JPS6133147B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a detection device for a light reflector such as a small piece of aluminum foil, and can be applied to, for example, a registered mail number slip detector for an automatic registered mail acceptance machine.

A conventional reflector detection device will be explained. 1st
The figure shows a schematic diagram of its configuration. 1 is a photo sensor block, and a planar photo sensor 2 such as a solar cell with wide directivity and almost equal sensitivity consisting of S ₁ , S ₂ . . . S _o is pasted on one plane. I'm wearing it. Light emitted from a filament lamp 3, which is a linear light source, is focused by a lens 4 and becomes a thin streak-like light beam 6 on an object to be detected 5. Since the reflected light 7 travels in various directions depending on the inclination of the detected object 5, the photo sensor block 1 has a large area and always receives the reflected light 7 from its light reflector 8. ing. When the light beam hits the aluminum foil of the light reflector 8, it reflects well, so one of the sensors 2 of the photo sensor block 1 receives a light that is considerably stronger than the light reflected from other parts of the object to be detected. is correct.

Fig. 2 is a circuit diagram of a conventional detection device, where S ₁ , S ₂ . . . S _o of the photo sensor 2 are diodes DA ₁ ,
The photo sensor 2 connected to the maximum value selection circuit 9 composed of _DA2 ... _DAo and receiving the strongest light among the reflected light 7 from the object 5 will output the highest output voltage. The output voltage A is input to an amplifier 10 and amplified, and the output B, which has passed through a differentiator circuit composed of a capacitor 11 and a resistor 12, is compared with a comparison voltage _E1 by a comparator 13.

FIG. 3 shows the relationship between the outputs A and B and the output C of the comparator 13 when the detected object 5 is moved in the direction of the arrow X in FIG. 1. The output A of the maximum value selection circuit 9 when the light from the filament lamp 3 hits the surface of the object to be detected 5 is _e1 , and the time when the light hits the light reflector 8 is e2, and the following ( ₁ If the comparison voltage _E1 is adjusted so that the condition of the equation ) is satisfied, a pulse-like voltage is obtained at the output C of the comparator 12 only when the aluminum foil that is the light reflector 8 is detected.

e ₁ <E ₁ <e ₂ −e ₁ However, such a conventional detection device has the following problem. When the object 5 to be detected is thick and reflects a lot of light, such as a white envelope, the distances between the filament lamp 3 and the object 5 and between the object 5 and the photo sensor block 1 are reduced, so that the distance between the object 5 and the photo sensor block 1 is reduced. The amount of reflected light 7 increases. Therefore e ₁ > E ₁
In some cases, the comparator 13 as shown in FIG.
A miss pulse Ep appears at the output C of. Furthermore, if cellophane tape is attached to the object to be detected 5, the light may be reflected on the surface and an output A similar to that obtained when detecting the predetermined light reflector 8 may be produced, resulting in a detection error. Furthermore, even if the aluminum foil is oriented in various directions, the photo sensor block 1 needs to be quite large in order to detect the reflected light, and the number of sensors is large, resulting in high cost.

The present invention proposes a light reflector detection device that can solve these detection errors and reduce the number of sensors, and one embodiment thereof will be described below.

In Figures 5a and 5b, 14 is the object to be detected, 15
16 is an aluminum foil as a light reflector provided on the detected object 14, and 16 is a sensor unit, which is installed facing the belt conveyor 17 for moving the detected object 14.
On a substrate 18, a light source 19 such as a lamp or a light emitting diode that emits widely directional scattered light, and a photo sensor 20 with a lens etc. are regularly arranged by the width of the object 14 to be detected. For example, limited to regular-sized mail items, length (14-23.5 cm), width (9-12 cm)
cm), thickness (1 cm or less), and belt conveyor 1 in the length direction (direction of arrow Y in Figure 10).
7 to move the detected object 14 and move the sensor unit 16.
When the sensor unit 16
The detection range is limited to 12 cm within the guides 21 and 22. Each of the photo sensors 20 S ₁ to S ₁₁ arranged in one row has a directivity of about 11 degrees, and senses only the state of the surface of the object 14 directly below it. For example, the sensor shown in FIG. 5a Unit 16 and detected object 1
If the distance h from 4 is 30 mm, the distance h is in a circle of about 12 mm.
But at 20mm, it only senses inside a circle of about 8mm. The mounting pitch p of the photo sensor 20 is 12 mm, and the size of the aluminum foil 15 is 12 mm x 12 mm, so the fifth
Place aluminum foil 1 directly under photo sensor S ₃ as shown in figure a.
5, the adjacent photo sensors _S2 and _S4 do not detect the aluminum foil 15. Even if the aluminum foil 15 is tilted as shown in FIG. 6, each of the photo sensors S ₂ to _{S 4} has directivity within the shaded range, so the reflected light from the distant light source 19 enters the range of the photo sensor S ₃ and other It does not fall within the range of photo sensors S ₂ and S ₄ . However, the aluminum foil 15 was placed exactly between photo sensors S ₂ and S ₃ .
, the reflected light enters both photo sensors S ₂ and S ₃ , so as shown in FIG. 5b, one more row of photo sensors S ₁₂ to S ₂₁ is connected to the photo sensors S ₁ to
Adjacent to column S ₁₁ and with photo sensor S ₁₂ located midway between photo sensors S ₁ and S ₂ , photo sensor S ₁₃
They are arranged in a staggered manner so that the photo sensors S ₂ and S ₃ are located at intermediate positions. Then, among the photo sensors S ₁₂ to S ₂₁ in this row, the photo sensor
Only S ₁₃ is sensed, and the adjacent photo sensors S ₁₂ and S ₁₄ are not sensed because reflected light does not hit them.

As mentioned above, since the width of a standard mail piece is limited to 12 cm, there are a total of 21 photo sensors S ₁ to S ₂₁ .
The light sources 19 are composed of 44 light sources L ₁ to L ₄₄ and are arranged surrounding the photo sensors S ₁ to _{S 21} as shown in FIG. 5b.

FIG. 7 is a block diagram of the detection circuit, and the detection principle will be explained according to the diagram. The light sources _L1 to _L44 emit light from the power source _E3 . The photo sensors S ₁ to _{S 21} are divided into four blocks according to odd numbered ones, even numbered ones, and columns, and each block has a diode DD ₁ to DD ₆ ,
It is connected to maximum value selection circuits 23 to 26 of the sensors, which are configured by DE ₁ to DE ₅ , DF ₁ to DF ₅ , and DG ₁ to DG ₅ . Now, assuming that there is an aluminum foil 15 directly below the photo sensor S ₃ as shown in FIG.
Outputs D to G of 26 are aluminum foil 15 for D.
This is the output value of photo sensor _S3 that detected E~
Since the output G detects characters and patterns on the detected object 15, it is smaller than the output D, and the voltage difference between them is also small. 27 to 30 are differential amplifiers,
When the input difference is zero, the output is zero. The outputs D and E are input to the differential amplifiers 27 and 28 as shown in the figure, and the outputs F and G are input to the differential amplifiers 29 and 30 as shown in the figure, so the output of the differential amplifier 27 is positive. At the maximum, the differential amplifier 28 is at the negative maximum, and the outputs of the differential amplifiers 29 and 30 are approximately zero. Then, the output of the differential amplifier 27 is selected as the output H of the maximum value detection circuit 31 composed of diodes DH ₁ to DH ₄ . Then, when the value of the output H is larger than the comparison voltage _E2 , the output J of the comparator 32 appears. A timing chart of each output D to J in this case is shown in FIG. However, this is the case where the aluminum foil 15 passes directly under the photo sensor _S3 as shown in FIG. 5a. The tip of the detected object 14 is a photo sensor S ₁ to _{S 11}
When they come to the column of photo sensors S ₁₂ to S 21 , the outputs D and E rise, and when they come to the column of photo sensors S 12 to S ₂₁ , the outputs F and G rise, but there is no voltage difference between them. When the aluminum foil 15 comes directly below the photo sensor _S3 , the output of the output D becomes the maximum, and an output pulse appears at the output H. Next, it passes between photo sensors S ₁₃ and S ₁₄ , but the outputs F and G
The same increase in output occurs, but since the difference is compared in the differential amplifier 29 or 30, the difference becomes zero and the output H does not appear.

Next, a case will be described in which the aluminum foil 15 passes not directly below the photo sensor _S3 but at a location slightly shifted from the photo sensor S3. In this case, the photo sensor S ₂ next to the photo sensor S ₃ is also exposed to light, and the outputs E and G are also exposed to the outputs D and F.
Although it is lower, the output comes out. and differential amplifier 2
The difference is taken from 7 to 30, and the output appears at output H. Then, the output H and the comparison voltage _E2 are compared,
A detection output J appears. The timing chart at that time is shown in FIG.

As can be seen by comparing the output H in FIG. 8 with the output B in FIG.
There are no missed pulses at the beginning of the passage. Furthermore, the first
Even when light is reflected from the cellophane tape 34 on the object to be detected 14 or cellophane 33 on the transparent window of a window-opened envelope to the sensor unit 16 as shown in Figure 0, the difference in the amount of light received by adjacent photo sensors 20 can be compared. Therefore, the difference becomes zero, and an error output pulse is unlikely to appear even in such a case. As a result, when processing envelopes, for example, errors in detecting number tags on envelopes that do not have aluminum foil number tags attached to them have been virtually eliminated.

In addition, since the difference in the photo sensor output is detected, the distance between the photo sensor 20 and the detected object 14 can be kept close to about 20 to 30 mm.
As shown in the figure, even if the aluminum foil is tilted, it can be detected by the relatively narrow sensor unit 16, and the photo sensor 2
The number of 0's can be reduced to 21 in total, and although the number of light sources 19 increases, the overall cost can be reduced.

The explanation so far has been limited to the detection of a small piece of aluminum foil 12 mm square, but the shape of the object may be round or triangular, and the size is not limited to 12 mm. It can be easily detected by changing the pitch of the arrangement and the distance between the detection target and the photo sensor.

In addition, the sensor unit 16 is fixed and the object to be detected 1 is
Although the case where the sensor unit 4 is moved has been described, conversely, even if the object to be detected is fixed and the sensor unit is moved, the detection can be performed in the same way.

As described above, according to the present invention, the sensor unit can match the arrangement pitch of the photo sensor with the light reflector, and when the light is reflected by the light reflector larger than a predetermined size, it is canceled out and there is no false detection, resulting in accurate detection. In addition, since the photo sensors are arranged in two rows in a staggered manner, even if a light reflector comes between the photo sensors in the first row, there will be no detection due to it, and the photo sensors in the second row will not detect it. Since the detection is performed, malfunctions and detection errors do not occur.

[Brief explanation of the drawing]

FIG. 1 is a conventional schematic configuration diagram, FIG. 2 is a conventional circuit configuration diagram, FIGS. 3 and 4 are timing charts thereof, and FIGS. 5a and 5b are sensor units showing an embodiment of the present invention. A cross-sectional view showing the arrangement of the object to be detected and a bottom view of the sensor unit, Fig. 6 is a cross-sectional view explaining the case where the light reflector is tilted, Fig. 7 is a circuit configuration diagram, and Figs. 8 and 9 are the same. The timing chart, FIG. 10, is a plan view showing the arrangement of the sensor unit and the object to be detected. 14... Object to be detected, 15... Aluminum foil (light reflector), 16... Sensor unit, 19, L ₁ to L ₄₄ ...
...Light source, 20, S ₁ to S ₂₁ ... Photo sensor, 23
~26...Maximum value selection circuit, 27-30...Differential amplifier, 31...Maximum value detection circuit, 32...Comparison circuit.

Claims (1)

[Claims] 1 multiple light sources for irradiating light to the reflector;
Two adjacent rows of photo sensors arranged in a straight line at intervals such that light reflected by the reflector of the light source can be received at two places or less at the same time are provided, and the arrangement of each photo sensor in one row is different from that of the other row. a sensor unit in which each photo sensor is arranged in a staggered manner so that the photo sensor is located between adjacent photo sensors;
A maximum value selection circuit divides the selected photo sensors in each column into blocks and selects the photo sensor that receives the strongest reflected light among each block, and the output of the maximum value selection circuit for each column. a detection circuit that detects a difference between the plurality of light sources, and a comparison circuit that compares an output of the detection circuit with a comparison voltage and outputs an output when any one of the detection outputs is larger than the comparison voltage, A light reflector detection device is placed around each photo sensor.