JP2001139189A - Paper thickness detection device and printing device - Google Patents

Abstract

(57) [Problem] To provide a paper thickness detection device capable of automatically and periodically correcting a sensor due to aging. SOLUTION: One light emitting element 8, a light receiving element 10 on a paper transport path 6, and a light receiving element 9 so as to receive a signal from the light emitting element 8 are installed.
In addition to measuring the paper thickness by measuring the phase of the waveform from, a stable measurement can be performed over a long period of time by periodically performing automatic correction by software in the CPU 13. When the thickness of the sheet is out of the predetermined range, the conveyance of the sheet is stopped to prevent a paper jam.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper thickness detecting device for measuring a paper thickness on a paper transport path of an image processing apparatus such as a copying machine or a printer.

[0002]

2. Description of the Related Art Generally, in an image processing apparatus such as a copying machine or a printer, a sheet is transported on a sheet transport path to perform a predetermined image forming process. When a printed matter is discharged in these image processing apparatuses, a trouble occurs in the image processing apparatus because the paper transport path transports two sheets at a time or the transported paper is poor. There was something. Conventionally, such a trouble in the image processing apparatus has been detected by a mechanical method such as a strain gauge to detect the thickness of the paper, but it is difficult to adjust the paper thickness measurement by the mechanical detection using the strain gauge or the like. However, stability and response were limited.
Therefore, with the improvement in printing speed in recent years, a paper thickness measuring device using a special sensor such as a non-contact displacement sensor has been proposed.

FIG. 6 is a diagram showing a configuration of a conventional paper thickness detecting device using a displacement sensor. The light emitted from the displacement sensor 3 is reflected by the sheet transport path 1 when there is no sheet 2 and returns to the displacement sensor 3. At this time, when the sheet 2 passes on the sheet transport path 1, the distance from the displacement sensor 3 changes by (L1−L2). This change appears as a change in the analog signal of the distance data, and is digitized by the A / D (analog / digital) converter 4 and passed to the CPU 5.

[0004]

However, in the displacement sensor 3 of the conventional paper thickness detecting device, since the installation angle is restricted and the reflection angle changes depending on the surface condition of the paper 2, the paper thickness is not always accurately determined. There was a problem that it could not be measured. In addition, a long-term use of the displacement sensor 3 causes a measurement error or the like of the paper thickness detecting device, and there is a problem that the displacement sensor 3 needs to be adjusted. The adjustment of the displacement sensor 3 due to such a temporal change is as follows.
It is often performed by a specialized maintenance person, and it is difficult to correct the displacement of the displacement sensor 3 in real time. On the other hand, with the recent increase in the number of functions such as double-sided printing and punching in printing apparatuses and copiers, paper outside a certain thickness range or rough paper tends to cause a failure in those apparatuses,
Since the paper feed stop condition is only when a paper size error occurs, a problem such as a paper jam occurs.

Accordingly, a first object of the present invention is to make it possible to perform stable paper thickness measurement, eliminate the need for sensor adjustment by maintenance personnel, etc., and to automatically and periodically correct the sensor with time. It is an object of the present invention to provide a paper thickness detecting device capable of performing the above. A second object of the present invention is to provide a printing apparatus capable of preventing occurrence of a trouble in advance by stopping paper feeding when paper is abnormal.

[0006]

According to the first aspect of the present invention, there is provided a transport path for transporting a sheet on which an image is to be formed and having a hole penetrating through the transport path surface, and a first light source for emitting a detection signal on an upper surface of the transport path. A light receiving element, provided on the same side as the first light emitting element, receives a reflected signal of a detection signal from the first light emitting element, and has a predetermined initial value;
A second light receiving element that is provided on the opposite side of the first light emitting element with respect to a transport path surface and receives a detection signal from the first light emitting element that has passed through a hole penetrating the transport path surface; Output control means for controlling the output of the first light-emitting element so that one light-receiving element approaches a predetermined initial value; and controlling the output control means when there is no sheet on which the image is formed in the transport path. A detection signal from the first light emitting element;
From the output signal of the first light receiving element that has received the reflection signal of the detection signal and the output signal of the second light receiving element that has received the detection signal, the first light receiving element and the second light receiving element
Correction means for calculating a correction coefficient so that the output signal of each of the light receiving elements approaches the initial value; and based on the correction coefficient calculated by the correction means, a reflection signal of the detection signal based on the presence or absence of a sheet on the transport path. The first object is achieved by providing a paper thickness detecting means for calculating a paper thickness from an output signal of the first light receiving element that receives the light.

According to a second aspect of the present invention, in the first aspect of the present invention, the correction means periodically adjusts the output signal of each of the first light receiving element and the second light receiving element to be the correction coefficient. The first object is achieved by performing automatic correction measurement / calculation in step (1).

According to a third aspect of the present invention, there is provided the paper thickness detecting device according to the first or second aspect, wherein the thickness of the paper on the conveyance path detected by the paper thickness detecting means is within a predetermined range. If not, the second object is achieved by stopping conveyance of the sheet as abnormal paper.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to FIGS. FIG.
FIG. 2 is a diagram illustrating a configuration of a paper thickness detection device according to the present embodiment. The paper thickness detecting device according to the present embodiment includes a light emitting element 8 provided above a detection hole 17 provided in the paper transport path 6.
A light receiving element 10 installed above the paper transport path 6 in the vicinity of the light emitting element 8 and a position below the detection hole 17 provided in the paper transport path 6 so as to be able to receive a detection signal from the light emitting element 8. A light receiving element 9 installed, a control circuit 11 for controlling the light emitting element 8, an arithmetic unit 12 for extracting a phase difference and a signal strength from a control waveform of the light emitting element 8 and input waveforms from the light receiving elements 9 and 10. And a CPU (Central Processing Unit) 13 for processing the extracted signal.

The light emitting element 8 is installed at a position at a distance L above the paper transport path 6. The light receiving element 10 is provided at a position separated from the paper transport path 6 by an upper distance L and a distance D from the light emitting element 8. The light receiving element 9 may be any position as long as it can receive a detection signal from the light emitting element 8 that has passed through the detection hole 17 provided in the paper transport path 6. The paper 7 is
Although it is conveyed in the conveyance direction from A to B in FIG. 1, there is no restriction on the conveyance speed. Further, the control circuit 11 and the arithmetic unit 12
The PU 13 can be used instead.

FIG. 2 is a flowchart showing the processing procedure of the correction algorithm according to the first embodiment. FIG. 3 is a diagram showing a driving signal of the light emitting element 8 and an output signal from the light receiving element 10. FIG. 4 is a diagram illustrating the intensity of a plurality of input lights applied to the light receiving element 8.

In the first embodiment, the reference of the detection signal to the light emitting element 8 in the detection of the paper thickness is determined, and the error due to the aging of the paper thickness detecting device is automatically corrected based on the reference value. . First, when the control circuit 11 gives the light emitting element 8 a drive signal 14 having a waveform shown by a broken line in FIG. 3, for example, in a state where the sheet 7 is not present on the sheet transport path 6 (step 2).
0), the light receiving element 10 outputs an output signal 15 having a waveform as shown by the solid line in FIG. And arithmetic unit 1
2 measures the Vmax value (see FIG. 3) which is the peak value of the output signal 15 from the light receiving element 10 (step 2).
1). The control circuit 11 adjusts the current value of the light emitting element 8 so that the Vmax value of the light receiving element 10 becomes the initial value V0 (where V0 is an arbitrary constant and is the initial value of the light receiving element 10). (Step 23).

When the Vmax value of the light receiving element 10 becomes V0 by adjusting the current value of the light emitting element 8 (Step 22;
Y), using the current value of the light emitting element 8 at that time as a reference value,
For example, it is stored in the memory of the CPU 13 (step 24). Next, in a state where the sensitivity of the light receiving element 10 is corrected by adjusting the current value of the light emitting element 8, the V of the light receiving element 9 is adjusted.
The maximum value is measured (step 25), and Vm of the light receiving element 9 is measured.
Similarly to the case of the light receiving element 10, the current value of the light emitting element 8 is adjusted so that the ax value approaches V0. And CPU1
The arithmetic unit 3 or the calculator 12 calculates and stores a correction coefficient using the current value of the light emitting element 8 when the Vmax value of the light receiving element 9 approaches V0 or V0 as a reference value (step 26).

Generally, the response speed of the light receiving element 9 and the light receiving element 10 has a correlation with the light intensity. Therefore, the phase difference δT when there is a light input of a constant intensity can be expressed by the following equation.

[0015]

## EQU1 ## δT = δt × F (V / V0)

After the sensitivity correction of the light receiving elements 9 and 10 is completed, for example, a waveform (pattern 1) as shown in FIG.
To 3) to the light emitting element 8, and by measuring a plurality of phase differences δt depending on a plurality of input light intensities I, F (V / V0)
Function can be obtained. The sensitivity correction may be performed by storing the reference value of the current value of the light emitting element 8 when the output signal of the light receiving element 10 becomes V0 in the control circuit 11 or the arithmetic unit 12.

In the paper thickness detecting apparatus of the present embodiment, by performing these sensitivity correction operations periodically by software, it is possible to correct the sensitivity fluctuation of the element due to the environment and deterioration, and to perform stable measurement. it can. Furthermore, in the paper thickness detecting device of the present embodiment, one light emitting element 8, a light receiving element 10 on the paper transport path 6, and a light receiving element 9 are installed so as to be able to receive a signal from the light emitting element 8. The thickness of the paper is measured by measuring the phases of the waveforms from the two light receiving elements 9 and 10, and the automatic correction is periodically performed by software in the CPU 13, thereby enabling stable measurement over a long period of time. In addition, the automatic correction of the sensitivity of the light emitting element 8, the light receiving element 9, and the light receiving element 9 and 10 of the paper thickness detecting device eliminates the need for troublesome maintenance such as adjustment of the sensor by a maintenance person or the like, so that maintenance cost can be reduced.

Next, a second embodiment will be described. When there is no sheet 7 on the sheet transport path 6, the light receiving element 10
The reflected light from the paper transport path 6 is incident on the sheet. At this time, the phase difference between the light receiving element 10 and the drive signal of the light emitting element 8 is represented by δ.
At t1, the intensity as the voltage is V1. On the other hand, when the paper 7 is present on the paper transport path 6, the phase difference of the light reflected by the surface of the paper 7 at the light receiving element 10 is δt2 and the intensity is V
Assuming 2,

[0019]

ΔT2 = δt2 × F (V2 / V1)

And (δt1−δT2) becomes the corrected phase difference. From the distance L between the light emitting element 8 and the light receiving element 10 and the paper transport path 6 and the distance D between the light emitting element 8 and the light receiving element 10, the optical path length L1 when there is no paper 7 is expressed by the following equation.

[0021]

L1 = 2 × (L2 + D2) 1/2

Optical path length L2 when there is a sheet 7 of thickness d
Is represented by the following equation.

[0023]

L2 = 2 × ((Ld) 2 + D2) 1/2

This optical path difference (L1-L2) is given by the following equation, where v is the speed of light.

[0025]

(L1-L2) = (δt1-δT2) × v

From the above, the paper thickness d can be obtained.

[0027]

D = L − ｛(2 (L2 + D2) 1 / 2− (δt
1−δT2) × v) 2 / 4−D2｝ 1/2

Next, a third embodiment will be described. FIG.
5 is a flowchart showing a processing procedure of abnormal paper detection according to the embodiment of the present invention. The abnormal paper detection according to the third embodiment includes detection by measuring the thickness of the paper (abnormal paper thickness) and detection of poor paper using the light receiving element 10 (abnormal paper quality). First, it is determined whether there is a sheet 7 on the sheet transport path 6 (step 30). If the paper 7 is present (Step 30; Y), the thickness of the paper 7 is measured (measurement of paper thickness) (Step 31), and the thickness of the paper 7 is within a predetermined range set in advance. It is determined whether or not it is (step 32). As a result of the paper thickness measurement, if the paper thickness is not within the predetermined range (Step 32; N), it is determined that the paper thickness of the paper 7 is abnormal. Step 33). When the result of the paper thickness measurement is within a predetermined range (Step 32;
Y), the output signal from the light receiving element 10 is measured (step 34), and it is determined whether or not this output signal is within a predetermined range. When the intensity signal V3 from the light receiving element 10 indicates a predetermined range or more (Step 35; N) despite the fact that there is a sheet having a certain thickness, it is assumed that the sheet has a rough surface condition. Then, it is determined that the sheet 7 has an abnormal sheet quality, the sheet feeding is stopped, error processing is performed, and a user is warned through the operation panel (step 33).

Further, even when the output of the light receiving element 10 is within the predetermined range or extremely low (step 35; N), it is assumed that the sheet is abnormal, and the sheet 7 is judged to be abnormal. Then, the paper supply is stopped, error processing is performed, and a warning is issued to the user through the operation panel (step 33).
The value of the predetermined range serving as a detection reference for the paper thickness abnormality detection and the paper quality abnormality detection may be set in the paper thickness detection device in advance, or may be set by the user from the operation panel or the like each time the device is used. You may make it.

In the paper thickness detecting device of the present embodiment, the CPU
At 13, the abnormal paper is determined according to the procedure shown in FIG. 5, and if the abnormal paper is determined to be abnormal by the abnormal paper feeding stop function, the paper feeding is immediately interrupted. Then, a warning can be given to the user through the operation panel or the like, and it is possible to prevent a trouble from occurring in advance, thereby improving the product reliability.

[0031]

According to the first aspect of the present invention, based on the calculated correction coefficient, a paper signal is obtained from an output signal of the first light receiving element which receives a reflection signal of the detection signal based on the presence or absence of a paper on the transport path. Since the thickness is calculated, a stable paper thickness measurement can be performed.

According to the second aspect of the present invention, the automatic correction measurement and calculation are periodically performed, so that maintenance-free operation can be realized by the automatic correction, and troublesome maintenance is not required, so that the maintenance cost is reduced. be able to.

According to the third aspect of the present invention, when it is determined that the sheet is abnormal, the sheet feeding is immediately stopped, and the sheet conveyance is stopped to prevent a paper jam in the apparatus in advance.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a paper thickness detecting device according to the present embodiment.

FIG. 2 is a flowchart showing a processing procedure of a correction algorithm according to the first embodiment.

FIG. 3 is a diagram showing a driving signal of a light emitting element and an output signal from a light receiving element.

FIG. 4 is a diagram illustrating the intensity of a plurality of input lights applied to a light receiving element.

FIG. 5 is a flowchart illustrating a processing procedure of abnormal paper detection according to the embodiment of the present invention.

FIG. 6 is a diagram showing a configuration of a conventional paper thickness detection device using a displacement sensor.

[Explanation of symbols]

 6 paper transport path 7 paper 8 light emitting element 9, 10 light receiving element 11 control circuit 12 arithmetic unit 13 CPU (central processing unit)

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) 2F065 AA06 AA24 AA30 BB01 BB15 CC02 DD00 EE00 EE09 FF02 FF13 FF44 GG08 GG12 HH12 HH15 JJ01 JJ05 JJ08 NN02 NN11 PP15 QQ00 QQ23 QQ25 SS09 3F05 DCA14A03 EA01

Claims (3)

[Claims] 1. A transport path that transports a sheet on which an image is to be formed and has a hole that penetrates a transport path surface, a first light emitting element that emits a detection signal on an upper surface of the transport path, and the first light emitting element. A first light receiving element provided on the same side and receiving a reflected signal of a detection signal from the first light emitting element and having a predetermined initial value; and a first light emitting element opposite to the first light emitting element via a conveyance path surface. A second light-receiving element that receives a detection signal from the first light-emitting element that has passed through a hole that penetrates the transport path surface, and the first light-receiving element approaches a predetermined initial value. An output control means for controlling an output of the first light emitting element; a detection signal from the first light emitting element under the control of the output control means when there is no sheet on which the image is to be formed in the transport path; Out of the first light receiving element that has received the reflected signal of Correction means for calculating a correction coefficient from a signal and an output signal of a second light receiving element which has received the detection signal so that output signals of the first light receiving element and the second light receiving element each approach an initial value. And a sheet thickness detection unit that calculates a sheet thickness from an output signal of the first light receiving element that receives a reflection signal of the detection signal based on the presence or absence of a sheet on the conveyance path based on the correction coefficient calculated by the correction unit. Means for detecting paper thickness. 2. The apparatus according to claim 1, wherein said correction means periodically performs automatic correction measurement and calculation such that output signals of said first light receiving element and said second light receiving element become the correction coefficients. Item 2. The paper thickness detecting device according to Item 1. 3. The apparatus according to claim 1, further comprising a sheet thickness detecting device, wherein the sheet thickness on the conveyance path detected by the sheet thickness detecting means is not within a predetermined range set in advance. A printing apparatus characterized in that conveyance of paper as paper is stopped.