JPS58172570A - Paper detector - Google Patents

Abstract

PURPOSE:To prevent misdetection of paper by outputting a checking signal for an optical sensing section when the output level is below a fixed value due contamination of the optical sensing section. CONSTITUTION:A reflection type optical sensor 1 is composed of a light emitting section 1a and a light detecting section 1b and the output of the light detecting section 1b (phototransistor or the like) enters positive terminals of comparators C1 and C2 in parallel. The comparators C1 and C2 have reference voltages (currents) of the first level B and the second level C with the output level A of the light detecting section 1b. The output of the light detecting section 1b is taken into a CPU2 through an I/O port to perform the computation and a paper detection signal 3 or a check signal 4 of a sensor unit are outputted. The check signal 4 of the sensor unit actuates an LED 5 to emit light thereby giving an alarm to a user.

Description

Detailed Description of the Invention: Regarding a paper detection device that detects with an optical sensor, the following device is designed to prevent erroneous detection when detecting paper, especially when the output of the light receiving section decreases due to a dirt trap in the sensor section. It is related to.

This type of paper detection device is installed, for example, in the transfer paper conveyance path of a copying machine, for checking the timing of each copying process, or
Used for checking paper jams.

However, as this optical sensor is used for a long time,
Paper dust, atmospheric dust, and dust inside the copying machine cause scattered toner, etc., which contaminates both the light-emitting and light-receiving parts, resulting in a decrease in the output level of the light-receiving part over time. It turns out.

Therefore, whether the output level at the time of paper detection rises or falls from the reference level, there is a habit of erroneous detection.

Conventionally, the only measures specific to paper detection devices using such optical sensors have been to prevent the effects of external light.

That is, as a countermeasure against noise caused by external light, a specific high frequency light is applied to the light emitting section of the optical sensor, and only that frequency is received at the light receiving section.

As described above, conventional methods have been devised to prevent false detection of paper due to external light, but no measures have been taken to prevent the sensor section from getting dirty as described above.

In view of these circumstances, the present invention was developed by a woman, and its purpose is to prevent erroneous detection of paper due to dirt on the optical sensor.

To this end, when the output level falls below a certain value due to dirt on the optical sensor section, this is detected and a sensor section check signal, which is a sensor section cleaning alarm signal, is output. . Based on such a signal, the J/C5xs, -zer, or t-bisman at the false detection level is informed of the timing for cleaning the optical sensor. explain.

FIG. 1 is a simplified block diagram of a control circuit according to an embodiment of the present invention. ,,.

In the figure, a reflective optical sensor 1 has a light emitting section 1m.

It consists of a light receiving section 1b, and the output of the light receiving section 1b (a phototransistor or the like is used) is input in parallel to each terminal of the comparators C1 and C. These comparators C1 and C are 5, which will be described later, and a light receiving section 1.
It has a reference voltage (matching current) of the second level O and the second level O for the output level b. The outputs of the comparators C and C2 are taken into the CPU U 2 via the Ilo port, where they are processed and a paper detection signal 3 or a sensor section check signal 4, which will be described later, is output as appropriate. This sensor unit check signal 4 causes, for example, an LED 5 to emit light, and the user is notified of the light emission of this LED 5.
FIG. 3 is a waveform diagram showing levels.

(a) tf shows the relationship between the paper detection signal and the second level in the initial state when there is no dirt on the optical sensor l; The second detection level is 0, and the first detection level is ■.

Therefore, when the optical sensor 1 detects paper in its initial state, ■〉0
The relationship is 〉■. The potential (2) is used in the active area, so it varies depending on the reflectance of the paper. Generally, the voltage is 20V or more for high-quality paper, and about 10V for color paper. In this embodiment, in order to provide some margin for these, the second level 0 is set to 4 to 4.
5v, and the second level O is set 1 to 2v higher than this level.

Here, the second level ■ is the paper detection level, and when the output level ■ of the light receiving section 1b exceeds this level, the CPU
2 outputs a paper detection signal 3. and the second
Level O is for checking the degree of contamination of the optical sensor 1, and when the output level (■) at the time of paper detection is lower than this level, the sensor check signal 4 is sent to the CPU.
It outputs 2 p. This sensor check signal 4 is a signal to inform the trench light sensor 1 that the paper is not so dirty as to cause false paper detection at that stage, but that it should be cleaned in advance. Then, as mentioned above, the sensor check signal 4 causes the LED 5 to emit light,
This will be specifically communicated to the outside world.

[Figure 2Cb] This shows changes in the output level when the degree of contamination of the Fi optical sensor 1 is different.

(1) There is a case where the degree of Vi contamination is small, and the output level when the paper passes is much higher than the second level 0 indicated by mouth. In this case, the sensor check signal is not output.

In (2), the output level A when the paper passes is higher than the second level C indicated by .Therefore, the paper detection signal 3 is output, but the optical sensor 1 is below the second level C indicated by . This shows the waveform when the surface is dirty.

In this case, as described above, the sensor check signal 4 is output.

(3) is the waveform when paper is present at the location of optical sensor 1 at the paper passing timing (arrival timing).
In other words, it is a waveform with a waveform having a lower peak value than the first rubel (3) shown by (c).

In this case, the paper detection signal is 3tiffi. Of course, in this case, it is possible to output a pH jam signal or a paper feed error signal from the CPU 2 instead of the paper detection signal 3 as appropriate.

Next, a timing chart and a flowchart when such a paper detecting device is used as a paper jam sensor of a copying machine will be explained based on FIGS. 3 and 4.

FIG. 3 is a timing chart of jam detection. In the figure, (1) is the print start signal, (2) is the paper feed clutch, and (3) is the paper feed sensor (application of paper detection device).
, (4) are each timing of the registration clutch.

If the paper is transported normally, the actual detection time T1 is set from the on-timing of the paper feed clutch to the set time T0, which is slightly longer than the time it takes to reach the paper feed sensor position.
Determine whether it is long or short. T1<T. If so, the paper is being conveyed normally, and the registration clutch (4) is turned on, but if T1>To, there is a jam (or paper feeding error), and a jam display is displayed externally. Do not turn on the resist clutch.

FIG. 4 is a flowchart of such a copying machine. This step (indicated by S) will be explained below.

Determine whether the S-1 print button is on.

Perform blur cleaning on the S-2 photoreceptor.

Turn on the S-3 drive motor, transfer, and separation charger.

Turn on S-4 paper feed clutch and others.

S-5 Set the above-mentioned 10 hours on the timer and start.08-6 Determine whether the timer is set up for the To time.

If it is within S-7T0 time, it will judge whether the paper feed sensor is on or off. If no, return to S-6. This S-7 detects the second level 0, and therefore, if YES, it means that the paper has reached the sensor section within a predetermined time (within To).

S-8 Timer reset S-9 Determine whether the second level 0 of the paper feed sensor is on or off. If yes, it is normal, so proceed to step 10.

5-10 Perform registration drive and other operations, and set the timer to 1.
Set for 8 hours. This 13 hours is for timing the optical scanner and other steps in step 12.

5-11 Timer T2 set-up judgment.

5-12 Optical scanner return on, exposure lamp off operation.

5-13 Home position On/off judgment.

5-14 Charger, optical scanner off operation and timer reset. This T, Fi step 1
These are the respective control timings described.

5-15 Timer T3 Time on/off judgment.

5-16 Plaid solenoid, regime; clutch,
Transfer, separate charger off.

5-17 Set timer T4. This is for main motor off timing.

5-18 Timer T4 time set-up judgment O 8-19 Main motor off operation.

5-20 If the timer exceeds To time, enter the jam subroutine.

5-21 Turn off the primary circuit as jam processing.

5-22 Jam reset switch on/off judgment.

5-23 In step 9, the output level of the paper feed sensor is set to the second level.
A warning will be displayed if the level is below O.

As stated above, the present invention is designed to detect paper at a stage before the output of the light receiving section of the optical sensor is reduced due to dirt and erroneously detects paper.
Since this is configured to give a warning, periodic maintenance and inspection will be smooth and the paper detection device will be highly reliable.

[Brief explanation of the drawing]

FIG. 1 shows a fl! according to an embodiment of the present invention. ! I control block diagram, Figure 2 (a), (b) waveform diagram showing the output of the light receiving part of the Vi optical sensor and the difference in the degree of dirt, Figure 3 is a timing chart for the following cases when used as a jam detection sensor in a copying machine , FIG. 4 is a flowchart of the copying program. 1... Optical sensor, 1b... Light receiving section, 3
・・・・・・Paper test 10 72 drawing test 3 Σ? j+

Claims (1)

[Claims] (1) In a device that detects conveyed paper using a reflective or transmissive optical sensor, set points of the first level and the second level are set to the detection voltage or detection current of the light receiving section of the optical sensor. The paper detection signal is provided at the second level, and the second level is used to check the optical sensor, and when the output level of the light receiving section becomes lower than this second level, the sensor A paper detection device whose % sign is that it outputs a check signal. (2. The paper detection device according to claim (1), wherein the optical sensor detects transfer paper of a copying machine.