Optical fiber distribution cabinet

Abstract

The application provides an optical fiber distribution cabinet, and relates to the technical field of optical fibers. The optical fiber distribution cabinet comprises an optical fiber distribution cover plate and a control module. The optical fiber distribution cover plate comprises a microstrip antenna array and a plurality of optical fiber ports. The microstrip antenna array is used for non-contact reading of label information of an optical fiber terminal. The optical fiber terminal is in a connected state with any target optical fiber port of the plurality of optical fiber ports. Each optical fiber port is configured with a corresponding indicator light. The control module is configured to receive the label information of the optical fiber terminal sent by the microstrip antenna array, and control the indicator light of the target optical fiber port in a connected state with the optical fiber terminal to switch to a target state according to the label information. Thus, the optical fiber distribution cabinet can check whether each optical fiber terminal is accurately inserted into the optical fiber port and is in a stable connected state with the optical fiber port in real time according to the indicator light state, thereby improving the efficiency of network operation and maintenance work and the reliability of the communication network, and further improving the service quality.

Description

Technical Field

[0001] This utility model relates to the field of optical fiber technology, and in particular to an optical fiber distribution cabinet. Background Technology

[0002] Optical fiber, with its high capacity and low loss transmission characteristics, is widely used in various communication scenarios such as data centers, telecommunications hubs, and enterprise parks. With the rapid development of communication technology, the scale of optical fiber networks has exploded, and the number of optical fiber ports carried by a single optical fiber distribution cabinet has exceeded one million, which poses unprecedented challenges to the management capabilities of optical fiber distribution cabinets.

[0003] However, the management of fiber optic distribution cabinets still relies heavily on manual operation. Manual management has inherent drawbacks such as low efficiency and susceptibility to errors, directly leading to a passive and inefficient state of network operation and maintenance, severely threatening the reliability of the communication network, and consequently causing a significant decline in the quality of communication services provided to users.

[0004] Therefore, how to improve the efficiency of network operation and maintenance, the reliability of communication networks, and further improve service quality has become an urgent technical problem to be solved. Utility Model Content

[0005] To address the aforementioned issues, this invention provides a fiber optic distribution cabinet that can improve the efficiency of network operation and maintenance, enhance the reliability of communication networks, and further improve service quality.

[0006] The present invention discloses the following technical solutions:

[0007] This application discloses an optical fiber distribution cabinet, which includes an optical fiber distribution cover and a control module. The optical fiber distribution cover includes a microstrip antenna array and several optical fiber ports. The microstrip antenna array is used for non-contact reading of the tag information of the optical fiber terminal. The optical fiber terminal is connected to any one of the several optical fiber ports. Each optical fiber port is configured with a corresponding indicator light.

[0008] The control module is configured as follows:

[0009] Receive the tag information of the optical fiber terminal transmitted by the microstrip antenna array;

[0010] Based on the tag information, the indicator light of the target optical fiber port that is in a connected state with the optical fiber terminal is switched to the target state.

[0011] Optionally, the control module is specifically configured as follows:

[0012] When it is determined, based on the tag information, that the preset terminal set includes the optical fiber terminal, the indicator light of the target optical fiber port that is in a connected state with the optical fiber terminal is switched to the target state.

[0013] Optionally, the fiber optic distribution cabinet further includes a fiber optic cable management device, wherein the fiber optic cable management device includes a fiber coiling mechanism and a guiding mechanism, the fiber coiling mechanism includes a first spiral track and a second spiral track, and the plurality of fiber optic ports include a first fiber optic port and a second fiber optic port.

[0014] The control module is also configured to:

[0015] When it is detected that the two ends of the same optical fiber are respectively inserted into the first optical fiber port and the second optical fiber port, a cable management path is generated according to the positional relationship between the first optical fiber port and the second optical fiber port. The first path point of the cable management path is the first spiral track, and the second path point of the cable management path is the second spiral track.

[0016] The optical fiber is guided by the guiding mechanism and stored in the first spiral track and / or the second spiral track.

[0017] Optionally, the control module is specifically configured as follows:

[0018] Based on the positional relationship between the first and second fiber optic ports, the remaining capacity of each spiral track in the fiber coiling mechanism, and the minimum bending radius threshold of the fiber, a fiber management path is generated.

[0019] Optionally, the guiding mechanism includes a drive motor electrically connected to the control module and a plurality of guide wheels, each of the guide wheels being coupled to the drive motor through a transmission mechanism;

[0020] The control module is specifically configured as follows:

[0021] Based on the described routing path, determine the target rotation angle of the plurality of guide wheels;

[0022] By sending a rotation command to the drive motor, the drive motor drives the plurality of guide wheels to rotate to the target rotation angle according to the rotation command;

[0023] The optical fiber is guided into the first spiral track and / or the second spiral track by several rotating guide wheels.

[0024] Optionally, a pressure sensor is provided on each of the spiral tracks, and the control module is further configured to:

[0025] When the pressure detection result of the pressure sensor determines that the remaining capacity of the spiral track in the fiber coiling mechanism is lower than the capacity threshold, the indicator light is controlled to switch to the alarm state.

[0026] Optionally, a tension sensor is provided on each of the guide wheels, and the control module is further configured to:

[0027] When the tension of the optical fiber is determined to be higher than the tension threshold based on the tension sensor result, the indicator light is controlled to switch to the alarm state.

[0028] Optionally, the radius of each spiral track in the fiber coiling mechanism is greater than 30 mm.

[0029] Optionally, the radius of each guide wheel in the guide mechanism is greater than 15 mm.

[0030] Optionally, each guide wheel in the guiding mechanism has a scratch-resistant coating on its surface.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] This invention provides a fiber optic distribution cabinet, which includes a fiber optic distribution cover and a control module. The fiber optic distribution cover includes a microstrip antenna array and several fiber optic ports. The microstrip antenna array is used for non-contact reading of the tag information of the fiber optic terminals. The fiber optic terminals are connected to any one of the target fiber optic ports. Each fiber optic port is equipped with a corresponding indicator light. The control module is configured to receive the tag information of the fiber optic terminals transmitted by the microstrip antenna array; and, based on the tag information, control the indicator light of the target fiber optic port connected to the fiber optic terminal to switch to the target state. This fiber optic distribution cabinet can check in real time whether each fiber optic terminal is accurately inserted into the fiber optic port and is in a stable connection state with the fiber optic port based on the indicator light status, thereby improving the efficiency of network operation and maintenance, the reliability of the communication network, and further improving the quality of service. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 A schematic diagram of a fiber optic distribution cabinet provided for an embodiment of this application;

[0035] Figure 2 A schematic diagram of another fiber optic distribution cabinet provided in an embodiment of this application;

[0036] Figure 3 A schematic diagram of an optical fiber distribution cover provided in an embodiment of this application;

[0037] Figure 4A A schematic diagram of a microstrip antenna array provided for an embodiment of this application;

[0038] Figure 4B This is a schematic diagram of a microstrip antenna array provided in an embodiment of this application. Detailed Implementation

[0039] As mentioned earlier, the management of fiber optic distribution cabinets still relies heavily on manual operation. Manual management has inherent drawbacks such as low efficiency and susceptibility to errors, directly leading to a passive and inefficient state of network operation and maintenance, severely threatening the reliability of the communication network, and consequently causing a significant decline in the quality of communication services provided to users.

[0040] In view of this, this application provides a fiber optic distribution cabinet that can check in real time, based on indicator light status, whether each fiber optic terminal is accurately inserted into the fiber optic port and in a stable connection state with the fiber optic port. This improves the efficiency of network operation and maintenance, the reliability of the communication network, and further enhances service quality. Furthermore, the fiber optic distribution cabinet in this application ensures fiber optic reliability through multiple methods. On one hand, by precisely controlling the bending radius of the fiber optic cable, both the spiral track in the fiber coiling mechanism and the guide wheel in the guiding mechanism ensure that the fiber optic cable is not damaged due to excessive bending during coiling and guiding. On the other hand, real-time monitoring of the remaining capacity of the spiral track and the fiber optic tension can promptly detect potential problems and issue alarms, preventing fiber optic cable damage caused by insufficient capacity or excessive tension. Both of these aspects improve the efficiency of network operation and maintenance, the reliability of the communication network, and further enhance service quality by ensuring fiber optic cable reliability.

[0041] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] Example 1

[0043] See Figure 1This figure is a schematic diagram of a fiber optic distribution cabinet provided in an embodiment of this application. Figure 1 It can be seen that the fiber optic distribution cabinet 1 includes a fiber optic distribution cover plate 11 and a control module 12.

[0044] The fiber optic distribution cover 11 includes a microstrip antenna array. This array employs high-frequency (e.g., 902-928MHz) microstrip patch antennas, arranged in a λ / 4 spacing matrix on the inner side of the fiber optic distribution cover 11 (λ being the signal wavelength), achieving near-field radio frequency coverage. When a fiber optic terminal with a passive RFID tag is inserted into the fiber optic port, the microstrip antenna array reads the tag information from the fiber optic terminal non-contactly via electromagnetic coupling. This non-contact reading method offers advantages such as ease of operation, no manual intervention required, and fast reading speed, significantly improving the efficiency of acquiring tag information from the fiber optic terminal.

[0045] The fiber optic distribution cover 11 also includes several fiber optic ports. The specific number of fiber optic ports depends on the design capacity of the fiber optic distribution cabinet 1 and the actual application requirements. Each fiber optic port is surrounded by a corresponding indicator light, such as an RGB LED indicator. The indicator lights have rich color display capabilities, and through different color combinations and flashing patterns, they can intuitively display various status information of the fiber optic port. This visual design allows maintenance personnel to quickly understand the connection status of the fiber optic terminals simply by observing the indicator light status without complex operations or professional knowledge, thus improving the efficiency and accuracy of maintenance work.

[0046] Control module 12 is configured as follows:

[0047] First, the control module 12 receives the tag information of the fiber optic terminal sent by the microstrip antenna array.

[0048] Subsequently, the control module 12, based on the tag information, controls the indicator light of the target fiber optic port, which is in a connected state with the fiber optic terminal, to switch to the target state. The target state is preset according to actual needs. For example, when the fiber optic terminal is inserted into the fiber optic port and is in a stable connection state, the indicator light may be solid green; when the fiber optic terminal is inserted into the fiber optic port but is in an unstable connection state, the indicator light may be flashing red. It should be noted that this application does not limit the specific indicator light state.

[0049] In summary, this application discloses a fiber optic distribution cabinet that can check in real time whether each fiber optic terminal is accurately inserted into the fiber optic port and is in a stable connection state with the fiber optic port based on the indicator light status. This improves the efficiency of network operation and maintenance, the reliability of the communication network, and further enhances service quality.

[0050] Example 2

[0051] See Figure 2 This figure is a schematic diagram of another fiber optic distribution cabinet provided in an embodiment of this application. Figure 2 It can be seen that the fiber optic distribution cabinet 1 includes a fiber optic distribution cover 11, a control module 12, and a fiber optic cable management device 13.

[0052] See Figure 3 This figure is a schematic diagram of an optical fiber distribution cover provided in an embodiment of this application. The optical fiber distribution cover 11 includes a microstrip antenna array and several optical fiber ports. See also Figure 4A This figure is a schematic diagram of a microstrip antenna array provided in an embodiment of this application. Figure 4A As shown, the microstrip antenna array includes 12 915M directional antennas (E1 - E12) for transmitting and receiving radio frequency (RF) signals. They are directionally arranged to cover a specific area, ensuring that the RF signals can effectively interact with RFID tags. The microstrip antenna array also includes RF switches for selectively connecting or disconnecting the signal path between the 915M directional antennas and subsequent RF circuitry. The RF circuitry includes: an RF power amplifier (i.e.,...) Figure 4A The RF power amplifier (in the array) amplifies the RF signal, enhancing its transmission power to ensure wider coverage. The RFID read / write ASIC is used for data exchange with RFID tags. The microcontroller unit (MCU) controls the entire microstrip antenna array and processes data. A DC-DC buck converter (i.e....) Figure 4A The DC-DC step-down converter in RS485 is used to convert a higher input voltage to a lower voltage to ensure stable operation. Figure 4A The PD485 PHY interface is used for communication with other devices. The RJ45 terminal provides an Ethernet interface for network connectivity.

[0053] The fiber optic cable management device 13 includes a fiber coiling mechanism and a guiding mechanism. The fiber coiling mechanism comprises several spiral tracks. The spiral track design provides an orderly and stable storage space for the optical fibers, allowing them to be wound and stored in a specific spiral shape within the fiber optic distribution cabinet. This storage method effectively avoids excessive bending, winding, and knotting of the optical fibers, reducing the risk of physical damage and ensuring the transmission performance of the fibers. Simultaneously, the spiral track layout facilitates the organization and retrieval of optical fibers, thereby simplifying operation and maintenance for maintenance personnel, improving the efficiency of network maintenance and the reliability of the communication network, and further enhancing service quality.

[0054] The guiding mechanism comprises several guide wheels and a drive motor, with each drive motor coupled to one of the guide wheels. The guide wheels guide the optical fiber, ensuring it moves along a predetermined path during coiling and cable management, preventing it from deviating from its correct position. The drive motors power the guide wheels, enabling flexible guidance and arrangement of the optical fiber. This design improves the efficiency and accuracy of fiber optic cable management, reduces the complexity and errors of manual operations, facilitates operation and maintenance by maintenance personnel, and ultimately improves the efficiency of network maintenance, the reliability of the communication network, and the quality of service.

[0055] It should be noted that the radius of each spiral track in the fiber coiling mechanism is greater than 30 millimeters. This ensures that the minimum bending radius requirement for optical fiber is met, guaranteeing its transmission performance and lifespan.

[0056] It should also be noted that the radius of each guide wheel in the guiding mechanism is greater than 15 millimeters. This allows the optical fiber to maintain a relatively large bending radius when passing through, reducing the risk of fiber damage.

[0057] It should also be noted that each guide wheel in the guiding mechanism has an anti-scratch coating on its surface. This reduces friction and wear between the optical fiber and the guide wheel, improving the lifespan of the optical fiber and the transmission quality.

[0058] Control module 12 is configured as follows:

[0059] First, the control module 12 receives the tag information of the fiber optic terminal sent by the microstrip antenna array.

[0060] Subsequently, based on the tag information, the control module 12 controls the indicator light of the target fiber optic port that is in a connected state with the fiber optic terminal to switch to the target state.

[0061] In one specific implementation, the control module 12 only switches the indicator light of the target fiber optic port that is connected to the fiber optic terminal to the target state when the preset terminal set is determined to include the fiber optic terminal based on the tag information. This is because in industries such as telecommunications, finance, and healthcare, where there are strict regulations regarding the security of business data, business data interaction can only occur after an authorized fiber optic terminal (belonging to the preset terminal set) is inserted into the fiber optic port. Conversely, when the preset terminal set is determined not to include the fiber optic terminal based on the tag information, the control module 12 needs to switch the indicator light of the target fiber optic port that is connected to the fiber optic terminal to the alarm state.

[0062] Control module 12 is also configured as follows:

[0063] First, when the two ends of the same optical fiber are detected to be inserted into the first optical fiber port and the second optical fiber port respectively, the control module 12 generates a cable management path according to the positional relationship between the first optical fiber port and the second optical fiber port.

[0064] Specifically, the control module 12 stores the three-dimensional coordinates of each fiber optic port within the fiber optic distribution cabinet. By calculating parameters such as the straight-line distance and relative direction between the coordinates of two fiber optic ports, and combining this with the distribution of the guide wheels and spiral tracks in the fiber optic cable management device 13, a cable management path can be planned from the first fiber optic port to the second fiber optic port, making full use of the guide wheels and spiral tracks for cable management. It can be understood that the first point of the cable management path is the first spiral track, and the second point of the cable management path is the second spiral track.

[0065] In another specific implementation, the fiber management path can be generated based on the positional relationship between the first and second fiber ports, the remaining capacity of each spiral track in the fiber coiling mechanism (including the currently wound fiber length and the remaining available winding length), and the minimum bending radius threshold of the fiber (the maximum permissible bending radius of the fiber that will not cause a significant increase in transmission loss or physical damage when bent). Therefore, by strictly adhering to the minimum bending radius threshold and rationally utilizing the spiral track capacity, physical damage to the fiber can be avoided during the coiling process, ensuring the fiber's transmission performance and lifespan.

[0066] Subsequently, through the guiding mechanism, the control module 12 pulls the optical fiber into the first spiral track and / or the second spiral track for storage.

[0067] In another specific implementation, relying solely on a fixed guiding mechanism may be insufficient for efficiently and accurately completing the fiber optic traction task. Therefore, the target rotation angle of several guide wheels can be determined based on the cable routing path. Subsequently, a rotation command is sent to the drive motor, causing the drive motor to drive the guide wheels to rotate to the target rotation angle according to the rotation command. The rotation command can include parameters such as the guide wheel's identifier, the target rotation angle, and the rotation speed. For example, the rotation command may exist in the form of a digital signal or communication protocol, such as "Guide wheel 1, target angle 30 degrees, rotation speed 5 revolutions per minute". Finally, the rotated guide wheels guide the optical fiber into the first and / or second helical tracks for storage. Thus, by accurately calculating the target rotation angle of the guide wheels, the accuracy of fiber optic traction can be improved, and the risk of fiber entanglement and damage during the traction process can be reduced.

[0068] It should be noted that with frequent fiber optic insertions, removals, and capacity expansions, the remaining capacity of the spiral track will gradually decrease. If this is not monitored and addressed promptly, continuing to insert fibers when the remaining capacity is insufficient may lead to fiber optic cable management issues, increase the risk of fiber damage, and even affect the reliability of the communication network, ultimately resulting in a significant decline in the quality of communication services provided to users. Therefore, pressure sensors can be installed on each spiral track.

[0069] The control module 102 is also configured to switch the control indicator to an alarm state when the remaining capacity of the spiral track in the fiber optic coiling mechanism is determined to be lower than the capacity threshold based on the pressure detection results of the pressure sensor. The capacity threshold is determined comprehensively based on the physical characteristics of the spiral track, the minimum bending radius requirement of the optical fiber, and practical operation and maintenance experience. This avoids continuing to insert optical fibers when the spiral track capacity is insufficient, preventing damage to the optical fiber due to excessive bending or tangling, improving the efficiency of network operation and maintenance, the reliability of the communication network, and further enhancing service quality.

[0070] It should also be noted that in fiber optic communication systems, the tension state of the optical fiber directly affects its transmission performance and lifespan. Excessive fiber tension can cause microscopic cracks or stress concentrations within the fiber. These damages accumulate gradually, eventually leading to increased fiber attenuation and affecting signal transmission quality. In extreme cases, the fiber may break due to excessive tension, impacting the reliability of the communication network and significantly degrading the quality of communication services provided to users. Therefore, tension sensors can be installed on each guide wheel.

[0071] The control module 102 is also configured to switch the control indicator to an alarm state when the tension of the optical fiber is determined to be higher than the tension threshold based on the tension sensor results. The setting of the tension threshold needs to comprehensively consider factors such as the type and specifications of the optical fiber, the operating environment, and the system's reliability requirements. Therefore, maintenance personnel can take measures before excessive optical fiber tension leads to increased signal attenuation, such as adjusting the fiber's routing path or reducing bending or twisting, thereby improving the efficiency of network maintenance and the reliability of the communication network, and further enhancing service quality.

[0072] In summary, this application discloses a fiber optic distribution cabinet that can check in real time, based on indicator light status, whether each fiber optic terminal is accurately inserted into the fiber optic port and maintains a stable connection with the port. This improves the efficiency of network operation and maintenance, the reliability of the communication network, and further enhances service quality. Furthermore, the fiber optic distribution cabinet in this application ensures fiber optic reliability through multiple methods. On one hand, by precisely controlling the bending radius of the fiber optic cable, both the spiral track in the fiber coiling mechanism and the guide wheel in the guiding mechanism ensure that the fiber optic cable is not damaged due to excessive bending during coiling and guiding. On the other hand, real-time monitoring of the remaining capacity of the spiral track and the fiber optic tension can promptly detect potential problems and issue alarms, preventing fiber optic cable damage caused by insufficient capacity or excessive tension. Both of these aspects improve the efficiency of network operation and maintenance, the reliability of the communication network, and further enhance service quality by ensuring fiber optic cable reliability.

[0073] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0074] The above description of the disclosed embodiments enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An optical fiber distribution cabinet, characterized by, The optical fiber distribution cabinet comprises an optical fiber distribution cover plate and a control module, wherein the optical fiber distribution cover plate comprises a microstrip antenna array and a plurality of optical fiber ports, the microstrip antenna array is used for non-contact reading of label information of an optical fiber terminal, the optical fiber terminal is in a connected state with any target optical fiber port of the plurality of optical fiber ports, and each optical fiber port is configured with a corresponding indicator light; The control module is configured to: receive the label information of the optical fiber terminal sent by the microstrip antenna array; According to the label information, control the indicator light of the target optical fiber port in communication with the optical fiber terminal to switch to a target state.

2. The fiber distribution hub of claim 1, wherein, The control module is specifically configured to: When it is determined according to the label information that a preset terminal set includes the optical fiber terminal, control the indicator light of the target optical fiber port in communication with the optical fiber terminal to switch to a target state.

3. The fiber distribution hub of claim 1, wherein, The optical fiber distribution cabinet further comprises an optical fiber storage and arrangement device, wherein the optical fiber storage and arrangement device comprises a fiber winding mechanism and a guide mechanism, the fiber winding mechanism comprises a first spiral track and a second spiral track, and the plurality of optical fiber ports comprises a first optical fiber port and a second optical fiber port. The control module is further configured to: When it is detected that two ends of the same optical fiber are inserted into the first optical fiber port and the second optical fiber port respectively, generate an arrangement path according to the positional relationship between the first optical fiber port and the second optical fiber port, wherein a first passing point of the arrangement path is the first spiral track, and a second passing point of the arrangement path is the second spiral track; The optical fiber is drawn into the first spiral track and / or the second spiral track through the guide mechanism.

4. The fiber distribution hub of claim 3, wherein, The control module is specifically configured to: Generate an arrangement path according to the positional relationship between the first optical fiber port and the second optical fiber port, the remaining capacity of each spiral track in the fiber winding mechanism and the minimum bending radius threshold of the optical fiber.

5. The fiber distribution hub of claim 3, wherein, The guide mechanism comprises a driving motor electrically connected with the control module and a plurality of guide wheels, and each guide wheel is coupled with the driving motor through a transmission mechanism. The control module is specifically configured to: According to the arrangement path, determine a target rotation angle of the plurality of guide wheels; Send a rotation instruction to the driving motor, so that the driving motor drives the plurality of guide wheels to rotate to the target rotation angle according to the rotation instruction; The optical fiber is drawn into the first spiral track and / or the second spiral track through the plurality of guide wheels after rotation.

6. The fiber distribution hub of claim 3, wherein, A pressure sensor is arranged on each spiral track, and the control module is further configured to: When it is determined according to the pressure detection result of the pressure sensor that the remaining capacity of the spiral track in the fiber winding mechanism is lower than a capacity threshold, control the indicator light to switch to an alarm state.

7. The fiber distribution hub of claim 5, wherein, A tension sensor is arranged on each guide wheel, and the control module is further configured to: When it is determined according to the tension sensor result of the tension sensor that the tension of the optical fiber is higher than a tension threshold, control the indicator light to switch to an alarm state.

8. The fiber distribution hub of any of claims 3-7, wherein, Each spiral track in the disc fiber mechanism has a radius greater than 30 mm.

9. The fiber distribution hub of claim 5 or 7, wherein, Each guide wheel in the guide mechanism has a radius greater than 15 mm.

10. The fiber distribution hub of claim 5 or 7, wherein, The surface of each guide wheel in the guide mechanism is provided with an anti-scratch coating.

Images