Withstand voltage test device suitable for ultrasonic electrotome bar

Abstract

The utility model provides a withstand voltage test device suitable for an ultrasonic electrotome bar. The withstand voltage test device comprises a test support; the fixed test base is fixed at one end of the test bracket; the movable testing base can move from one end of the testing support to the other end of the testing support under the action of external force, and the fixed testing base and the movable testing base are used for clamping insulating coating areas at different positions on the cutter bar to be tested; the first electric conductor is fixed on the testing support and arranged between the fixed testing base and the movable testing base so as to support a non-insulating area on the cutter bar to be tested, the fixed testing base and the movable testing base are used for being connected with a first electrode of an external power source, and the first electric conductor is used for being connected with a second electrode of the external power source; therefore, a voltage path is formed to test the voltage resistance of the insulating coating area on the cutter bar to be tested. The testing device provided by the utility model has the beneficial effects of being convenient to adjust, wide in application range and high in testing efficiency.

Description

Technical Field

[0001] The utility model relates to the technical field of withstand voltage testing, in particular to a withstand voltage testing device suitable for an ultrasonic electric knife bar. Background Art

[0002] The ultrasonic electrosurgery unit is a new type of surgical instrument that combines the advantages of both ultrasonic and electric scalpels. It can not only convert ultrasonic signals into mechanical vibrations for cutting, but also output high-frequency currents for blood vessel sealing, thus achieving better surgical results in clinical applications.

[0003] The main operating part of the ultrasonic electrosurgical knife is the waveguide rod, referred to as the knife rod. When working, the knife rod is used not only to transmit ultrasonic vibrations, but also to act as an electrode for high-frequency current. The inner sleeve outside the knife rod constitutes another high-frequency electrode. The two electrodes of the knife rod and the inner sleeve cooperate to discharge at the jaws to complete the surgical operation. This requires that the knife rod and the inner sleeve must be insulated except in the jaw area. At present, the insulation between the knife rod and the inner sleeve can be achieved by coating a certain thickness of insulating material on the knife rod.

[0004] In order to ensure the quality of the finished product of ultrasonic electrosurgical knife, the area on the knife rod coated with insulating material needs to be subjected to a withstand voltage test during the production process. Therefore, a withstand voltage test device is urgently needed to efficiently complete the withstand voltage test of the insulating part on such a knife rod. Utility Model Content

[0005] In order to solve the problems in the related technology, the utility model provides a pressure resistance testing device suitable for an ultrasonic electrosurgical knife rod, which can efficiently complete the pressure resistance test of the ultrasonic electrosurgical knife rod.

[0006] To this end, the utility model provides the following pressure resistance test device, which is suitable for ultrasonic electric knife rod, and the test device includes:

[0007] Test bracket;

[0008] A fixed test base is fixed to one end of the test bracket;

[0009] A mobile test base can be moved from one end of the test bracket to the other end under the action of an external force, and the fixed test base and the mobile test base are used to clamp the insulating coating areas at different positions on the tool rod to be tested;

[0010] A first conductor is fixed on the test bracket and is disposed between the fixed test base and the movable test base to support the non-insulated area on the tool rod to be tested;

[0011] The fixed test base and the movable test base are used to connect to the first electrode of the external power supply, and the first conductor is used to connect to the second electrode of the external power supply, thereby forming a voltage path to test the voltage resistance performance of the insulating coating area on the tool rod to be tested.

[0012] The test device provided by the utility model can realize the withstand voltage test of the knife rods of various length specifications through the cooperation of the mobile test base and the fixed test base, and can also be adjusted according to the distribution of the insulating parts on the knife rod, and can complete the withstand voltage test of multiple insulating parts on the knife rod at the same time. In addition, by setting multiple slots, the withstand voltage test of multiple knife rods can also be completed at the same time, which has the beneficial effects of convenient adjustment, wide application range and high test efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Other features, objectives and advantages of the present invention will become more apparent through the following detailed description of non-limiting embodiments in conjunction with the accompanying drawings.

[0014] Figure 1 A schematic diagram of a knife bar structure to which the pressure resistance test device provided by the utility model can be applied;

[0015] Figure 2 It is a structural schematic diagram of an embodiment of a tool bar pressure resistance testing device of the utility model;

[0016] Figure 3 A top view of an embodiment of a tool bar pressure test device of the utility model;

[0017] Figure 4 It is a structural schematic diagram of a mobile test base in an embodiment of the utility model;

[0018] Figure 5 It is a schematic diagram of the structure of a fixed test base in an embodiment of the utility model.

[0019] In the attached figure:

[0020] 100-tool bar; 110-tool head; 120-head insulation area; 130-tail insulation area;

[0021] 200-test device; 210-test bracket; 211-cable connector; 220-fixed test base; 221-tool bar stopper; 230-movable test base; 231-positioning mechanism; 232-first support plate; 233-second support plate; 234-first electrical substrate; 235-second electrical substrate; 236-tool bar limiting hole groove; 237-third support plate; 238-support column; 239-force structure; 2391-handle; 2392-movable rod; 2393-connecting component; 240-first conductor; 241-tool bar groove; 250-slide rail; 260-slider; 270-second conductor; 271-positioning groove. DETAILED DESCRIPTION

[0022] Hereinafter, exemplary embodiments of the present utility model will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily implement them. In addition, for the sake of clarity, parts not related to the description of the exemplary embodiments are omitted in the accompanying drawings.

[0023] In this specification, it should be understood that terms such as "including" or "having" are intended to indicate the presence of features, numbers, steps, behaviors, components, parts or a combination thereof disclosed in this specification, and are not intended to exclude the possibility that one or more other features, numbers, steps, behaviors, components, parts or a combination thereof exist or are added.

[0024] It should also be noted that, in the absence of conflict, the embodiments and features in the embodiments in this specification may be combined with each other.

[0025] The technical solution of the present utility model will be described in detail below with reference to the accompanying drawings and in combination with specific embodiments.

[0026] The main component inside the ultrasonic electrosurgical knife is the waveguide rod, also known as the knife rod, which is a metal conductor. When working, in addition to transmitting ultrasonic vibrations, the knife rod also needs to serve as an electrode for high-frequency current, and the inner sleeve outside the knife rod constitutes another electrode. The two electrodes of the knife rod and the inner sleeve cooperate to discharge at the jaws, which requires that the knife rod and the inner sleeve must be insulated except for the area at the jaws. At present, the insulation between the knife rod and the inner sleeve can be achieved by coating a certain thickness of insulating material on the knife rod. An economical and feasible coating method is to coat the insulating material on the areas at both ends of the knife rod and then expose it, and set a large area of ​​insulating rubber hose in other areas. Insulating rubber rings are also set at several locations on the entire knife rod to limit the position between the knife rod and the inner sleeve. In addition, according to the needs of surgical operations, ultrasonic electrosurgical knives can have different length specifications, so the knife rod will also have different length specifications.

[0027] Figure 1 A knife bar structure that can be used for pressure resistance testing using the testing device of the utility model is illustrated.

[0028] like Figure 1 As shown, the curved and tapered part at one end of the knife bar 100 is the knife head 110, and the head insulation area 120 near the knife head and the tail insulation area 130 at the tail end of the knife bar are coated with insulating materials. After completing the necessary tests, an insulating hose will be sleeved in the middle of the knife bar 100, so that the insulation performance between the knife bar and the inner sleeve can be maintained in the assembled ultrasonic electrosurgical knife. Insulating rubber rings will also be arranged at intervals on the knife bar, and there will also be insulating rubber rings on the insulating area 120 near the knife head and the insulating area 130 at the tail of the knife bar. This knife bar structure adopts a composite method of providing an insulating coating at both ends of the knife bar and an insulating sleeve in the middle, which can reduce the difficulty of processing, improve the product yield while ensuring insulation, and reduce costs.

[0029] Need to explain, Figure 1 The tool bar structure shown is only an example, and does not mean that the test device of the utility model cannot be used for tool bars of other structures, for example, a tool bar structure with three sections of insulating coating on the tool bar, a tool bar structure with a larger curvature of the tool head, etc. If there are multiple sections of insulating coating on the tool bar to be tested, the test device of the utility model can complete the test by increasing the number of mobile test bases and first conductors. If the curvature of the tool head is larger, the tool bar limit slot on the electrical substrate needs to be adaptively adjusted. The following embodiments are adapted to Figure 1 The knife bar shown is taken as an example to illustrate a specific implementation of the present utility model.

[0030] Figure 2 The structure of the embodiment of the tool bar pressure test device of the utility model is shown in FIG. Figure 3 A top view of the test device of this embodiment is shown.

[0031] like Figure 2 and Figure 3 As shown, the testing device in this embodiment can adapt to tool rods of different lengths by adjusting the position of the movable testing base. The testing device also has multiple tool rod testing positions and can test multiple tool rods at the same time.

[0032] like Figure 2 As shown, the testing device 200 comprises:

[0033] Test bracket 210;

[0034] A fixed test base 220 is fixed to one end of the test bracket 210;

[0035] The mobile test base 230 can be moved from one end of the test bracket 210 to the other end under the action of external force, and the fixed test base 220 and the mobile test base 230 are used to clamp the insulating coating areas at different positions on the tool rod to be tested;

[0036] The first conductor 240 is fixed on the test bracket 210 and is disposed between the fixed test base 220 and the movable test base 230 to support the non-insulated area on the tool rod to be tested;

[0037] The fixed test base 220 and the movable test base 230 are used to connect to the first electrode of the external power supply, and the first conductor 240 is used to connect to the second electrode of the external power supply, thereby forming a voltage path to test the voltage resistance performance of the area to be insulated coated on the tool rod to be tested.

[0038] According to the embodiment of the utility model, in the working state, the first conductor 240 and the fixed test base 220 and the movable test base 230 respectively form two voltage paths, and the insulating coating areas at both ends of the tool rod to be tested can be subjected to withstand voltage tests at the same time, thereby improving the test efficiency.

[0039] Furthermore, the testing device 200 may also include:

[0040] A slide rail 250 is fixed on the test bracket 210;

[0041] A slider 260 matching the slide rail 250 is disposed at the bottom of the mobile test base 230 . Under the action of external force, the mobile test base 230 can move from one end to the other end of the test bracket 210 along the slide rail 250 .

[0042] The slide rail 250 is arranged along the long side of the test bracket 210. By arranging the slide rail and the slider, the smooth movement of the mobile test base can be achieved, which has the advantages of low cost and high stability.

[0043] In the embodiment of the present utility model, the slide rails can be provided in multiple groups, such as Figure 2 As shown, a slide rail is provided along the two long sides of the test bracket 210, and correspondingly, two sliders 260 are also provided at the bottom of the mobile test base 230. Providing multiple sets of slide rails can further improve the smooth movement performance and make the mobile base more stable.

[0044] Furthermore, limit blocks may be provided at both ends of the slide rail to prevent the mobile test base 230 from being separated from the slide rail when moving to the two ends.

[0045] According to an embodiment of the present utility model, the testing device 200 may further include:

[0046] The second conductor 270 is fixed on the test bracket 210 and is used to connect to the first electrode of the external power supply. The second conductor 270 is arranged parallel to the slide rail 250 and is in electrical contact with the bottom surface of the mobile test base 230, so that the mobile test base 230 is connected to the first electrode of the external power supply through the second conductor 270.

[0047] By providing the second conductor, the mobile test base is not bound by the cable during movement, the performance of obtaining the test voltage is more stable, and the interference with the withstand voltage test is reduced.

[0048] In the embodiment of the present invention, the second conductor 270 may be in the shape of a long strip, with a length close to that of the slide rail, so that when the mobile test base moves to any position on the slide rail, the test voltage can be obtained from the second conductor.

[0049] Furthermore, a positioning groove 271 is provided at a preset position of the second conductor 270, and a positioning mechanism 231 is provided at the bottom of the mobile test base 230, and the positioning mechanism 231 is used for the mobile test base 230 to stay at the preset position under the restriction of the positioning groove 271 when moving. The positioning mechanism 231 is a conductor. A plurality of positioning grooves 271 can be provided, and their positions are adapted to the length specifications of the tool rod to be tested, so that when testing tool rods of different length specifications, it is convenient for the operator to quickly and accurately locate the position where the mobile test base 230 should stay. In some embodiments, the positioning mechanism 231 can be implemented by a ball plunger, and the ball plunger has a spring structure. The ball head moves into the positioning groove to achieve firm positioning, and it is also smoother when moving.

[0050] Figure 4 It is a structural schematic diagram of a mobile test base in an embodiment of the utility model.

[0051] like Figure 4 As shown, according to an embodiment of the present utility model, the mobile test base 230 in the test device 200 includes:

[0052] A first support plate 232 and a second support plate 233 parallel to each other, and,

[0053] A first electrical substrate 234 fixed on the first support plate 232 and a second electrical substrate 235 fixed on the second support plate 233. The first electrical substrate 234 and the second electrical substrate 235 are used to clamp the tool bar to be tested.

[0054] Under the action of external force, the first support plate 232 and the second support plate 233 move toward each other, so that the first electrical substrate 234 and the second electrical substrate 235 are pressed against each other, thereby applying voltage to the insulating coating area on the tool rod to be measured placed therebetween.

[0055] The thickness of the first electrical substrate 234 and the second electrical substrate 235 along the direction of the tool rod can be smaller than the length of the insulating area on the tool rod to be tested. When the tool rod to be tested is pressed, part of the insulating area to be tested is pressed into the electrical base, and this part of the area is the area covered with an insulating rubber ring. This is because the main contact point between the tool rod and the inner sleeve is at the insulating rubber ring, which is also the area where electrical breakdown is prone to occur. The focus of the withstand voltage test is on this area. The thickness of the first electrical substrate 234 and the second electrical substrate 235 along the direction of the tool rod can also correspond to the length of the insulating area on the tool rod to be tested, so that when the tool rod to be tested is pressed, the insulating area to be tested is all pressed into the electrical base. Through the upper and lower electrical substrates, it is simpler and more convenient to clamp the tool rod to be tested, which can be applied to the testing of tool rods of different thicknesses.

[0056] Furthermore, in the test device 200 in the embodiment of the utility model, the first electrical substrate 234 and the second electrical substrate 235 are further provided with a tool bar limiting hole groove 236, so that the tool bar to be tested is clamped and fixed in the tool bar limiting hole groove 236. The design of the limiting hole groove not only allows the tool bar to be tested to be placed stably on the electrical base, and does not cause the tool bar to move or roll due to the compression of the upper and lower electrical bases, but also increases the contact area between the electrical substrate and the insulating area on the tool bar, so that uniform discharge can be achieved during the withstand voltage test.

[0057] Multiple groups of limiting hole slots 236 can be provided, that is, multiple limiting hole slots 236 are spaced apart on the first electric base and the second electric base, so that multiple tool rods to be tested can be placed at the same time for withstand voltage testing.

[0058] Furthermore, a layer of conductive sponge can be attached to the surface of the first electrical substrate 234 and the second electrical substrate 235 that contacts the tool bar to be tested, and the conductive sponge can prevent the insulating coating of the tool bar from being damaged during the test. Similarly, a layer of conductive sponge can be attached to the surface of the first conductor 240 that contacts the tool bar to be tested, so as to prevent the external force from damaging the surface of the tool bar during the test.

[0059] In this embodiment, the mobile test base 230 further includes:

[0060] A third support plate 237, parallel to the second support plate 233;

[0061] A plurality of support columns 238, the support columns 238 penetrate through the second support plate 233 and are fixed to the first support plate 232 and the third support plate 233 respectively;

[0062] The force applying mechanism 239 is used to lift the second support plate 233 under the action of external force to separate the second electrical substrate 235 from the first electrical substrate 234 , or to press down the second support plate 233 to bring the second electrical substrate 235 closer to the first electrical substrate 234 .

[0063] The plurality of support columns 238 can stably support the first support plate 232, the second support plate 233 and the third support plate 237 in a parallel structure to ensure uniform application of external force. With this structure, the distance between the two electrical substrates can be adjusted smoothly, evenly and conveniently, especially when testing multiple tool bars at the same time, this structure is conducive to improving the test efficiency.

[0064] Figure 2 A method for implementing the force applying mechanism 239 is also shown in FIG. Figure 2 As shown, the force applying mechanism 239 includes a handle 2391 and a movable rod 2392 (see Figure 4 ) and connecting component 2393. The movable rod 2392 vertically penetrates the first support plate 237 and is fixed on the second support plate 233. The connecting component 2393 connects the handle 2391 and the movable rod 2392. When the operator applies a force of lifting or pressing down through the handle 2391, the connecting component 2392 transmits the force to the movable rod 2392, driving the second support plate 233 to produce corresponding movement. The force-applying mechanism can also adopt other structures, as long as it can achieve the purpose of converting the force into the movement of the second support plate. In one embodiment, the force-applying mechanism can adopt a horizontal clamp type elbow clamp, which uses the principles of lever, connecting rod mechanism, self-locking, etc. When the elbow clamp applies force, the second support plate is pressed down close to the first support plate. The force-applying mechanism using the elbow clamp can conveniently and quickly complete the pressing of the tool bar to be measured. Furthermore, a spring can be set on the support column between the second support plate and the first support plate, so that the second support plate can be rebounded to the initial position after the elbow clamp removes the external force.

[0065] Furthermore, the first support plate 232, the second support plate 233 and the third support plate 237 of the mobile test base 230 are all made of transparent insulating materials, such as transparent PVC materials. The use of transparent materials facilitates observation of the position adaptation of the mobile test base and the tool bar to be tested, as well as the contact between the mobile test base and the slide rail and the second conductor, thereby improving test efficiency.

[0066] In the testing device of the present invention, the fixed testing base and the movable testing base may have similar structures. Figure 5 A structure of a fixed test base in an embodiment of the utility model is illustrated.

[0067] like Figure 5As shown, the fixed test base 220 is similar in structure to the aforementioned mobile test base 230, except that the fixed test base 220 is fixed to one end of the test bracket 210. The fixed test base 220 also includes two support plates parallel to each other, and two electrical substrates respectively fixed on the two support plates, and the two electrical substrates are used to clamp the tool rod to be tested; under the action of external force, the two support plates approach each other, so that the two electrical substrates are pressed against each other, thereby applying voltage to the tool rod to be tested placed therein. The thickness of the two electrical substrates corresponds to the length of the insulating area at the top of the tool rod to be tested, so that when the tool rod to be tested is pressed, the insulating area at the top is completely pressed into the electrical base. The structure of clamping the tool rod to be tested by the upper and lower electrical substrates is simple and convenient, and can be applied to the testing of tool rods of different thicknesses.

[0068] The two electrical substrates of the fixed test base 220 are also provided with a knife bar limiting hole groove, so that the knife bar to be tested can be fixed in the knife bar limiting hole groove after being clamped. The design of the limiting hole groove not only allows the knife bar to be tested to be placed stably on the electrical base, and does not cause the knife bar to move or roll due to the compression of the upper and lower electrical bases, but also increases the contact area between the electrical substrate and the insulating area on the knife bar, which can discharge uniformly during the withstand voltage test. A layer of conductive sponge can also be pasted on the surface of the two electrical substrates of the fixed test base 220 that contact the knife bar to be tested, so as to protect the surface of the knife bar to be tested.

[0069] Multiple groups of limiting holes and grooves may be provided on the fixed test base 220 , corresponding one-to-one to the limiting holes and grooves provided on the mobile test base 230 .

[0070] like Figure 5 As shown, corresponding to the limiting hole groove on the test base, a plurality of tool rod grooves 241 may be arranged at intervals on the first conductor 240, so that a plurality of tool rods to be tested are placed flat in the tool rod grooves and undergo a withstand voltage test at the same time. The tool rod groove on the first conductor also increases the electrical contact area with the non-insulating area on the tool rod, which is conducive to completing the withstand voltage test stably and reliably. Preferably, the opening depth of the tool rod groove 241 arranged on the first conductor 240 is greater than the opening depth of the limiting hole groove on the electrical substrate of the test base, so as to ensure that the tool rod is stably placed in the tool rod groove 241 of the first conductor.

[0071] Furthermore, a tool bar stopper 221 is provided on the fixed test base 220 to limit the position of the tail of the tool bar to be tested. The tool bar stopper 221 facilitates the alignment of the tails of multiple tool bars to be tested and places them on the test base, and also prevents the tool bar from exceeding the test range after axial movement.

[0072] The positions and depths of the holes and grooves on the electrical substrate at the bottom of the fixed test base and the movable test base and on the first conductor should ensure that the tool bar to be tested can be placed horizontally.

[0073] In addition, a cable connector 211 connected to an external power source is also provided at the bottom of the test bracket 210. A test voltage is input through the external power source, and a current monitoring device is used to observe whether the insulation area of ​​the knife bar is broken down by the test voltage to complete the withstand voltage test.

[0074] Through the test device provided by the utility model, the cooperation of the mobile test base and the fixed test base can realize the withstand voltage test of the knife rods of various length specifications, and can also be adjusted according to the distribution of the insulating parts on the knife rod, and the withstand voltage test of multiple insulating parts on the knife rod can be completed at the same time. In addition, by setting multiple slots, the withstand voltage test of multiple knife rods can also be completed at the same time, which has the beneficial effects of convenient adjustment, wide application range and high test efficiency.

[0075] The above description is only a preferred embodiment of the utility model and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in the utility model is not limited to the technical solution formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the inventive concept. For example, the above features are replaced with the technical features with similar functions disclosed in the utility model (but not limited to) by each other to form a technical solution.

Claims

1. A pressure test device suitable for ultrasonic electrosurgical knife rod, characterized in that: include: Test bracket; A fixed test base is fixed to one end of the test bracket; A mobile test base can be moved from one end of the test bracket to the other end under the action of an external force, and the fixed test base and the mobile test base are used to clamp the insulating coating areas at different positions on the tool rod to be tested; A first conductor is fixed on the test bracket and is disposed between the fixed test base and the movable test base to support the non-insulated area on the tool rod to be tested; The fixed test base and the movable test base are used to connect to the first electrode of the external power supply, and the first conductor is used to connect to the second electrode of the external power supply, thereby forming a voltage path to test the voltage resistance performance of the insulating coating area on the tool rod to be tested.

2. The testing device according to claim 1, characterized in that: Also includes: A slide rail, fixed on the test bracket; A sliding block matched with the slide rail is provided at the bottom of the mobile test base. Under the action of external force, the mobile test base can move from one end of the test bracket to the other end along the slide rail.

3. The testing device according to claim 2, characterized in that: Also includes: A second conductor is fixed on the test bracket and is used to connect to the first electrode of the external power supply. The second conductor is arranged parallel to the slide rail and is in electrical contact with the bottom surface of the mobile test base, so that the mobile test base is connected to the first electrode of the external power supply through the second conductor.

4. The testing device according to claim 3, characterized in that: A positioning groove is provided at a preset position of the second conductor, and a positioning mechanism is provided at the bottom of the mobile test base. The positioning mechanism is used for the mobile test base to stay at the preset position under the restriction of the positioning groove when moving.

5. The testing device according to claim 1, characterized in that: The mobile test base comprises: a first support plate and a second support plate parallel to each other, and, A first electrical substrate fixed on the first supporting plate, and a second electrical substrate fixed on the second supporting plate, wherein the first electrical substrate and the second electrical substrate are used to clamp the tool rod to be measured; Under the action of external force, the first support plate and the second support plate move closer to each other, so that the first electrical substrate and the second electrical substrate are pressed against each other, thereby applying voltage to the insulating coating area on the tool rod to be measured placed therebetween.

6. The testing device according to claim 5, characterized in that: The first electrical substrate and the second electrical substrate are provided with a tool rod limiting hole groove, so that the tool rod to be measured can be fixed in the tool rod limiting hole groove after being clamped.

7. The testing device according to claim 5, characterized in that: The mobile test base also includes: a third support plate, parallel to the second support plate; A plurality of support columns, wherein the support columns penetrate through the second support plate and are respectively fixed to the first support plate and the third support plate; The force applying mechanism is used to lift the second support plate under the action of external force to separate the second electrical substrate from the first electrical substrate, or to press the second support plate downward to bring the second electrical substrate closer to the first electrical substrate.

8. The testing device according to claim 1, characterized in that: A plurality of tool rod grooves are arranged at intervals on the first conductor, so that a plurality of tool rods to be tested are placed flat in the tool rod grooves and undergo a withstand voltage test at the same time.

9. The testing device according to claim 1, characterized in that: The fixed test base is provided with a knife bar stopper for limiting the position of the tail of the knife bar to be tested.

10. The testing device according to claim 7, characterized in that: The first support plate, the second support plate and the third support plate of the mobile test base are all made of transparent insulating material.

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