CN216117910U - Pin point signal derivation testing mechanism and pin point testing jig - Google Patents

Abstract

The utility model discloses a pin point signal derivation testing mechanism and a pin point testing jig, and relates to the field of testing jigs. The device comprises a test board and a probe fixing component arranged above the test board, wherein a probe is fixed on the probe fixing component, one end of the probe is in contact with a product to be tested on the probe fixing component, and the other end of the probe is in contact with the test board; the test board comprises a receiving board and an output board which are connected integrally, wherein the receiving board is provided with a plurality of probe contacts corresponding to the end parts of the probes, and the output board is connected with a plurality of test rings corresponding to the probe contacts. This probe point signal derives accredited testing organization's survey test panel includes the dash receiver and the output board of body coupling, and the product information that receives through the dash receiver is transmitted to output board output and is detected, externally detects the information derivation that the probe contact received, when the product goes wrong, can find out problem probe contact and the components and parts that correspond fast, has improved the detection efficiency of manual operation's convenience and product.

Description

Pin point signal derivation testing mechanism and pin point testing jig

Technical Field

The utility model relates to the technical field of test fixtures, in particular to a pin point signal derivation test mechanism and a pin point test fixture.

Background

In the manufacture of electronic devices, a large number of PCBs are used, and the PCBs of the products need to be tested in order to ensure the reliability of the products. The pin point test fixture is a branch of the PCBA test fixture, and is mainly used for testing PAD points (welding points of electronic components to be welded on a PCB), pins (electronic components with pins such as resistors and often in hole shapes) and golden fingers (large copper points on the PCB) and other related functional tests;

the pin point test fixture generally includes testing arrangement and the push down device of setting in the testing arrangement upper end, testing arrangement is provided with the test and uses the probe, support through pushing down the device and press product and probe contact, thereby test, whether qualified according to the feedback information test PCB board of probe, nevertheless among the current pin point test fixture, the probe is excessive, it is too intensive to hold the pinhole, when the product goes wrong, can't find out problem pin point and the product components and parts that correspond fast, bring very big puzzlement for the staff, the efficiency of software testing has been reduced.

SUMMERY OF THE UTILITY MODEL

The utility model aims to solve the problems of the existing pressing mechanism, and provides a pin point signal derivation testing mechanism and a pin point testing jig which have reasonable and compact structural design, lead pin point information out of the existing pressing mechanism through a testing board for detection, and are convenient for quickly finding out a problem pin point and a corresponding product component when a product has a problem, thereby improving the detection efficiency of the product.

In order to achieve the purpose, the utility model provides the following technical scheme:

a pin point signal derivation testing mechanism comprises a testing plate and a probe fixing component arranged above the testing plate, wherein a probe is fixed on the probe fixing component, one end of the probe is in contact with a product to be tested on the probe fixing component, and the other end of the probe is in contact with the testing plate; the test board comprises a receiving board and an output board which are connected integrally, a plurality of probe contacts corresponding to the ends of the probes are arranged on the receiving board, a plurality of test rings corresponding to the probe contacts are connected to the output board, and a communication switch used for controlling the test rings to be electrically connected with the probe contacts is further arranged on the test board.

Preferably, the probe fixing assembly comprises a probe fixing plate, and a needle cover plate and a needle tail plate which are arranged on two sides of the probe fixing plate respectively, a plurality of limiting holes matched with the probes are formed in the probe fixing plate, the needle cover plate and the needle tail plate, and the probes can be limited in the through holes.

Preferably, a needle carrier plate fixing plate is fixed between the probe fixing plate and the needle tail plate, an opening for the probe to pass through is formed in the needle carrier plate fixing plate, and the probe is not in contact with the needle carrier plate fixing plate.

Preferably, the needle cover plate, the needle support plate fixing plate, the probe fixing plate and the needle tail plate are respectively provided with a corresponding positioning hole, and a positioning column is matched in the positioning holes.

Preferably, the output board is provided with a plurality of connecting holes distributed in an array manner, the test ring is connected in the connecting holes, and the test ring is also internally provided with a detachable connecting piece.

Preferably, the connecting member includes a connecting ring with an opening and conductive posts connected to two ends of the opening of the connecting ring, and the conductive posts are clamped in the test ring.

Preferably, one side of any row of the connecting holes is provided with a communication switch, and the communication switch can be used for controlling the connection or disconnection between the probe contact and the test ring.

Preferably, communication switches are arranged on two sides of any row of the connecting holes, and the communication switches on the two sides are connected in series.

Preferably, the test board is provided with an LED display lamp correspondingly connected with the communication switch.

A pin point test fixture comprises the test mechanism and a pressing mechanism positioned above the test mechanism, wherein the pressing mechanism is used for pressing a product to be tested to be in contact with one end of a probe; the pressing mechanism comprises a pressing plate, two sides of the pressing plate are both connected with a sliding plate and a side plate through a linkage module, and the sliding plate is positioned on the inner side of the side plate; a transmission module is arranged between the sliding plate and the side plate; the sliding plate and the side plate are respectively provided with a first displacement hole and a second displacement hole which are matched with the linkage module; one end of the linkage module is connected with the pressing plate, and the other end of the linkage module sequentially penetrates through the first displacement hole and the second displacement hole; when the transmission module drives the sliding plate to horizontally slide relative to the side plate, the second displacement hole is used for guiding the linkage module to be positioned in the first displacement hole to move up and down and driving the pressing plate to move up and down.

Compared with the prior art, the utility model has the beneficial effects that: the pin point signal derivation testing mechanism is reasonable and compact in design, the testing board comprises a receiving board and an output board which are integrally connected, the product and the receiving board are connected through the probes, signals can be conducted to a testing ring of the output board, information received by the probes is derived outside for detection, when the test fails, if the test fails, a tester can timely find out damaged probes through signal judgment of the testing ring, and if the test fails, a tester can quickly find out damaged components through a signal judgment problem area; the convenience of manual operation is improved, and the detection efficiency of products is improved simultaneously.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.

FIG. 1 is a block diagram of a pin signal derivation test mechanism in an embodiment of the present invention;

FIG. 2 is an exploded view of a pin signal derivation test mechanism in an embodiment of the present invention;

FIG. 3 is a block diagram of a test board of the pin signal deriving test mechanism according to an embodiment of the present invention;

FIG. 4 is a block diagram of a test loop of a pin signal derivation test mechanism in an embodiment of the present invention;

FIG. 5 is a diagram illustrating a pressing mechanism of the probing test fixture according to an embodiment of the present invention;

in the figure: 10 is a test board, 11 is a receiving board, 111 is a probe contact, 12 is an output board, 121 is a test ring, 1211 is a connecting ring, 1212 is a conductive post, 122 is a communication switch, 123 is an LED display lamp, 124 is a board card socket, 20 is a pin tail board, 30 is a pin carrier board fixing board, 31 is an opening, 32 is a positioning column, 40 is a probe fixing board, 50 is a pin cover board, 51 is a limiting hole, 60 is a pressing board, 61 is a linkage module, 62 is a control handle, 63 is an external connecting shaft, 64 is a gear, 65 is a rack, 66 is a side board, 67 is a sliding board, 68 is a clamping pin, and 69 is a clamping slot.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present application more comprehensible, the present application is described in further detail with reference to the accompanying drawings and the detailed description.

In the description of the present application, it is to be understood that the terms "intermediate," "top," "bottom," "inner," "outer," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the present application and simplicity in description, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed in a particular orientation, and be operated in a particular orientation, and thus should not be construed as limiting the present application. The terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present application, "a plurality" means two or more unless specifically limited otherwise.

In addition, unless expressly stated or limited otherwise, the terms "mounted," "connected," "secured," and the like are intended to be inclusive and mean, for example, that there may be a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art as appropriate.

In this application, unless expressly stated or limited otherwise, the first feature "on" or "under" the second feature may comprise direct contact of the first and second features, or may comprise contact of the first and second features not directly but through another feature in between. Also, the first feature being "on," "above" and "over" the second feature includes the first feature being directly on and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature includes the first feature being directly under and obliquely below the second feature, or simply meaning that the first feature is at a lesser elevation than the second feature.

Example (b): referring to fig. 1 to 5, the pin point signal derivation testing mechanism in this embodiment is mainly used in a pin point testing fixture, and aims at the problems that the existing pin point testing fixture has too many probes and too dense pin holes, and when a product has a problem, the defective pin point and a corresponding product component cannot be found out quickly, which brings great trouble to workers and reduces the testing efficiency. The probe point signal derivation testing mechanism comprises a testing board 10 and a probe fixing component arranged above the testing board 10, wherein a probe is fixed on the probe fixing component, one end of the probe is in contact with a product to be tested on the probe fixing component, and the other end of the probe is in contact with the testing board 10; the test board 10 includes a receiving board 11 and an output board 12 connected integrally, the receiving board 11 is provided with a plurality of probe contacts 111 corresponding to the ends of the probes, the output board 12 is connected with a plurality of test rings 121 corresponding to the probe contacts 111, and the test board 10 is further provided with a communication switch 122 for controlling the test rings 121 to be electrically connected with the probe contacts 111. In this embodiment, a product to be tested is placed on the probe fixing assembly, a pressing mechanism is further arranged above the product to be tested, and the product to be tested is pressed down through the pressing mechanism, so that two ends of the probe are respectively contacted with the test board 10 and the product to be tested, and information transmission is performed; the test board 10 comprises a receiving board 11 and an output board 12 which are integrally connected, the probe fixing assembly is located at the upper end of the receiving board 11, the output board 12 is connected with a plurality of test rings 121 corresponding to the probe contacts 111, and the test board 10 is further provided with a communication switch 122 for controlling the test rings 121 to be electrically connected with the probe contacts 111. The number of the probes and the number of the test rings 121 are both several, because the test rings 121 correspond to the probe contacts 111 one by one, each test ring corresponds to a different probe contact, i.e. the signal of each test ring is independent; the product and the receiving plate are connected through the probes, signals can be transmitted to the testing ring of the output plate, information received by the probes is led out to the outside for detection, when the test fails, if the test fails, testers can timely judge and find out damaged probes through the signals of the testing ring, and if the test fails, testers can quickly judge problem areas through the signals and find out damaged components; the convenience of manual operation is improved, and the detection efficiency of products is improved simultaneously.

Specifically, the probe fixing assembly comprises a probe fixing plate 40, and a needle cover plate 50 and a needle tail plate 20 which are respectively arranged on two sides of the probe fixing plate 40, wherein a plurality of limiting holes 51 matched with the probes are formed in the probe fixing plate 40, the needle cover plate 50 and the needle tail plate 20, and the probes can be limited in the through holes. In the embodiment, the number of the probes is a plurality, the number of the pinholes corresponds to the number of the probes, two ends of the probes are of a telescopic structure, a compression spring is arranged inside the probes, the two ends of the probe are controlled to stretch by the compression spring, so that the probe can be in full contact with a product to be detected, and the product to be detected or the probe is prevented from being crushed by the pressing plate 60, the product to be detected in the embodiment is a circuit board, the number of the probes and the positions of needle holes can be designed according to different circuit boards, one end of the probe is correspondingly contacted with the probe contact 111 on the receiving plate 11, the other end of the probe is contacted with a test point on the circuit board, so that the probe can transmit the information on the circuit board, and finally the information of the circuit board received by the probe contact 111 is output through the output board 12 and is externally connected with the testing equipment for detection, and judging whether the corresponding circuit elements of the probes or the circuit board corresponding to the probe contacts 111 are qualified or not by judging the information output by the test ring 121.

Specifically, a needle carrier plate fixing plate 30 is fixed between the probe fixing plate 40 and the needle tail plate 20, an opening 31 for the probe to pass through is formed in the needle carrier plate fixing plate 30, and the probe is not in contact with the needle carrier plate fixing plate 30. In the embodiment, the pin carrier plate fixing plate 30 is mainly used for fixing the probe fixing plate 40 and the pin tail plate 20, and in a specific embodiment, the pin cover plate 50, the pin carrier plate fixing plate 30, the probe fixing plate 40, and the pin tail plate 20 are all provided with corresponding positioning holes, positioning posts 32 are adapted in the positioning holes, and the positioning posts 32 can prevent the pin cover plate 50, the pin carrier plate fixing plate 30, the probe fixing plate 40, and the pin tail plate 20 from generating displacement in the horizontal direction, damaging the probe, and affecting the test result.

Specifically, a plurality of connecting holes distributed in an array are formed in the output plate 12, the plurality of probe contacts 111 are sequentially distributed, the test ring 121 is connected in the connecting holes, and a detachable connecting piece is further arranged in the test ring 121. In this embodiment, the connection holes are distributed in a square array, and the connection holes correspond to the probe contacts 111, for example, a first row of connection holes corresponds to a first row of probe contacts, a second row of connection holes corresponds to a second row of probe contacts, the connection holes are matched with test rings 121, and each test ring 121 corresponds to one probe contact 111; the connecting piece is conductively connected with the testing ring 121 so as to facilitate information transmission, and when a product is tested, whether components of each part of the product to be tested meet requirements or not is judged according to the position of the probe contact 111 corresponding to the testing ring 121. In this embodiment, as shown in fig. 4, the connecting element is inserted into the testing ring 121, the connecting element includes a connecting ring 1211 with an opening and conductive pillars 1212 connected to two ends of the opening of the connecting ring 1211, the connecting element is made of a metal material, the conductive pillars 1212 are clamped in the testing ring 121 to increase a contact area between the conductive pillars 1212 and an inner wall of the testing ring 121, and the external testing device is clamped on the connecting ring 1211.

Specifically, the connection holes are distributed in a square array on the output board 12, the test ring 121 is coaxially connected in the connection holes, the end of each row of connection holes is provided with a plurality of communication switches 122, that is, the communication switches 122 are electrically connected to the output board 12, and the communication switches 122 can be used for controlling the connection or disconnection between the probe contacts 111 and the test ring 121. When a single or a plurality of electronic components on a product to be tested need to be tested, an external test device is connected with the test ring 121 corresponding to the electronic component through a connecting piece, the corresponding communication switch 122 is opened, then the electronic component is accurately tested, and the external test device is controlled by controlling the communication switch 122. In a specific embodiment, the communication switches 122 are disposed on both sides of any row of the connection holes, and the communication switches 122 on both sides are connected in series, that is, the two communication switches 122 connected in series are used to control the connection or disconnection of the test ring 121 and an external test device. The main purpose of the communication switch 122 is to control the output of the signal of the test loop 121, and each time two communication switches 122 in the same row are turned on, that is, the signal output of the test loop 121 in the row is turned on, the signal output can be limited in this way to distinguish the signals of different areas received by different probe contacts 111. In this embodiment, the testing board 10 is provided with the LED display lamp 123 correspondingly connected to the communication switch 122, any one of the communication switches 122 corresponds to the LED display lamp 123, and the display state of the LED display lamp 123 is used to determine whether the communication switch 122 is turned on, so as to remind the operator of paying attention, thereby facilitating the testing process of the product.

Specifically, the pinpoint test of product often needs the cooperation of external integrated circuit board of collocation to go on, for the test of convenience, has integrated circuit board socket 124 simultaneously concurrently on surveying test panel 10 to external integrated circuit board carries out multi-functional test.

This mechanism for testing needle point signal derivation test reasonable in design is compact, survey test panel 10 including body coupling's dash receiver 11 and output board 12, the product information that receives through dash receiver 11 and transmit to output board 12 output detection, the information derivation that receives with probe contact 111 externally detects, when the product goes wrong, so that find out problem probe contact 111 and the product components and parts that correspond fast, the convenience of manual operation has been improved, improve the detection efficiency of product simultaneously.

In another embodiment, a pin point testing fixture is provided, which includes the testing mechanism in the above embodiment, and further includes a pressing mechanism located above the testing mechanism, the pressing mechanism is used for pressing a product to be tested to contact with one end of the probe; the pressing mechanism comprises a pressing plate 60, both sides of the pressing plate 60 are connected with a sliding plate 67 and a side plate 66 through a linkage module 61, and the sliding plate 67 is positioned on the inner side of the side plate 66; a transmission module is arranged between the sliding plate 67 and the side plate 66; the sliding plate 67 and the side plate 66 are respectively provided with a first displacement hole and a second displacement hole which are matched with the linkage module 61; one end of the linkage module 61 is connected with the pressing plate 60, and the other end of the linkage module 61 sequentially penetrates through the first displacement hole and the second displacement hole; when the transmission module drives the sliding plate 67 to horizontally slide relative to the side plate 66, the second displacement hole is used for guiding the linkage module 61 to move up and down in the first displacement hole, and driving the pressing plate 60 to move up and down, and pressing down the product to be detected through the pressing plate 60 to enable the product to be detected to accurately contact with the probe.

Specifically, referring to fig. 5, the pressing mechanism includes a pressing plate 60, both sides of the pressing plate 60 are connected to a sliding plate 67 and a side plate 66 through a linkage module 61, the sliding plate 67 is located inside the side plate 66 and can horizontally slide relative to the side plate 66, and a transmission module is arranged between the sliding plate 67 and the side plate 66; one end of the sliding plate 67 and the side plate 66, which are respectively provided with a first displacement hole and a second displacement hole matched with the linkage module 61, of the linkage module 61 is connected with the pressing plate 60, and the other end of the linkage module 61 sequentially penetrates through the first displacement hole and the second displacement hole and is sequentially matched with the first displacement hole and the second displacement hole; when the transmission module drives the sliding plate 67 to horizontally slide relative to the side plate 66, the first displacement hole is used for guiding the linkage module 61 to move up and down in the second displacement hole and driving the pressing plate 60 to move up and down. In the embodiment, an external shaft 63 is disposed between the two side plates 66, and the transmission module includes a gear 64 fixed at both ends of the external shaft 63 and located inside the side plates 66, and a rack 65 connected to the inside of the sliding plate 67 and adapted to the gear 64; the external shaft 63 can drive the sliding plate 67 to horizontally slide through the gear 64 and the rack 65.

To ensure that the slide plate 67 is only displaced in the horizontal direction and not in the vertical direction, in this embodiment the slide plate 67 is connected to the inner side of the side plate 66 by means of a locking pin 68, and the side plate 66 is provided with a horizontally arranged locking slot 69, and the locking pin 68 is adapted to the locking slot 69 and is horizontally movable along the locking slot 69. The clamping groove 69 is in a long strip shape, the sliding plate 67 is located in the clamping groove 69 through a limiting pin and slides relative to the side plate 66, and the number of the clamping pins 68 and the clamping grooves 69 is two or more. Therefore, when the sliding plate 67 moves relative to the side plate 66, the sliding plate is only displaced in the horizontal direction, so that the pressing plate 60 is vertically arranged at the working position and is positioned at the same position when pressed down at each time, and the testing efficiency of the testing jig is improved.

When using, the one end of external spiale 63 is connected with brake valve lever 62, through rotating brake valve lever 62, makes clamp plate 60 push down, and is concrete, operation brake valve lever 62 control external spiale 63 rotates, drives rack 65 rectilinear movement through gear 64, because curb plate 66 is fixed motionless, rack 65 drives sliding plate 67 to be located the horizontal direction of curb plate 66 inner wall and slides, and horizontal smooth motion is in the draw-in groove 69 of level setting through bayonet 68, guarantees that sliding plate 67 slides at relative curb plate 66 in the horizontal direction. Specifically, a first displacement hole is vertically arranged on the side plate 66, a second displacement hole is obliquely arranged on the sliding plate 67, and the upper end and the lower end of the first displacement hole are equal in height to the upper end and the lower end of the second displacement hole. Linkage module 61 includes the connecting block and connects in the first bearing of connecting block one end, the second bearing, first bearing, the second bearing passes through bolted connection in the one end of connecting block, the one end of connecting block is passed through first bearing and is connected with the cooperation of first displacement hole, be connected with the cooperation of second displacement hole through the second bearing, the other end of connecting block is fixed in on clamp plate 60, as first bearing, the second bearing is located the upper end position in first displacement hole and second displacement hole respectively, clamp plate 60 is in the reset state this moment, when transmission module drive sliding plate 67 slided forward, because curb plate 66 is fixed motionless, first displacement hole drive first bearing guide second bearing is located the downthehole reciprocating of second displacement, thereby drive clamp plate 60 straight up-down motion and push down the product that awaits measuring, make the product that awaits measuring accurately contact with the probe, the rate of accuracy of test has been improved.

The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and all the changes or substitutions should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.

Claims (10)

1. A pin point signal derivation testing mechanism is characterized by comprising a testing board and a probe fixing component arranged above the testing board, wherein a probe is fixed on the probe fixing component, one end of the probe is in contact with a product to be tested positioned on the probe fixing component, and the other end of the probe is in contact with the testing board; the test board comprises a receiving board and an output board which are connected integrally, a plurality of probe contacts corresponding to the ends of the probes are arranged on the receiving board, a plurality of test rings corresponding to the probe contacts are connected to the output board, and a communication switch used for controlling the test rings to be electrically connected with the probe contacts is further arranged on the test board.

2. The pin point signal deriving testing mechanism according to claim 1, wherein the probe fixing assembly includes a probe fixing plate, and a pin cover plate and a pin tail plate respectively disposed at two sides of the probe fixing plate, the pin cover plate, and the pin tail plate are respectively provided with a plurality of limiting holes adapted to the probes, and the probes can be limited in the through holes.

3. The pin point signal deriving and testing mechanism according to claim 2, wherein a pin carrier plate fixing plate is fixed between the probe fixing plate and the pin tail plate, the pin carrier plate fixing plate is provided with an opening for a probe to pass through, and the probe is not in contact with the pin carrier plate fixing plate.

4. The pin point signal deriving testing mechanism according to claim 3, wherein the pin cover plate, the pin carrier plate fixing plate, the probe fixing plate and the pin tail plate are respectively provided with a corresponding positioning hole, and a positioning post is adapted in the positioning hole.

5. The pin signal derivation test mechanism as claimed in claim 1, wherein the output board has a plurality of connection holes arranged in an array, the test ring is connected in the connection holes, and the test ring further has a detachable connection member.

6. The pin signal derivation test mechanism as claimed in claim 5, wherein the connector comprises a connection ring with an opening and a conductive pillar connected to two ends of the connection ring opening, the conductive pillar being engaged in the test ring.

7. The pin signal derivation test mechanism of claim 5, wherein a communication switch is disposed on one side of any row of the connection holes, and the communication switch is operable to control connection or disconnection between the probe contacts and the test ring.

8. The pin signal derivation test mechanism of claim 7, wherein communication switches are disposed on both sides of any row of the connection holes, and the communication switches on both sides are connected in series.

9. The pin point signal deriving testing mechanism according to claim 8, wherein the testing board is provided with an LED display lamp correspondingly connected to the communication switch.

10. A pinpoint test fixture, comprising the test mechanism according to any one of claims 1-9, further comprising a pressing mechanism located above the test mechanism, the pressing mechanism being used for pressing a product to be tested to contact with one end of the probe; the pressing mechanism comprises a pressing plate, two sides of the pressing plate are both connected with a sliding plate and a side plate through a linkage module, and the sliding plate is positioned on the inner side of the side plate; a transmission module is arranged between the sliding plate and the side plate; the sliding plate and the side plate are respectively provided with a first displacement hole and a second displacement hole which are matched with the linkage module; one end of the linkage module is connected with the pressing plate, and the other end of the linkage module sequentially penetrates through the first displacement hole and the second displacement hole; when the transmission module drives the sliding plate to horizontally slide relative to the side plate, the second displacement hole is used for guiding the linkage module to be positioned in the first displacement hole to move up and down and driving the pressing plate to move up and down.

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