet for allowing a flow of fluid to be purified to flow there through; a UV light source configured to emit UV light into the purifying chamber; and a control circuit according to claim 1, configured to control the UV light source.

12. A method for controlling a UV light source configured to emit UV light into a purifying chamber of a device for purifying a fluid, the method comprising: determining whether a flow of a fluid through the purifying chamber is present; upon determining presence of flow of fluid through the purifying chamber activate the UV light source; and during the UV light source being active: measure a radiant flux being emitted from the UV light source before the light emitted from the UV light source has entered the purifying chamber, compare the measured radiant flux with a reference radiant flux, and adjust a drive current of the UV light source based on the comparison; and upon determining non-presence of flow of fluid through the purifying chamber applying a drive current below a threshold to the UV light source, wherein the threshold is set so that the radiant flux of UV-light emitted from the UV light source is ≤5% of a maximum radiant flux of UV-light emitted from the UV light source.

13. (canceled)

14. The method according to claim 12, further comprising: determining a time period of non-presence of flow of fluid through the purifying chamber, and upon a length of the time period of non-presence of flow of fluid through the purifying chamber being above a threshold, activating the UV light source for a time period of 1-5 seconds.

15. The method according to claim 12, wherein the step of determining whether a flow of a fluid through the purifying chamber is present comprises measuring a flow rate of the fluid flowing through the purifying chamber, wherein the method further comprises adjusting the drive current of the UV light source based on the measured flow rate.

16. The method according to claim 12, wherein the step of measuring a radiant flux being emitted from the UV light source comprises measuring a UV-C light radiant flux and wherein the reference radiant flux is a UV-C light reference radiant flux.

17. The method according to claim 12, further comprising measuring a temperature of a LED of the UV light source, upon the measured temperature being above a predetermined threshold generate a LED overheat signal.

18. The method according to claim 12, further comprising upon the measured radiant flux being below a predetermined threshold generate a UV light source failure signal.

19. A non-transitory computer readable recording medium comprising program code portions configured to perform the method according to claim 12 when executed on the processor comprised in the control circuit of claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The above and other aspects of the present invention will now be described in more detail, with reference to the appended drawings showing embodiments of the invention. The figures should not be considered limiting the invention to the specific embodiment; instead they are used for explaining and understanding the invention.

[0035] FIG. 1 illustrates a control circuit.

[0036] FIG. 2 illustrates a device for purifying fluid comprising the control circuit.

[0037] FIG. 3 illustrates a flowchart for how to control a UV light source.

[0038] As illustrated in the figures, the sizes of layers and regions are exaggerated for illustrative purposes and, thus, are provided to illustrate the general structures of embodiments of the present invention. Like reference numerals refer to like elements throughout.

DESCRIPTION OF EMBODIMENTS

[0039] The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which currently preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided for thoroughness and completeness, and fully convey the scope of the invention to the skilled person.

[0040] With reference to FIGS. 1 and 2, there is disclosed a control circuit 100 for controlling a UV light source 204 of a device 200 for purifying a fluid. The device comprises a purifying chamber 202, wherein the fluid is purified when the device 200 is in use. The device 200 comprises the UV light source 204. The UV light source 204 is configured to emit UV light into the purifying chamber 202 of the device 200 for purifying a fluid. The device 200 uses UV light to decontaminate and purify fluid present in the purifying chamber 202 when the device 200 is in use. The device 200 further comprises the control circuit 100 to control the UV light source 204. In other words, the UV light emitted into the purifying chamber 202 is controlled when the device 200 is in use.

[0041] The control circuit 100 is configured to carry out overall control of the operations and functions of the UV light source 204 of the device 200. The control circuit 100 comprises a driver 102, a fluid flow sensor 104, a light sensor 106, a memory 108 and a processor 110.

[0042] The driver 102 is configured to provide the UV light source 204 with a drive current 118. The drive current 118 determines how much UV light that is emitted into the purifying chamber 202. In other words, the driver current 118 is correlated to the UV light output of the UV light source 204.

[0043] The UV light source 204 may comprise one or more UV LEDs. The one or more UV LEDs may be UV-C LEDs. The or more UV LEDs may be WICOP LEDs. WICOP LEDs may reduce the number of LEDs with remained efficiency of the device. WICOP LEDs have a smaller footprint than conventional LEDs. This may reduce a size of the UV light source 204. This may allow to make the device 200 small, allowing the device to be placed in small spaces. WICOP LEDs further require less power than regular LEDs. This may improve energy efficiency of the device. UV-C LEDs may provide the device with a more energy efficient UV light source.

[0044] The fluid flow sensor 104 is configured to determine whether a flow of a fluid through the purifying chamber 202 is present. Upon determining a presence or non-presence of fluid flow through the purifying chamber 202, the fluid flow sensor 104 is configured to generate a flow signal 112 indicative thereof. The fluid flow sensor 104 may be configured to measure a flow rate of a fluid flowing through the purifying chamber 202. The flow signal 112 may comprise data pertaining to the measured flow rate in the purifying chamber 202.

[0045] The light sensor 106 is configured to measure radiant flux of light emitted from the UV light source 204. Preferably, the light sensor 106 is arranged to measure radiant flux of light emitted from the UV light source 204 before the light emitted from the UV light source 204 has entered the purifying chamber 202. Hence, the light sensor 106 may be arranged in close proximity to the UV light source 204. The light sensor 106 is further configured to generate a radiant flux signal 114. The radiant flux signal 114 comprises data pertaining to the measured radiant flux. The light sensor 106 may be configured to measure UV-C light radiant flux. Light sensor 106 may be configured to continuously measure the radiant flux. The light sensor 106 may measure an initial radiant flux when the device 200 starts up for the first time. The light sensor 106 may be configured to generate an initial radiant flux signal comprising the value of the initial radiant flux. Data pertaining to the initial radiant flux may be stored in the memory 108 as a reference radiant flux 116. Hence, the memory 108 may comprise the reference radiant flux 116. The reference radiant flux 116 may be a UV-C light reference radiant flux. Alternative to measuring and storing the initial radiant flux measured at the first start-up of the device as the reference radiant flux 116, the reference radiant flux 116 may be stored in the memory 108 at manufacture of the control circuit 100, i.e. the reference radiant flux 116 may be a factory set reference radiant flux. A reference radiant flux 116 stored at manufacture of the control circuit 100 may be replaced with the initial radiant flux. Accordingly, the reference radiant flux 116 is a predetermined reference radiant flux. Upon the UV light source 204 is switched on for the first time, the at that time measured radiant flux may be set as the reference radiant flux 116. Alternatively, the reference radiant flux 116 may be a factory set reference radiant flux.

[0046] The memory 108 may be one or more of a buffer, a volatile memory, a non-volatile memory, a random access memory (RAM) or another suitable device. In a typical arrangement, the memory 108 may include a non-volatile memory for long term data storage and a volatile memory that functions as system memory for the control circuit 100. The memory 108 may exchange data within the processor 110, and possibly also the fluid flow sensor 104 and the light sensor 106, over a data bus.

[0047] The processor 110 may be a central processing unit (CPU), a microcontroller or a microprocessor. The processor 110 is configured to execute program code stored in the memory 108, in order to carry out operations and functions of the control circuit 100. The operations and functions of the control circuit 100 may be embodied in the form of executable logic routines, e.g., lines of code, software programs etc., that are stored on the memory 108 and are executed by the processor 110. Furthermore, the operations and functions of the control circuit 100 may be a stand-alone software application or form a part of a software application that carries out additional tasks related to the control circuit 100. The described operations and functions may be considered a method that the control circuit 100 is configured to carry out. Also, while the described operations and functions will be discussed as implemented in software, such functionality may as well be carried out via dedicated hardware or firmware, or some combination of hardware, firmware and/or software.

[0048] The processor 110 is configured to execute a UV light source activation function. The UV light source activation function may be configured to deactivate the UV light source 204 upon the flow signal 112 being indicative of non-presence of flow of fluid through the purifying chamber 202. In other words, when there is no flow of fluid in the purifying chamber 202, the UV light source 204 is switched to an off mode. The UV light source activation function is further configured to activate the UV light source upon the flow signal is indicative of presence of flow of fluid through the purifying chamber. In other words, when there is a flow of fluid in the purifying chamber 202, the UV light source 204 is switched to an on mode. Thus, the UV light source 204 may not use any power when there is no fluid to be purified present in the purifying chamber 202. This may improve the life span of the UV light source. This may achieve an efficient and environmentally friendly device for purification of fluid.

[0049] The processor 110 is further configured to execute a drive current setting function. The drive current setting function is configured to determine a drive current 118 for the driver 102. Especially, the drive current setting function is configured to, upon the UV light source being active, determine the drive current 118 for the driver 102. The drive current setting function is configured to set the drive current 118 for the driver 102 based on the measured radiant flux being comprised in the radiant flux signal 114 and the reference radiant flux 116 stored in the memory 108. This may be accomplished through comparing the measured radiant flux with the reference radiant flux 116 and thereafter setting the drive current 118 based on said comparison.

[0050] The drive current setting function may further be configured to base the setting of the drive current 118 for the driver 108 on the measured flow rate comprised in the flow signal 112. The drive current setting function may compensate a loss of radiant flux by adjusting the drive current 118 such that efficiency of the UV light source is retained.

[0051] The drive current setting function may further be configured to, upon the flow signal 112 being indicative of non-presence of flow of fluid through the purifying chamber 202, instruct the driver 102 to apply a drive current 118 below a threshold to the UV-light source 204. The threshold is preferably set so that the radiant flux of UV-light emitted from the UV light source is 5%, preferably 1%, of a maximum radiant flux of UV-light emitted from the UV light source 204. By this moisture may be expelled from the device 200 for purifying a fluid.

[0052] 4. The control circuit (100) according to any one of claims 1-3, wherein the processor (110) is configured to:

[0053] The UV light source activation function may be configured to determine a time period of non-presence of flow of fluid through the purifying chamber 202. The drive current setting function may be configured to, upon a length of the time period of non-presence of flow of fluid through the purifying chamber 202 is above a threshold, active the UV light source 204. Upon doing so, the drive current setting function is preferably set to activate the UV light source 204 to emit a radiant flux of ≥50% of a maximum radiant flux. The activation is preferably made for a time period of 1-5 seconds. Hence, during periods of no fluid through the purifying chamber 202 the UV light source 204 may be used to send “flashes” of UV light into the purifying chamber 202 in order to keep the purifying chamber 202 disinfected. This while minimizing the uptime for the UV light source 204. The “flashes” of UV light may be emitted with a predetermined periodicity. The periodicity may be once every 10 minutes to once every hour.

[0054] The processor 112 may further be configured to execute a fail test function. The fail test function is configured to check whether the radiant flux signal being indicative of that the measured radiant flux is below a predetermined radiant flux threshold. If so, the fail test function is configured to generate a UV light source failure signal. The predetermined radiant flux threshold may be factory set threshold. The predetermined radiant flux threshold may be indicative of how much UV-light that is needed to effectively purify and decontaminate the fluid. The predetermined radiant flux threshold may have different values depending on which type of fluid is to be purified in the purifying chamber 202. For example, the fail test function may be configured to generate the UV light source failure signal when the measured radiant flux is below 70% of the reference radiant flux.

[0055] In connection with FIG. 3, a method for controlling a UV light source (204) will be discussed. Especially, for controlling a UV light source (204) configured to emit UV light into a purifying chamber (202) of a device (200) for purifying a fluid. The steps of the method may be performed in any order suitable. The method comprises the following steps.

[0056] Determining S02 whether a flow of a fluid through the purifying chamber is present. Upon determining presence of flow of fluid through the purifying chamber activate S06 the UV light source. During the UV light source being active: measure S08 a radiant flux being emitted from the UV light source 204, compare S10 the measured radiant flux with a reference radiant flux 116, and adjust S12 a drive current of the UV light source based on the comparison. The act of measuring S08 the radiant flux being emitted from the UV light source 204 is preferably made on UV light emitted from the UV light source 204 before the light emitted from the UV light source 204 has entered the purifying chamber 204. Hence, preferably, UV light directly after the UV light source is measured.

[0057] The step of determining S02 whether a flow of a fluid through the purifying chamber 202 is present may comprise measuring a flow rate of the fluid flowing through the purifying chamber. The step of adjusting S12 the drive current of the UV light source may further be based on the measured flow rate.

[0058] The step of measuring S08 a radiant flux being emitted from the UV light source may comprise measuring a UV-C light radiant flux. The reference radiant flux may be a UV-C light reference radiant flux.

[0059] The method may further comprise measuring S14 a temperature of a LED of the UV light source. Upon the measured temperature being above a predetermined threshold a LED overheat signal may be generated.

[0060] The method may further comprise upon the measured radiant flux being below a predetermined threshold, generate S16 a UV light source failure signal.

[0061] The method may further comprise, upon determining non-presence of flow of fluid through the purifying chamber deactivate S04 the UV light source.

[0062] The method may further comprise, upon determining non-presence of flow of fluid through the purifying chamber, applying a drive current below a threshold to the UV light source.

[0063] The method may further comprise: determining a time period of non-presence of flow of fluid through the purifying chamber, and upon a length of the time period of non-presence of flow of fluid through the purifying chamber being above a threshold, activating the UV light source for a time period. The time period may be in the range of 1-5 seconds.

[0064] The person skilled in the art realizes that the present invention by no means is limited to the preferred embodiments described above. On the contrary, many modifications and variations are possible within the scope of the appended claims.

[0065] For example, the control unit 100 may further comprise a temperature sensor 120. The temperature sensor 120 may be configured to measure a temperature of the UV light source 204. The temperature sensor 120 may be configured to measure a temperature of an individual UV LED of the UV light source 204. The temperature sensor 120 may be configured to generate a temperature signal 122. For example, the temperature sensor 120 may be configured to measure a temperature at a P-N junction of the individual UV LED. The temperature signal 122 may comprise a temperature of a surrounding of the individual UV LED. The temperature signal 122 may comprise a temperature of the individual UV LED. The processor 110 may be configured to execute an overheat checking function. The overheat checking function is configured to use the temperature signal from the temperature sensor 120 as input. For example, the overheat checking function may be configured to, upon the temperature signal being indicative of that the temperature of an individual UV LED is above a predetermined temperature threshold generate a LED overheat signal. The overheat checking function may be configured to deactivate the individual LED upon the temperature signal being indicative of that the temperature of the individual LED is above the predetermined temperature threshold. The predetermined temperature threshold may be a factory set threshold.

[0066] Additionally, variations to the disclosed embodiments can be understood and effected by the skilled person in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measured cannot be used to advantage.