JP2001312115A - Color slippage detector for color copying machine or the like - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the color slippage detector of a color copying machine or the like by which adjustment is simplified as well as enhancing detection accuracy, and noises are reduced as far as possible and which is suitable for the reduction of a production cost. SOLUTION: This detector is provided with an LED projecting unit 32 to project a toner pattern 31 and a PD photodetector 33 to receive the reflected light of the toner pattern 31 by passing through a rod lens array 34 and a filter 35, and is provided with plural light-transmitting parts by which the toner patterns 31 are formed as plural toner patterns and which are formed so as to correspond to the plural toner patterns on the filer 35, and also is provided with a signal processing circuit by which an output signal outputted by the PD photodetor 33 when the toner pattern coincides with a part of the light- transmitting part is formed as a relative reference threshold and a detected signal is outputted by comparing the output signal outputted by the PD photodetor 33 when the toner pattern coincides with a whole light-transmitting part with the relative reference threshold.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color copying machine,
It is used as a toner position detecting sensor for automatically correcting a color shift occurring in a toner type color printer or the like.

[0002]

2. Description of the Related Art FIG. 10 is a simplified diagram showing a configuration example of a tandem image forming apparatus provided in a color copying machine.
As shown in the figure, the image forming apparatus is provided with image forming units 11, 12, 13, and 14 which are color-coded in four colors, and each image forming unit forms a toner image of each color on the upper surface of a transfer belt 15. Let it form. C is cyan, M is magenta, Y
Denotes a yellow image forming unit, and K denotes a black image forming unit.

When the transfer belt 15 is moved, the toner image formed on the belt 15 is collectively transferred onto a sheet 16 fed in a direction shown in FIG.

[0004] This image forming apparatus is advantageous for speeding up the transfer as compared with other apparatuses of the multi-rotation transfer type of the transfer belt. However, each image formed separately by the image forming sections 11 to 14 of each color is advantageous. Since the toner image is transferred so as to be superimposed on the sheet 16, the toner image is easily shifted in position for each color.
Various means have been proposed for correcting the positional deviation.

FIG. 11 shows a toner pattern 17 formed on the transfer belt 15 for detecting a positional shift of the toner image.
Then, the toner pattern 17 is detected by the detecting device 18 having the structure shown in FIG. 12, and the positional deviation is corrected based on the detection signal.

The detecting device 18 detects a toner pattern 17 formed on the transfer belt 15 through which light is transmitted. The detecting device 18 is disposed on the back side of the transfer belt 15 and has an LED (light emitting diode) light emitter 19. , And is projected toward the toner pattern 17, and the projected light is received by a CCD (solid-state imaging device) 20.

[0007] In this detecting device 18, the CCD 20 is a toner
The pattern image is converted into an electric signal and a detection signal is output. This detection signal is compared with a predetermined reference color value, and the color shift of each color is decomposed in the main scanning direction and the sub scanning direction. Then, the correction signal processed as described above is fed back to the write control system so as to cancel the color shift.

FIG. 13 shows a detecting device 21 for detecting a toner pattern 17 formed on a transfer belt 15 which is not permeable to light.
In this configuration, the light emitted from the LED projector 19 is reflected by the toner pattern 17 and received by the CCD 20, which is similar to the detection device 18 shown in FIG.

A detector 22 shown in FIG. 14 reflects the light emitted from the LED projector 19 at the edge of the toner pattern 17, and passes the reflected light through a condenser lens 23 to a PD (photodiode) light receiver 24. And outputs a detection signal. The LED projector 19 is designed to focus the light on the toner pattern 17 by sufficiently squeezing the emitted light.

A detecting device 25 shown in FIG. 15 is of a reflection type similarly to the detecting device 22 shown in FIG. 14, in which a power beam splitter 26 is provided on the light projecting path of the LED projector 19 and a PD.
A power beam splitter 27 and a condenser lens 23 are provided on the light receiving path of the light receiver 24.

A detecting device 28 shown in FIG. 16 prevents the detection margin from lowering due to the reflection from the transfer belt 15.
The center of gravity of the light diffused by the toner pattern 17 is detected by a two-division PD receiver 29.

[0012]

The detecting device 18 shown in FIG. 12 is provided with another reflection type sensor such as a toner density detecting device because the transfer belt 15 needs to transmit light. In some cases, the transfer belt 15 is affected by the object behind the transfer belt 15, so that the assembly and arrangement of parts is restricted.

Further, since the CCD 20 is used as a photodetector, image processing calculations are required. When the speed of the copying machine is increased, the error space length due to the delay time of the image processing cannot be ignored. The burden on the CPU increases.

In the detection device 21 shown in FIG. 13, the transfer belt 15 may be opaque, but the number of LEDs increases due to the structure of the light projector, and the cost increases. The image processing operation is the same as that of the detection device 18 described above.

Both the detecting device 22 shown in FIG. 14 and the detecting device 25 shown in FIG. 15 detect the edge position of the toner pattern 17, and both of them avoid the specular reflection component from the transfer belt 15. There is a difference in the method.

The detecting device 22 tilts the light projecting optical axis of the LED projector 19 so that only the diffuse reflection light from the toner pattern 17 is incident on the PD light receiving device 24. The detection device 25 detects the fluctuation of the polarization plane caused by the reflection of the toner pattern 17.

In these detectors 22 and 25, the detection accuracy is determined by the beam diameter of light emission or light reception, so that an attempt to increase the optical accuracy causes a reading error. In addition, since the detection range is reduced, the scattered toner is detected as noise, and the probability of malfunction is high.

The detecting device 28 shown in FIG. 16 does not restrict the light emitting beam of the LED light emitting device 19 extremely, and
7, the total diffuse reflection light component in the width direction is divided into two divided PD receivers 2.
The PD receiver 29 receives the light as a differential input, and detects the position of the pattern center of gravity from the zero cross point.

Therefore, the detection devices 18 and 21 described above
In addition to the above, it is advantageous not only in terms of light transmittance of the transfer belt 15, image processing time, and cost, but also the error of the detection position due to color is self-corrected because differential detection is performed. . Further, the detection accuracy, which is a problem of the detection devices 22 and 25, is also solved.

However, since there are a plurality of modes of color shift such as shift in the main scanning direction, magnification, inclination, and shift in the sub-scanning direction, a toner such as that shown in FIG. With respect to the pattern 17, it is necessary to provide sensors at a plurality of positions in a combination in which the shift mode can be determined.

When the sensors are provided at a plurality of positions as described above, since the relative positional accuracy of each sensor is limited in the installation process, the sensors must be installed with a margin for the installation position tolerance. The step of adjusting the timing of-occurs.

The detection device 27 can be said to have a wide range of light projection and detection and to have a margin for noise. However, the noise is processed by an amplifier for level-shifting the expected amount of noise. ing.

FIG. 17A shows output signals P1 and P2 of the two-divided PD light receiver 29, and FIG. 17B shows amplifier outputs AP1 and AP2 in which noise has been reduced. As shown in the figure, the signal portion of AP0 is generated in the amplifier output based on the decrease in the sensitivity of the PD light receiver 29, and this signal AP0 affects the detection accuracy.

In view of the above-mentioned circumstances, the present invention improves the detection accuracy, simplifies the adjustment, reduces the noise as much as possible, and is suitable for a color misregistration detecting apparatus such as a color copying machine suitable for reducing the production cost. The purpose is to provide.

[0025]

In order to achieve the above-mentioned object, according to the present invention, as a first invention, light is projected from a light projecting portion to a transfer belt portion provided with a detection pattern, and reflected light thereof is provided. In a color misregistration detecting device such as a color copier which performs color misregistration detection by confirming the position of a detection pattern based on an output signal of a light receiving section which receives light, a transfer belt is provided at regular intervals along a running direction. A plurality of arranged detection patterns, at least two light-transmitting portions formed at intervals corresponding to the intervals of the detection patterns, and a filter disposed on a light receiving path of the light receiving portion; In accordance with the movement of the detection pattern, the detection pattern includes holding means for holding an output signal of the light receiving section for receiving reflected light when the detection pattern matches a part of the light transmitting section, and the detection pattern is entirely Reflected light when it matches the translucent part of A color misregistration detecting device for a color copying machine or the like, characterized by comprising signal processing means for comparing an output signal of the light receiving section and a holding signal of the holding means and outputting a detection signal. I do.

In the detection device thus constructed, when the detection pattern matches the translucent portion of a part of the filter according to the movement of the detection pattern, the light reflected by the detection pattern becomes one. Light enters the light receiving section through the light transmitting section of the section. The output of the light receiving unit at that time is held by the holding unit.

Subsequently, according to the movement of the detection pattern,
The detection pattern matches all the light transmitting portions, and the light reflected by the detection pattern passes through all the light transmitting portions and enters the light receiving portion.
The output signal of the light receiving section at this time is compared with the holding signal of the holding means by the signal processing means, and the signal processing means outputs a detection signal as a result of the comparison.

The detection signal thus output is a pattern
The position detection signal of the detection pattern is output at a constant timing regardless of the toner color and the toner pattern density. As a result, a color misregistration detection device having high detection accuracy and easy adjustment can be obtained.

According to a second aspect of the present invention, in the detection device of the first aspect, the signal processing means reflects the detection pattern when the detection pattern coincides with all the light transmitting portions in accordance with the movement of the detection pattern. Holding means for holding an output signal of the light receiving portion for receiving light, and an output signal of the light receiving portion for receiving reflected light when a detection pattern matches a part of the light transmitting portion; A color misregistration detecting device such as a color copying machine is proposed, which is configured to output a detection signal by comparing with a holding signal. The detection device thus configured operates similarly to the detection device of the first invention.

According to a third aspect, in the detection device according to the first or second aspect, the noise includes means for pulsing the output signal of the light receiving section and means for detecting noise from the number of pulses counted in a predetermined time. A color misregistration detecting device for a color copying machine or the like, characterized by comprising a discriminating means, is proposed.

According to a fourth aspect of the present invention, in the detection device of the first or second aspect, there is provided a noise discriminating means comprising means for integrating an output signal of the light receiving section and means for detecting noise from the integrated value. A color misregistration detecting device such as a color copying machine is proposed.

The provision of such a noise discriminating means makes it possible to discriminate the noise by directly pulsing the output signal of the light receiving section and integrating it. As a result, a color misregistration detection device that can obtain a detection signal with as little noise as possible is obtained.

[0033]

Next, an embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, the detection device 30 of the present embodiment includes a toner formed on a transfer belt 15.
LE that projects light toward a pattern (detection pattern) 31
D projector 32, PD receiver 33 for receiving the reflected light of toner pattern 31, and P reflected light of toner pattern 31
It comprises a rod lens array 34 leading to the D light receiver 33 and a filter 35 provided between the PD light receiver 33 and the rod lens array 34. 2 and 3 show the arrangement of the PD light receiver 33, rod lens array 34, and filter 35 described above.

The above-mentioned LED projector 32 uses a narrow light distribution LED in which the beam is narrowed down to near the parallel light, and as shown in FIG. Is taken into the PD light receiver 33 only.

The light emitted from the LED projector 32 is a beam having a certain thickness so that the entire toner pattern 31 falls within the projection range. Furthermore, this L
The emission wavelength of the ED projector 32 is set to a wavelength at which the amount of reflected light increases in accordance with the spectral reflection characteristics of cyan, magenta, and yellow of the color copying machine toner. Therefore, it is preferable to set the range to 0.8 to 0.9 μm.

The PD light receiving device 33 has a PIN structure whose response performance is improved by applying a reverse bias. Printing speed of the copier is fast, on the order of ^{10 -5} seconds P
This is because it is necessary to maintain a margin in the PD response speed since the delay of the D light receiver 33 is converted into a micron-order error in terms of the space length on the transfer belt.

The rod lens array 34 includes a filter 35
It is used to form an erect equal-size real image on the top,
A sensor having a large depth of focus is used like a sensor used for a di-sensor or an LED printer.

The filter 35 is configured as a so-called Sudare space filter having a plurality of slit-shaped light transmitting portions. The filter 35 is, for example, a filter in which a light-transmitting portion formed of a slit window is formed on a thin metal plate by photo-etching or laser, or a light-shadow is drawn on a transparent resin film such as polyester to form a slit-shaped light transmitting portion. Use the formed filter.

The plurality of light transmitting portions of the filter 35 have a shape conforming to the toner pattern 31 formed on the transfer belt 15. That is, as shown in FIG. 4A, in the present embodiment, three elongated toner patterns 31 are formed on the transfer belt 15 as the toner patterns 31.
a, 31b, 31c are formed at equal intervals, and the filter 35 is provided with three light-transmitting portions 35a, 35b, 35c having shapes corresponding to the toner patterns 31a, 31b, 31c at equal intervals. is there.

Then, the toner patterns 31a, 31b,
As shown in FIG. 4, 31c and the light-transmitting portions 35a, 35b, 35c adjust the width WF of each light-transmitting portion to the width WT of each toner pattern, and the distance DF between each light-transmitting portion. Is adjusted to the distance DT between each of the toner patterns.

With this configuration, the toner patterns 31a, 31b, 31c and the light transmitting portions 35a, 35c are formed.
The relative positional accuracy of the b and 35c can be uniquely dependent on the accuracy of the light-transmitting portion of the filter 35, and a large tolerance is given to the mount dimensional tolerance of the combined rod lens array 34 and PD light receiver 33. it can.

FIG. 5 shows the light transmitting portions 35a and 35 of the filter 35.
b, 35c for the toner patterns 31a, 31b, 3
1c shows the relative position. FIG. 6 shows a change in the output of the PD light receiver 33 according to the relative position between the light transmitting portion and the toner pattern.

The toner patterns 31a, 31b, and 31c move as the transfer belt 15 moves as shown in FIGS.
(E), and as a result, the light transmitting portions 35a, 35
The output signal of the PD light receiver 33 receiving the reflected light from the toner pattern 31 passing through b and 35c has a triangular waveform with the pitch width of the light transmitting portion. That is, the peak level is 1: 2:
Triangular wave signals that change at a ratio of 3: 2: 1 are sequentially output.

Note that the filter is provided with four light transmitting portions,
If one toner pattern is formed, 1: 2: 3: 4:
A triangular wave signal that changes at a ratio of 3: 2: 1 is output.

FIG. 7 is a block diagram showing an example of the signal processing circuit 40 for processing the output signal of the detection device 30 described above. As shown in the figure, a preamplifier 41 amplifies a triangular wave output signal S1 output from a PD light receiver 33, and amplifies the amplified signal S2 with a peak hold circuit 42 and a binarization circuit 43.
And the waveform shaping circuit 44.

Then, the pulse of the output signal S 1 pulsed by the waveform shaping circuit 44 is sent to the ring counter 45. The counter 45 counts the trigger generation timing of the peak hold circuit 42.

The count signal of the ring counter 45 is sent to a noise discriminating circuit 46, which discriminates noise by this circuit 46, and then sends it to a timing pulse generating circuit 47. The timing pulse generation circuit 47 sends a trigger pulse to the peak hold circuit 42 and the binarization circuit 43.

The signal processing circuit 40 applies the toner pattern 31 to each of the light transmitting portions 35a, 35b, 35c of the filter 35.
5 (B), which is the immediately preceding detection process in which all of a, 31b, 31c match, ie, the relative position of the light transmitting portion and the toner pattern is the immediately preceding FIG. 5 (C). When this happens, the ring counter 45 is set so as to amplify the triangular wave signal output from the PD light receiver 33 and hold the peak value.

That is, the peak values P1, P2, and P3 of the output signal of the PD light receiver 33 shown in FIG. 8 are held by the peak hold circuit 42. The peak values are those after amplification. Further, the triangular waveforms 51 and 5 shown in FIG.
Reference numerals 2 and 53 denote output signals of the PD light receiver 33 when toner colors having different reflectances or toner patterns having different reflection light amount density differences are detected.

The peak value P held as described above
1, P2 and P3 are relative reference threshold signals R1, R2 and R3
Is sent to the binarization circuit 43. Then, the binarizing circuit 43 outputs the PD when all the toner patterns coincide with each of the light transmitting portions of the filter 35, that is, in the state of FIG.
The triangular wave signal (the maximum detection signal) output from the light receiver 33 and the relative reference threshold signal are digitized and compared, and the comparison result is output as a binarized detection signal S0.

The detection signal S0 output in this way is output at a constant detection timing time T0 regardless of the toner color reflectance and the toner density different in the amount of reflected light, and the level of the detected triangular wave signal. Output as a signal. As a result, no deviation of the detection timing position occurs.

When three slits (light-transmitting portions) having the same width and the same interval are provided as in this embodiment, the detection timing position is about 33% before the slit width from the center of the slit pattern. In the case of detecting the toner pattern 17 shown in FIG. 11 in the detection device configured as described above, a large number of detection devices are installed to detect the pattern displacement.

The detection device 22 shown in FIG. 14 shown as a conventional example
Alternatively, as in the case of the detection device 25 in FIG. 15, when the amount of diffuse reflection light or the amount of change in the polarization wave due to diffusion is detected and detected using a fixed threshold R0 set in advance, as shown in FIG. The detection timing positions are T1, T2, T3
It shifts like

The triangular waveforms 61 and 62 shown in FIG.
Reference numeral 63 denotes an output signal of the PD light receiver 24 which detects toner colors having different reflectivities or toner patterns having different reflected light intensity densities.

Although the embodiment has been described above, the number of light-transmitting portions provided in the filter 35 may be arbitrarily increased or decreased since it may be determined in accordance with the toner pattern.

In the above-described embodiment, the output signal of the PD light receiver is pulsed, and the noise is determined from the count value of the pulse. However, the output signal of the PD light receiver is integrated, and the noise is calculated from the integrated value. It is possible to adopt a configuration for determining.

Further, in implementing the present invention, the peak value of the triangular wave signal immediately before the output signal of the PD light receiver 33 becomes the maximum triangular wave signal is held as a relative reference threshold, and this relative reference threshold is held. A configuration in which the threshold value is compared with the maximum output signal can be adopted.

Further, the peak hold circuit 42 uses the peak value of the maximum output signal of the PD light receiver 33 as a relative reference threshold value.
, And then compares the output signal of the PD light receiver 33 and the relative reference threshold signal to output the detection signal S0.

[0059]

As described above, the color misregistration detecting apparatus according to the present invention can detect at a fixed timing position irrespective of toner colors having different reflectivities or nato-density differences having different amounts of reflected light. it can.

As a result, the detection device has a high detection accuracy with a small detection position error due to the toner color. In addition, since the filter is used, the structure can be simplified, which is suitable for reducing the production cost. It becomes a detection device.

When a large number of detection devices are arranged, it is necessary to adjust the installation positions of the detection devices. However, since the detection devices of the present invention are individually set in the light-transmitting portion of the filter, adjustments are made for each installation. Can be simplified, and the adjustment can be omitted.

Further, the detection device of the present invention is provided with noise discriminating means for pulsating the output signal of the light receiving section and discriminating noise from the pulse count value, or discriminating noise from the integrated value of the output signal. Is very little affected by the above.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a detection device according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a light receiving component provided in the detection device.

FIG. 3 is a side view of a light receiving component provided in the detection device.

FIG. 4 is a simplified diagram showing a light-transmitting portion of a filter provided in the detection device and a toner pattern formed on a transfer belt.

FIG. 5 is an explanatory diagram showing a relative positional relationship between a light transmitting portion of the filter and a toner pattern.

FIG. 6 is a waveform diagram showing an output signal of a light receiving section provided in the detection device.

FIG. 7 is a block diagram illustrating a signal processing circuit that processes an output signal of the light receiving unit.

FIG. 8 is a signal waveform diagram for explaining the operation of the signal processing circuit.

FIG. 9 is a signal processing waveform diagram of an output signal output by a conventional detection device.

FIG. 10 is a simplified diagram showing a configuration example of a tandem image forming apparatus provided in a color copying machine.

FIG. 11 is a view showing a conventional example of a toner pattern formed on a transfer belt.

FIG. 12 is a configuration diagram showing a conventional example of a transmissive detection device.

FIG. 13 is a configuration diagram showing a conventional example of a reflection type detection device.

FIG. 14 is a configuration diagram showing a conventional example of a detection device for detecting a pattern edge by inclining the optical axis of a projector.

FIG. 15 is a configuration diagram showing a conventional example of a detection device for detecting fluctuation of a polarization plane caused by reflection of a toner pattern.

FIG. 16 is a configuration diagram showing a conventional example of a detection device provided with a two-segment PD receiver.

FIG. 17 (A) is a waveform diagram showing an output signal of a two-part PD photodetector. FIG. 17B is a waveform chart showing the output signal difference output from the two-segment PD receiver.

[Explanation of symbols]

 Reference Signs List 30 detector 31a, 31b, 31c Toner pattern 32 LED projector 33 PD receiver 34 Rod lens array 35 Filter 35a, 35b, 35c Light transmitting unit 40 Signal processing circuit

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H027 DA38 DA50 DE02 EB04 EC06 EC20 ED24 EE02 EE07 EF09 2H030 AA01 AB02 AD12 AD17 BB02 BB23 BB42 BB56 2H032 BA09 CA01 CA13 5C074 AA07 AA10 AA11 BB24 BB11 CC26 DD26 JJ35 KK16

Claims (4)

[Claims] 1. A light emitting unit which emits light from a light projecting unit to a transfer belt provided with a detection pattern, and confirms the position of the detection pattern based on an output signal of a light receiving unit which receives the reflected light, and detects a color shift. In a color misregistration detection apparatus such as a color copier for performing detection, a plurality of detection patterns arranged at regular intervals along a running direction are provided on a transfer belt, and the intervals are adjusted to the above-mentioned detection patterns. At least two light-transmitting portions formed at a distance are provided, and the filter arranged on the light-receiving path of the light-receiving portion and the detection pattern coincide with some light-transmitting portions according to the movement of the detection pattern. And a holding unit for holding an output signal of the light receiving unit for receiving the reflected light when the reflected light is received. The output signal of the light receiving unit for receiving the reflected light when the detection pattern matches all of the light transmitting portions, and The detection signal is compared with the holding signal of the holding means. A color misregistration detecting device for a color copying machine or the like, comprising a signal processing means for outputting. 2. The color misregistration detecting device according to claim 1, wherein the signal processing means reflects reflected light when the detection pattern coincides with all of the translucent portions in accordance with the movement of the detection pattern. Holding means for holding an output signal of the light receiving portion for receiving the reflected light when the detection pattern matches a part of the light transmitting portion; A color misregistration detecting device for a color copying machine or the like, wherein the color misregistration detecting device outputs a detection signal by comparing with a signal. 3. The color misregistration detecting device according to claim 1, further comprising means for pulsing an output signal of the light receiving section, and means for detecting noise from the number of pulses counted in a predetermined time. A color misregistration detecting device for a color copying machine or the like. 4. The color misregistration detecting device according to claim 1, further comprising a noise discriminating means comprising means for integrating an output signal of the light receiving unit and means for detecting noise from the integrated value. A color misregistration detecting device such as a color copying machine.