JPH03144488A - Laser display device - Google Patents

Abstract

PURPOSE:To prolong the service life of each driving mechanism, especially, a bearing by rotating a polygon mirror around an axis parallel to a light source orientating direction and independently controlling laser beams output in parallel from plural light sources. CONSTITUTION:The device is provided with a rotating/driving means 30 rotating the polygon mirror 3, which reflects all laser beams from the plural light sources 11... 11 that are oriented in one-dimensionally and output laser beams in the same direction or in parallel and leads them to a screen 2, around the axis parallel to the orientating direction of the light sources 11... 11. In addition, the control means 20 and 21 independently controlling laser beams outputted from the plural light sources 11... 11 are provided. Consequently, any character and graphic can be displayed with a dot pattern, and the rotational frequency of the polygon mirror 3 is reduced in proportion to the number of the laser light sources 11, thereby prolonging the service life of the bearing.

Description

[Detailed description of the invention] <Industrial application field> The present invention relates to a display device using laser light.

<Prior art> A laser display device displays desired characters, graphic patterns, etc. on the screen by scanning laser light from a semiconductor laser or the like on the screen and simultaneously controlling ON/OFF of the laser light output. Conventionally, a raster scanning method has been used as a method for scanning laser light in a locking device.

FIG. 6 shows a block diagram of a laser display device using a raster scanning method.

After each laser beam corresponding to each wavelength of red, green, and blue, oscillated by gas lasers 61 and 62 and having only the first-order diffracted light extracted by an AOM (acousto-optic modulator) 63, passes through a collimator 64, Beam splitter 65
The colors are synthesized by This color-combined laser light is reflected by a polygon mirror 66, further reflected by a galvanometer mirror (vibration scanner) 67, and guided onto a screen 68.

Now, in the raster scanning method, when the laser beam scans l lines in the X direction on the screen 68 by rotating the polygon mirror 66, the galvanometer mirror 66 is driven to move the scanning line by one line in the Y direction. By sequentially repeating this operation, the laser beam is scanned over the entire surface of the screen 68.During this scanning, each AOM 63 is driven and controlled according to input signals from, for example, a television camera or a video tape recorder, and the laser beam is scanned over the entire surface of the screen 68. Desired characters, graphic patterns, etc. are displayed on the screen 68 by adjusting whether or not the screen 68 is irradiated with light and the color.

<Problems to be Solved by the Invention> By the way, according to the conventional display device using the raster scanning method, in order to obtain an image to which the flickering phenomenon is not perceptible to the naked eye, the number of revolutions of the polygon mirror must be set to 150.
It is necessary to set the rotation speed to 00 rpm or more, and accordingly, the galvano mirror must also be driven at high speed. For this reason, not only is the cost of each drive mechanism high, but also the lifespan of each drive mechanism, especially the life of the bearings, is very short, necessitating frequent maintenance.

Furthermore, in order to synchronize the scanning operations of the polygon mirror and galvano mirror, a He-Ne laser, a detector, a control circuit, etc. are required, and optical adjustment of this optical system and the polygon mirror and galvano mirror is extremely difficult. Met.

<Means for Solving the Problems> The present invention has been made to solve the above-mentioned problems all at once, and its configuration will be explained with reference to FIGS. 1 and 2, which correspond to embodiments. The present invention provides a plurality of lights iz...11 that are arranged in a one-dimensional direction and output laser beams in the same direction and parallel to each other, and a group of laser light sources 11...
A polygon mirror 3 for reflecting all the laser beams from 11 and guiding them to the screen 2, and the polygon mirror 3
a driving means 30 for rotating the plurality of lights a11, .
- It is characterized by being equipped with a control means (modulation drive circuit 20 and signal processing circuit 21) that individually controls each of the 11 laser light outputs.

Effect> A group of laser beams from the plurality of laser light sources 11...11 is reflected by the polygon mirror 3 and irradiated onto the screen 2;
By rotating the screen 2, the screen 2 is simultaneously scanned, and by individually controlling ON/OFF of the laser light output from each light source 11 during this scanning, arbitrary characters and figures can be displayed in a dot pattern. can do. Here, the rotation speed of the polygon mirror 3 can be lowered in proportion to the number of arrayed laser light sources 11 compared to a conventional raster scan type device.

<Example> Embodiments of the present invention will be described below based on the drawings.

First, a schematic configuration of an embodiment of the present invention will be explained with reference to the block diagram shown in FIG.

The optical system according to the embodiment of the present invention includes an optical pink array 1 that outputs a plurality of laser beams, a polygon mirror 3 that reflects a group of laser beams from the array 1 and guides them to a screen 2, and the polygon mirror 3. It is constituted by an r/theta optical system 4 disposed along the path of the laser beam between the screen 2 and the screen 2. The control system also includes a modulation drive circuit 20 connected to the optical pickup array 1 and its signal processing circuit 21,
It is composed of a drive unit 30 that rotates the polygon roller 3, and a CPU 5 that controls a signal processing circuit 21.

Next, the structure of each part will be explained.

First, as shown in FIGS. 2 and 3, the optical pickup array 1 consists of 24 pickup modules 10.
...10 are sequentially stacked in the Y direction.

One pickup module 10 is an anamorphic pickup module consisting of a semiconductor laser 11 disposed in a cylindrical housing 14 with a diameter of 10 mm, a collimating lens 12 and two cylindrical lenses 13a and 13b sequentially disposed on the optical axis of the semiconductor laser 11. It is composed of a beam expander 13.

The wavelength of the laser beam oscillated by the semiconductor laser 11 is in the 670 nm band. Further, the collimating lens 12 has a focal length of 4.
49, and the NA is 0650. Since the output beam of the semiconductor laser 11 is an elliptical beam, the anamorphic beam expander 13 shapes it into a circular beam.
direction) Do and the short axis (Y direction) Di, the beam diameter is expanded by Do/Di times only in the Y direction using two cylindrical lenses 13a and 13b. That is, the cylindrical lens 13a.

Letting each focal length of the lens 13b be f, , f2, the following relationship holds true between the above Do and Df.

Do fz Di r Therefore, by determining the ratio of the focal lengths f, , r of the two cylindrical lenses based on this equation, the beam diameter of the output beam of the semiconductor laser 1 can be made circular.

The optical pick amplifier array 1 configured as described above outputs 21 laser beams parallel to each other in the same direction. The diameter of each beam is 8InI11, and the pitch between each beam is IOM.

Further, each semiconductor laser is independently pulse-modulated by the modulation drive circuit 20.

The polygon mirror 3 is a four-sided mirror whose aluminum alloy surface is coated with a Si○ film, and its reflectance is at a wavelength of 670 nm.
It is more than 80% of the light. Also, polygon mirror 3
As shown in FIG. 4, it has a three-tiered structure.

The Y-direction length of the -stage mirror surface is 81 marks, so the total length is 243 marks, which corresponds to the width of the laser beam group from the optical pickup array 1 in the Y direction.

The polygon mirror 3 is rotated by a drive unit 30, and by this rotation, a group of laser beams from the optical pick array 1 is scanned on the screen z in the X direction. The rotation speed of this polygon mirror 3 is set to 2250 rpm.

As a result, the scanning period of the laser beam group on the screen 2 is 15, since the polygon mirror 3 is a four-sided mirror.
It becomes 0Hz. Further, the scanning line length X is determined by the maximum value of the deflection angle θ of the polygon mirror 3 and the distance between the rotation center of the polygon mirror 3 and the screen 2, as shown in FIG.

The r/θ optical system 4 is for forming a plane image of the laser beam group reflected by the polygon mirror 3 on the screen 2. That is, the imaging plane of the laser beam scanned by the polygon mirror 3 has an arc shape, and when this is projected onto a plane, the scanning line becomes nonlinear as x = f tan θ, so as shown in FIG. An f/theta optical system 4, which is a combination of two lenses, is used to form a linear scanning line of x=f/theta.

Here, the rotation drive unit 30 moves the rotation position of the polygon mirror 3 to a previously set position, for example, the rotation position of the polygon mirror 3.
The polygon mirror 3 is configured to generate a timing pulse every time the polygon mirror 3 rotates by 90 degrees with reference to the position where the diagonal line of the polygon mirror 3 coincides with the traveling direction of the laser beam group from the optical pink-up array 1. That is, each time the laser beam group scans one frame on the screen 2 by the rotation of the polygon mirror 3, a timing pulse is output from the rotation drive unit 30, and this timing pulse is input to the signal processing circuit 21.

The signal processing circuit 21 uses the timing pulse from the rotary drive unit 30 as a synchronization signal to time-divide the period (1/150 seconds) during which the laser beam group scans the screen 2 for one frame, and processes the data according to information from the CPU 5. The semiconductor laser 11.
... is configured to supply a command signal to the modulation drive circuit 20 in order to perform eleven pulse modulations.

According to the embodiment of the present invention having the above configuration, the polygon mirror 3
By rotating the screen 2, 24 laser beams can be scanned simultaneously on the screen 2, and by independently modulating each semiconductor laser 11 during the scanning, the ON/OFF state of each laser beam output can be controlled. It becomes possible to control the OFF state, and thereby a dot pattern of 24 dots in the Y direction, such as characters or figures, can be displayed on the screen z.

When the above-described embodiments of the present invention are used as road information display devices, there are great advantages over conventional self-luminous display boards. In other words, the conventional display board is configured such that light sources such as incandescent lamps are arranged in a dot matrix of 15 x 13 per character, and an arbitrary character is displayed by turning each lamp on and off. I needed a lamp.

Therefore, for example, to display 10 characters, 1950
lamps are required, and the total weight of the display device is 3000 ~
It had reached around 4000 kg.

Moreover, its power consumption is as high as 3.5 Kw. In contrast, in the device of the present invention, in order to display equivalent information, the number of semiconductor lasers may be approximately 30 to 40.
The number of lamps can be reduced to about 1,150 or less compared to the conventional 1,950 lamps. Therefore, the overall weight of the device is extremely light, and installation work and maintenance of the device are facilitated.

Furthermore, the power consumption is less than 1/10 of the conventional one, which is advantageous in terms of running costs. Furthermore, since it is a screen illumination method, the viewing direction can be said to be almost all directions in front of the screen. Note that the output power of the semiconductor laser is sufficient for use as a display device at the current technology level.

<Effects of the Invention> As explained above, according to the present invention, a plurality of laser light sources are arranged in the direction of the primary source, and a group of laser light from the laser light sources is guided onto the screen by a polygon mirror. By rotating only the polygon mirror, it is possible to scan the laser beam over the entire surface of the screen, which simplifies the structure and makes optical adjustments and other tasks extremely easy compared to conventional raster scan systems. Become. Further, a synchronizing laser, a control circuit, etc. of the vertical synchronization system are not required. Furthermore, the rotation speed of the polygon mirror can be lowered compared to the conventional one, and the life of its drive mechanism etc. is greatly improved.

Furthermore, when the device of the present invention is used, for example, as a road information display device, it can be made smaller and lighter in weight and consume less power than conventional self-luminous display boards. The effect is also great.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. FIG. 2 is a longitudinal sectional view of the optical pickup array 1, and FIG. 3 is a front view thereof. FIG. 4 is a side view of the polygon mirror 3. FIG. 5 is an explanatory diagram of the r/θ optical system 4. FIG. 6 is a block diagram showing an example of the configuration of a conventional raster scan type laser display device. 1... Optical pickup array 2... Screen 3... Polygon mirror 4... f/θ optical system 5... CPU 11... 11... Semiconductor laser 20... Modulation drive circuit 21...Signal processing circuit 30...Rotation drive unit

Claims (1)

[Claims] A plurality of light sources that are arranged in one dimension and output laser beams in the same direction and parallel to each other, and a polygon mirror that reflects all the laser beams from the group of laser light sources and guides them to the screen. , a driving means for rotating the polygon mirror around an axis parallel to the arrangement direction of the light sources, and a control means for individually controlling laser light outputs of the plurality of light sources.