JPS5845742B2 - optical scanning device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in an optical scanning device that draws scanning lines for reading barcodes.

Recently, in supermarkets, etc., in order to automatically manage sales and inventory, etc., barcodes are attached to products, and the barcodes are scanned using optical scanning to detect the reflected light from the barcodes. A device has been proposed that converts the signal into an electrical signal and inputs it into an electronic computer.

Although there are various means for drawing this scanning line, the present inventors have previously proposed a scanning device using a hologram that is inexpensive and capable of drawing any scanning mode.

This apparatus is shown in FIG.

As shown in the figure, a plurality of hologram pieces 2 are provided on the circumference of a disk 1, and the hologram pieces 2 are irradiated with a laser beam 3 from a laser nave LA to rotate the disk 1 in the direction of arrow A.

There are two types of hologram pieces 2, one for drawing long scanning lines, indicated by 7, and one for drawing short scanning lines, indicated by 8.

The scanning line 7 is deflected by the prism 4 and projected onto the reading window 9.

The scanning line 8 is rotated 900 times by the dope prism 5 to become a scanning line 8', which is reflected by the reflecting mirrors 6a and 5b and overlapped with the scanning line I at the reading window 9.

However, according to this device, in order to draw the scanning line I and the scanning line 8 separately, the scanning line 8 is drawn at a position where the laser beam 3 is deflected by a predetermined angle. The scanning line 8 is projected obliquely onto the reading window 9.

When reading a UPC (Universal Product Code) label, orthogonal scanning lines are required.

Therefore, it is necessary to overlap the scanning line 7 as shown in FIG.

Then, as is clear from the figure, the area where the scanning lines 7 and 8 are orthogonal becomes narrower, and the reading area becomes narrower.

Next, to explain the reason why the scanning line 8 is projected obliquely to the reading window, the hologram piece 2 is made by cutting out a part surrounded by a rectangular frame from a hologram plate 10 having an image forming function, as shown in FIG. I'm using something like this.

The deflection direction at the center of each hologram piece is line 11
a, 11b, 11c, and 11d, and are focused at a focal point.

The hologram pieces cut out as shown in FIG. 4 are placed on the circumference of the disk as shown in FIG.

Each hologram piece is irradiated with a laser beam 3 at a specific location, and since each hologram has a deflection angle as shown in FIG.
When rotated, when the laser beam irradiates the center of each hologram piece, the laser beam becomes a line 11a', 1 lb'
, 11c', and 11d', and a straight line 12 is formed by connecting the imaging positions.

This imaging position rotates left and right by the same amount from the straight line 12 around the center 02.

Therefore, scanning lines as shown in FIG. 2 are drawn.

For this reason, the present inventors previously proposed the following optical scanning device in Japanese Patent Application No. 51-158673 (Japanese Unexamined Patent Publication No. 53-101443).

That is, by cutting out a hologram piece in a direction perpendicular to a line sh inclined by a deflection angle δ with respect to the center line Wa, as shown in FIG. I tried to draw a scanning line.

However, since the hologram pieces are cut out to have the same length as shown in FIG. 6, the actual scanning lines have different lengths as shown in FIG.

For this reason, the size of the scanning window must be adjusted to the length of the shortest scanning line, making it impossible to obtain a large scanning window.

To obtain a large scan window, the shortest scan line must be made longer.

For this purpose, the hologram piece can be made longer, but
The longer scanning line becomes even longer, drawing unnecessary γS scanning lines, and the reading speed becomes slower by this amount.

Furthermore, as the hologram piece becomes longer, the disk becomes larger.

The purpose of the present invention is to eliminate such drawbacks, and the purpose is to create a system in which lines connecting respective focal points from a rotating disk and a member provided on the disk and having a function of converging light. It has a deflection piece cut out to pass through the center of rotation of the disk, a light beam that irradiates the deflection piece, and a rotating optical system, and irradiates the deflection piece at one point of the rotating disk and passes through the deflection piece. In an optical scanning device that draws a scanning line by rotating the beam by the rotating optical system and projecting it onto a reading window, the length from the center of the rotating disk to the position where the deflection piece is placed is R.
', the angle between the lines connecting both ends of the scanning line of the desired length to be drawn and the center of the rotating disk is θ, the radius of the rotating disk is R2 the length between the scanning lines is H2 times the reference from the edge of the rotating disk An optical scanning device characterized in that a deflection piece cut out so that the length to the scanning line is h, the length of the deflection piece becomes R·θ(R+h )/(R+h )+H and arranged on a rotating disk.

The present invention will be described in detail below based on examples.

In the present invention, as shown in FIG. 9, each hologram piece is cut out so that its length is non-uniform.

By cutting out in this manner, scanning lines of uniform length as shown in FIG. 10 can be drawn.

This will be explained with reference to FIGS. 11 and 12.

The scanning line drawn by placing the hologram piece cut out as shown in FIG. 9 on the disk becomes as shown in FIG. 11.

Here, a case where scanning lines A and C are made to have the length of scanning line B will be described.

If the radius of the disk is R, the length from the outer edge of the disk to the scanning line B is h, and the angle with respect to the center is θ, then the length BL of the scanning line B is BL=(R+h)・θ...・・・
(1) becomes.

Similarly, the length from scanning line B to scanning lines A and C is H.
Then, the length AL of scanning line A is AL-((R0h)-H)・θ...
(2), and the length CL of the scanning line C is CL=((R+h)+H)・θ...
・(3) becomes.

Here, in order to set BL=AL=CL, the angles of the scanning lines must be adjusted by θ' and θ'', as shown in FIG.

Therefore, formula (2) can be changed to AL-((R1h)-H)・θ'...
(4) and formula (3) as CL-1(R+h)+H)・θ" ・・・・・・・
... (5) may be used.

Calculating the θ′ and θ′bo values, respectively, L From BL Then, From CL=BL becomes.

This angle is equal to the angle between the ends of the hologram piece and the line connecting the center O of the disk 12.

Therefore, if the length between the position of the hologram piece on the disk and the center of the disk 12 is R', then the length of each hologram piece is as follows.

Next, the cutout positions of the hologram pieces having lengths HA, HB, and HC will be explained with reference to FIG. 13.

The deflection angle of each hologram piece is equal to the angle between each hologram piece and the center 02 of the hologram plate.

Therefore, the hologram piece h that draws the scanning line B is centered at a position on the center line and the same distance as the line segment SB from the center 02, and the hologram piece a that draws the scanning line A is tilted by QA with respect to the center line. , and the hologram piece C is centered at a position separated from the center line 02 by the same distance as the line segment SA, and the hologram piece C is tilted by DC with respect to the center line and is separated from the center line by the same distance as the line segment SC. Cut the length according to the formula.

As described above, according to the present invention, it is possible to make the length of the scanning lines uniform.

I explained above using a hologram piece as an example, but it is a cutout of a convex lens.

It may also be cut out from a diffraction grating created by cutting grooves.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an optical scanning device to which the present invention is applied, FIGS. 2, 3, and 5 are diagrams showing scanning lines drawn by a conventional device, and FIG. 4 is a diagram showing a scanning line drawn by a conventional device. Figure 6 is a diagram showing a method of cutting out a hologram piece that was previously proposed by the present invention, and Figure 7 is a diagram showing a method of cutting out a hologram piece as previously proposed by the present invention.
8 is a diagram showing the scanning line drawn by the hologram piece cut out as shown in FIG. 6, FIG.
Figure 0 shows the scanning lines drawn by hologram pieces cut out by the method shown in Figure 9, and Figures 11 and 12 show the steps for determining the length of each hologram piece to draw scanning lines of uniform length. 13 are diagrams for explaining the cutout position of the hologram piece. In the figure, 1 is a disk, 2 is a hologram piece, and 3
is a laser beam, 4 is a prism, 5 is a dope prism, 6a
, 6b is a reflecting mirror, 7 and 8 are scanning lines, 9 is a window, and 10 is a hologram plate.

Claims (1)

[Claims] 1. A rotating disk, and a deflection piece cut out from a member provided on the disk and having a function of converging light so that a line connecting each focal point passes through the center of rotation of the disk. , has a light beam that irradiates the deflection piece, and a rotating optical system, irradiates the deflection piece at one point of the rotating disk, and rotates the beam that has passed through the polarization piece by the rotating optical system onto the reading window. In an optical scanning device that draws a scanning line by superimposing a projection on the surface of the disk, the length from the center of the rotating disk to the position where the deflection piece is placed is R'. The angle between the line connecting both ends of the scanning line of the desired length to be drawn and the center of the rotating disk is θ, and the radius of the rotating disk is R2.
If the length between the scanning lines is H, and the length from the edge of the rotating disk to the reference scanning line is h, then cut out the length of the deflection piece so that it becomes R'・θ(R+h)/(R+h)±H. An optical scanning device characterized in that an object is arranged on a rotating disk.