Optical pattern detecting apparatus

An optical pattern detecting apparatus has a ball lens (2), a light emitting device such as LED (3) and a light receptor such as photodiode (4), the latter two (3, 4) being disposed side-by-side with their optical axis substantially in parallel so that light from the light emitting device (3) passes is converged by the ball lens (2) onto barcode mark (7) and light reflected from said barcode mark (7) is guided by the same ball lens (2) to the light receptor (4); and by use of the ball lens, the apparatus can stably detect the barcode mark even at inclination of the apparatus to the surface of the barcode mark.

FIELD OF THE INVENTION AND RELATED ART STATEMENT 
1. Field of the Invention 
The present invention relates to an optical pattern detecting apparatus for 
detecting a barcode for identifying a commodity printed by or affixed to 
the commodity, a barcode for recognizing the data for reservation of a TV 
program in the video tape recording program system and various other 
patterns recognition apparatuses. 
2. Description of the Related Art 
In recent years, in product shipping sections in factories, department 
stores and the like, a barcode system has been widely adopted. In the 
system, a seal or the like indicating a barcode is affixed to or directly 
printed on a packing box or the like, to identify a large quantity of 
commodities. And the barcode is read optically to perform controls of 
going-in and -out and stocks of commodities. Besides, in the case of 
recording a TV program, a system begins to be employed which makes 
reservation processing by optically reading the barcode of a program from 
a barcoded table of stations or channels, the dates and the like, to 
reserve in advance the program desired to be recorded. 
Various barcode sensors are employed for reading such barcodes, and among 
them, for a pen-type sensor for reading still barcodes while held by hand 
and moved on the barcode surface. A barcode sensor as shown in FIG. 5 has 
been known so far. 
FIG. 5 shows a conventional barcode sensor, wherein a casing 11, there 
provided LED 12 as a light source, optical fibers 13 for transmitting 
light from the LED 12 to a tip reading part 14 of the casing 11. A read 
hole 15 is formed at the center of the tip reading part 14 for introducing 
light reflected on the barcode surface. A convex lens 16, a light stop 17 
and an aperture 18 are provided between a photoreceptor 19, such as in 
phototransistor and the read hole 15. The photoreceptor 15 receives the 
light condensed in the aperture 18 and converts it into an electric signal 
and gives it to an amplifier 20 wherefrom output signal is issued. 
Light from the LED 12 is irradiated from the tip reading part 14 onto the 
barcode surface through the optical fibers 13. Light signal based on high 
level and low level of the reflected light caused by the white portion and 
the black portion of the barcode is introduced through the read hole 15, 
travels through the convex lens 16, the stop 17 and the aperture 18, and 
is detected by the photoreceptor 19. The output signal of the 
above-mentioned amplifier 20 is shaped into accurate pulse signals by 
waveform shaping circuit, and is inputted to a microcomputer, and the 
content of the barcode is decoded. 
In the above-mentioned conventional constitution, light from the LED 12 is 
introduced into the optical fibers 13 and the light is irradiated without 
lens onto the barcode surface to form a spot light. Therefore, the 
efficiency of condensing light is low, and thereby a satisfactory quantity 
of light is not obtainable, and the length of light path is long. Thereby, 
the size of the apparatus becomes large, and expensive parts such as 
optical fibers are required. Resultantly, the number of parts becomes 
large, and the cost becomes high including the cost required for 
assembling and adjustment increases. Besides, a detection error is liable 
to be produced due to inclination from the posture of normal to the 
barcode surface, and thereby the operability is poor. 
OBJECT AND SUMMARY OF THE INVENTION 
In light of the above-mentioned conventional problems, the present 
invention purposes to provide an optical pattern detecting apparatus of 
small-sized and simple constitution, which can be fabricated at a low 
cost, and has a good operability. 
The optical pattern detecting apparatus in accordance with the present 
invention comprises: 
a light emitting device, 
a photoreceptor, 
a common lens which condenses light irradiated from the light emitting 
device onto a surface having a pattern and further guides light reflected 
from the surface to the photoreceptor, and 
a common light stop installed between the light emitting device and the 
lens, as well as, between the photoreceptor and the lens. 
In addition, the above-mentioned light source part is preferably 
constituted with the light emitting device and a cylindrical reflecting 
surface installed in front of it. 
According to the optical pattern detecting apparatus of the present 
invention, since the light irradiated from the light emitting device 
travels through the light stop, and is converged by the ball lens and is 
irradiated in a spot shape onto the pattern detecting surface, a 
satisfactory amount of light is obtainable, and the diameter of the spot 
can be set to a required uniform value by means of the light stop. 
Therefore a high resolution can be secured. Also, since the reflected 
light is received by the photoreceptor through the same ball lens and the 
same light stop, a simple and compact constitution is made with the light 
emitting device, and photoreceptor, the light stop and the ball lens. 
Thereby, a small-sized and economical detecting apparatus is provided. 
Furthermore, since the light is condensed in a spot shape by the ball 
lens, a detection error is hard to be produced even if the apparatus is 
inclined from the state that light axis of the apparatus is normal to the 
pattern detecting surface. Thereby, the operability can be much improved. 
In addition, by installing a cylindrical reflecting surface in the light 
source part, the distribution of light quantity on the light emitting 
surface of the light emitting device can be properly adjusted.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Hereinafter, description is made on a preferred embodiment in accordance 
with the present invention based on FIG. 1 through FIG. 4. 
A casing 1, for instance, of plastic mold consists of two half parts to be 
bonded at the plane including the center-axis, and the both half parts are 
connected by a disengageable engagement means 101, 102. A ball lens 2 is 
disposed at one end in the center-axial direction of this casing 1, and a 
light emitting device such as LED 3 and a photoreceptor such as a 
photodiode such as a photodiode 4 are disposed apart by a proper distance 
from this ball lens 2 with their optical axes in substantially parallel 
relation to and on both sides of the center-axis of the casing 1. Then, a 
light stop 5 is disposed at a proper position between the ball lens 2 and 
the light emitting device 3 and the photoreceptor 4 in a manner concentric 
with the center-axis of the casing 1. In front of the light emitting 
device 3, a cylindrical reflecting surface 6 is formed in a manner that 
the outer periphery of the light emitting device 3 is extended in the 
center-axial direction. 
The relative arrangement of the light emitting device 3, the photoreceptor 
4, the light stop 5 and the ball lens 2 of the embodiment is set in a 
manner that: among the light irradiated from the light emitting device 3, 
the rays passing through the light stop 5 reaches the ball lens 2, and is 
condensed on a pattern detecting surface 7 which is located with a 
predetermined gap, for example, 0.5 mm from the ball lens 2 on the 
center-axis of the casing 1. Further, the diameter of hole of the light 
stop 5 is set so that the diameter of the spot light on the pattern 
detecting surface becomes about 200 .mu.m. 
In addition, the apparatus is constituted in a manner that the outside of 
the casing 1 is covered with a covering sheath 8, so that the tip portion 
of this sheath 8 is to be slided along over the pattern detecting surface 
7. Thereby, the interval between the ball lens 2 and the pattern detecting 
surface 7 is kept at the above-mentioned predetermined value. The outer 
surface of the tip portion is formed in such a spherical shape that the 
spot light does not deviate largely from the pattern detecting surface 7, 
even if the apparatus is inclined to the normal of the pattern detecting 
surface 7. 
Next, description is made on the operation of the above-mentioned 
embodiment. On a chip 3a of the light emitting device 3, as shown in FIG. 
3, an electrode 3c is formed at and covering the center portion of a light 
emitting surface 3b. Therefore, the distribution of light irradiated from 
this light emitting device 3 has a dip at the center portion as shown by a 
full line curve in FIG. 4. However, in the above-mentioned constitution, 
the light irradiated onto the periphery is reflected by the cylindrical 
reflecting surface 6 installed in front of the light emitting diode 3, and 
hence is condensed on the center portion. Therefore, as shown by a broken 
line curve in FIG. 4, such a satisfactory distribution of light quantity 
is obtained that the light quantity of the center portion is maximum. The 
component of light, which is irradiated from the light emitting device 3 
but is adjusted of its distribution of light quantity by the cylindrical 
reflecting surface 6 around the light path, further is limited by the 
light stop 5 and then reaches the ball lens 2. Such adjusted and limited 
light beam is irradiated in a spot of uniform light distribution on the 
pattern detecting surface 7 at the position facing the center-axis of the 
casing 1. Since this spot light is set to about 200 .mu.m as mentioned 
above, a detection with high resolution can be performed. The light is 
reflected from the pattern detecting surface 7 and travels along a light 
path which is in symmetry to the light path of the above-mentioned 
irradiated light with respect to the center-axis of the casing 1. The 
reflected light is finally received by the photoreceptor 4 through the 
ball lens 2 and the light stop 5. Then, a change of quantity of the 
reflected light due to a barcode or the like pattern is detected by this 
photoreceptor 4, and is converted into an electric signal. Thereby, the 
information of the pattern is read from the electric signal. 
Although the invention has been described in its preferred form with a 
certain degree of particularity, it is understood that the present 
disclosure of the preferred form has been changed in the details of 
construction and the combination and arrangement of parts may be resorted 
to without departing from the spirit and the scope of the invention as 
hereinafter claimed.