Apparatus and method for reading two-dimensional symbols

An optical reading apparatus for reading a two-dimensional symbol includes a housing having an opening portion for confronting the symbol, a gripping portion, and a serial I/F for transmitting a two-dimensional code data corresponding to the two-dimensional symbol to an external apparatus. LEDs mounted near the opening portion generate light to illuminate the two-dimensional symbol. A mirror reflects light reflected from the two-dimensional symbol toward the gripping portion. An automatic diaphragm mechanism regulates the light from the mirror. A two-dimensional type CCD generates electrical signals corresponding to the regulated light. Image processing circuits convert the electrical signals to the two-dimensional code data.

BACKROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to optical reading apparatus, and more 
particularly to optical reading apparatus which can read two-dimensional 
symbols and a method for reading the same. 
2. Description of the Related Art 
An optical reading apparatus is disclosed in U.S. Pat. No. 4,528,445. This 
optical reading apparatus is used to read a bar code of only one row as a 
one-dimensional symbol. FIG. 1 shows various symbol codes. FIG. 1 (a) 
shows a conventional bar code as a one-dimensional symbol. The 
conventional optical reading apparatus for reading the bar code is 
explained next. Light generated by a light source in a housing is 
illuminated on the bar code after being condensed. Reflected light from 
the bar code is transmitted to a reading sensor through a lens and a 
diaphragm member so that an image of the bar code is imaged on the reading 
sensor. Output signals from the reading sensor are decoded. 
Symbol codes other than the bar code are known too. In order to provide 
more information in the symbol codes and to allow the symbol code to be 
smaller or more compactly shaped, several new symbol codes have been 
adopted. For example, a two-dimensional bar code as shown in FIG. 1 (b) 
which has two or more rows of bars or a calra code as shown in FIG. 1 (c). 
These symbol codes are called two-dimensional symbols. 
An optical reading apparatus for reading the two-dimensional symbol is 
disclosed in European Laid-open Patent Publication No. 0385478 published 
Sep. 5, 1990, and shown in FIGS. 2 and 3. FIG. 2 is a perspective view of 
optical reading apparatus disclosed in the European publication. This 
optical reading apparatus 1 is a gun-shaped device having a pistol-grip 
type of handle 3, and a movable trigger 5. A detecter circuit or the like 
is activated by the operater operating the movable trigger 5. The optical 
reading apparatus 1 usually is connected to a host computer via a wire 
cable 7. A plastic housing 9 contains a light source, a detecter, optics 
and a signal processing circuit. A light-transmissive window 11 in the 
front end of the plastic housing 9 allows the outgoing light beam 13 to 
exit and the incoming reflected light 15 to enter. 
FIG. 3 is an exploded view of the optical reading apparatus shown in FIG. 
2. The light beam 13 from the light source 17 is illuminated on a 
two-dimensionai bar code 19 through a first lens 21. The reflected light 
15 from the two-dimensional bar code 19 is transmitted to a 
light-responsive array 23 through a second lens 25 so that an image of the 
two-dimensional bar code 19 is imaged on the light-responsive array 23. An 
output of this light-responsive array 23 is transferred to a memory array 
(not shown) to provide a binary representation (bit-mapped) of the image 
of the two-dimensional bar code 19. This bit-mapped representation is 
decoded. 
The above described optical reading apparatus for reading two-dimensional 
symbol is a pistol type. Therefore, when the operator uses the optical 
reading apparatus, the accuracy of the reading can depend on the stability 
of the optical reading apparatus, based on the steadiness with which the 
user holds the apparatus. 
SUMMARY OF THE INVENTION 
Accordingly, it is an object of the present invention to provide optical 
reading apparatus which may solve the above described deficiencies in the 
related art. 
In order to achieve the above object of the present invention, there is 
provided an optical reading apparatus for reading a two-dimensional 
symbol, the apparatus including a housing having an opening portion for 
confronting the two-dimensional symbol and a gripping portion for holding 
by an operator, the apparatus comprising, means, mounted near the opening 
portion, for generating light to illuminate the two-dimensional symbol 
through the opening portion, means for directing the light reflected from 
the two-dimensional symbol toward the gripping portion, means for 
regulating the light directed from the directing means to provide 
regulated light, means, responsive to the regulated light, for generating 
electrical signals, the generating means including a plurality of 
photosensitive elements arranged in a two-dimensional form, means for 
converting the electrical signals into a two-dimensional code data. 
Further in accordance with the present invention, there is provided a 
method for reading a two-dimensional symbol using optical reading 
apparatus including a housing having an opening portion for confronting 
the two-dimensional symbol and a gripping portion for holding by an 
operator, comprising the steps of, generating light to illuminate the 
two-dimensional symbol through the opening portion, directing light 
reflected from the two-dimensional symbol toward the gripping portion, 
regulating the directed light, receiving the regulated light, generating 
electrical signals in response to the regulated light, converting the 
electric signals into a two-dimensional code data.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Preferred embodiments of the present invention will now be described in 
more detail with reference to the accompanying drawings. A first 
embodiment of the present invention will now be described with reference 
to FIGS. 4 to 11. FIG. 4 is a perspective view of an optical reading 
apparatus of a first embodiment of a present invention. FIG. 5 is a 
secticnal view of the optical reading apparatus of the first embodiment of 
the present invention. A seamless housing 101 which is made of 
light-weight materials, for example a plastic or the like, has a hole 103 
in an end of the housing 101 and an opening 105 (reading portion) in an 
other end of the housing 101. The hole 103 is provided to insert a wire 
cable 107 including a power line and signal lines and the like. The wire 
cable 107 is fixed by a protection member 109 to the housing 101. This 
optical reading apparatus 100 has an LCD (Liquid Crystal Display) 111, and 
a movable switch 113 used to designate the starting of a read operation. 
The LCD 111 is mounted in the top of the housing 101. The movable switch 
113 is mounted in the side of the housing 101. The portion of housing 101 
adjacent hole 103 is shaped as a gripping portion 102. An axis 112 of 
gripping portion 102 forms an angle larger than 90 degrees (for example 
110 degrees) with an axis 114 through the side of housing 101 terminating 
at reading portion 105, when the reading portion 105 is directed at the 
two-dimensional symbol printed on the surface of the recording media, for 
example label, gripping portion 102 forms an angle with the surface. As a 
result, an operator may easily direct the reading portion 105 on to the 
two-dimensional symbol. 
The reading portion 105 side of the housing 101 contains several light 
sources 115 and a reflecting mirror 117. Each light source 115 consist of 
an LED (Light Emitting Diode) 115a (FIG. 7) and a diffusion lens 115b made 
of a plastic to equally diffuse light from the LED. As a result, light 
from the light sources is equally illuminated on the two-dimensional code. 
The reflecting mirror 117 is mounted in the bend portion 110 of the 
housing 101 at a prescribed angle relative to a direction of the reading 
portion 105. A prism may be thus, as the reflecting mirror. 
The hole 103 side of the housing 101 contains a circuit portion 119 
connected with the wire cable 107 and a two-dimensional type CCD (Charge 
Coupled Device) 121. The circuit portion 119 includes an LCD/buzzer 
control circuit, a main control circuit, a decode circuit, a code image 
processing circuit, an image signal processing circuit and the like as 
will be described later. The circuit portion 119 is constituted by 
layering the plural substrates. Parts which constitute each circuit are 
mounted on one or both sides of each substrate. 
The two-dimensional type CCD 121 is electrically connected with the circuit 
portion 119 and aligned to receive the image from the reflecting mirror 
117. The two-dimensional type CCD 121 has plural elements arranged in a 
two-dimensional matrix (usually effective numbers of the elements are 250k 
elements, if higher resolution is needed, effective numbers of the 
elements are larger than 400k elements). While CCD 121 is provided as a 
two-dimensional light-responsive device, other types of light-responsive 
devices are also suitable. 
The optical reading apparatus 100 in this invention has an automatic 
diaphragm mechanism 123, combination lenses 125 and a filter 127 for 
eliminating useless light, such as ambient light between the reflecting 
mirror 117 and the two-dimensional type CCD 121. Regulating means 
comprises the automatic diaphragm mechanism 123, the combination lenses 
125, the filter 127 and the like. 
The automatic diaphragm mechanism 123 will now be explained. There are 
various kinds of recording media carrying optically readable information, 
such as the two-dimensional symbol. For instance, taking an example of 
calra code labels, it is to be noted that the reflection factor of the 
calra code labels has a variation due to the difference in color, material 
or due to a stain thereon. Since the optical reading apparatus 100 detects 
the information of the calra code from the difference in reflection factor 
between dark (black) blocks and light (white) blocks, an amplitude of the 
output signal from the two-dimensional type CCD 121 used in the optical 
reading apparatus 100 is small when the reflection factor is low. On the 
other hand, when reading the calra code printed on a high reflection 
factor label, the output signal exhibits large amplitude. In this way, the 
output signal level changes due to the difference in reflection factor of 
the calra code labels, and therefore, this can result in an unstable 
reading because it is difficult to shape the waveform of an electrical 
signal. Also, when a high-intensity external light is applied to the 
label, the output signal from the two-dimensional type CCD 121 can be 
saturated resulting in an unreadable condition. The automatic diaphragm 
mechanism 123 is provided to obviate the above described potential 
difficulties. 
FIG. 6 is a perspective view of the automatic diaphragm mechanism 123. The 
automatic diaphragm mechanism 123 comprises a diaphragm member 123a, a 
control ring 123b, a connecting rod 123c, a first gear 123d, a first 
rotary shaft 123e, a second gear 123f, a motor 123g, a second rotary shaft 
123h, and a worm gear 123i. The control ring 123b for controlling the 
diaphragm member 123a is connected with the diaphragm member 123a through 
the connecting rod 123c. The connecting rod 123c rotates to the right 
according to the control ring 123b rotating in the clockwise direction. 
Then an opening of diaphragm member 123a becomes wider. If the connecting 
rod 123c rotates in the anticlockwise direction, the opening of diaphragm 
member 123a becomes narrower. 
The first gear 123d is engaged with teeth shaped on part of the control 
ring 123b. The first gear 123d is connected with second gear 123f through 
the first rotary shaft 123e. The second gear 123f is engaged with the worm 
gear 123i mounted on the second rotary shaft 123h driven by the motor 
123g. Therefore, a rotational force generated by the motor 123g is 
transmitted to the control ring 123b through the second rotary shaft 123h, 
the worm gear 123i, the second gear 123f, the first rotary shaft 123e and 
the first gear 123d. The control ring 123b rotates in the clockwise 
direction or the anticlockwise direction in accordance with the rotating 
direction of the second rotary shaft 123h. The connecting rod 123c moves 
with the control ring 123b and, as a result, opening of the diaphragm 
member 123a is controlled in accordance with the moving of connecting rod 
123c. 
The combination lenses 125 are mounted to focus the image of the 
two-dimensional symbol on the two-dimensional type CCD 121 when the 
reading portion 105 is located within 0.5 inch of the recording media on 
which the two-dimensional symbol has been printed, for example a label. 
The combination lenses 125 also operate to regulate a distortion of the 
image. In this embodiment, the combination lenses 125 are used, but an 
aspherical lens can be used. 
The movable switch 113 and the buzzer 129 are electrically connected with 
the circuit portion 119. The buzzer 129 is used to inform of an occurrence 
of an error or the completion of reading by changing a sound level or 
number of the generated sounds. 
FIG. 7 is a block diagram relating to the circuit portion 119. The circuit 
portion 119 comprises a CPU 131, an EEPROM (Electrically Erasable 
Programmable Read Only Memory) 133, a DRAM 135, a masking type ROM 137, a 
decode circuit 139, a serial interface (serial I/F) 141, a code image 
processing circuit 143, an image signal processing circuit 145, a light 
source driver 147, an LCD driver 149, an input-output device (I/O device) 
151 and an option interface (option I/F) 153. These circuit elements are 
connected to one another through bus line 155 consisting of an address 
bus, a data bus and a control bus. 
The EEPROM 133 stores control programs for the CPU 131 and initial values. 
The DRAM 135 stores data inputted to the CPU 131 and outputted from the 
CPU 131. The masking type ROM 137 stores several data formats used to 
convert from image data to code data corresponding to the types of 
two-dimensional symbols. Therefore, this optical reading apparatus 100 may 
read the calra code and the two-dimensional bar code and the like. The 
decode circuit 139 converts from the image data to the code data in 
accordance with the format data. The decode circuit 139 is an IC of the 
gate array type. The serial I/F 141 performs a function for controlling 
the data communications between the optical reading apparatus 100 and an 
external apparatus, for example a host computer. The image signal 
processing circuit 145 performs a function of amplifying a signal from the 
two-dimensional type CCD 121 and controlling the two-dimensional type CCD 
121. The light source driver 147 drives LEDs 115a. The LCD driver 149 
performs a function of displaying an image on the LCD 111 in accordance 
with the image data from the code image processing circuit 143 and 
displaying messages which indicate an error state or a read complete state 
or the like in accordance with commands from the CPU 131. A signal from 
the movable switch 113 is inputted to the I/O device 151. A signal 
outputted to the buzzer 129 is outputted from the I/O device 151. The 
option I/F 153 performs a function of controlling the data communications 
by radio communications or optical communications, for example an infrared 
transmission or the like, between the optical reading apparatus 100 and an 
external apparatus. 
The LCD/buzzer control circuit includes the LCD driver 149 and the I/O 
device 151. The main control circuit includes the CPU 131, EEPROM 133, 
DRAM 135 and serial I/F 141. 
FIG. 8 (a) is a block diagram of the code image processing circuit 143. The 
code image processing circuit 143 comprises an analog-to-digital converter 
circuit (A/D converter circuit) 143a, a frame memory 143b and an image 
processing circuit 143c. These circuit elements are connected to one 
another through the bus line 155. 
The A/D converter circuit 143a converts image signals from the image signal 
processing circuit 145 to digital signals. The frame memory 143b stores 
image data generated in accordance with the digital signals. The image 
data is generated by binarizing the digital signals in accordance with a 
predetermined threshold level. The image processing circuit 143c outputs 
the image data in the frame memory 143b to the LCD driver 149 to output 
the image data to the LCD 111. Further, when the image data which 
represents the two-dimensional symbol is stored in the frame memory 143b, 
the image processing circuit 143c reads the image data representing the 
two-dimensional symbol from the frame memory 143b and rotates the read 
image data to correct its two-dimensional orientation, if necessary. After 
correcting, image data representing the two-dimensional symbol is 
outputted to the DRAM 135. 
FIG. 8 (b) is a block diagram of the image signal processing circuit 145. 
The image signal processing circuit 145 comprises a signal processing 
circuit 145a, a ROM 145b, a defect correction circuit 145c, a shutter 
control circuit 145d, a timing signal generator 145e, a horizontal driver 
145f, a vertical driver 145g, a synchronizing signal generator 145h and a 
diaphragm mechanism control circuit 145i. These circuit elements are 
electrically connected with one another. 
The signal processing circuit 145a amplifies signals outputted from the 
two-dimensional type CCD 121. The ROM 145b stores defect data which 
indicates defects of the elements relating to the two-dimensional type CCD 
121. Such defects of the elements are those resulting from the 
manufacturing process of the CCD. The defect correction circuit 145c 
performs a function of correcting a timing of the timing signal generated 
by the timing signal generator 145e. The shutter control circuit 145d 
controls an output time which the timing signal generator 145e outputs as 
a timing signal when the recording media on which the two-dimensional 
symbol is printed is moving. The timing signal generator 145e generates 
the timing signal in accordance with signals from the defect correction 
circuit 145c and the shutter control circuit 145d. The horizontal driver 
145f and the vertical driver 145g designate the read element in accordance 
with the timing signal outputted from the timing signal generator 145e. 
The synchronizing signal generator controls a timing in accordance with 
which the outputting signal from the two-dimensional type CCD 121 is 
transmitted to the signal processing circuit 145a. The diaphragm mechanism 
control circuit 145i drives the motor 123g of the automatic diaphragm 
mechanism 123 to maximize the difference between a high level and a low 
level of the image signal outputted from the signal processing circuit 
145a. 
FIG. 9 is a block diagram of the option I/F 153. The option I/F 153 
comprises a modulation circuit 153a, a demodulation circuit 153b, a 
waveform shaping circuit 153c, a communication LED 153d, a photo 
transistor 153e and a driving circuit 153f. 
The waveform shaping circuit 153c connects with the modulation circuit 153a 
for performing radio transmissions and the demodulation circuit 153b for 
performing radio receiving. The driving circuit 153f connects with the 
communication LED 153d for performing infrared transmissions and the photo 
transistor 153e for receiving infrared signals. The waveform shaping 
circuit 153c and the driving circuit 153f are connected with the bus line 
155. 
An image is always displayed by the LCD 111 without regard to operation of 
the movable switch 113. When the movable switch 113 is not in the 
on-state, the image signal processing circuit 145 amplifies the outputting 
signals outputted from the two-dimensional type CCD 121 and outputs the 
image signals to the code image processing circuit 143. The code image 
processing circuit 143 generates the image data in accordance with the 
image signals and outputs the image data to the LCD driver 149. Therefore, 
an image is displayed by the LCD 111. The automatic diaphragm mechanism 
123 is also always activated. 
FIG. 10 is a flow chart showing a reading processing of the optical reading 
apparatus 100. Whether or not the movable switch 113 is in the on-state is 
judged in step 201. This step is repeated if the movable switch 113 is not 
in the on-state. If the movable switch 113 is in the on-state, the 
YES-path is taken. When the YES-path is taken, the LEDs 115a are activated 
in step 203. The image signals outputted from the image signal processing 
circuit 145 are transmitted to the code image processing circuit 143 in 
step 205. 
The automatic diaphragm mechanism 123 is controlled by the diaphragm 
mechanism control circuit 145i before the image signals is outputted from 
the image signal processing circuit 145. The operation of the diaphragm 
mechanism control circuit 145i is explained next. The signals outputted 
from the two-dimendional type CCD 121 are amplified by the signal 
processing circuit 145a and transmitted to the diaphragm mechanism control 
circuit 145i as image signals. The diaphragm member 123a of the automatic 
diaphragm mechanism 123 is controlled by the diaphragm mechanism control 
circuit 145i to maximize the difference between a high level and a low 
level of the image signals outputted from the signal processing circuit 
145a. When the difference becomes maximized, then the image signals are 
outputted from the image signal processing circuit 145 to the code image 
processing circuit 143. 
The image signals are binarized by the code image processing circuit 143 in 
step 207. The binarized data are transmitted to the frame memory 143b and 
stored in the frame memory 143b as the image data in step 209. 
Step 211 is explained next. The image data stored in the frame memory 143b 
is displayed by the LCD 111. Further, whether or not image data includes 
the image data which indicates the two-dimensional symbol is judged. If 
the image data does not include the image data which indicates the 
two-dimensional symbol, the LCD 111 and the buzzer 129 are activated to 
inform the operator that an image of the two-dimensional symbol has not 
been obtained. When the image data includes the image data which indicates 
the two-dimensional symbol, image data which indicates the two-dimensional 
symbol is read, and, the read image data is rotated to correct its 
two-dimensional orientation. After correcting, the image data which 
indicates the two-dimensional symbol is stored in the DRAM 135. 
The image data which indicates the two-dimensional symbol in the DRAM 135 
is transmitted to the decode circuit 139 to be converted from the image 
data to two-dimensional code data in step 213. The decode process is 
explained next. The type of two-dimensional symbol which has been 
indicated as image data, for example the calra code or the two-dimensional 
bar code or the like, is judged. The format data are read from the masking 
type ROM 137 to determine a correspondence to the type of two-dimensional 
symbol being judged. The image data which indicates the two-dimensional 
symbol is converted to the two-dimensional code data in accordance with 
the format data read. 
Whether or not the decode process is finished in the normal state is judged 
in step 215. If the decode process is finished in the normal state, i.e., 
without occurrence of problems, then the YES-path is taken. When the state 
is not normal (not can generate the two-dimensional code data), step 201 
is executed again after outputting a message to the LCD 111 indicating a 
reading error. When the state is not normal (not can generate the 
two-dimensional code data), steps 205 to 215 may be executed a prescribed 
number of times, before outputting the message. 
When the YES-path is taken, the LEDs 115a are turned off in step 217. A 
message which indicates that reading is finished is outputted to the LCD 
111 or the buzzer 129 in step 219. The two-dimensional code data is 
transmitted to the external apparatus through the serial I/F 141 or the 
option I/F 153 in step 221. Step 201 is executed again after transmitting 
the two-dimensional code data. 
The reading operation of the calra code shown in FIG. 1(c) by the optical 
reading apparatus 100 in this embodiment will be described next. 
The operator operates the optical reading apparatus 100 by positioning the 
reading portion 105 within 0.5 inch of the label. Then, the operator may 
confirm the position of the calra code by the image displayed on the LCD 
111. Therefore, the operator may locate the optical reading apparatus 100 
to the best position with respect to the calra code. The LEDs 115a are 
activated in response to the operator operating the movable switch 113. 
Light generated from the LEDs 115a illuminates the bar code after being 
diffused. Reflected light from the calra code is reflected in the 
direction of the two-dimensional type CCD 121 by the reflecting mirror 117 
and transmitted to the two-dimensional type CCD 121 through the filter 
127, the combination lenses 125 and the automatic diaphragm mechanism 123. 
The useless light in the reflected light is eliminated by the filter 127. 
The image of the calra code is imaged by the combination lenses 125 on the 
two-dimensional type CCD 121. 
The reflected light is converted to electrical signals by the elements of 
two-dimensional type CCD 121 in accordance with the quantity of light. The 
electrical signals are outputted to the image signal processing circuit 
145 as output signals. 
The output signals are amplified by the signal processing circuit 145a in 
the prescribed timing and outputted to the diaphragm mechanism control 
circuit 145i as image signals. The diaphragm mechanism control circuit 
145i drives the motor 123g of the automatic diaphragm mechanism 123 to 
regulate the opening quantity of the diaphragm member 123a to maximize the 
difference between a high level and a low level of the image signals 
outputted from the signal processing circuit 145a. Therefore, the quantity 
of the reflected light received by the two-dimensional type CCD 121 is 
regulated to the best quantity by the automatic diaphragm mechanism 123 in 
a short time. As a result, the level of the image signals outputted from 
the image signal processing circuit 145 become the most suitable level for 
binarization (the difference between a high level (indicating the white 
blocks) and a low level (indicating the black blocks) of the image signals 
is maximized). When the automatic diaphragm mechanism 123 is regulated to 
maximize the difference between a high level and a low level of the image 
signals, then the image signals are outputted from the image signal 
processing circuit 145 to the code image processing circuit 143. 
The code image processing circuit 143 converts the image signals to the 
image data which includes the image data which indicates calra code. The 
generated image data is stored in the frame memory 143b and transferred to 
the LCD driver 149 to display at the LCD 111. The code image processing 
circuit 143 reads the image data which indicates the calra code from the 
frame memory 143b and rotates the read image data to correct the 
orientation. After correcting, image data which indicates the calra code 
is stored in the DRAM 135. 
The image data which indicates the calra code in the DRAM 135 is decoded to 
two-dimensional code data which has been indicated as the calra code in 
accordance with the format data stored in the masking type ROM 137 
corresponding to the calra code by the decode circuit 139. The generated 
two-dimensional code data which has been indicated as the calra code is 
transmitted to the external apparatus through the serial I/F 141 or the 
option I/F 153. 
FIG. 11 is a display view showing an image of calra code as shown in FIG. 1 
(c) on the LCD 111. When the operator operates the optical reading 
apparatus 100 at a correct position relative to the calra code, the image 
of the calra code is displayed in the middle of the LCD 111 as shown in 
FIG. 11(a). The operator may recognize that the optical reading apparatus 
100 is located in the correct position relative to the calra code. 
When the operator operates the optical reading apparatus 100 out of 
position from the correct position relative to the calra code, the image 
of the calra code is displayed on the LCD 111 as shown in FIG. 11(b). Only 
part of the image of the calra code is displayed by the LCD 111. The 
operator may recognize that the optical reading apparatus 100 is located 
out of position from the correct position relative to the calra code. 
Therefore, the operator can relocate the optical reading apparatus 100 to 
the correct position by guidance from seeing the image of the calra code 
on LCD 111. When the image of the calra code is displayed in the middle of 
the LCD 111, the optical reading apparatus 100 may certainly read the 
two-dimensional code data by operating the movable switch 113. 
When the operator locates the optical reading apparatus 100 to a skewed 
position relative to the calra code, the image of the calra code is 
displayed on the LCD 111 as shown in FIG. 11(c). The operator may 
recognize that the optical reading apparatus 100 is located in a skewed 
position relative to the calra code. Therefore, the operator may surely 
relocate the optical reading apparatus 100 to the correct position by 
guidance from seeing the image of the calra code on LCD 111. 
A second embodiment of the present invention will now be described with 
reference to FIGS. 12 to 14. The optical reading apparatus 100 indicated 
in the first embodiment includes the LCD 111 and the LCD driver 149 to 
display an image of the two-dimensional symbol read by the optical reading 
apparatus 100. However, the optical reading apparatus 300 indicated in the 
second embodiment does not include such a feature. Before the description 
proceeds, it is noted that like parts are designated by like reference 
numerals throughout the accompanying drawings, and therefore the detailed 
description thereof are not repeated. 
FIG. 12 is a perspective view of an optical reading apparatus 300 of a 
second embodiment of a present invention. FIG. 13 is a sectional view of 
the optical reading apparatus 300 of the second embodiment of the present 
invention. The optical reading apparatus 300 comprises a housing 101, a 
hole 103, an opening 105, a wire cable 107, a protection member 109, a 
movable switch 113, light sources 115, a two-dimensional type CCD 121, an 
automatic diaphragm mechanism 123, combination lenses 125, a filter 127, a 
buzzer 129, a reflecting semi-transmissive mirror 301, a window portion 
303, an information LED 305 and a circuit portion 307. 
The reflecting semi-transmissive mirror 301 reflects a part of reflecting 
light from a two-dimensional symbol toward the two-dimensional type CCD 
121. The reflecting semi-transmissive mirror 301 is mounted in a bend 
portion at a prescribed angle relative to a direction of the reading 
portion 105. The reflecting semi-transmissive mirror 301 transmits the 
other part of incident light from the two-dimensional symbol. 
The window potion 303 is provided as a clear glass or clear plastic window 
and is mounted in a position to intercept the light which is transmitted 
through reflecting semi-transmissive mirror 301. 
The information LED 305 is used to inform the operation of an error or that 
reading is complete. 
FIG. 14 is a block diagram relating to the circuit portion 307. The circuit 
portion 307 comprises a CPU 131, an EEPROM (Electrically Erasable 
Programmable Read only Memory) 133, a DRAM 135, a masking type ROM 137, a 
decode circuit 139, a serial interface (serial I/F) 141, a code image 
processing circuit 143, an image signal processing circuit 145, a light 
source driver 147, an input-output device (I/O device) 309 and an option 
interface (option I/F) 153. These circuit elements are connected to one 
another through bus line 155 which includes an address bus, a data bus and 
a control bus. A signal from the movable switch 113 is inputted to the I/O 
device 309. A signal outputted to the buzzer 129 and the information LED 
305 are outputted from the I/O device 309. 
Operation of the optical reading apparatus 300 in the second embodiment is 
explained next. 
When the operator operates the optical reading apparatus 300 at a correct 
position against the calra code, the calra code is displayed in the middle 
of the window portion 303. Based on the display, the operator may 
recognize whether the optical reading apparatus 300 is located in the 
correct position relative to the calra code. 
When the operator operates the optical reading apparatus 300 out of the 
position from the correct position relative to the calra code, only part 
of the calra code is displayed in the window portion 303. The operator may 
recognize that the optical reading apparatus 300 is located out of the 
position from the correct position relative to the calra code. Therefore, 
the operator may surely relocate the optical reading apparatus 300 to the 
correct position by guidance from seeing the image of the calra code 
through the window portion 303. When the calra code is displayed in the 
middle of the window portion 303, the optical reading apparatus 300 may 
certainly read the two-dimensional code data as calra code by operating 
the movable switch 113. 
When the operator locates the optical reading apparatus 300 to a skewed 
position relative to the calra code, the display of the calra code in the 
window portion 303 is skewed. The operator may recognize that the optical 
reading apparatus 300 is located in a skewed position relative to the 
calra code. Therefore, the operator may surely relocate the optical 
reading apparatus 300 to the correct position by guidance from seeing the 
image of the calra code through the window portion 303. 
Accordingly, optical reading apparatus as shown above, may read a 
two-dimensional symbols such as a calra code. Further, the apparatus is 
compact, so that operation is easy. 
The present invention has been described with respect to a specific 
embodiment. However, other embodiments based on the principles of the 
present invention should be obvious to those of ordinary skill in the art. 
Such embodiments are intended to be covered by the claims.