JP2011203591A - Projector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a projector device capable of detecting the position of a projection lens and detecting the driving range end of the projection lens without using a linear sensor and a microswitch.SOLUTION: The projector includes: a DC motor 201 for driving the projection lens; and a back electromotive force detection circuit 202 for detecting the number of rotations based on the back electromotive force generated from the DC motor 201; wherein the driving range end of the projection lens is detected by comparing the number of rotations when the projection lens is normally driven and the number of rotations when the projection lens reaches the driving range end, and also, the position of the projection lens is detected by counting the number of rotations from the end.

Description

  The present invention relates to a projector apparatus, and more particularly to a projector having a function for detecting the number of revolutions from the back electromotive force of a motor and detecting the end of the driving range of the projection lens and a function for detecting the position of the projection lens in the horizontal, vertical and focal directions. It relates to the device.

  2. Description of the Related Art Conventionally, there is a projector device that has a lens shift function as a kind of projector device that projects an electric video signal on a screen as a projected image. The lens shift function moves the position of the projection lens to adjust the projection angle when you want to display the projected image on a projection screen that is placed with respect to the location where the projector is installed. It is a function. Among projector devices having such a lens shift function, there are those having a function of detecting the horizontal and vertical positions of the projection lens and the end of the driving range of the projection lens.

  FIG. 2 shows a projector device having a conventional lens shift function described in Patent Document 1. In FIG.

  A projector apparatus with a lens shift function shown in FIG. 2 includes a light source 101 that emits light, a light modulation element 102 that modulates light emitted from the light source 101, and light modulated by the light modulation element 102 on a screen 103. A projection lens 104 to project, a lens shift unit (105h, 105v, 106) for moving the projection lens 104 on a plane perpendicular to the optical axis 102x of the light modulation element 102, horizontal and vertical lens position detection sensors 107, 108 and a switch for detecting the end of the driving range of the lens.

JP 2001-215610 A

  However, the conventional configuration requires a linear sensor to detect the position of the projection lens, and has a problem that a micro switch is required to detect the end of the driving range of the projection lens.

  The present invention solves the above-described conventional problems, and an object of the present invention is to provide a projector device that can detect the position of the projection lens and the end of the driving range without using a linear sensor and a microswitch.

  In order to solve the above-described conventional problems, the projector according to the present invention includes a DC motor counter electromotive force detection circuit for driving the projection lens, and detects the rotation speed of the DC motor from the counter electromotive force. The lens position information and the end of the driving range are detected.

  According to the present invention, the position of the lens can be obtained without using the linear sensor conventionally used for detecting the position of the projection lens in the horizontal direction, the vertical direction, and the focus direction and the microswitch used for detecting the end of the driving range. Since the end of the driving range can be detected, the cost can be reduced.

FIG. 3 is a block diagram showing a basic configuration of position detection of the drive lens and end detection of the drive range of the projector device in Embodiment 1 of the present invention. Configuration diagram of a projector device with a conventional lens shift function

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 is a block diagram showing a basic configuration of position detection of a driving lens and edge detection of a driving range of the projector device according to Embodiment 1 of the present invention. The projector apparatus includes a DC motor 201, a counter electromotive force detection circuit 202, a motor drive circuit 203, and a microcomputer 204 as main components.

  In FIG. 1, a DC motor 201 is for driving a projection lens in a horizontal direction, a vertical direction, and a focal direction, and one DC motor 201 is used in each direction.

  The counter electromotive force detection circuit 202 detects a counter electromotive force generated from the DC motor 201 and detects the number of rotations from the counter electromotive force.

  The motor drive circuit 203 is for driving the DC motor 201 and drives the DC motor 201 to rotate forward or reverse.

  The microcomputer 204 obtains the rotational speed of the DC motor 201 from the back electromotive force detection circuit 202, detects the position information of the projection lens, and controls the driving of the DC motor 201.

  The projector apparatus includes a circuit that detects a counter electromotive force of a DC motor that drives the projection lens, and detects the rotational speed of the DC motor from the counter electromotive force. By obtaining the rotation speed when the motor is driven within the drive range of the projection lens, and comparing the rotation speed at the normal time with the rotation speed that changed when the lens came to the end of the drive range Detect the end of the driving range. By counting the number of rotations from that end, the lens moving distance can be calculated, and the lens position can be detected.

  According to the present invention, it is possible to detect the position of the projection lens and the end of the driving range without using a linear sensor and a micro switch.

DESCRIPTION OF SYMBOLS 101 Light source lamp 102 Light modulation element 103 Screen 104 Projection lens 105h, 105v Motor 106 Lens fixing plate 107 Horizontal lens position detection sensor 108 Vertical lens position detection sensor 201 DC motor 202 Back electromotive force detection circuit 203 Motor drive circuit 204 Microcomputer

Claims (2)

A projection lens;
A motor for driving the projection lens;
A counter electromotive force detection circuit that detects a counter electromotive force of the motor, and obtains the rotational speed of the DC motor from the counter electromotive force detected by the counter electromotive force detection circuit, and obtains position information of the projection lens from the rotational speed. Control means for outputting a control signal for controlling the position of the motor;
And a motor drive circuit for driving the motor based on a control signal of the control means.   2. The projector according to claim 1, wherein the back electromotive force detection circuit detects an end of a driving range of the projection lens by acquiring a rotation speed of the DC motor and comparing it with a normal operation time.

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