Patent Publication Number: US-2015086938-A1

Title: Attachment for a photopolymerization device and charging station therefore

Description:
The invention relates to a charging station for a wireless photopolymerization device for curing of light-polymerizable dental materials, whereby the photopolymerization device comprises a reservoir for electrical power, in particular an accumulator/rechargeable battery or a capacitor, and whereby the charging station comprises at least one electrically conductive charging contact by means of which an electrically conductive connection to an electrically conductive mating charging contact of the photopolymerization device for charging the reservoir for electrical power is established, when the photopolymerization device is connected to the charging station. 
     The invention also relates to a wireless photopolymerization device for curing of light-polymerizable dental materials, whereby the photopolymerization device comprises a reservoir for electrical power, in particular a rechargeable battery or a capacitor, and whereby the photopolymerization device comprises at least one electrically conductive charging contact by means of which an electrically conductive connection to an electrically conductive mating charging contact of a charging station for the photopolymerization device can be established for charging the reservoir when the photopolymerization device is connected to the charging station. 
     Furthermore, the invention relates to an attachment for connecting a wireless photopolymerization device to a charging station and a photopolymerization device comprising a charging station, a hand-guidable photopolymerization device, and an attachment. 
     Photopolymerization devices are used for curing dental restoration materials. The dental restoration materials are plastic materials, and are used, for example, to produce plastic fillings, dentures or parts thereof, whereby the photopolymerization device irradiate the dental restoration materials with light of an appropriate wavelength and the plastic material is cured by the irradiation. 
     A photopolymerization device in the form of a dental hand-piece having a housing and, disposed therein, an LED as a light source that emits blue light, is known from DE 20 2004 001 189 U1. The photopolymerization device comprises a rechargeable battery, which is used to operate the LED. Said rechargeable batteries are charged by plugging the photopolymerization device into a charging station, which is connected to the mains supply by means of a lead in order to charge the rechargeable battery of the photopolymerization device. Plugging the photopolymerization device into the charging station, the electrical charging contacts of the photopolymerization device and of the charging station become connected to each other. 
     Charging contacts for Li-ion rechargeable batteries are commonly designed for low voltages (&lt;10 V DC) and low currents (&lt;1 A DC) designed, resulting in a high quality contact design. Pin, spring lever, and sliding contacts are known for this purpose. Charging contacts are subject to natural wear with heavy use and aging or soiling resulting from the application. By proper design and selection of materials, such as a gold coating of the charging contacts, the wear can be reduced but not prevented. Similarly, cleaning efforts by the user are not expedient as this may damage the charging contact or its surface. Thus far, charging stations for photopolymerization devices use fixed charging contacts, contact pairs or strips, which interrupt the charging function in the presence of wear or defect and thus render the entire charging station or the photopolymerization device unusable. 
     This is disadvantageous in that the electrical charge contacts for charging the rechargeable battery wear out, and therefore the life of the charging stations and photopolymerization devices is limited or at least there is a need to repair parts of the devices. 
     Therefore, the object of the invention is to overcome the disadvantages of the prior art. In particular, a way is be found to reduce the effort caused by the wear of the charging contacts. In this context, the cost, in particular, as caused by the repair of the charging contacts, is to be reduced. 
     The object of the invention is solved by a charging station for a wireless photopolymerization device for curing of light-polymerizable dental materials, whereby the photopolymerization device comprises a reservoir for electrical power, in particular an accumulator such as a rechargeable battery or a capacitor, and whereby the charging station comprises at least one electrically conductive charging contact by means of which an electrically conductive connection to an electrically conductive mating charging contact of the photopolymerization device for charging the is established when the photopolymerization device is connected to the charging station, wherein the electrically conductive charging contact is part of an attachment that can be or is secured to the charging station in releasable manner, whereby the electrically conductive charging contact in the attachment is connected in electrically conductive manner to at least one second electrically conductive charging contact of the charging station, when the attachment is secured to the charging station. 
     According to the invention, a wireless photopolymerization device shall not be understood to mean a device having a design that is completely free of leads, but rather a device that is not connected to an external power source, such as an electrical outlet, by means of a lead for the purpose of supplying power. Preferably, the wireless photopolymerization device can be guided by hand. Then, the device can easily be inserted with one hand. A charging contact of the attachment shall be understood to mean both the part, which provides an electrical connection through a mating contact as well as the connection from one to the next point of contact in the attachment. 
     Charging stations according to the invention can be provided with the electrically conductive connection being a plug-in connection. 
     Plug-in connections are simple and inexpensive to implement and are easy to operate. 
     Furthermore, the invention can provide the attachment to comprise a securing element by means of which the attachment can be or is secured to the charging station, whereby the securing element preferably is a thread engaging a mating thread of the charging station, and/or the securing element is at least one screw by means of which the attachment can be or is screwed to the charging station. 
     By means of said securing elements, a stable connection of the attachment to the charging station can be produced that withstands even the mechanical stresses of a plug-in process. 
     According to a further embodiment, the invention can provide the attachment to be lockable or locked to the charging station and/or the attachment and the charging station to form a bayonet closure. 
     Said securing means can be connected easily and quickly and therefore provide for enhanced ease of use. 
     According to a further particularly advantageous embodiment, the invention can provide that at least one charging contact, preferably the electrically conductive charging contact of the attachment, comprises a coating, at least partially, preferably a refinement, particularly preferably a noble metal coating, and/or that the attachment comprises two charging contact pins or a USB port that include the charging contact. 
     This design attains stable and reliable electrical contacting. In this context, of course, only the parts of the charging contact comprising a surface that may contact a mating contact need to be coated. The wiring on the inside of the attachment is not coated. 
     The objects of the invention are also solved by a wireless photopolymerization device for curing photo-polymerizable dental materials, whereby the photopolymerization device comprises a reservoir for electrical power, in particular a rechargeable battery or a capacitor, and wherein the photopolymerization device comprising at least one electrically conductive charging contact by means of which an electrically conductive connection to an electrically conductive mating charging contact for the photopolymerization device for charging the reservoir can be established, when the photopolymerization device is connected to the charging station, in which the electrically conductive charging contact is part of an attachment that can be or is secured in releasable manner to the photopolymerization device, whereby the electrically conductive charging contact in the attachment is connected, in electrically conductive manner, to at least one second electrically conductive charging contact in the photopolymerization device, when the attachment is secured to the photopolymerization device. 
     The invention can provide the electrically conductive connection to be a plug-in connection in this context. 
     Further, the invention can provide the attachment to comprise a securing element by means of which the attachment can be or is secured to the photopolymerization device, whereby the securing element preferably is a thread that engages a mating thread of the photopolymerization device, and/or the securing element is at least one screw by means of which the attachment can be or is screwed to the photopolymerization device. 
     According to a further particularly preferred embodiment, the invention can provide that the attachment can be or is locked to the photopolymerization device and/or that the attachment and the photopolymerization device form a bayonet closure. 
     The advantages of these last embodiments are the same as those described with regard to the attachment to the charger. 
     Further, the invention can provide the photopolymerization device to comprise a light source, preferably an LED, for curing a polymerizable plastic material that preferably emits light of a wavelength between 380 nm to 500 nm, more preferably comprising at least two wavelength peaks, most preferably between 400 nm and 405 nm and 455 nm and 460 nm. 
     These wavelengths are particularly well suited to achieve photopolymerization. These wavelengths are particularly well suited, in particular for dental plastics. 
     The invention can also provide the LED light source to emit in a power range of 800 mW/cm 2  to 2000 mW/cm 2 , preferably between 1200 mW/cm 2  and 1800 mW/cm 2 . 
     The invention can also provide the photopolymerization device to comprise charge control electronics by means of which the charging of the reservoir for electrical power is controlled or regulated. 
     The integration of the charge control electronics (control) into the hand-piece, i.e. into the photopolymerization device, is advantageous in that a compact design is ensured and the charge control electronics can directly access the accumulator or the reservoir for electrical energy. 
     Photopolymerization devices according to the invention can also be provided appropriately such that at least one charging contact, preferably the electrically conductive charging contact of the attachment, comprises a coating, at least partially, preferably a refinement, particularly preferably a noble metal coating, and/or that the attachment comprises two charging contact pins or a USB port, which include the charging contact. 
     The objects of the invention are also solved by an attachment for connecting a wireless photopolymerization device to a charging station, whereby the attachment is suitable for being secured to said charging station and/or to said photopolymerization device. 
     Another solution of the objects of the invention can be implemented through a photopolymerization apparatus comprising a charging station, particularly a charging station according to the invention, a hand-guidable photopolymerization device, in particular a photopolymerization device according to the invention, whereby the photopolymerization device comprises at least one reservoir for electrical power, preferably a rechargeable battery, and the photopolymerization device comprises at least one attachment having a charging contact and whereby the attachment or attachments can be or are secured to the charging station and/or the attachment or attachments can be or are secured to the photopolymerization device, whereby the attachment provides or the attachments provide at least one electrically conductive connection by means of which the reservoir for electrical power can be charged. 
     In all embodiments having a rechargeable battery in the photopolymerization device, the invention can provide that the rechargeable battery to be a Li-ion rechargeable battery. 
     The invention is based on the surprising finding that, having a replaceable attachment with the charging contact integrated into it, it is feasible to provide a photopolymerization device or a charging station for said photopolymerization device, in which the charging contact can be renewed simply by replacing the attachment. By integrating the wearing pars, namely the charging contact, into an easily replaceable attachment, is becomes feasible to avoid costly repair of the photopolymerization device and/or of the charging station for the photopolymerization device. 
     The invention is therefore based on the surprising rationale to sub-divide the actual charging contact (bracket, pin, clip, spring, etc.) into two contacts that are arranged successively and to implant the wearing working contact (charging station versus photopolymerization device/hand piece) by means of a mountable attachment (adapter or insert) in simple manner even for untrained users. The cascade contacts thus formed thus have an increased service life and can be replaced by the user of the photopolymerization device any number of times according to need. 
     Charging contacts according to the prior art are firmly connected to the charging station or to the photopolymerization device and/or its electronics to the effect that said charging stations and photopolymerization devices need to be replaced or repaired by the manufacturer or a service engineer if a defect occurs. Considering the price of the contact materials versus the resulting effort, this is an inefficient approach as compared to charging stations and photopolymerization devices according to the invention. 
     An example of a design according to the invention is a photopolymerization device for dental restoration materials including a photopolymerization device, as a hand-piece, having an LED light source, whereby the LED light source emits in a single-or multiple-wavelength range(s) from 380 nm to 500 nm, in particular with at least two wavelengths peaks, preferably in two wavelength ranges of 400 nm to 405 nm and 455 nm to 460 nm, whereby the LED light source emits in a power range from 800 mW/cm 2  to 2,000 mW/cm 2 , preferably between 1,200 mW/cm 2  and 1,800 mW/cm 2 , and the photopolymerization device comprises a replaceable and rechargeable accumulator, preferably Li-ion storage battery, in the hand-piece, which can be charged with electrical voltage or to which voltage can be applied by a separate base station or charging station of the photopolymerization device, whereby 
     the photopolymerization device is designed to have at least two charging contact parts in the hand-piece and/or the charging station in the form of cascade contacts; 
     the working contacts are integrated in an attachment such as an adapter or an insert which is replaceable by simple activities by the customer; 
     the voltage is supplied to the charging station by means of USB ports; and 
     charge control electronics, which is situated completely in the hand-piece. 
     The contacting of the cascade is implemented in the manner of a series circuit, wherein the charging contacts are connected in series. 
     The present invention shifts the “wearing charging contact” into its own integrated but easily removable part of the housing (the attachment), which in turn is connected by means of the same- or different-type charging contacts to the actual charger housing. 
    
    
     
       In the following, further embodiments of the invention shall be illustrated with reference to four schematic figures, without, however, limiting the invention. In the figures: 
         FIG. 1 : shows a schematic cross-sectional view of a photopolymerization apparatus according to the invention comprising a photopolymerization device, a charging unit, and an attachment; 
         FIG. 2 : shows a schematic cross-sectional view of a particularly preferred embodiment of an attachment according to the invention inserted into a charging station, in which the photopolymerization device is inserted; 
         FIG. 3 : shows a schematic perspective view of a charging station according to the invention having an unsecured attachment according to the invention; and 
         FIG. 4 : shows a schematic perspective view of the underside of the charging station according to the invention according to  FIG. 3  with an attachment according to the invention being ready to be inserted. 
     
    
    
       FIG. 1  shows a schematic cross-sectional view of a photopolymerization apparatus according to the invention comprising a charging station  1  that is connected to a power grid, a hand-guidable photopolymerization device  2 , and an attachment  4 . The photopolymerization device  2  (hand-piece) comprises a replaceable battery  6  in its housing in the area of a handle body, which is adapted to be held in one hand. Preferably, the rechargeable battery is a Li-ion rechargeable battery. The bottom end of the photopolymerization device  2  has a first electrical charging contact  8  arranged on it, which comprises two metal pins and thus is formed in the manner of a plug. The charging contact  8  is connected by means of two electric leads  10  to the rechargeable battery  6 , so that rechargeable battery  6  can be charged when an electrical voltage is applied to the metal pins of the electrical charging contact  8 . 
     A controller  12  is arranged inside the handle of the photopolymerization device  2 , inter alia, for controlling the charging process of the rechargeable battery  6 . In addition, the controller  12  is suitable for processing signals from an input facility  14 , which can just as well be a simple switch or a rotary switch. The input facility  14  can be used, at least, to turn the photopolymerization device  2  on and off, whereby preferably the power of the emitted light and/or the duration of the illumination is/are adjustable as well. The controller  12  can also be used to control a display facility (not shown), such as, for example, one or more LEDs, such that the user can see whether or not the photopolymerization device  2  is just being loaded and/or whether the photopolymerization device  2  is fully charged. The controller  12  also processes the signals from the input facility  14  and uses them as the basis to control an LED  16  that can be used to emit white or blue light that is suitable for curing a polymerizable plastic material. 
     The photopolymerization device  2  is plugged by means of the metal pins into the attachment  4 , which comprises two metal-lined recesses for the metal pins of the first charging contacts  8  in the appropriate places for this purpose. The recesses in the attachment can comprise resilient, elastic metal brackets such that a spring contact is formed. The recesses are connected by electrical lines  20  in the attachment  4  to an electrical charging contact  18  of the attachment  4 , which comprises two metal pins. The resilient, elastic metal brackets are also part of the charging contact  18  of the attachment. The attachment  4  thus forms a cascade plug. 
     The attachment  4  is plugged by means of the metal pins  18  into electrically conducting recesses of the charging station  1 , and is secured by means of a thread (not shown) to a mating thread of the charging station  1  (not shown). The charging station  1  is essentially a stand that allows the charging station  1  to be set up stably. Likewise, the charging station  1  can, however, also be secured to a bracket on a wall or a pole. Two electrical lines  22 , which extend on the interior of the charging station  1 , connect the recesses of the charging station  1  in electrically conductive manner to a power cord  24  which terminates in a mains plug  26  by means of which the charging station  1  can be connected to a socket for a common mains supply. If applicable, a transformer (not shown) can be provided in the charging station  1 , power cable  24  or mains plug  26 . 
     When the photopolymerization device  2  is connected to the charging station  1  by means of the attachment  4 , the rechargeable battery  6  is charged as controlled by the controller  12 . If the metallised recesses in the attachment  4  are worn out by frequent use, the attachment  4  can be unscrewed from the charging station  1  and simply replaced by a new attachment  4  with intact recesses. Because of the ease of replacement of the attachment  4 , it is particularly advantageous for the invention to provide that the metals and/or coating of the recesses of the attachment  4  are less hard than the metal pins of the charging contact  8  of the photopolymerization device  2 , such that the charging contact  8  wears only slowly and the signs of wear and tear occur mainly on the recesses of the replaceable attachment  4 . 
     As an alternative to the illustrated embodiment, the attachment  4  could be also firmly connected to the photopolymerization device  2 . However, this increases the weight of the photopolymerization device  2  that is to be held by hand. Therefore, it is prefered to secure the attachment  4  to the charging station  1  in order to keep the weight of the hand-guided photopolymerization device  2  as low as possible. 
     Moreover, the invention could provide for securing an attachment  4  each on both the photopolymerization device  2  as well as on the charging station  1 . The wear and tear of the charging contacts then occurs only in the recesses of the first attachment  4  on the charging station  1  and the charging contacts (metal pins) of the second attachment (not shown). This design allows wear and tear of the charging contacts of the photopolymerization device  2  and of the charging station  1  to be strictly prevented. This embodiment is particularly preferred as a general principle for all embodiments of the invention and shall not be limited to the present embodiment. To ensure good electrical contact, the recesses and the metal pins can be finished with a metal layer that prevents oxidation of the surfaces of the contacts. Oxidation would lead to a deterioration of the electrical contact. In this context, it is not necessary to use costly gold coatings or similarly costly noble metal coatings since the longevity of the recesses and charging contacts  18  of the attachments  4  is not essential. This shall also be understood as a preferred general principle according to the invention and is not limited to the present embodiment. 
       FIG. 2  shows a schematic cross-sectional view of a particularly preferred embodiment of an attachment  54  according to the invention inserted into a charging station (of which only a board  65  is shown in  FIG. 2 ) with inserted photopolymerization device  52  of which only the lower part is shown in  FIG. 2 . The photopolymerization device  52  comprises two metallic ring contacts  53  as charging contacts, which are electrically insulated from each other and are connected to a rechargeable battery (not shown) inside the photopolymerization device  52 . The rechargeable battery can be charged by means of the ring contacts  53  by applying an electrical voltage, which is or can be controlled through a controller (not shown) of the photopolymerization device  52 . 
     The attachment  54  comprises a bar  55  and two charging contact pins  56  made of plastic. The plastic parts can be manufactured through an injection moulding process. On recess  57  each is provided in the charging contact pins  56  and has two charging contacts  58  of the attachment  54  extend through them, which thus make electrical contact with the ring contacts  53  of inserted photopolymerization device  52 . The charging contacts  58  are narrow, arcuate, preloaded metal tapes (charging contact springs) secured to the charging contact pins  56  by means of a fixation  59 . The fixation  59  can be implemented by means of screws or rivets. In principle, a firm gluing is conceivable as well. 
     Two reinforced recesses  60  are provided as screw holes  60  in the bar  55 . The attachment  54  can be firmly connected to the charging station through said screw holes  60 . For this purpose, the charging station comprises two matching recesses with internal threads (not shown). The charging contact pins  56  with the charging contacts  58  reach through two recesses of a circuit board  65  of the charging station. A spacer  66  is provided on the circuit board  65  and ensures that the fully inserted photopolymerization device  52  is in correct position by defining a limit stop. Two metallic contact surfaces  68  are provided on the circuit board  65  as charging contacts of the charging station. The circuit board  65 , the spacer  66 , and the contact surfaces  68  are part of the charging station to which they are firmly and rigidly connected. When the attachment  54  is secured to the charging station, one end each of the metal leaf spring  58  presses against the contact surfaces  68 , thus establishing an electrically conductive connection between the charging contact  58  of the attachment  54  and the electrical lines of the charging station connected to the contact surfaces  68 . When the photopolymerization device  52  is being plugged into a recess (not shown) in the charging station provided for this purpose, the respective other ends of the charging contact spring  58 , or a curvature of the charging contact spring  58  on the other side of the fixation  59 , press against the ring contacts  53  of the photopolymerization device  52 , thus establishing an electrical connection between the ring contacts  53  and the contact surfaces  68  by means of the charging contact  58 . 
     The contact surfaces  68  are connected to a mains grid or any other voltage source by connecting the charging station to a power outlet by means of the electric leads and a cable and a power plug. 
       FIG. 3  shows a schematic perspective view of a charging station  71  according to the invention having a non-secured attachment  54  according to the invention. The design of the attachment  54  is the same as that of the attachment shown in  FIG. 2   54  The attachment  54  comprises a bar  55  as a base, in which two feed-throughs for two screws  90  are provided by means of which the attachment  54  can be secured from below in the bottom of the charging station  71 . 
     Two charging contact pins  56  bearing the charging contact springs  58  and/or the charging contact  58  of the attachment  54  are arranged at a right angle to the bar  55 . The bar  55  and the charging contact pins  56  are manufactured in one piece from plastic material. The attachment  54  is inserted from below into the charging station  71  in the area of one recesses  72  for insertion of a photopolymerization device (not shown) and secured in this place with the screws  90 . The drawn lines in the recess  72  and at the front of the charging station  71  are intended to merely indicate, in a perspective view, the orientation of the walls and have no further meaning presently. A rail could be provided in this area just as well, though, which allows for the insertion of a photopolymerization device hand-piece to take place in one orientation only. The recess  72  has a circular cross section. 
     The charging station  71  comprises a light-emitting diode (=LED)  74  that serves to display the charging status of the reservoir for electrical power of an inserted photopolymerization device. In addition or alternatively, the LED  74  serves as an indicator of a connected voltage supply by means of a power cord  78 . The LED  75  serves as an indicator of the light intensity measured with a sensor  76 . 
       FIG. 4  shows a schematic perspective view of the underside of the inventive charging station  71  according to  FIG. 3  having an attachment  54  according to the invention that is ready to be inserted. As is evident from  FIG. 4 , the attachment  54  is being inserted into a matching recess on the underside of the charging station  71 . Accordingly, the attachment  54  could also be called insert  54 . The charging contact pins  56  extend through a circuit board (not shown) that bears the charging contacts in the form of two contact surfaces (not shown) of the charging station  71 , as shown in  FIG. 2 , and extend into the recess  72  (which is shown in  FIG. 3 ). Here, the leaf springs of the charging contacts  58  can be associated with mating contacts of a photopolymerization device by inserting the photopolymerization device into the recess  72 . The contact surfaces of the charging station are contacted by the other ends of the leaf springs of the charging contacts  58 . The contact surfaces are connected by means of a power cord—also called power lead— 78  to a voltage source. 
     The attachment  54  is secured by means of the screws  90 , which are passed through screw holes  60 , to the threaded holes  77 , which comprise a mating thread for the screws  90 . 
     Four rubber feet  73  are arranged on the underside of the charging station  71  and ensure secure footing of the charging station  71  even during insertion and removal of the photopolymerization device. 
     The features of the invention disclosed in the foregoing description, as well as in the claims, figures and exemplary embodiments, can be essential for the implementation of the various embodiments of the invention both individually and in any combination. 
     LIST OF REFERENCE NUMBERS 
     
         
           1 ,  71  Charging station 
           2 ,  52  Photopolymerization device 
           4 ,  54  Attachment insert 
           6  Reservoir, in particular accumulator, Rechargeable battery 
           8 ,  18  Charging contact 
           10 ,  20 ,  22  Electrical line 
           12  Controller 
           14  Input device switch rotary switch 
           16  LED for photopolymerization 
           24 ,  78  Cable or power cord 
           26  Plug 
           53  Ring contact 
           55  Bar 
           56  Charging contact pin 
           57  Recess 
           58  Charging contact spring leaf spring 
           59  Fixation 
           60  Screw hole 
           65  Circuit board 
           66  Spacer 
           68  Contact surface 
           72  Receptacle for photopolymerization device handheld unit 
           73  Stand 
           74  LED indicating the applied voltage supply 
           75  Indicator of the light intensity measured with a sensor  76   
           76  Sensor 
           77  Threaded hole 
           78 ,  24  Power cord or cable 
           90  Screw