JPH04364592A - Optical reader - Google Patents

Abstract

PURPOSE:To provide an optical reader which is low-priced and does not receive the influence of the change with the passage of time due to the dust, etc., and the dispersion of the detected substance. CONSTITUTION:A photo transistor 79b outputs a signal in accordance with the light from a light emitting part 79a reflected by the detected substance. A CPU 70 successively stores a maximum value VMAX and a minimum value VMIN of an output signal into a RAM 72, and sets a reference value VREF at the middle of the maximum value VMAX and the minimum value VMIN. Subsequently, by comparing the reference value VREF and the output value of the photo transistor 79b, the binary information recorded at the detected substance is recognized. So as to set the reference value VREF at the middle of the maximum value VMAX and the minimum value VMIN, the CPU 70 changes a PWM duty, adjusts the light emitting quantity of the light emitting part 79a and recognizes the binary information recorded at the detected substance subsequently.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical reading device that uses an optical detector to read binary information such as a bar code.

0002

[Prior Art] Figure 1 shows the configuration of a conventional optical reading device.
Shown in 1. This optical reading device irradiates a detected object with a light beam emitted by a light emitting element 91 such as an LED or a semiconductor laser, and detects the reflected light with a light receiving element 93 such as a photodiode or a phototransistor. The light receiving element 93 outputs a signal according to the intensity of the reflected light. This output is amplified by an amplifier 94 and sent to a comparator 9 together with a reference value for comparison.
5, the comparator 95 compares the output with a comparison reference value and outputs binary information of a high signal or a low signal.

The optical reading device also includes a variable resistor 92 for adjusting the amount of light emitted from the light emitting element 91, and a variable resistor 96 for adjusting the comparison reference value.

0004

[Problems to be Solved by the Invention] However, in the conventional device, the variation in the amount of light emitted from the optical element 91 is large, for example, several times in the brightness of the LED, and several times in the output current of the phototransistor, and it is necessary to correct it. Therefore, adjusting means such as the variable resistor 92 and the variable resistor 96 is required. Furthermore, if the above-mentioned optical reading device is incorporated into a machine such as a copying machine or printer as a device for inputting characteristics such as copying or printing as a barcode signal, the optical reading device becomes large and expensive, so This was an impediment to making machines smaller and cheaper.

Furthermore, when used in a machine, the optical element 91 and the light receiving element 93 may become dirty due to dirt, dust, etc.
The light emitting element 91 may not be correctly detected in each machine due to the inability to correctly detect binary information or variations in the characteristics of the element itself.
Since the distance between the light-receiving element 93 and the light-receiving element 93 is different, it is necessary to readjust the light receiving element 93 after it is assembled into the machine.

[0006]Furthermore, the reading accuracy may be lowered due to dirt on the object to be detected or variations in print density.

The present invention has been made to solve the above-mentioned problems, and aims to be inexpensive and not affected by changes over time due to dust or the like or by variations in objects to be detected. An object of the present invention is to provide an optical reading device.

[0008]

[Means for Solving the Problems] In order to achieve this object, the optical reading device of the first invention includes a light emitting element that irradiates light onto an object to be detected, a light emitting element that receives light reflected by the object to be detected,
In an optical reader comprising a light receiving element that outputs a detected value according to the amount of light received, and a recognition means that recognizes binary information on the detected object by comparing the output value of the light receiving element and a reference value. , storage means for storing maximum and minimum output values of the light receiving element, and reference value changing means for changing the reference value to an intermediate value between the maximum and minimum values stored in the storage means.

[0009] Furthermore, the optical reading device of the second invention includes:
A light-emitting element that irradiates light onto the object to be detected, a light-receiving element that receives the light reflected by the object and outputs a detected value according to the amount of received light, and compares the output value of the light-receiving element with a reference value. Accordingly, in an optical reading device comprising a recognition means for recognizing binary information on an object to be detected, the storage means stores the maximum and minimum output values of the light receiving element, and the reference value is stored in the storage means. The light emitting device includes an adjusting means for adjusting at least one of the amount of light emitted by the light emitting element and the sensitivity of the light receiving element so that the amount of light is located between the maximum value and the minimum value.

0010

[Operation] In the optical reading device of the first invention having the above configuration, the object to be detected is scanned while irradiating the object with light, and the light receiving element receives the reflected light from the object to be detected, and the amount of light received is adjusted accordingly. Outputs the detected value accordingly. Then, the maximum value and the minimum value of the output of the light receiving element are stored in the storage means, and the reference value changing means sets the reference value between the maximum value and the minimum value. after that,
The recognition means recognizes the binary information on the object to be detected by comparing the set reference value and the output value of the light receiving element.

Further, in the optical reading device of the second aspect of the invention, the adjusting means adjusts the amount of light emitted from the light emitting element so that the intermediate value between the maximum value and the minimum value stored in the storage means becomes equal to the reference value. Adjust the sensitivity of the light receiving element.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment embodying the first invention will be described below with reference to the drawings. Incidentally, since the processing after reading the information is explained in detail in Japanese Patent Laid-Open No. 1-280758, only the information adding method and reading method will be described here.

FIG. 2 is a schematic diagram of the photosensitive recording medium storage cassette 11, in which the elongated photosensitive recording medium 12 is placed on the feed shaft 14.
It is stored in the cassette 11 in a wound state. The cover 15 shields the photosensitive recording medium 12 from light, and
The feed shaft 14 and the winding shaft 24 are supported. Characteristic information 80 in the form of a bar code shown in FIG. 3 is added to the winding shaft 24. This information consists of a 4-bit start information section 80a and a 9-bit characteristic information section 80b indicating the characteristics of the photosensitive recording medium.
The content "1110" is a combination that does not appear in the characteristic information section 80b.

When the cassette 11 is installed in an image forming apparatus such as a color copying machine, the winding shaft 24 is moved by the shaft presser 2 attached to the image forming apparatus, as shown in FIG.
5 through a roller 78. An optical reading sensor 79 is mounted on the surface of the shaft presser 25 facing the winding shaft 24.
is arranged, and is installed so as to face the characteristic information 80. Note that the configuration of the image forming apparatus is explained in detail in Japanese Patent Application Laid-Open No. 1-280758, so a description thereof will be omitted here.

Next, a schematic circuit configuration of this embodiment is shown in FIG. A ROM 71, a RAM 72, an A/D converter 73, and a motor drive circuit 76 are connected to the CPU 70. This motor drive circuit 76 drives a motor (not shown) connected to the winding shaft 24.

The optical reading sensor 79 includes a light emitting section 79
a and a phototransistor 79b. This light emitting portion 79a constitutes a light emitting element of the present invention, and the phototransistor 79b constitutes a light receiving element.

The A/D converter 73 is connected to the output of the phototransistor 79b, and receives the characteristic information 80.
The output of the phototransistor 79b corresponding to the reflected light is converted into digital data.

Further, a constant current circuit 74 is connected to the CPU 70 through an integrating circuit 75. A PWM signal is input from the CPU 70 to the integrating circuit 75, and the constant current circuit 74 controls the light emitting section 7 in proportion to the output of the integrating circuit 75.
9a is driven with constant current. The amount of light emitted from the light emitting section 79a can be controlled by the duty of the PWM signal.

The RAM 72 has the phototransistor 79
A maximum value storage area 72a (its storage contents are referred to as "VMAX") for storing the maximum value of the amount of light received by the phototransistor 79b, and a minimum value storage area (its storage contents are referred to as "VMIN") for storing the minimum value of the phototransistor 79b. ) 72b, an average value storage area for storing the average value of the amount of light received by the phototransistor 79b (the storage content is referred to as "VAV") 72c, a reading number storage area (the storage content is designated as "SAMPLE")
”) 72d, a reference value storage area (its storage contents are “VREF”) 72e, and a PWM duty storage area (its storage contents are “DUTY”) 72f.

Next, the operation of this embodiment will be explained with reference to FIGS. 5 and 6.

As shown in FIG. 4, when the cassette 11 is set in the image recording apparatus, a signal is sent from the CPU 70 to the motor drive circuit 76 (S1), and the motor (not shown) rotates to perform the winding process. As the shaft 24 rotates, the optical read sensor 79 will scan the characteristic information 80 . Further, at this time, the CPU 70 sends out a PWM signal with a constant duty (S2), and the light emitting section 79a emits light with a constant brightness, thereby projecting light onto the characteristic information 80.

Data reading is then performed according to the data reading processing routine shown in FIG. 9 (S3).

In the data reading processing routine, first,
The memory content of the reading number storage area 72d is “SAMPL”.
E" is reset (S11), and then the received light data is read 16 times every 1 msec, and the average value "VA
V'' is calculated and stored in the average value storage area 72c (S12).

[0024]Then, the storage content "VMAX" of the maximum value storage area 72a and the storage content "VMAX" of the average value storage area 72c are stored.
VAV” is compared (S13), and the maximum value “VMAX” is
When the average value "VAV" is larger (S13: YES), the average value "VAV" is stored in the maximum value storage area 72a (S14), and the value is set as the maximum value "VMAX". Then, S17, which will be described later, is executed.

On the other hand, the average value “V
AV" is small (S13: NO), the storage content "VMIN" of the minimum value storage area 72b and the average value "VAV
” are compared (S15), and when the average value “VAV” is smaller than the minimum value “VMIN” (S15: YES), the average value “VAV” is stored in the minimum value storage area 72b (S15).
16), the value is set as the minimum value "VMIN". Then, S17, which will be described later, is executed.

Furthermore, the average value “VMAX” is calculated from the maximum value “VMAX”.
VAV” is small (S13: NO), and the minimum value “VM
When the average value “VAV” is larger than “IN” (S15:N
In case O), S17, which will be described later, is executed.

[0027] In S17, the number of readings storage area 7
2d's memory content is the number of readings "SAMPLE"
1 is added to ``SAMPLE'', and the read count value ``SAMPLE'' becomes 2.
It is determined whether or not the value exceeds 00 (S18). If the number of readings “SAMPLE” does not exceed 200 (S1
8: NO), the above S12 and subsequent steps are executed again, and when the reading count value "SAMPLE" exceeds 200 (S18:
YES), that is, the cycle of S12 to S17 above is 2
When the process is repeated 00 times, this process ends.

After that, the maximum value "VMAX" stored in the maximum value storage area 72a and the minimum value storage area 72b
The intermediate value between the minimum value "VMIN" and the minimum value "VMIN" stored in the
REF" (S4).

[0029] When the setting of the reference value "VREF" is completed,
This reference value "VREF" is compared with the next read data and recognized as binary data (S5). And C.P.
In U70, the measured values are sequentially recorded in RAM72, and the start information "1110" (black: 1, white: 0)
Waits for the detection of data (S5, S6). When the start information is detected, the characteristic information 80 is read by comparing it with the set reference value "VREF" (S7). In this example, "110110010" will be read.

In this embodiment, the CPU 70 is shown in FIG.
, 6 constitute the reference value changing means and recognition means of the present invention.

FIG. 7 shows the output results of the optical reading device of this embodiment, and FIG. 7(a) shows the maximum output of the optical reading sensor 79 and the characteristic information 80 The output REF when the distance d from
1 and FIG. 7B shows the output REF2 when the output of the optical sensor 79a is the minimum and the distance d is the maximum. Since the black density of the characteristic information 80 at this time uses a low value of Macbeth density of 1.0, the difference in density between black and white is considerably smaller than in reality.

At this time, in the case of REF1, the optical reading device of this embodiment sets the reference value "VREF" to 3.5V by the data reading processing routine shown in FIG.
In addition, in the case of REF2, the reference value "VREF" is 0.8V
is set to Since the binary data is recognized based on the set reference value "VREF", the optical reading device of this embodiment can correctly read the characteristic information 80 under any conditions.

[0033] Note that the maximum value "VMAX" and the minimum value "VM
IN' may be an approximate value when scanning a distance where both black and white information will necessarily appear, and the intermediate value may also be an approximate value. Alternatively, a value shifted by a certain value from either the black or white value may be used as the reference value.

Next, an embodiment embodying the second invention will be described based on FIGS. 8 and 9.

The configuration of this embodiment is the same as that of the first embodiment of the invention, so a description thereof will be omitted, and the operation will be explained with reference to FIGS. 8 and 9.

When the cassette 11 is set as shown in FIG. 4, a signal is sent from the CPU 70 to the motor drive circuit (S
21) When the motor (not shown) rotates, the winding shaft 24 rotates, and the optical reading sensor 79 scans the characteristic information 80. The predetermined reference value “VR
EF" (for example, VREF=128) is stored in the reference value storage area 72e in advance (S22). Thereafter, a PWM duty determination processing routine is executed to determine the amount of light emitted from the light emitting section 79a (S22).

FIG. 9 shows a flowchart of the PWM duty determination routine. First, the initial value 128 (S3
1) is stored. Then, similarly to the first embodiment of the invention described above, the data reading processing routine shown in FIG. 6 is executed to calculate the maximum value "VMAX" and the minimum value "VMIN" (S3).

After that, the maximum value "VMAX" stored in the maximum value storage area 72a and the reference value storage area 72e are
Calculate the difference V0 between the reference value "VREF" stored in (S32), and if V0<0 (S33: NO), the reference value "V
REF" does not exist, the storage content "DUTY" in the PWM duty storage area 72f is greatly increased (S
35), Execute the data reading processing routine again (
S3).

On the other hand, if V0>0 (S33: YES), the difference V1 between the reference value "VREF" and the minimum value "VMIN"
is calculated (S35), and if V1<0 (S36: NO)
Since the reference value "VREF" does not exist between the maximum value "VMAX" and the minimum value "VMIN", the stored content "DUTY" of the PWM duty storage area 72f is greatly reduced (S37), and the data reading processing routine is executed again. (S3).

[0040] If V1>0 (S36: YES), there is a reference value "VMAX" between the maximum value "VMAX" and the minimum value "VMIN".
VREF" exists, and the V0 and V1
It is determined whether the absolute value of the difference has reached less than 10 (
S38).

[0041] The absolute value of the difference between V0 and V1 is 10 or more (S3
8: NO), compare the magnitude relationship between V0 and V1 (S39), and if V0-V1>0 (S39: YES)
, the memory contents of the PWM duty storage area 72f “DU
TY" is decreased by 2 (S40), and the data reading processing routine is executed again (S3). On the other hand, V0−V1<
In the case of 0 (S39: NO), the memory content "DUTY" of the PWM duty storage area 72f is increased by 2 (S4
1) Execute the data reading processing routine again (S
3).

[0042] By repeating each of the steps S3 to S41, the storage contents of the PWM duty storage area 72f are
When the absolute value of the difference between V0 and V1 becomes less than 10 (S37: YES) by increasing or decreasing PW
The M duty determination processing routine ends.

By this PWM duty determination processing routine, the light emitting section 79 is adjusted so that the reference value "VREF" is approximately at the center between the maximum value "VMAX" and the minimum value "VMIN".
The amount of light emitted by a is determined, and the difference between black and white detection levels becomes maximum.

After the duty is determined, the start bit is detected and the characteristic data is read in the same way as in FIG. 5 (S5 to S7).

The experimental confirmation results are shown in FIG. This figure shows the case where the duty of the light emitting section 79a is automatically changed when the parts vary to the worst condition, and a black-white level difference of 3V can be secured.

Furthermore, instead of changing the amount of light emitted from the light emitting section 79a, the sensitivity of the phototransistor 79b (the resistance value of the detection resistor or the amplification factor of the amplifier) may be changed.

Further, the characteristic information does not need to be recorded on the shaft as in the above embodiment, but may be recorded on a sheet.

[0048]

[Effect of the invention] As is clear from the detailed description above,
According to the present invention, while the light emitting element irradiates light onto the object to be detected and the light receiving element detects the reflected light, a reference value for binary discrimination is automatically set, and the reference value is the output of the light receiving element. The amount of light emitted by the light emitting element and the sensitivity of the light receiving element can be adjusted so that the amount of light emitted by the light emitting element and the sensitivity of the light receiving element are located between the maximum value and the minimum value.

Therefore, it is possible to simplify the optical reading device and eliminate the need for adjustment, resulting in a significant cost reduction effect. moreover,
Since variations in parts, the effects of dust, etc., and even variations in objects to be detected can be automatically corrected, it is possible to configure an extremely stable optical reading device.

[Brief explanation of the drawing]

FIG. 1 is a schematic circuit configuration diagram of the present optical reading device.

FIG. 2 is a schematic perspective view of a photosensitive recording medium storage cassette.

FIG. 3 is a diagram showing characteristic information of an object to be detected.

FIG. 4 is a side view showing a state in which the photosensitive recording medium storage cassette is stored.

FIG. 5 is a flowchart showing the operation of the first invention.

FIG. 6 is a flowchart showing a data reading processing routine.

FIG. 7 is a diagram showing the output of the optical reading device.

FIG. 8 is a diagram showing an operation flowchart of the second invention.

FIG. 9 is a flowchart showing a PWM duty determination processing routine.

FIG. 10 is a diagram showing the output of the optical reading device.

FIG. 11 is a configuration diagram of a conventional optical reading device.

[Explanation of symbols]

79a Light emitting part (light emitting element) 79b Phototransistor (light receiving element) 72
RAM (memory means)

Claims (2)

[Claims] [Claim 1] A light-emitting element that irradiates light onto an object to be detected;
A light receiving element receives the light reflected by the detected object and outputs a detection value according to the amount of received light, and by comparing the output value of the light receiving element and a reference value, the binarization on the detected object is performed. An optical reading device comprising a recognition means for recognizing information, a storage means for storing the maximum and minimum values of the output value of the light receiving element, and a reference value located between the maximum and minimum values stored in the storage means. An optical reading device comprising: a reference value changing means for changing a reference value. [Claim 2] A light-emitting element that irradiates light onto an object to be detected;
A light receiving element receives the light reflected by the detected object and outputs a detection value according to the amount of received light, and by comparing the output value of the light receiving element and a reference value, the binarization on the detected object is performed. An optical reader comprising a recognition means for recognizing information, a storage means for storing maximum and minimum output values of the light receiving element, and a reference value located between the maximum and minimum values stored in the storage means. 1. An optical reading device comprising: adjusting means for adjusting at least one of the amount of light emitted by the light emitting element or the sensitivity of the light receiving element so that the light emitting element is positioned in the same position as the light emitting element.