JPH0418184B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a levitation device for levitating a part of a portable device, such as a small movie projector.

For example, in the case of a small projector as shown in Figure 1,
A flotation device A is provided at the front of the main body 1. This levitation device A has a levitation leg 4 attached to a front leg 2 that moves up and down by rotating a dial 3. When the levitation leg 4 is retracted, the projection optical axis 6 emitted from the lens 5 of the projector is horizontal. However, when the dial 3 is turned and the floating legs 4 are extended, the front part of the main body 1 floats up using the rear legs 7 as a fulcrum as shown in FIG. 2, and the optical axis 6 is directed upward.

After the projection is finished in this state, the levitation foot 4
Sometimes I forget to put it back. If the projector is transported with its levitation legs exposed, it will be unstable and may fall due to vibrations and be damaged.
This is a problem, and even if it is not transported, there is a risk that it will fall over and be damaged during storage.

This invention aims to solve the above-mentioned problems, and is designed so that the floating feet that are extended during projection, etc. are automatically retracted to their original position as soon as they are lifted up after use. be.

That is, the structure of the present invention consists of a rotatable dial and a floating foot having a screw shaft screwed into a screw hole in the center of the dial, and by rotating the dial, the floating foot can be raised and lowered relative to the dial. In a portable device having a flotation device configured to hold the dial, the dial is slightly movable up and down with respect to the main body of the device, and the screw shaft mounting portion of the main body has a sliding member with a low coefficient of friction that contacts the upper surface of the dial, and a friction member that contacts the upper surface of the dial. Provide a braking member with a large coefficient,
When the weight of the device is applied to the levitation foot, the upper surface of the dial is pressed against the control member, and when the weight of the device is not applied to the levitation foot, the dial is configured to contact only the sliding member, and the screw shaft is A return spring is attached that allows the screw shaft to be retracted while rotating the dial when the dial is only in contact with the sliding member.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Details of the flotation device of the present invention will be explained below based on an embodiment shown in the accompanying drawings. A dial 3 is provided in a recess formed in the lower part of the frame 8 of the main body 1 of the projector, and a screw shaft 11 is provided in the screw hole 10 in the center.
is screwed in.

The center of a floating leg 4 is fixed to the lower end of the screw shaft 11, and leg rubbers 12 are fixed to both sides of the lower part.

The floating legs 4 are located at the lower part of the cover-shaped front legs 2 fixed to the frame, and a guide shaft 14 fixed to another part of the floating legs 4 is loosely fitted into a guide hole of the front legs 2 to prevent the floating legs 4 from rotating. do.

The screw shaft 11 is a guide tube 13 provided on the frame 8.
The lower end of a return spring 15 is connected to the screw shaft 11 which is loosely fitted into the screw shaft 11 and protrudes from the upper end thereof, and the upper end of this spring 15 is engaged with an engaging piece 16 fixed to the frame 8, so that the screw shaft 11 is fixed to the spring. 15 to constantly pull it upward.

The sleeve 18 and the coil spring 19 that press the sleeve 18 onto the dial 3 at all times are fitted into the large diameter portion 17 at the bottom of the guide tube 13. Since the sleeve 18 is an example of a sliding member, the friction coefficient of the contact surface is small. choose something.

Reference numeral 20 denotes an annular part fitted with a circumferential groove on the lower end surface of the large diameter portion 17. Since this part 20 is an example of a braking member, one with a large coefficient of friction is selected.

Even when the return spring 15 is stretched to its strongest state, the elasticity is weaker than that of the coil spring 19, and when no upward load is applied to the leg rubber 12, the dial 3 comes into contact with the sleeve 18 and presses against the pads 20. Avoid contact. However, the return spring 15 should have sufficient force to lift the floating foot 4.

Further, the male thread of the screw shaft 11 and the lead angle and thread angle of the screw hole 10 into which it is screwed have little resistance to rotation of the dial 3, and when the dial 3 cannot move in the axial direction, the screw shaft 11
The value is set so that when the dial 3 is moved in the axial direction, the dial 3 rotates.

Here, based on FIG. 4, symbols for required parts are determined as follows.

Da Effective diameter of the screw Db Center diameter of the sleeve Dc Center diameter of the part θ Lead angle of the screw α Thread angle Fa, Fa′ Vertical force applied to the threaded portion Ta, Ta′ Dial 3 is rotated by the load applied to the threaded portion Torques Tb, Tb' to be applied Braking torque due to friction on sleeve 18 part Tc Braking torque due to friction on part 20 μa Friction coefficient between screw shaft 11 and dial 3 μb Friction coefficient between sleeve 18 and dial 3 μc Between part 20 and dial 3 Friction coefficient Pt, Pt' Tensile force Ps, Ps' of return spring 15 Compressive force Pp of coil spring 19 Force applied to part 20 Weight of projector applied to 122 leg rubbers W Weight of components of levitation leg 4 Leg rubber 12 is in the air If it is floating in In order for the floating leg 4 to retract, Ta>Tb must be satisfied.

∴Da{sinθ−μa/cos(α/2) ・cosθ}＞μb・Db … When load Q is applied to leg rubber 12, Fa′=Q+Pt′−W Fa′>Ps′, and coil spring 19 is compressed. , the dial 3 is in close contact with the pad 20.

Pp=Fa′−Ps′ Therefore, the torque that brakes the rotation of dial 3 by friction is T=Tb′+Tc =μb・Ps′・Db/2+μc(Fa′−Ps′)Dc/2 In this case, dial 3 should not rotate, so T>Ta′ ∴Db/2μb・Ps′+μc(Fa′−Ps′)・Dc/2>Fa′
・Da/2 {sinθ−μa/cos(α/2)・cosθ} Therefore, Ps′(μb・Db−μc・Dc)+μc・Dc・Fa′>Da・Fa′
{sinθ−μa/cos(α/2)・cosθ}... It is sufficient to select each value that satisfies each of the above expressions. In the example, the following steps were taken.

μa＝μb＝0.1 μc＝0.6 Da＝10mm Db＝18mm Dc＝36mm Pt≒Pt′＝2Kg W＝0.5Kg θ＝20゜α＝30゜Q＝10Kg Therefore, the leg rubber 12 is floating in the air In the case, Fa=Ps=2-0.5=1.5Kg The left side of the equation is 10×{sin20゜−0.1/cos15゜×cos20゜} =2.45 The right side of the equation is 0.1×18=1.8, so 2.45>1.8 and the leg rubber is 12
When is floating in the air, the levitation legs 4 are retracted.

When a load is applied to the leg rubber 12, Fa′=10+2−0.5=11.5Kg Ps′≒Ps=1.5Kg ∴Fa′＞Ps′ Pp=11.5−1.5=10Kg The left side of the equation is 1.5×(0.1×18− 0.6×36) + 0.6×36 , the dial 3 does not rotate and the floating foot 4 remains at the extended position.

Therefore, by using this flotation device, even if you forget to put the flotation device back, the flotation device will automatically be retracted to its original position when you lift the device, preventing damage to the device during transportation. , and equipment handling is simplified.

Although the embodiment has been described with respect to a movie projector, it can also be used in various portable devices other than movie projectors.

[Brief explanation of drawings]

1 and 2 are side views showing various states of a projector having a flotation device, FIG. 3 is a partially enlarged vertical side view showing an embodiment of the flotation device of the present invention, and FIG. 4 is the main part of the same. FIG. 2 is a further enlarged vertical side view. 1...Main body, 3...Dial, 4...Floating foot,
10...Screw hole, 11...Screw shaft, 15...Return spring, 18...Sleeve as a sliding member, 20
...Patut as a braking member, A...Floating device.

Claims (1)

[Claims] 1 A levitation device consisting of a freely rotatable dial and a levitation foot having a screw shaft screwed into a screw hole in the center of the dial, and configured so that the levitation foot can be raised and lowered relative to the dial by rotating the dial. In a portable device having a device, the dial is slightly movable up and down with respect to the main body of the device, and the screw shaft mounting portion of the main body is provided with a sliding member with a small friction coefficient that contacts the top surface of the dial and a braking member with a large friction coefficient. and configured such that when the weight of the device is applied to the levitation foot, the upper surface of the dial is pressed against the braking member, and when the weight of the device is not applied to the levitation foot, the dial contacts only the sliding member,
The flotation device for a portable device further includes a return spring attached to the screw shaft for retracting the screw shaft while rotating the dial when the dial is in contact only with the sliding member.