JP2000152559A - Shock absorbing mechanism of motor power transfer device and cassette loading device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shock absorbing mechanism of a motor power transfer device wherein the number of components is small, an expensive motor is unnecessary, the cost is low, layout in a small space is possible as compact constitution, strict setting and management of a spring load are unnecessary. SOLUTION: A shaft guide 18 is fixed to a rotating shaft 6a of a motor 6. A shaft 19 to which a worm gear 9 is fixed is arranged on the axial extension line of the rotating shaft 6a. The shaft 19 is so constituted that rotation and movement in the axial direction are possible. A compression coil spring 26 energizing the shaft 19 to one side of the axial direction is installed. A shaft guide 18 is linked with the shaft 19 via a linkage means 21 constituted of engaging trenches 18b and engaging protrusions 19a. When the shaft guide 18 engages with the shaft 19 at the one side position energized by the coil spring 26, both of them rotate collectively, and the shaft 19 is displaced toward the other side of the axial direction in opposition to the energizing force of the coil spring 26, their engagement is broken and the shaft 19 rotates with no load.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor power transmission device for transmitting a driving force of a motor, and a shock absorbing mechanism of the motor power transmission device for absorbing a shock transmitted from a power output side via a power transmission system. The present invention also relates to a cassette loading device for loading a cassette by a driving force of a motor, and to a shock absorbing mechanism of the cassette loading device for absorbing a shock transmitted from a cassette holder via a power transmission system.

[0002]

2. Description of the Related Art A motor power transmission device having a motor and a power transmission system for transmitting the driving force is used for various devices, for example, a cassette loading device of a VTR (video tape recorder). . This cassette loading device has a cassette holder for holding a cassette, and loads the cassette holder between a cassette insertion position and a cassette mounting position. That is, when a user inserts a cassette into the cassette holder located at the cassette insertion position and the cassette is inserted to a predetermined position, the cassette loading device is driven to move the cassette holder to the cassette mounting position.
When a cassette eject command is issued at the cassette mounting position, the cassette loading device is driven to move the cassette holder to the cassette insertion position, and the user can pull out the cassette.

Since the cassette loading device that performs such an operation includes a portion that is directly operated by the user, the device is operated under severe use conditions, for example, when the cassette is inserted into the cassette holder with an excessive insertion force. There is also.
Since the insertion of a cassette with a high impact deforms or destroys the driving parts and peripheral parts of the cassette loading device, the following means have conventionally been used as the shock absorbing means.

[0004] The first means is to strengthen the parts themselves such as increasing the gear tooth thickness.

[0005] As a second means, a motor (coreless motor) having a small initial torque (the inherent rotation torque of the motor itself in a no-load state) is used, and the impact force is absorbed by the motor.

As a third means, a shock is absorbed by a friction clutch gear structure. FIG. 7 is an exploded perspective view of the friction clutch gear structure. In FIG. 7, a small gear 50 is press-fitted into one end of a metal shaft 51. The metal shaft 51 includes an integral body of a metal spacer 52 and a pad 53 and an integral body of a large gear 54, a pad 55, and a metal spacer 56. They are inserted in order. The large gear 54 is rotatably supported by the metal shaft 51 and is disposed in a state interposed between the pair of pads 53 and 55. A weight spring 57 and a metal spacer 58 are further inserted into the metal shaft 51 in this order, and an E-ring 59 for preventing a component from coming off is engaged with the other end of the metal shaft 51.

That is, the large gear 54 is provided with a conical spring 57.
Is normally held together with the metal shaft 51 by being held between the pair of pads 53 and 55 by the spring force of
The rotation of the metal shaft 51 is transmitted to the output gear,
When a certain or more rotational load is applied from the output side, the pad rotates independently against the frictional force of the pair of pads 53 and 57, thereby absorbing a shock.

As a fourth means, a spring having a long coil length is used as a joint part, and a shock is absorbed by expansion and contraction of the spring.

[0009]

However, according to the first means, the impact force is merely transferred to a portion other than the reinforced portion, resulting in a so-called "wet play", which is not very effective.

[0010] The second means has a problem that the cost of the motor is about 20 times as expensive as that of a general-purpose product, which causes a significant increase in cost.

According to the third means, the friction clutch gear structure has a large number of components as shown in FIG. 7, making assembly difficult and costly. Also, a conical spring 5
Since the performance is determined by the pressing force of No. 7 and the frictional force between the pair of pads 53 and 55, the setting and management of the spring load are troublesome.

The fourth means requires a coil length equal to or longer than the insertion stroke of the cassette, and in order to obtain a sufficient cushioning effect, the coil length is set so that the load change of the spring does not fluctuate much due to expansion and contraction. Since the length must be long, a large space is required for the layout of the cassette loading device. In addition, the reaction force from the spring that pushes the cassette back against the insertion stroke of the cassette increases in proportion, so that the feel when inserting the cassette is not so good.

[0013] The problems other than the feeling of cassette insertion are the same for motor power transmission devices other than the cassette loading device.

Therefore, the present invention has been made to solve the above-mentioned problems, and has a small number of parts, does not require the use of an expensive motor, is inexpensive, and has a compact structure with a small space. It is an object of the present invention to provide a shock absorbing mechanism for a motor power transmission device, which enables a layout of the motor power transmission device and does not require strict setting and management of a spring load. Another object of the present invention is to provide an impact absorbing mechanism of a cassette loading device which does not hinder the feel of cassette insertion, in addition to the above objects.

[0015]

According to a first aspect of the present invention, a shaft guide is fixed to a rotating shaft rotated by driving a motor, and a worm gear is fixed on an extension of the rotating shaft to which the shaft guide is fixed. A shaft is disposed, the shaft is rotatable, and is configured to be movable between a first position and a second position in the axial direction, the shaft is held at the first position in the axial direction, and Shaft position holding means for allowing movement to the second position side when a certain pressing force acts is provided, and the shaft guide and the shaft are connected via a connecting means. The shaft guide and the shaft engage with each other at a position on the first position side held by the shaft position holding means, so that the shaft guide and the shaft rotate integrally, and When the shaft is displaced toward the second position in the axial direction against the holding force of the holding means, the engagement between the shaft guide and the shaft is released, and the shaft guide and the shaft are rotatable separately and independently. This is a shock absorbing mechanism for a motor power transmission device characterized in that the shock absorbing mechanism is constituted as follows.

According to a second aspect of the present invention, a shaft guide is fixed to a rotating shaft rotated by driving a motor, and a shaft to which a worm gear is fixed is disposed on an extension of the rotating shaft to which the shaft guide is fixed. The shaft is rotatable, and is configured to be movable between a first position and a second position in the axial direction. The shaft is held at the first position in the axial direction, and a pressing force equal to or more than a certain value is maintained. A shaft position holding means for allowing movement to the second position side when actuated is provided, and the shaft guide and the shaft are connected via a connecting means. The shaft guide and the shaft engage with each other at the position on the first position side held by the force, so that the shaft guide and the shaft rotate integrally, and When the shaft is displaced to the second position side in the axial direction against the holding force of the shaft, the engagement between the shaft guide and the shaft is released, and the shaft guide and the shaft are rotatable independently and separately. A shock absorbing mechanism for a cassette loading device, characterized in that:

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

1 to 6 show one embodiment of the present invention.
This embodiment shows a case where the motor power transmission device is a cassette loading device of a VTR (video tape recorder). 4 is a side view of the cassette loading device in a normal state, FIG. 5 is a side view of the cassette loading device when a high impact is applied, and FIG. 6 is an exploded perspective view of a main part near a motor.

In FIGS. 4 and 5, a pair of side plates 2 and 2 are spaced apart from each other on the chassis 1 (only one is shown in the drawings, and the other is not shown; the same applies hereinafter).
The holder guide grooves 3 are provided at two locations on each inner side surface of the pair of side plates 2. Each of the holder guide grooves 3 is composed of a horizontal portion and a vertical portion which is continuous at the rear end thereof. Each guide pin 5 of the cassette holder 4 is inserted into each holder guide groove 3.

The cassette holder 4 has a frame shape capable of holding the cassette K, and is arranged in a space between the pair of side plates 2. The cassette holder 4 is configured to be guided by the holder guide groove 3 and move between a cassette insertion position (the position in FIGS. 4 and 5) and a cassette mounting position. At the cassette insertion position, the cassette K is close to a cassette insertion slot (not shown), and the user can insert the cassette K into the cassette holder 4 from the cassette insertion slot and pull out the cassette K inserted into the cassette holder 4 from the cassette insertion slot. Is available.

As shown in FIG. 6, the motor 6 is fixed to one of the side plates 2 and 2 by using a motor bracket 7, and the rotation of a rotating shaft 6a of the motor 6 is transmitted through a shock absorbing mechanism 8 to a worm gear 9. Is transmitted to the worm wheel 10 that meshes with the worm wheel. The configuration of the shock absorbing mechanism 8 will be described later.

The worm wheel 10 has one side plate 2, 2
A small-diameter gear 11 is integrally fixed to the worm wheel 10. A large-diameter intermediate gear 12 meshes with the small-diameter gear 11, and the large-diameter intermediate gear 12 is rotatably supported by one of the side plates 2 and the motor bracket 7. A small-diameter intermediate gear 13 is integrally fixed to the large-diameter intermediate gear 12, and the small-diameter intermediate gear 13 meshes with one intermittent gear 14.

The one intermittent gear 14 is connected to the other intermittent gear (not shown) disposed on the other side plate (not shown) via a rotary shaft 15. , 4 are rotatably supported by a pair of side plates 2, 2. A turning arm 16 is fixed to each of the intermittent gears 14.
7 are provided. The guide pins 5 of the cassette holder 4 are engaged with the respective cam grooves 17.

FIG. 1 is an exploded perspective view showing a shock absorbing mechanism of the cassette loading device, FIG. 2 is a cross-sectional view showing the shock absorbing mechanism in a normal state, and FIG. 3 shows a shock absorbing mechanism receiving a high shock. It is sectional drawing.

1 to 3, the shock absorbing mechanism 8 has a shaft guide 18, and the shaft guide 18 is fixed to the rotating shaft 6a of the motor 6 by press fitting. A shaft insertion hole 18a is formed in the shaft guide 18, and the engagement groove 1 communicates with the shaft insertion hole 18a and extends in the radial direction at 120-degree rotation intervals.
8b are formed. The shaft guide 18 is formed with an evacuation chamber 18c for an engagement projection 19a, which will be described later, and the evacuation chamber 18c is open to the engagement groove 18b.

The shaft 19 is disposed on an extension of the rotating shaft 6a to which the shaft guide 18 is fixed. On one end side of the shaft 19, there are provided engaging projections 19a projecting radially at 120-degree rotation intervals. ing. One end of the shaft 19 provided with the engaging projection 19a is inserted into the shaft guide 18 using the shaft insertion hole 18a and the engaging groove 18b.

The engaging groove 18b and the engaging projection 19a constitute a connecting means 21 for connecting the shaft guide 18 and the shaft 19, and the shaft guide 18 is in the engaged state.
And the shaft 19 are integrally rotated. Engagement projection 1
When the shaft 9a has escaped from the engagement groove 18b to the evacuation chamber 19c, the shaft guide 18 and the shaft 19 are rotated independently.

When the engagement projection 19a enters the engagement groove 18b from the retreating chamber 19c, the engagement projection 19a is connected to the engagement groove 18b at each entrance side of the engagement groove 18b and the engagement projection 19a. Are formed as tapered portions 22 and 23 (shown in FIGS. 2 and 3) so that they can be easily inserted into the holes.

The other end of the shaft 19 is rotatably supported by the motor bracket 7 via a pivot bearing 24. The pivot bearing 24 is configured so as not to fall off when the shaft 19 is shifted within a predetermined distance in the axial direction. ing. In other words, the first position (the position in FIG. 2) in which the engagement protrusion 19a on the other end is engaged with the engagement groove 18b while the shaft 19 maintains the state supported by the pivot bearing 24 and the shaft guide 18. And engagement groove 1
It is configured to be movable in the axial direction between a second position (the position in FIG. 3) that is separated from the escape chamber 8b and enters the evacuation chamber 18c.

The worm gear 9 is inserted into the shaft 19. The worm gear 9 is engaged with the shaft 19 so as to rotate integrally with the worm gear 9, and is restricted from moving in the axial direction by an E-ring 25.
Has been prevented from coming off. Also, this shaft 19
A compression coil spring 26 serving as shaft position holding means and a disc-shaped polyslider 20 are inserted into the worm gear 9 and the polyslider 2.
0.

The shaft 19 is axially moved to a first position side (FIG. 2) by the spring force of the compression coil spring 26.
(In the direction of arrow A), and the urging force holds the engaging projection 19a at a position where it engages with the engaging groove 18b. The poly-slider 20 regulates one end of the shaft 19 so as not to come off from the shaft guide 18 by the spring force of the compression coil spring 26, and serves as a sliding surface of the compression coil spring 26 that rotates together with the worm gear 9.

Next, the operation of the above configuration will be described. As shown in FIG. 4, when the cassette holder 4 is at the cassette insertion position and the user inserts the cassette K into the cassette holder 4 and the cassette K is inserted to the predetermined insertion position, for example, the cassette-in switch is turned on. The motor 6 is driven. When the motor 6 is driven, the rotating shaft 6 of the motor 6
a rotates, and the rotation rotates the shaft guide 18. Here, as shown in FIG. 2, the shaft 19 is located at the first position side in the axial direction by the spring force of the compression coil spring 26, and the engagement protrusion 19a is formed in the engagement groove 18b.
The shaft guide 1
The rotation of 8 is transmitted to the shaft 19 via the connecting means 21.

The worm gear 9 rotates together with the shaft 19, and the worm wheel 10 rotates by this rotation.
This rotation is transmitted from the small-diameter gear 11 to the large-diameter intermediate gear 12, and transmitted from the small-diameter intermediate gear 13 to the pair of intermittent gears 14, 14. When the pair of intermittent gears 14 and 14 rotates,
The pair of swing arms 16, 16 rotate together. The rotation of the pair of swing arms 16, 16 causes the cassette holder 4 to rotate.
Is pressed, and the cassette pin 5 moves in the holder guide groove 3. The movement of the cassette pin 5 in the holder guide groove 3 moves the cassette holder 4 from the cassette insertion position to the cassette mounting position.

In the above operation process, as shown in FIG. 5, there is a case where the user inserts the cassette K into the cassette holder 4 with high impact, and when such insertion is performed, the impact force is increased. Power is transmitted through a power transmission system. That is, the power is transmitted to the cassette holder 4, the turning arm 16, the intermittent gear 14, the small-diameter intermediate gear 13, the large-diameter intermediate gear 12, and the worm wheel 10.
Is further transmitted to the worm gear 9.

Then, a rotational force and an axial force F act on the worm gear 9 by the transmitted impact force, and the axial force F is applied to the compression coil spring 2.
6, the shaft 19 moves toward the second position in the axial direction (the direction of the arrow B in FIG. 2) against the spring force as shown in FIG. Then, the engaging projection 19a of the shaft 19 is separated from the engaging groove 18b of the shaft guide 18 and enters the evacuation chamber 18c. When the engagement projection 19a and the engagement groove 18b are disengaged in this manner, the shaft 19 is substantially in a no-load state and can be rotated independently, so that the shaft 19 is rotated by the force in the rotation direction of the impact force. This allows the impact force to escape. Therefore, even when the user inserts the cassette K into the cassette holder 4 with a high impact, the power transmission system components and peripheral components are not deformed or damaged.

When the impact force is eliminated, the shaft 19 is pressed toward the first position in the axial direction by the spring force of the compression coil spring 26.
Moves in the direction indicated by the arrow A in FIG. 3, and the engaging projection 19a reenters the engaging groove 18b, so that the subsequent cassette loading operation becomes possible. Here, when the engagement protrusion 19a is inserted into the engagement groove 18b, both inlet sides are formed by the tapered portions 22 and 23, and the insertion is guided by the tapered portions 22 and 23, so that the insertion is smooth. Is done.

The shock absorbing mechanism 8 includes the shaft guide 1
8, the shaft 19 which can be moved in the axial direction, the connecting means 21 for connecting them, the compression coil spring (shaft position holding means) 26, the polyslider 20 and the like can be constituted, so that the number of parts is small and the cost is low. The shock absorbing mechanism 8 is assembled by press-fitting the shaft guide 18 into the rotating shaft 6a of the motor 6 and inserting the polyslider 20, the compression coil spring 26, and the worm gear 9 into the shaft 19 from the other end in this order. It is mounted using the ring 25. One end of the shaft 19 is inserted into the shaft guide 18. Then, one end of the shaft 19 (the engagement protrusion 1) is opposed to the spring force of the compression coil spring 26.
9a) is inserted into the evacuation chamber 18c of the shaft guide 18, and the other end of the shaft 19 is inserted into the pivot bearing 24 mounted on the motor bracket 7, so that the assembly is easy and the cost is low because the assembly is easy.

Further, the impact absorbing mechanism 8 does not need to use a long-span spring as in the prior art, so that it can be laid out in a small space with a compact configuration. In addition, since it is not necessary to use a motor (coreless motor) having a small initial torque (the inherent rotational torque of the motor itself in a no-load state), it is sufficient to use an inexpensive motor, so that the cost is also reduced. .

Furthermore, since the minimum impact force absorption point (setting of impact resistance) is determined by the performance of the spring force (holding force) of the compression coil spring (shaft position holding means) 26 alone, the exact load of the spring (holding) load is determined. No special setting / management is required. Further, since there is no reaction force from the spring for pushing back the cassette K with respect to the insertion stroke of the cassette K, there is no hindrance to the cassette insertion feeling.

In the above embodiment, the shaft position holding means is constituted by the compression coil spring 26.
Any structure may be used as long as the shaft 19 is held at the first position side in the axial direction, and when the pressing force of a certain degree or more acts, the shaft 19 is allowed to move to the second position side. However, if the biasing means such as the compression coil spring 26 is used as the shaft position holding means, when the impact force is eliminated, the engaging projection 19a enters the engaging groove 18b again by the biasing force as described above, There is an advantage that the subsequent cassette loading operation can be performed. Further, as the urging means, an elastic body (for example, rubber) or the like may be used instead of the spring. However, the use of a spring is preferable because the load (spring force) can be easily set and managed and the durability is excellent.

In the above embodiment, the engagement groove 18b is provided integrally with the shaft guide 18, and the engagement projection 19a is provided integrally with the shaft 19. Therefore, these members are provided separately from the shaft guide 18 and the shaft 19. It may be provided as.
However, if they are provided integrally as in this embodiment, the number of parts can be reduced.

According to the above embodiment, the case where the motor power transmission device is a cassette loading device of a VTR (video tape recorder) has been described. However, an audio cassette, a disk (CD, MD, floppy disk, etc.) Can be applied to not only a loading device for loading a tray on a tray, but also all motor power transmission devices in which an impact is transmitted to a power transmission system.

According to the above embodiment, the shock absorbing mechanism 8 is provided near the motor 6 by fixing the shaft guide 18 to the rotating shaft 6a of the motor 6 itself. The location to be performed is not limited, and is appropriately determined based on the arrangement of components of the power transmission system, the space, and the like.

According to the above embodiment, the engagement projection 1
9a and the engagement groove 18b, the tapered portions 22,
Although 23 is formed, it may be provided on only one of them.
However, when both are provided, the insertion becomes smoother.

[0045]

As described above, according to the first aspect of the present invention, the shaft guide is fixed to the rotating shaft rotated by the driving of the motor, and the worm gear is provided on the shaft extension of the rotating shaft to which the shaft guide is fixed. Is arranged, the shaft is configured to be rotatable and movable between a first position and a second position in the axial direction, and the shaft is held at the first position in the axial direction. And a shaft position holding means for allowing movement to the second position side when a certain pressing force is applied, and connecting the shaft guide and the shaft via a connecting means, wherein the connecting means comprises: A first position in which the shaft is held by the shaft position holding means;
At the position on the position side, the shaft guide and the shaft engage with each other, the shaft guide and the shaft rotate integrally, and the shaft moves in the axial direction against the holding force of the shaft position holding means. The shock absorbing mechanism of the motor power transmission device is configured such that when the shaft guide is displaced to the second position, the engagement between the shaft guide and the shaft is released and the shaft guide and the shaft are rotatable separately and independently. When an impact force from the power output side acts on the worm gear, the shaft moves to the second position side in the axial direction and is connected by the external force acting on the worm gear in the axial direction against the urging force of the urging means. Since the connection of the means is disconnected and the shaft rotates alone with no load,
Motor power transmission with a small number of parts, low cost without the need for expensive motors, layout in a small space as a compact configuration, and no need to strictly set and manage spring loads. An impact absorbing mechanism of the device can be provided.

According to the second aspect of the present invention, the shaft guide is fixed to the rotating shaft that is rotated by the driving of the motor, and the shaft to which the worm gear is fixed is disposed on an extension of the rotating shaft to which the shaft guide is fixed. The shaft is rotatable and movable between a first position and a second position in the axial direction, the shaft is held at the first position in the axial direction, and the pressing force is equal to or more than a predetermined value. A shaft position holding means for allowing movement to the second position side when pressure is applied is provided, and the shaft guide and the shaft are connected via a connecting means. The shaft guide and the shaft engage with each other at the position on the first position side held by the above, and the shaft guide and the shaft rotate integrally, and the shaft position holding means When the shaft is displaced toward the second position in the axial direction against the holding force, the engagement between the shaft guide and the shaft is disengaged, and the shaft guide and the shaft are rotatable independently and independently. Since the impact absorbing mechanism of the power transmission device is configured, when an impact force from the power output side acts on the worm gear, the shaft is axially opposed to the urging force of the urging means by an axial external force acting on the worm gear. Moving to the second position side in the direction, the connection of the connecting means is disconnected, and the shaft is in a no-load state and rotates alone, so the number of parts is small, and
It does not require the use of expensive motors, so it is inexpensive, has a compact configuration and can be laid out in a small space, does not require strict setting and management of the spring load, and also has a hindrance to the cassette insertion feel. It is possible to provide an impact absorbing mechanism of the cassette loading device that does not come.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing an impact absorbing mechanism of a cassette loading device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a normal state of the shock absorbing mechanism of the cassette loading device according to the embodiment of the present invention.

FIG. 3 is a cross-sectional view of the cassette loading device according to the embodiment of the present invention when the shock absorbing mechanism receives a high shock.

FIG. 4 is a normal side view of the cassette loading device according to the embodiment of the present invention.

FIG. 5 is a side view of the cassette loading device according to the embodiment of the present invention when receiving a high impact.

FIG. 6 is an exploded perspective view of a main part near a motor according to the embodiment of the present invention.

FIG. 7 is an exploded perspective view of a friction clutch structure according to a conventional example.

[Explanation of symbols]

 Reference Signs List 6 Motor 6a Rotating shaft 8 Shock absorbing mechanism 9 Worm gear 18 Shaft guide 18b Engagement groove 19 Shaft 19a Engagement protrusion 21 Connecting means 22, 23 Tapered part 26 Compression coil spring

Claims (2)

[Claims] 1. A shaft guide is fixed to a rotating shaft rotated by driving of a motor, and a shaft to which a worm gear is fixed is disposed on an axis extension of the rotating shaft to which the shaft guide is fixed, and the shaft is rotatable. The shaft is configured to be movable between a first position and a second position in the axial direction, the shaft is held at the first position in the axial direction, and the second position is formed when a pressing force exceeding a certain level acts. A shaft position holding means allowing movement to the side, and connecting the shaft guide and the shaft via a connecting means, wherein the connecting means comprises a first position in which the shaft is held by the shaft position holding means. At the side position, the shaft guide and the shaft engage with each other to rotate the shaft guide and the shaft integrally, and the shaft guide and the shaft rotate against the holding force of the shaft position holding means. The shift of the axial 2
When the shaft guide and the shaft are displaced toward the position side, the engagement between the shaft guide and the shaft is released, and the shaft guide and the shaft are configured to be rotatable independently and independently. mechanism. 2. A shaft guide is fixed to a rotating shaft rotated by driving of a motor, and a shaft with a worm gear fixed is disposed on an axis extension of the rotating shaft to which the shaft guide is fixed, and the shaft is rotatable. The shaft is configured to be movable between a first position and a second position in the axial direction, the shaft is held at the first position in the axial direction, and the second position is formed when a pressing force exceeding a certain level acts. A shaft position holding means allowing movement to the side is provided, and the shaft guide and the shaft are connected via a connecting means; and the connecting means holds the shaft with a holding force of the shaft position holding means. At a position on the first position side, the shaft guide and the shaft engage with each other to rotate the shaft guide and the shaft integrally, and resist the holding force of the shaft position holding means. When the shaft is displaced to the second position side in the axial direction, the engagement between the shaft guide and the shaft is released, and the shaft guide and the shaft are configured to be rotatable independently and independently. Shock absorbing mechanism of cassette loading device.