Power transmission device

• US 8,864,325 B2
• Filed: 05/07/2009
• Issued: 10/21/2014
• Est. Priority Date: 05/26/2008
• Status: Active Grant

• Current Assignee: Nippon Seiki Company Limited
• Original Assignee: Nippon Seiki Company Limited
• Inventors: Maruyama, Kazuya, Jinushi, Kouichi, Adachi, Yoshiko
• Primary Examiner(s): Chambers, Troy
• Assistant Examiner(s): VU, ALEXANDER T
• Application Number:
  US12/992,249
• Publication Number:
  US 20110061482A1
• Time in Patent Office: 1,993 Days
• Field of Search: 74/892.3, 74/892.5, 74/892.6, 74/893.2, 74/893.3, 74/893.7, 74/893.9, 74/893.4, 359/841, 359871-877, 248/229.16, 248/229.26, 248/488
• US Class Current: 359/873
• CPC Class Codes: B60K 2370/1529 Head-up displays
• CPC Class Codes: B60K 35/23 Head-up displays [HUD] optical aspects of head-up displays G02B27/01
• CPC Class Codes: F16H 25/2015 Means specially adapted for stopping actuators in the end position; Position sensing means
• CPC Class Codes: F16H 25/2021 with means for avoiding overloading
• CPC Class Codes: G02B 27/0149 characterised by mechanical features G02B27/0176 takes precedence
• CPC Class Codes: Y10T 74/18576 including screw and nut

Abstract

A power transmission device which is free from a possibility of breakage of a driving member is provided. A stepping motor (driving member) 61a configured to be driven on the basis of a command signal from a controller 70, a lead screw portion 61c configured to be rotationally driven in association with the drive of the stepping motor 61a, and a power transmitting member 65 configured to move along an axial direction X of the lead screw portion 61c in accordance with the rotation of the lead screw portion 61c and transmit a power to a power transmitted member 42e are provided, and the controller 70 is configured to control the output of the command signal to the stepping motor 61a to be stopped when the power transmitting member 65 is not moved along the axial direction X.

Claims

1. A power transmission device comprising:

a driving member configured to be driven on the basis of a command signal from a controller;

a lead screw portion configured to be rotationally driven in association with the drive of the driving member; and

a power transmitting member configured to move along an axial direction of the lead screw portion in accordance with the rotation of the lead screw portion to transmit the power to a power transmitted member,

characterized in that;

the controller is configured to control the output of the command signal to the driving member to be stopped so that electric current is not supplied to an exciting coil of the driving member when the power transmitting member is not moved along the axial direction,

the power transmitting member includes a pair of projecting portions that each come into point contact with the power transmitted member so as to sandwich the power transmitted member,

the power transmitted member rotates about an axis of rotation,

the power transmitting member transmits power through the point contact to the power transmitted member to rotate the power transmitted member about the axis of rotation,

the power transmitting member is formed with an insertion portion configured to allow insertion of a guide shaft which extends substantially parallel to the lead screw portion, and

a movement of the power transmitting member along the axial direction of the lead screw portion causes a holder connected to the guide shaft to rotate about an axis of rotation.

2. The power transmission device according to claim 1, comprising a moving member configured to be engaged with the lead screw portion and move along the axial direction in accordance with a thrust given by the rotation of the lead screw portion,

characterized in that the power transmitting member moves along the axial direction synchronously with the movement of the moving member.

3. The power transmission device according to claim 1, wherein a concave mirror is connected to the holder, and movement of the power transmitting member along the axial direction of the lead screw portion further causes an angular position of the mirror to be adjusted.

4. The power transmission device according to claim 1, wherein the axis of rotation of the power transmitted member is orthogonal to the movement direction of the power transmitting member along the axial direction of the lead screw.

5. The power transmission device according to claim 1, wherein the pair of projecting portions of the power transmitting member are disposed so as to oppose each other across a predetermined gap, and the power transmitted member is interposed in the gap so as to come into point contact with each projecting portions.

6. A power transmission device comprising:

a driving member configured to be driven on the basis of a command signal from a controller;

a lead screw portion configured to be rotationally driven in association with the drive of the driving member; and

a power transmitting member configured to move along an axial direction of the lead screw portion in accordance with the rotation of the lead screw portion to transmit the power to a power transmitted member,

characterized in that;

the controller is configured to control the output of the command signal to the driving member to be stopped so that electric current is not supplied to an exciting coil of the driving member when the power transmitting member is not moved along the axial direction,

the power transmitting member includes a pair of projecting portions that each come into point contact with the power transmitted member so as to sandwich the power transmitted member,

the power transmitted member rotates about an axis of rotation,

the power transmitting member transmits power through the point contact to the power transmitted member to rotate the power transmitted member about the axis of rotation,

the pair of projecting portions of the power transmitting member are disposed so as to oppose each other across a predetermined gap, and the power transmitted member is interposed in the gap so as to come into point contact with each projecting portions, and

a width direction of the gap measured between the pair of projecting portions of the power transmitting member is parallel to the movement direction of the power transmitting member along the axial direction of the lead screw.

7. The power transmission device according to claim 6, wherein the axis of rotation of the power transmitted member is orthogonal to the movement direction of the power transmitting member along the axial direction of the lead screw.