JPH08166231A - Sheet thickness discriminator - Google Patents

Abstract

PURPOSE: To measure the accurate thickness of a sheet by regarding the signal level range where the corresponding counter shows the maximum number of counts as the thickness of a variety of paper, out of counters corresponding to each signal level range by this device. CONSTITUTION: This sheet thickness discriminator is provided with a first signal level L1 for judging that a sheet is caught with a pair of rollers and a second signal level L2 for terminating the sampling of the thickness of a sheet, and the thickness of the sheet is sought covering the sampling data until cutting off the second signal level L2 after cutting off the first signal level L1 to a series of sampling data from the sensors or until passage of specified time. For the objective sampling data, counters are provided for every signal level range, and these counters count which signal level range the sampling data belong to. The ranges 1, 2, and 3 which show the phased thickness of the sheet are stipulated by signal levels REF1, 2, 3, and 4 in view of the output levels of sheet thickness discriminating sensors.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet thickness discriminating apparatus for sheets such as paper sheets that are passed through an image forming apparatus such as a copying machine, a printer or a printing machine.

[0002]

2. Description of the Related Art In a sheet thickness discriminating apparatus in an image forming apparatus such as a copying machine, a printer, a printing machine, etc., a difference between an average value of a sensor signal before a sheet enters a roller pair and an average value after the sheet enters. There is one that is the thickness of the sheet. FIG. 5 shows an example of the output signal of the thickness discriminating sensor when the sheet is passed through the conventional sheet thickness discriminating apparatus, and FIG. 6 shows the sheet thickness discriminating apparatus having the roller pair configuration. In FIG. 6, the sheet thickness component is obtained from the difference in the average value of the sampled data before and after the signal level SL of the thickness determination sensor falls below a certain signal level SL.

When the sensor output signal is yi, the average value before and after the sheet enters the sheet thickness discriminating apparatus having a roller pair configuration is as follows.

[0004]

[Outside 1] Here, the sampling numbers are n ₁ and n ₂ .

From this, the signal indicating the desired sheet thickness is

[0006]

[Outside 2] I was trying.

[0007]

However, in the above-mentioned prior art, when the vibration of the movable roller occurs when the sheet plunges in or out, the number of samplings n ₁ and n ₂ is increased to reduce the influence of the vibration on the sheet thickness signal. Unless the value is reduced or sampling is performed through a filter, the value of the equation (2) includes the vibration component of the movable roller, so that it is difficult to obtain an accurate sheet thickness.

[0008]

According to the present invention, a first signal level for determining that a sheet is nipped by a pair of rollers and a second signal level for ending sheet thickness sampling are set. The sheet thickness is obtained by setting the sampling data from the first signal level to the second signal level after cutting the series of sampling data from the sensor or until the predetermined time elapses. A counter device is provided for each of a plurality of signal level ranges with respect to the target sampling data, and the signal level range to which the sampling data belongs is counted.

[0009]

In the sheet thickness discriminating apparatus having the above structure, the signal level range showing the maximum count number among the counters corresponding to the respective signal level ranges is the thickness of the paper sheet. By this method, the CPU in the image forming apparatus can know the thickness of the sheet step by step by referring to the counter, which brings about the effect of reducing the load on the CPU.

[0010]

EXAMPLE An example of the sheet thickness discriminating apparatus according to the present invention will be described.

FIG. 1 shows an output signal waveform of a sheet thickness discriminating sensor when a sheet is passed through the sheet thickness discriminating apparatus of the present invention.

When the output signal waveform of the sheet thickness discrimination sensor is wavy, the eccentric component of the roller pair in FIG. 4 appears.
The first signal level L1 for determining that the roller pair shown in FIG. 4 holds the sheet is set near the signal level before the sheet is held, and the first signal level for ending the sheet thickness sampling is set. The second signal level is set to be higher than the first signal level within the signal level range 1.

The ranges 1, 2, and 3 showing the stepwise sheet thickness are
Signal level considering the output level of the sheet thickness determination sensor
Specified by REF1,2,3,4.

FIG. 2 shows a counter device for counting in which signal level range the signal sampled by the sheet thickness discriminating sensor is present. 1 is a sheet thickness discriminating sensor and 2 is an output from the sheet thickness discriminating sensor. The first signal level L1 for distinguishing between the signal and the roller pair nipping the sheet
And a second signal level L2 for ending the sheet thickness sampling are input signals, and a counter enable signal CE indicating whether the signal data sampled by the sheet thickness determination sensor is a count target or a non-target is output. It is a counter control unit.

Reference numeral 3 designates Ref.N, Ref. (N + 1), (N = 1,2,3) and output signals from the sheet thickness discrimination sensor as input signals, and Re
Sheet thickness range divided by fN and Ref. (N + 1), (N = 1,2,3)
A comparator circuit that determines whether or not an output signal from the sheet thickness determination sensor is present in N, and if present, generates an output signal INC that increments the counter.

Reference numeral 6 is a CPU of the image forming apparatus.

Reference numeral 7 is a memory connected to the CPU of the image forming apparatus.

Reference numeral 5 denotes an I / O which is interposed between the CPU of the image forming apparatus and the counter device for determining the sheet thickness, and which controls the CPU 6 to refer to the count result and to send the reset signal RES command to the counter device. is there.

Reference numeral 4 is an increment signal INC of the comparison circuit 3.
And counter enable signal CE and I / O5 of counter control unit 2
It is a counter circuit that inputs the reset signals RES and the like from and outputs the count result to I / O5.

Reference numerals 8, 9 and 10 are counters for the graduated sheet thickness ranges 1, 2 and 3, respectively. In Fig. 1, ○ indicates sampling data that is not counted by the counter device, and ● indicates sampling data that is counted.

FIG. 3 is a count value of each signal level range when the signal waveform of the sheet thickness discrimination sensor of FIG. 1 is input to the counter device shown in FIG.

FIG. 4 shows a sheet thickness discriminating mechanism according to the present invention. In the sheet conveying path, a roller pair composed of a fixed roller and a movable roller biased by a spring so as to face the roller pair. It has a sensor that reads the amount of movement of the movable roller when the sheet passes.

In the sheet thickness discriminating apparatus including the sheet thickness discriminating mechanism shown in FIG. 4 and the counter device shown in FIG.
The count result of the signal waveform of the sheet thickness discrimination sensor of
It looks like Figure 3. Therefore, the CPU 6 of FIG. 2 determines that the passed sheet has a thickness in the range 2 showing these maximum values. After that, the counter device is reset in preparation for the next sheet thickness determination.

[0024]

As described above, by using the sheet thickness discriminating apparatus according to the present invention, it is possible to make a stable sheet thickness discrimination against the sudden noise generated when the sheet plunges into the roller pair. become. In addition, the CP of the image forming device
In U, there is an effect that the degree of freedom in the circuit design and the like is increased because it is freed from the interruption work every time the sheet thickness data is sampled.

[Brief description of drawings]

FIG. 1 is a diagram showing an output signal waveform of a paper sheet thickness determination sensor.

FIG. 2 is a block circuit diagram of a counter device of the paper sheet thickness determination device.

3 is a diagram showing a count value when the output signal waveform of the paper sheet thickness determination sensor of FIG. 1 is input to the counter device of the paper sheet thickness determination device of FIG.

FIG. 4 is a diagram showing a paper sheet thickness determination mechanism.

FIG. 5 is a diagram showing an output signal waveform of a conventional sheet thickness determination sensor.

FIG. 6 is a diagram showing a conventional paper sheet thickness determination mechanism.

[Explanation of symbols]

 1 Paper Thickness Discrimination Sensor 2 Counter Control Section 3 Comparison Circuit 4 Counter Circuit 5 I / O 6 CPU 7 Memory 8, 9, 10 Counter for Paper Thickness Range 1, 2, 3 11 Lower Roller 12 Movable Roller 13 movable roller urging spring 14 paper sheet 15 sensor 16 conventional lower roller 17 conventional movable roller 18 conventional movable roller urging spring 19 conventional sheet 20 conventional interrupting sensor 21 conventional Shut off lever

Claims (4)

[Claims] 1. A roller pair composed of a first roller fixed in the middle of a sheet conveying path, a movable second roller opposed to the first roller, and a sheet passing through the roller pair. A sheet thickness discriminating apparatus having a sensor for reading the movable amount of the second roller. 2. The sheet thickness discriminating apparatus according to claim 1, wherein the peripheral length of the second roller corresponds to the minimum sheet length in the sheet conveying path direction. 3. A first discrimination level for discriminating that a sheet is sandwiched by the roller pair and a sheet thickness for sampling the movable amount data sampled by the sensor. The thickness of the sheet after the movable amount data is sampled based on the second determination level, and after the movable amount data cuts off the first determination level to the second determination level. 3. The sheet thickness discriminating apparatus according to claim 1, further comprising a sampling means for sampling the sheet thickness. 4. A counter for counting each range of the first discrimination level and the second discrimination level is provided, and it is counted in which range the movable amount data sampled by the sensor is, and the maximum count number is set. 5. The sheet thickness discriminating apparatus according to claim 3, further comprising a discriminating means for discriminating the sheet thickness stepwise from the signal level range shown.