JP4681866B2 - Projection display device - Google Patents

Description

  The present invention relates to a projection display device that uses projected light from a light source to enlarge and project a display image displayed on a display device such as a liquid crystal panel onto a projection surface via a projection optical system.

  Conventionally, an image displayed on a liquid crystal panel by illuminating a liquid crystal panel through an illumination optical system such as an integrator lens, a mirror, or a polarizing plate using a high-intensity light source such as an ultra-high pressure mercury light source as shown in FIG. Alternatively, a liquid crystal projector 2 that enlarges and projects an image on a screen via a lens barrel 1 having a projection lens is known.

  Conventionally, because the optical and mechanical sensitivity of back movement in the environment is low, it is inconspicuous even if image quality degradation occurs. As a result, temperature changes greatly affect image quality.

  FIG. 6 is a graph showing a temperature (° C.) rise in the lens barrel 1 with respect to time (min). As time elapses after the light source is turned on, the temperature of the lens barrel 1 rises and a focus shift occurs, resulting in deterioration of the image quality of the display image.

  Furthermore, even in lens barrels in other fields, a focus shift occurs due to a change in environmental temperature. As a proposal for the correction, focus correction is performed from the signals of the temperature detection means and the position detection means as in Patent Documents 1 and 2. A configuration is known in which the deterioration of image quality is corrected.

JP-A-8-179187 Japanese Patent Laid-Open No. 10-20172

  However, in Patent Documents 1 and 2 described above, the number of component parts is increased and the system is complicated.

  The object of the present invention is to solve the above-mentioned problems and to perform image quality degradation by performing simple focus correction with a reduced number of parts by performing focus correction corresponding to the time axis when performing focus correction of the projection lens. An object of the present invention is to provide a projection display device that prevents the above-described problem.

  The technical feature of the projection display device according to the present invention for achieving the above object is that a display image displayed on a display device is projected onto a projection surface via a projection optical system using irradiation light from a light source. In the projection display apparatus for projecting, the time measuring means for measuring the lighting time of the light source, the correction amount determining means for determining the focus correction amount based on the measurement result by the time measuring means, and the projection optics based on the focus correction amount And adjusting means for adjusting the focus of the system.

According to the projection display device of the present invention, the amount of focus deviation corresponding to the passage of time after the light source is turned on is calculated, and simple focus correction with a reduced number of parts is performed to degrade the image quality of the projected image on the projection surface. Can be prevented.

  Further, if a time table corresponding to the standard mode, the aperture mode, and the silent mode is provided and the focus correction is supported for each mode of the system, correction with higher accuracy can be performed.

The present invention will be described in detail based on the embodiment shown in FIGS.
FIG. 1 shows a configuration diagram of an optical system, a mechanical system, and an electrical system of a focus correction mechanism of a projection display device. A first group barrel 12 having a focus lens group is coupled to a focus ring 11, and a first group barrel is coupled. 12 has a female helicoid on its outer periphery and is engaged with the male helicoid of the fixed cylinder 13.

  On the inner peripheral side of the fixed barrel 13, a second group barrel 14, a third group barrel 15, a fourth group barrel 16, and a fifth group barrel 17 are sequentially arranged from the first group barrel 12 side. This constitutes a moving lens group that moves during zooming. The sixth group lens barrel 18 is connected to the flange surface side of the rear end of the fixed cylinder 13 by screws, and an adjustment spacer is sandwiched between the abutting faces so as to perform back adjustment. An electric diaphragm 19 is connected to the third group lens barrel 15, and a cam ring 20 is fitted on the outer peripheral side of the fixed cylinder 13 so as to rotate and slide at a fixed position.

  A zoom gear 21 is fixed to the outer diameter side of the cam ring 20, meshes with the output gear 24 of the zoom motor 23 fixed to the holding member 22 on the outer diameter side of the fixed cylinder 13 by screws, and the driving force is transmitted to the zoom gear 21. The The zoom position of the second group lens barrel 14 is detected by a zoom position sensor 25.

  Further, a focus motor 26 is fixed to the holding member 22 fixed to the fixed cylinder 13 via a focus base plate (not shown), and the driving force of the focus motor 26 meshes with the gear of the focus ring 11 via the output gear 27. In addition, it is configured to transmit to the focus ring 11.

  The output of the CPU 30 is connected to the zoom motor 23 and the focus motor 26 via the zoom drive unit 31 and the focus drive unit 32, respectively. The CPU 30 has a timer 33 having first and second time measuring means, and a data memory. 34 is connected.

The data memory 34 has a time table shown in the graph of the focus shift amount (cm) corresponding to the time axis of FIG. In addition, since the temperature change range is limited by the use conditions of the lens barrel 1, the data memory 34 is corrected according to the temperature rise for the corresponding times A1 to A7 (min) for each use mode of the standard mode, aperture mode, and silent mode. The time table shown in the graph of FIG. 3 having the amounts B1 to B8 (mm) is also provided.

  FIG. 4 shows an operation flowchart. When the switch is turned on (step S1), the light source is turned on (step S2), and time measurement is started by the first time measuring means of the timer 33 (step S3). At the same time, the zoom size is adjusted manually by the zoom motor 23 via the zoom drive unit 31 to manually determine the projection size, and the focus motor 26 via the focus drive unit 32 is used to match the best focus position by manual focus adjustment. (Step S4).

  The time is measured by the second time measuring means of the timer 33 from the time when the focus is matched to the best focus (step S5). By calibrating the correction amount using the second time measuring means, more accurate correction is possible. However, depending on the sensitivity of the optical system to the focus, the second time measuring means may not be used. The focus adjustment may be performed by timekeeping by the first timekeeping means.

  The CPU 30 identifies the zoom position at the time of determining the projection size (telephoto T / intermediate M / wide angle W) based on the information of the zoom position sensor 25, and information on the on / off of the motorized diaphragm 19 is provided to the CPU 30. (Step S6).

  Based on these pieces of information, the CPU 30 selects use data 1 to 3 for each of the standard mode, the silent mode, and the aperture mode from the time table of FIG. 3 (step S7), and obtains a correction amount for the corresponding mode by counting time. Next, the focus correction amount is calculated on the basis of the time table of the deviation amount by the timing of FIG. 2, the correction amount for each mode is added to the focus correction amount for calibration, and transmitted from the CPU 30 to the focus driving unit 32 ( Step S8), the focus motor 26 is driven (Step S9), the focus lens group of the first group barrel 12 is moved, and focus correction is performed.

  Thereafter, the process returns to step S7, and the time measurement by the timer 33 is repeated until the temperature change is stabilized, and the focus deviation with respect to the time measurement is repeatedly corrected according to the flowcharts based on the time tables of FIG. 2 and FIG. Then, the focus correction is terminated because the temperature change is stabilized.

It is a block diagram of an optical system, a mechanical system, and an electrical system. It is a graph of the relationship of the focus shift | offset | difference with respect to projection elapsed time. It is a graph of the correction amount according to mode with respect to time. It is an operation | movement flowchart figure. It is a perspective view of a projection display apparatus. It is a graph of the temperature change of the lens barrel with respect to time.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Focus ring 12 1st group barrel 13 Fixed cylinder 14 2nd group barrel 15 3rd group barrel 16 4th group barrel 17 5th group barrel 18 6th group barrel 19 Electric diaphragm 20 Cam ring 23 Zoom Motor 25 Zoom position sensor 26 Focus motor 30 CPU
33 Timer 34 Data memory

Claims (4)

  In the projection display device that projects the display image displayed on the display device onto the projection surface using the irradiation light from the light source via the projection optical system, the time measuring means for measuring the lighting time of the light source, A projection display apparatus comprising: a correction amount determining unit that determines a focus correction amount based on a measurement result by a time measuring unit; and an adjusting unit that performs focus adjustment of the projection optical system based on the focus correction amount. . A plurality of use modes having different temperature generation states due to lighting of the light source, and the correction amount determination means calibrates the determined focus correction amount by adding a correction amount for the time measurement for each use mode. The projection display device according to claim 1.   The second time measuring means for measuring time after matching the best focus position, and calibration means for calibrating the correction amount with respect to the time measured by the second time measuring means. Projection display device. The projection display device according to any one of claims 1 to 3 , wherein the focus correction amount is stored as a time table for the timekeeping .

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