JPH04195010A - Lens driving mechanism - Google Patents

Abstract

PURPOSE:To simplify construction and to lessen the torque increase for the purpose of decreasing errors by directly coupling an external screw to a motor shaft, forming an internal screw part as a halved nut or rack shape and applying force thereto from >=2 points. CONSTITUTION:A lens is held in a holding member 3 held by a 1st guide rod 5 and a 2nd guide rod 6. Further, the internal screw part 7 is formed as the halved nut or rack shape and is screwed onto a lead screw 2 and is fixed to the holding member 3 via a leaf spring 9. A step motor 1 is driven to move the lens holding member 3 on the optical axis whole the member is regulated by the 1st and 2nd guide rods 5, 6 via the internal screw part 7 screwed onto the lead screw 2 and the leaf spring 9. The central position of the lens is aligned always to the position of the internal screw 7 and the lens is moved with high accuracy in this way without rotating the holding member 3.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a lens drive mechanism, and more particularly to the removal of adverse effects due to mechanical errors caused by a lens drive force transmission system.

[Conventional technology]

As described in Japanese Patent Application Laid-Open No. 63-94210, a conventional lens driving device measures errors occurring in a transmission system using a detector and corrects the errors.

In addition, in the method of using gears in the transmission mechanism, errors that occur when the rotation direction is changed are reduced by using two gears to eliminate errors or by adjusting the distance between the centers of the driving gear and the driven gear.

In addition, in a transmission mechanism using a lead screw, the female thread is biased in one direction by a coil spring to reduce errors.

[Problem to be solved by the invention]

In the conventional technology described above, the lens is accurately moved in the optical axis direction by measuring and correcting errors occurring in the drive mechanism using a detector. Therefore, a detector is required, and calculations are required to correct the detected values, making the construction complicated.

This error occurring in the drive mechanism will be explained using FIG. 2. FIG. 2 shows the posture of the lens when the lens is moved leftward and rightward in the drawing. The force that moves the lens is applied at point A in the diagram. The applied force also generates a force that rotates the lens. Therefore, the amount of movement B at the center of the lens is different from the amount of movement of point A in the figure.

In the conventional example described above, this error in the amount of movement of the lens is corrected by the detection.

Furthermore, the method of biasing the female screw with a coil spring has a problem in that the load varies depending on the amount of movement of the female screw.

SUMMARY OF THE INVENTION An object of the present invention is to provide a lens drive mechanism that has a simple structure, minimizes unnecessary increases in torque in order to reduce errors, and can keep the load constant.

[Means to solve the problem]

In order to achieve the above objective, a lead screw (male thread) is directly connected to the motor shaft, the female thread part is a half-nut or rack-shaped female thread part, and by applying force from two places, the lens This reduces the rotating force generated in the

[Effect]

The lead screw (male thread) coaxial with the motor shaft is
Rotated by a motor (eg, step motor).

The female thread that engages with the lead screw is moved by the rotation of the lead screw. The female screw is integrated with the holding member, and since the lens is held by the holding member, the lens moves as the female screw moves. The holding member is guided by two guide rods,
Movement of the female screw moves the lens along the optical axis.

The female screw is in the form of a half nut or rack.
It is fixed to the holding member using an elastic member such as a phosphor bronze plate.

By using two sets of the above-mentioned lead screws and female screws and applying force for movement at two places at the same time, the force for rotating the holding member is canceled out.

Since the holding member is not rotated, the position of the center of the lens is always the same as the position of the female screw, and the lens can be moved with high precision.

〔Example〕

A first embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

FIG. 1 is a side view of the first embodiment of the present invention, and FIG.
The figure is a perspective view of essential parts. 1 is a motor (for example, a step motor), and 2 is a lead screw, which is coaxial with the shaft of the motor 1. A holding member 3 holds the lens 4. 5 is the first guide lot, 6
is the second guide rod. The first guide rod 5 and the second
The lens 4 held by the holding member 3 moves on the optical axis 10 (in the left-right direction in the drawing) by the guide rod 6 .

Reference numeral 7 denotes a half-nut-shaped or rack-shaped female screw portion, which is screwed into the leat screw 2. The female screw portion 7 is fixed to the holding member 3 via a plate spring 9 (for example, a phosphor bronze plate). When step motor 1 is driven, lead screw 2
rotates, and the threaded part 7 that screws into the lead screw 2 is fixed to the holding member 3 via the phosphor bronze plate 9, and is regulated by the first guide rod 5 and the second guide rod 6. Move the lens 4 onto the optical axis.

According to this embodiment, the female threaded portions 7 are provided at two locations on the holding member 3, and by applying rotation equivalent to the same amount of movement to the two motors 1 at the same time, a force is applied to rotate the lens 4. will be moved without giving any. This results in
Even when the rotational direction of the Riet screw 2 is changed, the center position of the lens moves without causing an error due to rotation.

Next, a second embodiment of the present invention will be described using FIG. 3.

FIG. 3 is a perspective view of essential parts of a second embodiment of the present invention.

In the present invention, there is only one step motor 1, and the rotation amount is transmitted to the gear 213 through the gear 111 and the intermediate gear 12.
Rotate. Both the female screw 7 and the lead screw have the same pitch and the same diameter. The other parts are the same as those in the first embodiment, and are given the same reference numerals.

When the step motor 1 is rotated, the gear 111 rotates, the gear 213 also rotates by the same amount, and the two leat screws 2 rotate by the same amount. Thereby, the operation is the same as that of the first embodiment.

According to this embodiment, the same effects as in the first embodiment can be obtained by using only one stepping motor 1.

Next, a third embodiment of the present invention will be described using FIG. 4.

FIG. 4 is a perspective view of essential parts showing a third embodiment of the present invention. In this embodiment, the pulley 1 is attached to the lead screw 2.
This embodiment differs from the second embodiment in that a pulley 15 and a pulley 216 are provided, and the pulley 115 and pulley 216 are connected via a belt 14. Other components are denoted by the same reference numerals as in the second embodiment.

The operation in the above configuration is such that the two leat screws 2 are
Pulley 115. The second embodiment is the same as the second embodiment except that it is rotated in the same direction by the pulley 216 and the belt 14 and by one stepping motor 1, and the effects are also the same.

The next embodiment of the present invention will be described with reference to FIG.

FIG. 5 is a perspective view of essential parts showing the next embodiment of the present invention. In this figure, two leat screws 2 are provided with a gear 117 and a gear 218, respectively.
18 are connected by a chain 19. The same components as in the second embodiment are given the same amount.

In the above configuration, the two leat screws 2 are rotated at the same rotation speed by the gear 117 and the gear 218 connected by the chain 19, so they are driven by one stepping motor 1, and the others are driven by the second embodiment. The same is true.

Furthermore, the effects are also similar to those of the second embodiment.

A further embodiment of the present invention will be described with reference to FIGS. 6 and 7.

FIG. 6 is a perspective view of a main part showing a further embodiment of the present invention, and FIG. 7 is a sectional view of a main part of FIG. 6. In this figure, a leaf spring 20 is formed into a dogleg shape, a female screw 21 is connected above the spring, and a lead screw 2 facing upward in the figure is pressed down. There is only one stepping motor 1, and only this motor 1 rotates the lead screw 2 and moves the holding member 3. The female screw 21 is composed of two screws. This will be explained using FIG. 7. FIG. 7 is a sectional view of the female screw 21 when viewed from arrow C in FIG. 6. The female screw 21 is provided with a front screw 22 and a rear screw 23 at both ends, and is screwed into the leat screw 21 with these two screws.

In the above configuration, the force of the lead screw 2 that drives the holding frame 3 is transmitted to the front screw 22 and the rear screw 23. The forces transmitted to each are approximately the same amount, and the mutual forces cancel out the force that rotates the holding frame 3.

As a result, in this embodiment, since the holding frame 3 does not rotate, the position of the lens moves without causing an error due to rotation.

A further embodiment of the present invention will be described with reference to FIG.

FIG. 8 is a perspective view of essential parts of this embodiment. In this figure, a bushing 24 is provided along the guide rod 5, a part of the bushing 24 is cut out, and a rond pusher 28 is provided in the cutout part. The rod presser 28 is pressed against the guide rod 5 by a presser spring 25 that presses the rod.

With the above configuration, a force pushing downward in the figure always acts on the holding frame 3 due to the reaction force of the pushing spring 25 pushing the lot pusher 28. Since this force is applied from two places, the holding frame 3 cannot rotate.

As a result, in this embodiment, the holding frame 3 does not rotate even if a rotating force due to a force driving the holding frame 3 is applied from another part. Therefore, the position of the center of the lens moves without causing errors due to rotation.

Further, the next embodiment will be explained using FIG. 9. FIG. 9 is a perspective view of essential parts showing this embodiment.

The difference in configuration between FIG. 9 and FIG. 8 is that the bushing 26 is shorter and the rod receiver 27 is fixed integrally.

In this embodiment, the lot receiver 27 is made of a low-friction material such as polyacetal resin, and the lot pusher 28 is also made of a low-friction material, so that the force generated by the pushing spring 25 is Frictional force can be reduced.

This has the effect of reducing the force required to move the holding frame 3. Other effects are the same as in FIG. 8.

〔Effect of the invention〕

According to the present invention, since the holding member is not rotated, the position of the center of the lens is always the same as the position of the female screw, and the lens can be moved with high precision.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of one embodiment of the present invention, Fig. 2 is a perspective view of the main part of Fig. 1, Fig. 3, Fig. 4, Fig. 5, Fig. 6, Fig. 8.
9 are perspective views of main parts showing other embodiments of the present invention, FIG. 7 is a sectional view of main parts of FIG. 6, and FIG. 10 is a conceptual diagram showing a conventional technique. 1. Stepping motor, 2. Lead screw, 3. Holding member, 7, 21.・Female thread, 9, 20.・Plate spring 26... Bush. 1st figure 9 plate lg agency 2 fertilization closed 34N key 71 7 spring screw row 4 figure 7 straight plate 5 concealed Z communication! Introduction Figure 6 Shoulder 7 Flash 8 Hi 24 Hupatshu 9th flash

Claims (1)

[Scope of Claims] 1. A lens holding member that holds a lens, a male screw member that is rotationally driven by a motor, and a lens that is engaged with the male screw member and when the male screw member is rotationally driven, A female threaded member that moves in a certain direction along with this, and a female threaded member and the lens holding member are coupled, and the movement of the female threaded member in the certain direction is prevented from moving in the certain direction. a coupling member that moves the lens holding member along a guide member and drives the holding lens by transmitting a signal thereto; A lens drive mechanism characterized by 2. The lens drive mechanism according to claim 1, wherein there are two sets of motors that rotate the male screw member. 3. The lens drive mechanism according to claim 1, further comprising a transmission member that transmits rotation of one of the male screw members to the other male screw member. 4. The lens drive mechanism according to claim 3, wherein the transmission member includes three gears. 5. The lens drive mechanism according to claim 3, wherein the transmission member is a connecting member that connects two pulleys. 6. The lens drive mechanism according to claim 3, wherein the transmission member is a chain member connecting two gears and the gears. 7. In claim 1, in the lens drive mechanism including the lens holding member, the male screw member, the female screw member, and the coupling member, the female screw member is connected to two separate engagement portions. a limiting member that engages with the male threaded member and limits movement of the holding member in the certain direction; and a limiting member that is fitted and held inside the holding member, A lens drive mechanism characterized by being positioned substantially on a line connecting the center. 8. In claim 1, a lens drive mechanism including the lens holding member and the limiting member includes a guide member that fits into the limiting member and is fixed separately from the lens holding member; and a guide member that is in contact with the guiding member. In a lens drive mechanism including a pressing member and a pressing member that presses the pressing member against the lens holding member, one or two sets of the pressing member and the pressing member are provided, and the inclination of the lens holding member is controlled. A lens drive mechanism characterized by regulation. 9. In the lens drive mechanism according to claim 8, a receiving member that contacts the guiding member is provided on the opposite side of the pressing member and the guiding member, and the receiving member is fixed integrally with the lens holding member. A lens drive mechanism characterized by: