JP4149604B2 - Sensor unit - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sensor unit that compares a signal level of a sensor with a slice level and outputs the comparison result.
[0002]
[Prior art]
For example, an optical sensor is used as a sensor for detecting the conveyance state of the paper sheet. An optical sensor is composed of a light emitting element (for example, a light emitting diode) and a light receiving element (for example, a phototransistor). When there is no paper, the light sensor emits light from the light emitting element to output a high level voltage signal. When the paper sheet passes, the light of the light emitting element is blocked by the paper sheet and does not reach the light receiving element, thereby outputting a low level voltage signal.
[0003]
The signal level of the optical sensor and a predetermined reference voltage level, so-called slice level, are compared by a comparator, and the conveyance state of the paper sheet is detected by the output signal of the comparator.
[0004]
That is, if the signal level of the optical sensor is equal to or higher than the slice level, a bright signal (logic “1” signal) indicating that there is no paper sheet, and if the optical sensor signal level is lower than the slice level, the paper sheet is passing. A dark signal (logic “0” signal) representing that is obtained.
[0005]
However, the level of the signal of this optical sensor gradually decreases due to the lifetime, the influence of the ambient temperature, the adhesion of dust, and the like.
[0006]
As a means to compensate for this level decrease over time, an amplifier is conventionally provided between the connection of the sensor and the comparator, and the gain of the amplifier (gain) is regularly adjusted during maintenance and inspection. Yes. Specifically, the clerk adjusts the optical axis between the light emitting element and the light receiving element while looking at the output voltage of the amplifier, finds the point where the output voltage of the amplifier is maximum, and then turns the adjustment volume. Adjust the amplifier gain.
[0007]
[Problems to be solved by the invention]
Adjustment of the amplifier gain as described above is very troublesome for the staff.
[0009]
Therefore, the present invention can automatically compensate for a decrease in the level of the sensor signal over time without being affected by temporary dust adhesion, thereby eliminating the need for adjustment of the amplifier gain and the burden on the attendant. An object of the present invention is to provide a sensor unit that can reduce the above.
[0010]
In addition, the present invention can automatically compensate for a decrease in the level of the sensor signal over time without being affected by temporary dust adhesion, etc. It is an object of the present invention to provide a sensor unit that can alleviate the above-mentioned problem and can accurately notify the sensor when it is necessary to clean the sensor.
[0011]
[Means for Solving the Problems]
The sensor unit of the present invention is set by the sensor, the monitoring means for periodically monitoring the signal level of the sensor, the setting means for setting the slice level corresponding to the monitoring result of the monitoring means, and the setting means. Comparing means for comparing the slice level with the signal level of the sensor, the setting means sets a new slice level only when the change in the monitoring result of the monitoring means is less than a predetermined value, and the monitoring result When the change in is more than a predetermined value, the same slice level as before is maintained.
[0012]
The sensor unit of the present invention includes a plurality of sensors, conversion means for converting the signal levels of these sensors into digital data, monitoring means for periodically monitoring each digital data of the conversion means, Setting means for sequentially setting slice levels corresponding to each monitoring result, comparison means for comparing each slice level set by this setting means with each digital data of the conversion means, and each comparison result of this comparison means Holding means, and the setting means sets a new slice level only when a change in the monitoring result of the monitoring means is less than a predetermined value, and when the change in the monitoring result is a predetermined value or more It is characterized by maintaining the same slice level as before.
[0013]
The sensor unit of the present invention includes a plurality of sensors, a selection means for sequentially selecting signals from these sensors, a conversion means for converting the level of each signal selected by the selection means into digital data, and this conversion Monitoring means for periodically monitoring each digital data of the means, setting means for sequentially setting slice levels corresponding to the monitoring results of the monitoring means, each slice level set by the setting means, and the conversion means Comparing means for comparing each digital data, and holding means for holding each comparison result of the comparing means, and the setting means is new only when the change in the monitoring result of the monitoring means is less than a predetermined value. A slice level is set, and when the change in the monitoring result is a predetermined value or more, the same slice level as before is maintained.
[0014]
Further, the sensor unit of the present invention needs to be cleaned when the change in the monitoring result of the monitoring means is equal to or greater than a predetermined value and the number of changes greater than or equal to the predetermined value reaches a predetermined value. It is further characterized by further comprising an informing means for informing the user.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
[0020]
As shown in FIG. 1, a plurality of sensors, for example, optical sensors Sa, Sb,... Sn are connected to a multiplexer 1 which is a selection means. The multiplexer 1 sequentially selects and outputs signals from the respective optical sensors (hereinafter referred to as sensor signals) by repeating scanning in a time division manner.
[0021]
Each sensor signal selected by the multiplexer 1 is supplied to an A / D (analog / digital) converter 2 which is a conversion means. The A / D converter 2 converts the voltage level of each sensor signal into digital data.
[0022]
Each digital data of the A / D converter 2 is supplied to the comparator 3 and input to the CPU 10 via the input port 5.
[0023]
In addition to the input port 5, the slice level RAM 6, ROM 11, RAM 12, display 13, and cleaning confirmation switch 14 are connected to the CPU 10.
[0024]
The slice level RAM 6 temporarily stores the slice level read from the RAM 12 by the CPU 10. The ROM 11 stores a control program for the sensor unit. The RAM 12 stores slice levels corresponding to the optical sensors Sa, Sb,. The display 13 is prepared to inform the operator that the optical sensor needs to be cleaned. The cleaning end switch 14 is operated when the cleaning of the optical sensor is completed.
[0025]
The comparator 3 sequentially compares each digital data from the A / D converter 2 with the slice level in the slice level RAM 6. Each comparison result is held in a latch 4 which is a holding means. Each held content of the latch 4 is an output.
[0026]
The CPU 10 controls the entire sensor unit and includes the following [1] to [3] as main functions.
[0027]
[1] Monitoring means for periodically monitoring each digital data input from the A / D converter 2.
[0028]
[2] Setting means for reading out the slice level corresponding to the monitoring result of the monitoring means from the RAM 12 and sequentially setting it in the slice level RAM 6. As a specific setting, a new slice level is set only when the change in the monitoring result is less than a predetermined value, and when the change in the monitoring result is greater than or equal to the predetermined value, the same slice level as before is held.
[0029]
[3] A character on the display 12 indicating that the optical sensor needs to be cleaned when the change in the monitoring result of the monitoring means exceeds a predetermined value and the number of changes exceeding the predetermined value reaches a predetermined value. Informing means for notifying by display and continuing the notification until the cleaning end switch 14 is operated.
[0030]
A timing circuit 7 outputs a timing signal for synchronizing the operations of the multiplexer 1, the A / D converter 2, the comparator 3, the latch 4, the input port 5, and the slice level RAM 6.
[0031]
Next, the operation of the above configuration will be described with reference to the flowchart of FIG.
[0032]
Signals from the optical sensors Sa, Sb,... Sn are sequentially selected and output by the multiplexer 1. Each selected sensor signal is converted into digital data by the A / D converter 2, supplied to the comparator 3, and input to the CPU 10 via the input port 5.
[0033]
The comparator 3 compares each digital data from the A / D converter 2 with each slice level from the slice level RAM 6. If the content (signal level) of the digital data is equal to or higher than the slice level, the comparator 3 outputs a bright signal (logic “1” signal). If the content (signal level) of the digital data is less than the slice level, the comparator 3 outputs a dark signal (logic “0” signal). These bright and dark signals are temporarily held in the latch 4 and output in parallel in a form corresponding to the optical sensors Sa, Sb,.
[0034]
The CPU 10 reads the digital data (step 101), and the contents of the digital data are monitored regularly, for example, every day or every hour (step 101). Examples of the periodic monitoring results are shown in FIGS.
[0035]
In the example of FIG. 3, the change in the monitoring result is less than the predetermined value until the monitoring timing D. At the monitoring timing E, the change in the monitoring result is greater than or equal to the predetermined value, that is, abruptly changed (significantly decreased). ). After the monitoring timing F, the change in the monitoring result is in a state less than a predetermined value. As a cause of the sudden change at the monitoring timing E, it is conceivable that temporary dust is attached to the optical sensor.
[0036]
In the example of FIG. 4, the change in the monitoring result is less than the predetermined value until the monitoring timing D, and the change in the monitoring result is greater than or equal to the predetermined value, that is, abrupt change at the monitoring timings E and F (significant decrease). is doing). Then, after the monitoring timing F, the change in the monitoring result is less than a predetermined value. As a cause of the sudden change in the monitoring timings E and F, the contamination of the optical sensor can be considered.
[0037]
If the change in the monitoring result is less than the predetermined value (NO in step 102), the slice level corresponding to each monitoring result (for example, 50% value of the monitoring result) is sequentially updated and set (step 105). At the same time, the count value C for counting the number of times is cleared (step 106).
[0038]
If the monitoring result changes suddenly (YES in step 102), the slice level that has been set up to that point is held as it is (step 103), and no update setting is made. At the same time, the count value C is incremented by 1 (step 104).
[0039]
When sudden changes in the monitoring result continue like the monitoring timings E and F, the count value C reaches the predetermined value “2” (YES in step 107). At this time, a letter indicating that the optical sensor needs to be cleaned is displayed on the display 12 (step 108).
[0040]
The operator notices that the optical sensor is dirty by looking at the display, and actually performs a cleaning operation on each optical sensor. After the implementation, the operator operates the cleaning confirmation switch 14.
[0041]
When the cleaning confirmation switch 14 is operated (YES in step 109), the character display is canceled on the display device 12, and the processing from step 101 is executed again. The operation timing of the cleaning confirmation switch 14 is shown in FIG.
[0042]
As described above, the signal level of each optical sensor is regularly monitored, and the slice level corresponding to each monitoring result is sequentially set to automatically compensate for the level decrease of the sensor signal over time. Can do. Therefore, it is not necessary to adjust the amplifier gain as in the prior art, and the burden on the staff can be reduced.
[0043]
In particular, a new slice level is set only when the change in the monitoring result is less than a predetermined value, and when the change in the monitoring result is greater than or equal to the predetermined value, the same slice level is maintained. It is possible to automatically compensate for a decrease in the level of the sensor signal over time without being affected by the adhesion of dust.
[0044]
If the change in the monitoring result is equal to or greater than the predetermined value and the number of changes greater than or equal to the predetermined value reaches the predetermined value, the fact is displayed based on the determination that the optical sensor needs to be cleaned. Since the characters are displayed on the container 12, the operator can surely grasp the necessity of the cleaning work.
[0045]
In the above embodiment, the optical sensor has been described as an example, but the type of sensor is not limited. In addition, the present invention is not limited to the above-described embodiments, and various modifications may be made without departing from the scope of the invention.
[0046]
【The invention's effect】
As described above in detail , according to the present invention, the signal level of each optical sensor is periodically monitored, and a new slice level is set only when the change in the monitoring result is less than a predetermined value. Since the same slice level as before is maintained when the value is over the predetermined value , the sensor signal can be automatically compensated for a decrease in level over time without being affected by temporary dust adhesion. Thus, it is possible to provide a sensor unit that can reduce the burden on the clerk without requiring adjustment of the amplifier gain .
[0047]
In addition, according to the present invention, when the change in the monitoring result is equal to or greater than a predetermined value and the number of changes greater than or equal to the predetermined value reaches the predetermined value , the sensor is notified. Therefore, it is possible to provide a sensor unit capable of accurately informing the situation where cleaning is required.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of an embodiment.
FIG. 2 is a flowchart for explaining the operation of the embodiment.
FIG. 3 is a diagram showing an example of a monitoring result in the same embodiment.
FIG. 4 is a diagram showing another example of the monitoring result in the embodiment.
[Explanation of symbols]
1 ... Multiplexer (selection means)
2 ... A / D converter (conversion means)
3 ... Comparator (comparison means)
4 ... Latch (holding means)
10 ... CPU
14 ... Cleaning confirmation switch

Claims (4)

A sensor,
Monitoring means for periodically monitoring the signal level of the sensor;
Setting means for setting a slice level corresponding to the monitoring result of the monitoring means;
Comparing means for comparing the slice level set by the setting means with the signal level of the sensor,
The setting unit sets a new slice level only when the change in the monitoring result of the monitoring unit is less than a predetermined value, and holds the same slice level as before when the change in the monitoring result is a predetermined value or more. Sensor unit characterized by Multiple sensors,
Conversion means for converting the signal levels of these sensors into digital data;
Monitoring means for periodically monitoring each digital data of the converting means;
Setting means for sequentially setting slice levels corresponding to the monitoring results of the monitoring means;
Comparing means for comparing each slice level set by the setting means with each digital data of the converting means,
Holding means for holding each comparison result of the comparison means,
The setting unit sets a new slice level only when the change in the monitoring result of the monitoring unit is less than a predetermined value, and holds the same slice level as before when the change in the monitoring result is a predetermined value or more. Sensor unit characterized by Multiple sensors,
Selection means for sequentially selecting the signals of these sensors;
Conversion means for converting the level of each signal selected by the selection means into digital data;
Monitoring means for periodically monitoring each digital data of the converting means;
Setting means for sequentially setting slice levels corresponding to the monitoring results of the monitoring means;
Comparing means for comparing each slice level set by the setting means with each digital data of the converting means,
Holding means for holding each comparison result of the comparison means,
The setting unit sets a new slice level only when the change in the monitoring result of the monitoring unit is less than a predetermined value, and holds the same slice level as before when the change in the monitoring result is a predetermined value or more. Sensor unit characterized by Further provided is a notifying means for notifying that the sensor needs to be cleaned when the change in the monitoring result of the monitoring means is not less than a predetermined value and the number of changes exceeding the predetermined value has reached a predetermined value. The sensor unit according to any one of claims 1 to 3, wherein the sensor unit is provided.

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