JPH10122863A - Method and device for displaying light spot - Google Patents

Abstract

PROBLEM TO BE SOLVED: To display light spots on the surface of a ceiling by maintaining the distance between two spots which become reference points at the same value even when the distance between a light source and surface of the ceiling varies. SOLUTION: A light spot displaying device is provided with a laser oscillator 5 which emits light toward a ceiling at a distance from the surface 100 of the ceiling, a convex lens 6 which is positioned in the middle of the route of light to the surface 100 from the oscillator 5 and expands the light emitted from the oscillator 5, a light shielding plate 8 which is positioned in the middle of the route of light to the surface 100 from the lens 6 and has a plurality of through holes corresponding to the light spots displayed on the surface 100, and a lens moving device 7 which changes the length of the route of light between the lens 6 and light shielding plate 8 by moving the lens 6. The advancing direction of the light passed through the trough holes of the plate 8 is changed by changing the distance between the lens 6 and plate 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light spot display method and a light spot display device. The present invention relates to a light spot display method and a light spot display device.

[0002]

2. Description of the Related Art Positioning when an anchor or the like is hit on a ceiling has been conventionally performed by the following method.

[0003] That is, a method of climbing a stepladder and directly applying a measure to the ceiling surface to measure and position, a method of measuring a reference point on a floor surface corresponding to the ceiling surface, and climbing the stepladder to determine a reference value of the floor surface. This is a method in which the point is moved downward and the corresponding ceiling is marked out.

[0004] However, the above-mentioned method is a very dangerous operation, and the above-mentioned method cannot be performed unless there are two workers, and it takes a long time to settle down. .

Therefore, as a method for solving this problem, a method described in Japanese Utility Model Laid-Open Publication No. 64-34507 has been proposed. In this method, first, a reference point is dimensioned on the floor surface corresponding to the ceiling surface, and then a reference position indicator for emitting a laser beam is installed at the reference point on the floor, and the laser beam is emitted from the reference position indicator. The light spot is displayed by irradiating the ceiling with the laser beam, and then climbing on a stepladder to mark the light spot on the ceiling. If positioning is performed by this method, it is not necessary to measure the size by applying a measure to the ceiling surface, so that dangerous work is reduced, and the work can be performed by one person.

However, in this method, only one light spot is displayed on the ceiling by one operation, and when positioning a plurality of points, a plurality of reference points are provided on the floor surface and each reference point is provided. It was necessary to perform positioning at each point while moving the reference position indicator, which was troublesome and took a long time to work.

Therefore, as disclosed in JP-A-5-285861, there has been proposed an apparatus capable of simultaneously performing a plurality of positioning operations. In this apparatus, a halogen bulb is irradiated from below the transparent film on which the installation position of the ceiling appliance is drawn, and an image of the transparent film is projected on the ceiling surface to perform positioning. By doing so, it is possible to simultaneously position a plurality of points simply by drawing a plurality of installation positions on the transparent film in advance.

[0008]

However, in the apparatus described in Japanese Patent Application Laid-Open No. 5-285611, when the height from the light source to the ceiling changes, the installation position of the ceiling fixture projected on the ceiling shifts. I will.

To cope with this, two methods can be considered. One is a method of preparing several kinds of transparent films corresponding to the height dimension to the ceiling in advance. This method requires a number of transparent films having different height dimensions to the ceiling, and the number is infinite and impractical.

Another method is to prepare a gantry, a spacer or the like having a required height and arrange it between the floor and the apparatus so that the height from the light source to the ceiling is always the same. Is the way. However, this method also requires as many mounts and spacers as there are different heights to the ceiling, and the number is infinite and impractical. In addition, there is a problem that it is not possible to cope with a case where the height to the actual ceiling surface is lower than the reference height to the ceiling surface of the device.

The present invention has been made to solve such a conventional problem. Even if the distance to the ceiling changes, the distance between two reference light spots with respect to the ceiling is displayed in the same manner. It is an object of the present invention to provide a light spot display method and a light spot display device capable of arbitrarily changing a distance between two light spots which is a reference when a distance from the ceiling to the ceiling is constant. I do.

[0012]

The present invention has the following features to attain the object mentioned above.

(1) That is, in the light spot display method according to the present invention, light emitted from a light source is spread through an optical element, and then irradiated on a light-shielding plate having a plurality of through-holes. In the light spot display method of projecting a plurality of light spots corresponding to the through holes on the display target by projecting the light source on the display target, by changing a separation dimension between the optical element and the light shielding plate, Are characterized by displaying the same distance between two reference light spots on display objects having different distances.

Even if the distance between the light source and the display object changes, the direction of light emitted from the through hole is changed by changing the distance between the optical element and the light shielding plate having the through hole. The distance between the two light spots displayed on the display object can be the same.

The two reference light spots displayed on the display objects having different distances from the light source may be any light point as long as the positional relationship between the display objects corresponds.

(2) In another light spot display method according to the present invention, a light emitted from a light source is spread through an optical element, and then is applied to a light-shielding plate having a plurality of through-holes. In the light spot display method of projecting a plurality of light spots corresponding to the through holes on the display target by projecting the light source on the display target, by changing a separation dimension between the optical element and the light shielding plate, The present invention is characterized in that display objects located at the same distance are displayed by changing the distance between two reference light spots.

For a display object located at the same distance from the light source, by changing the distance between the optical element and the light shielding plate, the direction of the emitted light passing through the through hole is changed, and the display object is displayed. The position of the light spot to be made can be changed. Therefore, the distance between the two light spots displayed on the display object can be changed.

As the reference two light spots displayed on the display objects having the same distance from the light source, any light point may be selected as long as the positional relationship between the display objects corresponds.

(3) A light spot display device according to the present invention is a light spot display device which emits light and displays a light spot on a display object. (A) A light source which is located apart from the display object and emits light. (B) an optical element arranged in the path of light from the light source to the display object to spread the light emitted from the light source; and (c) an optical element in the path of light from the optical element to the display object. (D) moving at least one of the optical element and the light shielding plate to move the optical element and the light shielding plate; And a variable means for varying the length of a light path connecting the two.

After the light emitted from the light source is passed through the optical element and spread, the light is applied to a light-shielding plate having a plurality of through-holes, and the light transmitted through the through-holes is projected onto an object to be displayed, thereby corresponding to the through-holes. A plurality of light spots are displayed on the display object.

The light source can be exemplified by a laser oscillator, but is not limited to this. When the light source is a laser transmitter, the laser light emitted from the laser oscillator is parallel light, and all the laser light is incident on the optical element and spread, so that there is no waste of energy.

The optical element may have any configuration as long as it has a function of expanding transmitted light.
Optical lenses (such as a combination of a convex lens, a concave lens, a cylindrical lens, and two concave and convex lenses) can be exemplified.

When a convex lens is used, the light emitted from the convex lens passes through the focal point of the convex lens, spreads, and is irradiated on the light shielding plate. The shape of the through hole provided in the light shielding plate,
Various shapes such as a circle, a star, and a cross can be adopted.

The light source, the optical element and the light shielding plate are similarly applied to the light spot display method described in the above (1) and (2). The variable means may be configured to move the light shielding plate by fixing the optical element, or may be configured to move the optical element by fixing the light shielding plate, or the optical element and the light shielding plate May be moved at the same time, and as long as the length of the light path connecting the optical element and the light shielding plate can be made variable.

The angle of incidence of light entering the through hole can be changed by moving the optical element or the light shielding plate by the variable means to change the length of the light path connecting the optical element and the light shielding plate. .

Thus, even if the distance between the optical element and the display object changes, the distance between the two light spots, which are the reference points displayed on the display object, can be adjusted to the same value.
Alternatively, the distance between two reference light points can be changed for a display object located at the same distance from the light source.

That is, by using the light spot display device, the light spot display methods (1) and (2) can be performed. The light spot display device according to the present invention is configured such that any one of a distance between the light source and the display target and a distance between two reference light spots displayed on the display target is constant. To
A scale having an index corresponding to the other remaining separation dimension, and a pointer which moves in accordance with the separation dimension between the optical element and the light shielding plate and indicates the index of the scale corresponding to the separation dimension, Is also good.

The scale will be described in detail. When the distance between the light source and the object to be displayed is different, the light point display device is designed so that the distance between the two light spots as the reference displayed on the object to be displayed is constant. When it is desired to use the scale, the scale index corresponds to the distance between the light source and the display target. With this configuration, the distance between the two reference light spots can be easily made constant simply by adjusting the pointer to the index corresponding to the distance between the display object to be displayed and the light source.

Further, when it is desired to use a light spot display device so that the distance between two reference light spots can be varied for a display object whose distance from the light source is always constant.
It is assumed that the scale index corresponds to the distance between two light spots serving as references displayed on the display object. With this configuration, the distance between the two reference light spots can be easily adjusted to the desired size simply by adjusting the pointer to the index corresponding to the desired distance between light spots.

The objects to be displayed in the inventions described in the above (1), (2) and (3) are not particularly limited as long as they can display light spots, and include wall surfaces including ceiling surfaces, floor surfaces, and side walls. Examples can be given.

The light spot display device of the present invention can be used when the display object is a wall surface and the wall surface is blacked out.

[0032]

FIG. 1 is a block diagram showing an embodiment of the present invention.
Will be described with reference to the drawing of FIG.

[First Embodiment] A first embodiment of a light spot display device according to the present invention will be described with reference to FIGS. It should be noted that the light spot display device according to the present embodiment is used in a case where blackout is performed on a ceiling surface of a building.

As shown in FIGS. 1 and 2, the light spot display device 1 is configured such that a frame 3 is rotatably attached to a support leg 2 by a coupler 4. The light spot display device 1 is installed on a floor surface 110 located below a ceiling surface (display target) 100 to be marked out by the support legs 2.

A coupler 4 for rotatably connecting the support leg 2 and the frame 3 has a structure like a universal joint. The frame 3 swings three-dimensionally with respect to the support leg 2 in almost all directions. It has a function to enable it. Since the coupler 4 is a well-known technique, a detailed description thereof will be omitted.

The frame 3 has a box shape having an opening 3a at the top, and its interior is divided into upper and lower rooms by a partition plate 3b provided below the coupler 4. On the frame 3, a laser transmitter (light source) 5, a convex lens (optical element) 6, a lens moving device (variable means) 7, a light shielding plate 8, and a battery 9 are attached.

More specifically, a light-shielding plate 8 is attached to the opening 3a of the frame 3. As shown in FIG. 3, the light-shielding plate 8 is formed in a circular sheet shape, and a large number of through-holes 10 formed through the light-shielding plate 8 are arranged vertically and horizontally at a predetermined equal pitch. Through hole 1
0, the through hole 10a located at the center of the light shielding plate 8 is formed to have a slightly larger diameter than the other through holes 10, and the center through hole 1
0a can be distinguished.

On the upper surface of the partition plate 3b and on the axis of the frame 3, a laser transmitter 5 for emitting a laser beam toward the light shielding plate 8 is provided. The convex lens 6 supported by the lens moving device 7 is arranged between the light shielding plate 8 and the light shielding plate 8. Here, the central axis of the laser light emitted from the laser transmitter 5, the optical axis of the convex lens 6, and the central axis of the central through hole 10a in the light shielding plate 8 coincide with the axis A of the frame 3. Is set.

The convex lens 6 is moved by the lens moving device 7
The convex lens 6 is supported concentrically with the light shielding plate 8 while keeping the optical axis of the convex lens 6 and the central axis of the through hole 10a concentrically. As shown in FIG. 4, the lens moving device 7 includes a handle 11 rotatably supported by the frame 3, a pinion gear 12 connected to the handle 11 and rotating synchronously with the handle 3, and meshes with the pinion gear 12 to vertically move the frame 3. It comprises a rack gear 13 movably mounted and a support arm 14 fixed to the rack gear 13, and the convex lens 6 is fixed to the tip of the support arm 14.

By rotating the handle 11 of the lens moving device 7 forward or backward, the convex lens 6 approaches or separates from the light-shielding plate 8, and the separation dimension C between the convex lens 6 and the light-shielding plate 8 can be changed. Thereby, the length of the light path can be changed.

The rack gear 13 of the lens moving device 7
A pointer 15 is fixed to the frame 3. The pointer 15 is inserted into a vertically extending insertion hole 16 provided in the frame 3, and moves up and down on the outside of the frame 3 as the rack gear 13 moves. I have.

A scale 17 is displayed on the outer surface of the side of the insertion hole 16 of the frame 13 as shown in FIGS.
The tip of the pointer 15 points to the index on the scale 17. The index of the scale 17 differs depending on how the light spot display device 1 is used, which will be described later in detail.

A battery 9 serving as a power source for the laser oscillator 5 is built in the frame 3 and below the partition plate 3b. The weight of the battery 9 is extremely heavy, so that the center of gravity of the light spot display device 1 excluding the support legs 2 is
It is arranged below the connector 4 for connecting the support leg 2 and the frame 3. Therefore, the axis A of the frame 3 always faces in the vertical direction, so that the direction of the laser beam emitted from the laser transmitter 5 can always be vertically upward.

Further, a projection 18 extending downward is provided on the bottom surface of the frame 3 and on the axis of the frame 3, and this projection 18 is directed vertically downward.
Next, a method of using the light spot display device 1 will be described. This light spot display device 1 can be used for implementing the following light spot display methods (i) and (ii).

(I) A display method in which, with respect to a plurality of ceiling surfaces 100 having different distances from the floor 110, the distance between two reference light spots displayed on the ceiling 100 is kept constant. Hereinafter, this display method is referred to as a first display method.)

(Ii) For a plurality of ceiling surfaces having the same distance from the floor surface 110 to the ceiling surface 100, the distance between two reference light spots displayed on the ceiling surface is changed to a desired size. A display method for displaying the display (hereinafter, this display method is referred to as a second display method) Hereinafter, a method of using the light spot display device 1 in each display method will be described.

(I) First Display Method When the light spot display device 1 is used for the first display method, the height (separation dimension) H from the floor surface 110 to the ceiling surface 100 is used as an index of the scale 17. A dimension (numerical value) corresponding to is attached.

A ceiling surface 100 from which ink is to be obtained
Is measured in advance to the floor surface 110 therebelow, and the floor surface 110 is previously marked with a center point B immediately below the position of the ceiling surface 100 as the center of the mark. .

Next, the light spot display device 1 is arranged so that the tip of the projection 18 is located above the center point B that has been marked on the floor surface 110. Then, the handle 11 is rotated so that the pointer 15 of the lens moving device 7 points to a previously measured index on the scale 17 indicating the distance from the floor surface 110 to the ceiling surface 100.

Next, a switch (not shown) is turned on to electrically connect the battery 9 and the laser transmitter 5, and the laser beam 20 is emitted from the laser oscillator 5. Laser light 20
Is expanded when passing through the convex lens 6 and illuminated on the light-shielding plate 8, and only light that has passed through the through holes 10 and 10 a of the light-shielding plate 8 is illuminated on the ceiling surface 100 and corresponds to the through-hole 10 (10 a). The light spot P is displayed on the ceiling surface 100.

For example, when the height H from the floor surface 110 to the ceiling surface 100 is 2.5 meters, the handle 1
By rotating 1, the pointer 15 is adjusted to the index "2.5" on the scale 17 as shown in FIG. Then, as shown in FIG. 1 or FIG. 7, the distance between the two light points P1 and P2 serving as the reference of the light point P displayed on the ceiling surface 100 is S.

Thereafter, for example, the height H from the floor 110
If you want to ink on the 2 meter ceiling surface 100,
By rotating the handle 11, the pointer 15 is set to the index "2.0" on the scale 17 as shown in FIG. Then, guideline 15
The convex lens 6 comes closer to the light shielding plate 8 when the index is set to the index “2.0” than when the index is set to the index “2.5”.
As a result, the spread angle of light passing through the through hole 10 increases.

As a result, also in this case, as shown in FIG. 2 or FIG. 7, the distance between the reference two light spots P1 and P2 displayed on the ceiling surface 100 having a height of 2 meters is defined as:
S of the same size as that of the ceiling surface 100 having a height of 2.5 meters can be set. In other words, the position of the index on the scale 17 is set in advance so that the distance between the two reference light points P1 and P2 is the same.

The reference two light spots are not limited to P1 and P2, but may be a ceiling surface 10 having a height of 2.5 meters.
If there is a correspondence between the two light spots displayed at 0 and the two light spots displayed on the ceiling surface 100 having a height of 2 meters, any two light spots can be selected. For example, the light spots P3 and P4 in FIG. 7 may be set as two reference light spots.

As described above, the height H from the floor surface 110 is obtained.
Can be displayed with the same distance S between the two reference light points P, P, which are displayed on the ceiling surface 100.

In this embodiment, the index corresponding to the distance between the floor surface 110 and the ceiling surface 100 is indicated by a scale 17.
However, an index corresponding to the distance between the convex lens 6 and the ceiling surface 100 may be used as the scale 17.

(Ii) Second Display Method In the second display method, the height H from the floor surface 110 to the ceiling surface 100 is determined by the plurality of ceiling surfaces 100 for which ink removal is to be performed.
At the same height (for example, 2.5 meters).

When the light spot display device 1 is used for the second display method, the size corresponding to the distances S1, S2,... Sn between the two light spots P1, P2 serving as the reference is used as an index of the scale 17. (Numerical value).

A ceiling surface 100 from which ink is to be obtained
Is inscribed in advance as a center point B immediately below the position of the ceiling of the ceiling 100 on the floor surface 110 corresponding to.

Next, the light spot display device 1 is arranged so that the tip of the projection 18 is located above the center point B that has been marked on the floor surface 110. Then, the handle 11 is rotated so that the pointer 15 of the lens moving device 7 points to the index on the scale 17 indicating the desired distance between light spots.

Next, a switch (not shown) is turned on to electrically connect the battery 9 and the laser transmitter 5, and the laser beam 5 is emitted from the laser oscillator 5. Laser light 20
Is expanded when passing through the convex lens 6 and illuminated on the light-shielding plate 8, and only light that has passed through the through holes 10 and 10 a of the light-shielding plate 8 is illuminated on the ceiling surface 100 and corresponds to the through-hole 10 (10 a). The light spot P is displayed on the ceiling surface 100.

For example, when it is desired to set the distance between the two light spots P1 and P2 as the reference displayed on the first ceiling surface 100A to S1, the handle 11 is rotated and the pointer 15 is set to the index "17" on the scale 17. S1 ”. Then, as shown in FIG. 8, the distance between the two light points P1 and P2 which is the reference of the light point P displayed on the ceiling surface 100A is S1.

Thereafter, when the light point P is displayed on another ceiling surface 100B having the same height H from the floor surface 110 with the distance between the two reference light points being S2 larger than S1. By rotating the handle 11, the pointer 15 is adjusted to the index "S2" of the scale 17 to bring the lens 6 closer to the light shielding plate 8. As a result, the spread angle of light passing through the through hole 10 increases.

As a result, as shown in FIG. 9, the distance between the two reference light points P1 and P2 displayed on the ceiling surface 100B can be increased to S2. In other words, the position of the index on the scale 17 is set in advance so that the distance between the two reference light points P1 and P2 becomes a desired size.

Note that how to set the two reference light spots is free, as in the case of the first display method.

[Second Embodiment] Next, a second embodiment of the light spot display device 1 according to the present invention will be described with reference to FIGS.
2 will be described.

Light spot display device 1 according to second embodiment
Is used when the light spots are displayed on the ceiling surface to be displayed on a row-by-row basis or when only one row is displayed. The light spot display device 1 according to the second embodiment is
This embodiment differs from the third embodiment in that a cylindrical lens 19 is used instead of the convex lens 6 and that the light shielding plate 8
Since the other configuration is the same as that of the first embodiment, the same parts in the drawings are denoted by the same reference numerals, and description thereof will be omitted. The description will be omitted, and only the differences will be described below.

As shown in FIG. 9, the light-shielding plate 8 is formed in a circular sheet shape, and a plurality of through-holes 10 formed through the light-shielding plate 8 are linearly arranged at a predetermined equal pitch. Of the through holes 10, the through hole 10a located at the center of the light shielding plate 8 is formed to have a slightly larger diameter than the other through holes 10 so that the central through hole 10a can be distinguished.

The cylindrical lens 19 has no refraction in a plane including the direction of the generatrix, but produces the same refraction in a plane perpendicular to the generatrix. That is, the laser beam 36 whose beam has been narrowed down is applied to the cylindrical lens 59.
When passing through, the light becomes linear light parallel to the generating line. This cylindrical lens 19 is fixed to the tip of the support arm 14 of the lens moving device 7.

Laser light 2 emitted from laser transmitter 5
Numeral 0 passes through the cylindrical lens 19 to become linear light parallel to the generating line, and is irradiated on the straight line including the through holes 10 in the light shielding plate 8. As a result, the through hole 1 of the light shielding plate 8
Only the light that has passed through 0 and 10a is applied to the ceiling surface 100, and the light spot P corresponding to the through hole 10 (10a) is displayed on the ceiling surface 100 in a straight line as shown in FIG.

By using the light spot display device 1 in the second embodiment, as in the case of the first embodiment, (i) a plurality of distances different from the floor surface 110 are different. With respect to the ceiling surface 100, a display method of displaying a constant distance between two light spots, which are displayed on the ceiling surface 100, as a reference, and (ii) the distance between the floor surface 110 and the ceiling surface 100 is the same. With respect to the plurality of ceiling surfaces, a display method of changing the distance between two reference light spots displayed on the ceiling surface to a desired size can be implemented.
Both methods of use are the same as in the first embodiment, and a description thereof will be omitted.

[0072]

As described above, according to the light spot display method of the present invention, the distance from the light source can be reduced by changing the distance between the optical element and the light shielding plate. Different reference objects can be displayed with the same distance between two reference light spots on different display objects.

According to the second light spot display method of the present invention, the distance between the light source and the light source is changed by changing the distance between the optical element and the light shielding plate. It is possible to display the target by changing the distance between the two reference light spots.

Further, according to the light spot display device of the present invention including the light source, the optical element, the light shielding plate, and the variable means, the two light spot display methods can be easily implemented. Further, in the light spot display method of the present invention, one of the distance between the light source and the display target and the distance between the two light spots serving as the reference displayed on the display target is kept constant, and the other is left. A scale having an index corresponding to the separation dimension, and a pointer which moves in accordance with the separation dimension between the optical element and the light shielding plate and indicates an index of the scale corresponding to the separation dimension, By adjusting the pointer to the scale, the two light spot display methods can be more easily performed.

Further, by using the light spot display device according to the present invention, it is possible to easily perform a blacking-out operation on a wall surface such as a ceiling as a display object.

[Brief description of the drawings]

FIG. 1 is a sectional view of a light spot display device according to a first embodiment of the present invention.

FIG. 2 is a sectional view of the light spot display device according to the first embodiment of the present invention.

FIG. 3 is a plan view of a light shielding plate of the light spot display device according to the first embodiment of the present invention.

FIG. 4 is a perspective view of variable means of the light spot display device according to the first embodiment of the present invention.

FIG. 5 is a front view of a frame of the light spot display device according to the first embodiment of the present invention.

FIG. 6 is a front view of a frame of the light spot display device according to the first embodiment of the present invention.

FIG. 7 is a plan view showing light spots displayed on the ceiling surface by the light spot display device according to the first embodiment of the present invention.

FIG. 8 is a plan view showing light spots displayed on the ceiling surface by the light spot display device according to the first embodiment of the present invention.

FIG. 9 is a plan view showing light spots displayed on the ceiling surface by the light spot display device according to the first embodiment of the present invention.

FIG. 10 is a sectional view of a light spot display device according to a second embodiment of the present invention.

FIG. 11 is a plan view of a light shielding plate of a light spot display device according to a second embodiment of the present invention.

FIG. 12 is a plan view showing light spots displayed on a ceiling surface by the light spot display device according to the second embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 light spot display device 5 laser oscillator (light source) 6 convex lens (optical element) 7 lens moving device (variable means) 8 light shielding plate 15 pointer 17 scale 10, 10a through hole 19 cylindrical lens (light source) 100 ceiling surface (display target) P light spot

Claims (8)

[Claims] 1. A light emitted from a light source is spread through an optical element, and then irradiated on a light-shielding plate having a plurality of through-holes, and the light transmitted through the through-holes is projected on a display object to correspond to the through-holes. In the light spot display method of displaying the plurality of light spots on the display object, by changing a separation dimension between the optical element and the light shielding plate, a reference to a display object having a different distance from the light source is provided. A light spot display method, characterized in that the two light spots are displayed with the same separation dimension. 2. A light emitted from a light source is spread through an optical element, and is then applied to a light-shielding plate having a plurality of through-holes. In the light spot display method of displaying the plurality of light spots on the display object, the distance between the optical element and the light shielding plate is changed to be a reference for the display object located at the same distance from the light source. A method for displaying a light spot, wherein the distance between two light spots is changed and displayed. 3. A light spot display device which emits light to display a light spot on a display object, comprising: (a) a light source located at a distance from the display object to emit light; (C) an optical element arranged in the path of the light to the object to spread the light emitted from the light source, and (c) arranged in the path of the light from the optical element to the display object and displayed on the display object. And (d) moving at least one of the optical element and the light shielding plate to move a light path connecting the optical element and the light shielding plate. A light spot display device comprising: a variable means for changing the light spot. 4. The light spot display device according to claim 3, wherein the light source is a laser oscillator. 5. The light spot display device according to claim 3, wherein the optical element is a convex lens. 6. The light spot display device according to claim 3, wherein the light shielding plate is a fixed system, and the optical element is moved by the variable means. 7. When one of a distance between the light source and the display object and a distance between two reference light points displayed on the display object is constant, the other distance remains. A scale having an index corresponding to a dimension; and a pointer which moves in accordance with a separation dimension between the optical element and the light shielding plate and indicates the index of the scale corresponding to the separation dimension. The light spot display device according to claim 3. 8. The light spot display device according to claim 3, wherein the display target is a wall surface, and is used for marking the wall surface.