A fixture for lens assembly

Abstract

The present invention relates to the field of lens assembly technology, specifically a lens assembly fixture comprising a coaxially arranged active ring seat, a passive ring seat, and a central receiving seat; the active ring seat is located above the passive ring seat and is provided with at least three radially retractable receiving joints and positioning heads in the circumferential direction; the passive ring seat is evenly distributed around the circumference of the lens seat and has at least three hinged clamping jaws. The present invention has a highly integrated overall mechanical structure, facilitating efficient and accurate assembly of the lens body and frame, and has low reliance on automatic positioning systems. This not only facilitates efficient and stable batch assembly, but also offers low production costs. It effectively prevents frictional damage caused by lens body deflection and offers the advantage of convenient material handling.

Description

Technical Field

[0001] The present invention relates to the technical field of lens assembly, in particular to a clamp for lens assembly. Background Art

[0002] During the lens assembly process, the lens needs to be installed into the frame, such as Figure 1 As shown in the figure, due to the small gap between the lens and the frame, in order to avoid the lens from being misaligned during assembly, which may result in it not being able to be smoothly installed in the frame or causing friction damage, the lens and frame need to be assembled in a coaxial state.

[0003] Currently, there are two main methods for assembling lenses and frames. One involves manually controlling an assembly tool with an adsorption head to absorb the lens and install it into the frame. During the assembly process, the position of the frame and lens is manually adjusted to ensure complete assembly. While this assembly process offers greater flexibility, it is inefficient, and manual operation cannot effectively prevent friction damage to the lens caused by deflection. The other method is mechanical automated assembly, where automated equipment such as a manipulator absorbs and removes the lens, combined with an automated positioning system to quickly install the lens into the frame. However, the entire assembly system is relatively complex and has high production costs. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a lens assembly fixture for installing a lens body in a lens frame, a lens assembly fixture for installing a lens body in a lens frame, comprising a coaxially arranged active ring seat, a passive ring seat and a central receiving seat; the active ring seat is located above the passive ring seat and is provided with at least three radially telescopic receiving joints and positioning heads in the circumferential direction; the passive ring seat is evenly arranged with at least three hinged clamping claws in the circumferential direction, and an elastic member is connected between the clamping claws and the passive ring seat; the central receiving seat is located in the passive ring seat; a synchronous seat is axially slidably connected to the passive ring seat, and the synchronous seat is hinged to each clamping claw through a plurality of connecting rods; the active ring seat is provided at the lower side There are synchronous parts and limit heads. The limit head limits the synchronous seat from the bottom so that the clamping claws are in an open state. When the active ring seat is in the initial position, the socket head extends to form the mirror body bearing area, the positioning head separates from the mirror body, and the clamping claws remain in an open state so that the mirror frame placement area on the passive ring seat is exposed. When the active ring seat moves downward, the synchronous seat releases the limit so that the clamping claws automatically clamp the mirror frame in the center and expose the center receiving seat as the passive ring seat moves downward. Then the positioning head extends to limit the mirror body so that the mirror body is placed in the center on the center receiving seat. When the active ring seat moves up and resets, the mirror frame moves up accordingly and automatically completes the assembly work with the mirror body. Then the clamping claws open and release the mirror frame under the limit of the limit head.

[0005] In a possible implementation, it also includes a downward stabilizing head. After the mirror body falls to the central receiving seat, the downward stabilizing head limits the mirror body from above, and automatically releases the limit after the mirror body and the frame are assembled.

[0006] In one possible implementation, the downward-pressing stabilizing head includes a sliding frame with a contact end and a limit locking member set at a fixed point. The sliding frame is elastically slidably connected to the active ring seat. The sliding frame moves synchronously when the active ring seat moves downward. When the contact end contacts the mirror body, the position of the sliding frame is locked by the limit locking member.

[0007] In one possible implementation, it also includes upper and lower limit members; the socket head includes: a plurality of telescopic members evenly distributed circumferentially; a gear set arranged in the active ring seat, the gear set corresponding to the telescopic members one by one; two racks meshing with the corresponding gear set, one of the racks being fixed on the telescopic member, and the other rack sliding vertically through the active ring seat; the limit member is used to limit the moving stroke of the vertically sliding rack.

[0008] In one possible implementation, the positioning head includes: a mounting seat elastically slidably connected to the active ring seat in the vertical direction; a positioning rod slidably mounted on the mounting seat, one end of the positioning rod being a wedge-shaped head; a limiting ring fixed on the active ring seat and cooperating with the wedge-shaped head of the positioning rod to control the extension of the positioning rod; and an interval limiting portion that limits the moving range of the mounting seat.

[0009] In one possible implementation, the center receiving seat includes a center shaft with a receiving area on the top; a sliding connecting frame is connected between the active ring seat and the center shaft, the sliding connecting frame is fixedly connected to the active ring seat and slidingly connected to the center shaft; the passive ring seat is slidably matched with the center shaft through an elastic reset member.

[0010] In a possible implementation, the passive ring seat is provided with a positioning groove that cooperates with the lower end of the synchronizer.

[0011] The above one or more technical solutions in the embodiments of the present invention have at least one of the following technical effects: the present invention provides a lens assembly fixture, in the process of the active ring seat moving down, the positioning head first automatically completes the positioning of the lens body, and then accurately centers the lens body on the center receiving seat, at the same time, the clamping claw automatically clamps the positioning frame in the center before the lens body is placed on the center receiving seat and moves down to expose the center receiving seat, and after the lens body is placed, it automatically moves up and automatically completes the assembly work with the lens body, after the assembly is completed, the clamping claw can automatically release the clamping and fixing state of the lens frame, which is convenient for removing the assembly body and placing a new frame to continue the assembly work. In summary, the overall mechanical structure of the present invention is highly integrated, which is convenient for efficiently and accurately completing the assembly work of the lens body and the frame, and has a low dependence on the automatic positioning system, which is not only convenient for efficient and stable batch assembly work, but also has a low production cost, and can effectively avoid friction damage caused by the deflection of the lens body, and has the advantage of high convenience in taking and placing materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1It is a schematic diagram of the structure after the convex lens and the frame are assembled.

[0013] Figure 2 This is a schematic diagram of the overall structure of a lens assembly fixture provided by an embodiment of the present invention.

[0014] Figure 3 It is a partial structural schematic diagram of a lens assembly fixture provided by an embodiment of the present invention.

[0015] Figure 4 The figure is a partial cross-sectional structural diagram of a lens assembly fixture provided by an embodiment of the present invention.

[0016] Figure 5 yes Figure 3 Enlarged view of point A in the middle.

[0017] Figure 6 The present invention is a schematic structural diagram of a passive ring seat and a synchronous seat of a lens assembly fixture provided by an embodiment of the present invention.

[0018] Figure 7 The present invention is a schematic structural diagram of an unlocking head, an unlocking member, and a limiting locking member of a lens assembly fixture provided by an embodiment of the present invention.

[0019] Figure 8 The present invention is a schematic structural diagram of a telescopic member, a gear set and a rack of a lens assembly fixture provided by an embodiment of the present invention.

[0020] Figure 9 The diagram is a schematic diagram of the exploded structure of a mounting seat and an active ring seat of a lens assembly fixture provided by an embodiment of the present invention.

[0021] In the figure: 1. mirror body; 2. mirror frame; 3. active ring seat; 4. passive ring seat; 5. central receiving seat; 51. receiving area; 52. central axis; 6. socket head; 61. telescopic member; 62. gear set; 63. rack; 7. positioning head; 71. mounting seat; 72. positioning rod; 73. limiting ring; 8. clamping claw; 9. elastic member; 10. synchronous seat; 11. connecting rod; 12. synchronous member; 13. limiting head; 14. downward stabilizing head; 141. contact end; 142. sliding frame; 143. limiting locking member; 144. unlocking head; 145. unlocking member; 146. limiting block; 15. limiting member; 16. interval limiting part; 17. sliding connecting frame; 18. positioning groove; 19. fixed seat. DETAILED DESCRIPTION

[0022] To make the above-mentioned objects, features, and advantages of the present invention more readily apparent, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings. The following description sets forth numerous specific details to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways than those described below, and those skilled in the art may make similar modifications without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0023] See also Figure 1 、 Figure 2 、 Figure 3 and Figure 4A lens assembly fixture is used to install a lens body 1 in a lens frame 2. The lens assembly fixture includes a fixed seat 19, a limit head 13, an active ring seat 3, a passive ring seat 4, and a center receiving seat 5. The active ring seat 3, the passive ring seat 4, and the center receiving seat 5 are coaxially arranged, and the active ring seat 3 is located above the passive ring seat 4 and is vertically slidably installed on the fixed seat 19. The active ring seat 3 is provided with a radially retractable socket 6 and a positioning head 7. The positioning head 7 and the socket 6 are evenly distributed along the circumference of the active ring seat 3, and the positioning head 7 is located above the socket 6. The passive ring seat 4 is evenly arranged with at least three clamping claws 8 in an elastic hinged state. An elastic member 9 is connected between each clamping claw 8 and the passive ring seat 4. The center receiving seat 5 is located in the passive ring seat 4 and is distributed with a gap between the passive ring seat 4. The center receiving seat 5 is fixedly installed on the fixed seat 19 and can pass through the middle of the lens frame 2. In the initial state, the receiving head 6 extends (i.e., stretches) to form a discontinuous receiving area, the mirror body 1 is placed on the receiving area, and the clamping claw 8 is in an open state under the limit of the limit head 13, so that the central area of ​​the passive ring seat 4 is exposed to form a placement area, and the mirror frame 2 is placed on the placement area. The receiving area and the placement area are both in an exposed state, which is convenient for the placement and removal of the mirror body 1 and the frame 2. During the assembly process, the active ring seat 3 moves downward so that the mirror body 1 falls on the central receiving seat 5. During this process, the positioning head 7 synchronously extends inward (i.e., extends toward the inside of the active ring seat 3) to limit the side of the mirror body 1, so that the mirror body 1 is in a centered state until the mirror body 1 is accurately placed on the central receiving seat 5. In addition, during the downward movement of the active ring seat 3, the limit head 13 first automatically releases the limit on the clamping claw 8, so that the clamping claw 8 is under the action of the elastic member 9. The mirror frame 2 is clamped and centered by rotating it inward from bottom to bottom to align the centered mirror body 1. Then the passive ring seat 4 drives the mirror frame 2 to move down with the active ring seat 3, providing working space for the active ring seat 3 until the mirror body 1 falls stably and accurately on the center receiving seat 5. Then the receiving head 6 contracts to release the receiving state, the active ring seat 3 is reset, and the receiving head 6 is extended again to form a receiving area. The passive ring seat 4 is moved up and reset with the active ring seat 3. During this process, the mirror frame 2 automatically completes the assembly with the mirror body 1 as the passive ring seat 4 moves upward. After assembly, the clamping claw 8 is again limited by the limit head 13 and is in an open state, which is convenient for taking out the mirror body 1 and the frame 2 after assembly. Then the frame 2 to be assembled and the mirror body 1 are placed again, and the above process is repeated to continuously assemble the mirror body 1 and the frame 2. During the entire working process, it is only necessary to actively control the lifting and lowering movement of the active ring seat 3 to smoothly complete the assembly of the mirror body 1 and the frame 2. The high degree of integration facilitates the efficient and stable completion of the assembly work. During the assembly process, the mirror body 1 and the frame 2 remain in a state of precise alignment, which effectively improves the stability and smoothness of the assembly process. In addition, the receiving area and the placement area are in a fully exposed state before and after assembly, which facilitates the stable and rapid loading and unloading of materials.

[0024] See Figure 2 、 Figure 3 and Figure 4 The passive ring seat 4 and the sliding connection frame 17 are both slidably connected to the central receiving seat 5. The central receiving seat 5 includes a central shaft 52 with a receiving area 51 on the top. The sliding connection frame 17 is slidably connected to the central shaft 52. The passive ring seat 4 is coaxially slidably connected to the central shaft 52, which is conducive to improving the integration of the overall structure. An elastic reset member is connected between the passive ring seat 4 and the central shaft 52. When the active ring seat 3 moves upward, the elastic reset member automatically controls the passive ring seat 4 to move upward and reset. Figure 3 As shown, the sliding connection frame 17 is a U-shaped structure, and the middle portion of its horizontal section is vertically slidably connected to the central shaft 52.

[0025] See Figure 3 、 Figure 4 and Figure 6 The passive ring seat 4 is axially slidably connected to a synchronous seat 10, which is hinged to each clamping claw 8 through a number of connecting rods 11. Under the restriction of the synchronous seat 10, each clamping claw 8 performs clamping or opening movement synchronously, so that the frame 2 in the clamping state is stably in the center position.

[0026] See Figure 3 、 Figure 4 and Figure 6 The synchronous seat 10 is connected to a limit rod, and the limit head 13 is a ring-shaped limit structure and the limit head 13 is fixedly mounted on the sliding connecting frame 17. In the initial state, the limit head 13 contacts and limits the limit rod from the bottom side, and then limits the synchronous seat 10. The synchronous seat 10 uses the connecting rod 11 to make each clamping claw 8 synchronously in the open state. When the active ring seat 3 drives the sliding connecting frame 17 to move downward, the limit head 13 moves downward accordingly, the limit rod loses its limit, and then the synchronous seat 10 loses its limit. The clamping claw 8 rotates inward under the action of the elastic member 9 to clamp and fix the frame 2. At the same time, the clamping claw 8 cooperates with the synchronous seat 10 to move vertically downward through the connecting rod 11.

[0027] See Figure 2 、 Figure 3 and Figure 7 The lower side of the active ring seat 3 is connected to a synchronizer 12. When the synchronizer seat 10 loses its restriction and the clamping claws 8 clamp the mirror frame 2 and center it, the synchronizer 12 that moves downward with the active ring seat 3 rests on the passive ring seat 4, causing the passive ring seat 4 to move downward with the active ring seat 3.

[0028] See Figure 2 、 Figure 3 、 Figure 4 and Figure 7The present invention further includes a downward stabilizing head 14, which restrains the mirror body 1 from above after the mirror body 1 lands on the central receiving seat 5 and releases the restraint after the mirror body 1 and the mirror frame 2 are assembled. The downward stabilizing head 14 includes a sliding frame 142 with a contact end 141 and a fixed-point limiting locking member 143. The sliding frames 142 are symmetrically distributed and elastically slidably connected to the sliding connecting frame 17. The limiting locking member 143 is correspondingly mounted on the fixed seat 19. When the active ring seat 3 drives the sliding connecting frame 17 to move downward, so that the clamping claw 8 rotates inward under the action of the elastic member 9 to clamp and fix the mirror frame 2, the active ring seat 3 continues to move downward. When the active ring seat 3 moves down until the mirror body 1 falls on the receiving area 51, the active ring seat 3 continues to move downward, and the receiving head 6 separates from the mirror body 1. At this time, the mirror body 1 falls on the receiving area 51, and the position of the mirror body 1 remains unchanged. The contact end 141 moves downward with the active ring seat 3, that is, the contact end 141 moves downward relative to the mirror body 1, and the contact end 141 gradually approaches the mirror body 1 and rests on the mirror body 1 from above. A rubber layer is provided on the contact end 141 to avoid damaging the mirror body 1. At this time, the limit locking member 143 automatically locks the sliding frame 142 in the current position; the limit locking member 143 is elastic When the clamping head is slidably connected to the fixed seat 19, the sliding frame 142 is provided with a clamping groove corresponding to the clamping head. When the clamping mouth is aligned with the clamping head, the clamping head will automatically insert into the clamping groove under the action of the corresponding elastic force, locking the sliding frame 142 in the current position; when the active ring seat 3 moves up, the sliding frame 142 does not move up therewith, so that the mirror body 1 is stably in the docking assembly state. At the same time, the elastic reset member automatically controls the passive ring seat 4 to move up and reset, and the mirror frame 2 is automatically assembled with the mirror body 1 in the stable docking state as the passive ring seat 4 moves up. After the assembly is completed, the limit locking member 143 releases the locked state, and the sliding frame 142 is reset under the action of the corresponding elastic force; wherein, the unlocking process of the limit locking member 143 is automatically completed during the upward movement of the sliding frame 142, such as Figure 7 As shown, an unlocking head 144 with a wedge-shaped area and an unlocking member 145 cooperating with the wedge-shaped area are elastically slidably connected in the card slot. The unlocking member 145 extends downward to the outside of the sliding frame 142. A limiting block 146 is fixedly provided on the sliding connecting frame 17. After the mirror body 1 and the frame 2 are assembled, the limiting block 146 moves upward as the sliding connecting frame 17 moves upward, pushing the unlocking member 145 to move upward synchronously. The unlocking member 145 cooperates with the wedge-shaped area to move the unlocking head 144 toward the limiting locking member 143 and push the limiting locking member 143 out of the card slot to complete the unlocking work.

[0029] See Figure 2 、 Figure 3 、 Figure 4 and Figure 8, the socket head 6 includes a telescopic member 61, a gear set 62 and a rack 63. The telescopic member 61 is evenly distributed along the circumference of the active ring seat 3 and is radially slidably installed on the active ring seat 3. The gear set 62 corresponds to the telescopic member 61 one by one and is rotatably installed on the active ring seat 3. Each gear set 62 meshes with two racks 63. The gear set 62 includes two coaxial gears with different diameters, one of which is fixedly connected to the telescopic member 61 and the rack 63 is meshed with the gear with a larger diameter. The other rack 63 slides vertically through the active ring seat 3 and the rack 63 is meshed with the gear with a smaller diameter. Limiting members 15 are provided above and below the active ring seat 3. The limiting members 15 are fixed on the fixed seat 19. In the initial state, the telescopic member 61 is fixedly connected to the active ring seat 3 and is radially slidably installed on the active ring seat 3. When the active ring seat 3 moves downward, causing the mirror body 1 to land on the receiving area 51 and then continue to move downward, the vertical rack 63 moves upward relative to the active ring seat 3 under the limit of the lower limit member 15, causing the gear group 62 to rotate and the telescopic member 61 to move outward (i.e., toward the outside of the active ring seat 3) through the rack 63 fixedly connected to the telescopic member 61, and no longer in the receiving state. Then, when the active ring seat 3 moves upward and is about to return to its original position, the vertical rack 63 moves downward relative to the active ring seat 3 under the limit of the upper limit member 15, causing the gear group 62 to rotate in the opposite direction. Then, the telescopic member 61 extends inward through the rack 63 fixedly connected to the telescopic member 61, and once again enters the receiving state. The upper limit member 15 is an annular structure that simultaneously limits the position of multiple vertical racks 63, and the lower limit member 15 is an L-shaped limit frame, which corresponds one-to-one with the vertical racks 63.

[0030] See Figure 2 、 Figure 3 、 Figure 4 、 Figure 5 and Figure 9The cam 73 is a kind of fixed frame 7 that is fixed on the workbench 71, and the cam 73 is a kind of fixed frame 7 that is fixed on the workbench 71. The cam 73 is a kind of fixed frame 7 that is fixed on the workbench 71. The cam 73 is a kind of fixed frame 7 that is fixed on the workbench 71. The cam 73 is a kind of fixed frame 7 that is fixed on the workbench 71. Part 16 is a limit groove and is symmetrically opened on the fixing seat 19. The mounting seat 71 moves vertically along the limit groove. When the active ring seat 3 moves down to the point where the mirror body 1 is about to fall on the center receiving seat 5, the mounting seat 71 stops moving down under the limit of the limit groove. At this time, the limit ring 73 continues to move down with the active ring seat 3 and cooperates with the wedge-shaped head to make the positioning rod 72 extend synchronously to limit the mirror body 1, so that the mirror body 1 remains centered and falls on the center receiving seat 5. Then the active ring seat 3 continues to move down, and the telescopic member 61 gradually moves outward until it is no longer in the receiving state. At this time, the limit locking member 143 automatically locks the sliding frame 142 in the current position.

[0031] See Figure 3 and Figure 4 The passive ring seat 4 is provided with a positioning groove 18 that cooperates with the lower end of the synchronizer 12. The synchronizer 12 is inserted into the corresponding positioning groove 18 as the active ring seat 3 moves downward, stably linking the active ring seat 3 and the passive ring seat 4 together, further improving the stability of the assembly process.

[0032] In the embodiments of the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Furthermore, a first feature being "above," "above," or "above" a second feature may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. A first feature being "below," "below," or "below" a second feature may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0033] In the description of the present invention, it should also be noted that, unless otherwise expressly specified or limited, the terms "disposed," "connected," "installed," and "connected" should be understood in a broad sense. For example, they may refer to fixed or detachable connections, integral or sliding connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; or internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0034] The embodiments of this specific implementation method are all preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, any equivalent changes made based on the structure, shape, and principle of the present invention should be included in the scope of protection of the present invention.

Claims

1. A lens assembly fixture for mounting a lens body on a lens frame, characterized in that: It includes an active ring seat, a passive ring seat and a center receiving seat which are coaxially arranged; The active ring seat is located above the passive ring seat and is provided with at least three radially telescopic sockets and positioning heads in the circumferential direction; At least three hinged clamping jaws are evenly arranged around the passive ring seat, and an elastic member is connected between the clamping jaws and the passive ring seat; The central receiving seat is located in the passive ring seat; the passive ring seat is axially slidably connected to a synchronous seat, which is hinged to each clamping claw through a number of connecting rods; A synchronizer and a limit head are provided on the lower side of the active ring seat. The limit head limits the synchronizer seat from below to keep the clamping jaws in an open state. When the active ring seat is in the initial position, the socket head extends to form the mirror body bearing area, the positioning head is separated from the mirror body, and the clamping claws remain open to expose the mirror frame placement area on the passive ring seat; When the active ring seat moves down, the synchronous seat releases the limit so that the clamping claws automatically center the frame and expose the center receiving seat as the passive ring seat moves down. Then the positioning head extends to limit the mirror body so that the mirror body is centered on the center receiving seat. When the active ring seat moves up and resets, the mirror frame moves up accordingly and automatically completes the assembly work with the mirror body, and then the clamping claw opens under the limit of the limit head to release the mirror frame.

2. A lens assembly fixture according to claim 1, characterized in that: It also includes a downward stabilizing head. After the mirror body falls to the central receiving seat, the downward stabilizing head limits the mirror body from above, and automatically releases the limit after the mirror body and the frame are assembled.

3. The lens assembly fixture according to claim 2, wherein: The downward-pressing stabilizing head includes a sliding frame with a contact end and a limit locking member set at a fixed point. The sliding frame is elastically and slidably connected to the active ring seat. The sliding frame moves synchronously when the active ring seat moves downward. When the contact end contacts the mirror body, the limit locking member locks the position of the sliding frame.

4. The lens assembly fixture according to claim 1, wherein: It also includes upper and lower distributed limiters; The socket comprises: Multiple telescopic parts evenly distributed around the circumference; A gear set is arranged in the active ring seat, and the gear set corresponds to the telescopic member one by one; Two racks meshing with corresponding gear sets, one of which is fixed on the telescopic member, and the other vertically slides through the active ring seat; the limiter is used to limit the movement of the vertically sliding rack.

5. The lens assembly fixture according to claim 1, wherein: The positioning head comprises: A mounting seat elastically slidably connected to the active ring seat in the vertical direction; A positioning rod is slidably mounted on the mounting seat, and one end of the positioning rod is a wedge-shaped head; A limiting ring fixed on the active ring seat and cooperating with the wedge-shaped head of the positioning rod to control the extension of the positioning rod; The range limiter restricts the movement of the mounting base.

6. The lens assembly fixture according to claim 1, wherein: The central receiving seat includes a central shaft with a receiving area on the top; A sliding connection frame is connected between the active ring seat and the central shaft. The sliding connection frame is fixedly connected to the active ring seat and slidably connected to the central shaft. The passive ring seat is slidably matched with the central shaft through an elastic reset piece.

7. The lens assembly fixture according to claim 1, wherein: The passive ring seat is provided with a positioning groove which matches the lower end of the synchronizer.

Images