JP2001356641A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device which detects the thickness of a transfer material accurately when the transfer material is fed and arrives at a thickness detection sensor at the time of starting an image forming operation. SOLUTION: The image forming device 1 by which a transfer part forms an image by transferring an image to a transfer material S by to an image information signal transmitted from the outside has a pair of carrying rolls 12 and 13 which carry the transfer material S, and the thickness detection sensor 28 which detects the thickness of the transfer material S. The sensor 28 is located further upstream than the transfer part 4 in the direction where the transfer material S is carried. When the transfer material S arrives at the detecting position of the detection sensor 28, the thickness of the transfer material S is detected in the state that the carried state of the transfer material S is changed by the pair of carrying rolls 12 and 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus which detects the thickness of a transfer material and varies image forming conditions based on the result.

[0002]

2. Description of the Related Art Transfer materials have different characteristic values such as resistance and heat capacity for each type. The characteristic value of the transfer material affects the image forming characteristics. For example, in the case of a laser beam printer or an LED printer using an electrophotographic process, the best image can be obtained by changing the image forming conditions of the electrophotographic process according to the various characteristics.

More specifically, the resistance value of the transfer material is determined by the transfer conditions when the toner image developed on the photosensitive member is transferred to the transfer material, and the heat capacity is determined by applying heat and pressure to the toner image transferred to the transfer material. The image quality can be optimized by changing the fixing conditions at the time of fixing. Therefore, conventionally, control for detecting the thickness of the transfer material and correcting the image forming conditions has been performed.

[0004]

However, the conventional image forming apparatus is susceptible to flutter of the transfer material being conveyed by the thickness detection sensor and swinging of the convey roller, and the like. In some cases, the thickness of the transfer material cannot be accurately detected due to factors such as speed and unevenness in the thickness of the transfer material.

Therefore, according to the present invention, the feeding is started at the start of the image forming operation, and when the transfer material reaches the thickness detecting sensor,
An object of the present invention is to provide an image forming apparatus capable of accurately detecting the thickness of a transfer material.

[0006]

In order to solve the above problems, a typical configuration of an image forming apparatus according to the present invention is that a transfer section transfers an image to a transfer material by an image information signal sent from the outside. In an image forming apparatus for forming an image, the image forming apparatus includes conveying means for conveying a transfer material, and thickness detecting means for detecting a thickness of the transfer material, wherein the thickness detecting means is located upstream of the transfer section in the conveying direction of the transfer material. When the transfer material reaches the detection position of the thickness detecting means, the thickness of the transfer material is detected in a state where the transfer state of the transfer material is changed by the transfer means.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] A first embodiment of an image forming apparatus according to the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram of an image forming apparatus, FIG. 2 is an explanatory diagram of a thickness detecting unit, FIG. 3 is an explanatory diagram of a thickness detecting unit, FIG. FIG. 5 is a view for explaining transfer material conveyance and thickness detection, FIG. 6 is a flowchart for explaining the operation of the image forming apparatus, and FIG. 7 is a view for explaining thickness detection means.

As shown in FIG. 1, the image forming apparatus 1 comprises a feeding section 2, a conveying section 3, a transfer section 4, a fixing section 5, and a discharge section 6.

(Feeding Unit) In the feeding unit 2, the transfer material S is loaded on the manual feed tray 7 and the feeding cassette 8, and is selectively fed to the conveying unit 3. When the paper is fed from the manual feed tray 7, the feeding is started by the pickup roller 9, and
The paper is fed to the transport unit 3. When the paper is fed from the feeding cassette 8, the feeding is started by the pickup roller 10, and
The sheet is fed to the transport unit 3 by the feed roller 11.

(Conveying Unit) The conveying unit 3 has conveying roller pairs 12 and 13 as conveying means for conveying the transfer material S, and the transfer material S fed to the conveying unit 3 is transported by the conveying roller pair 12. The sheet is conveyed to the detection position of the thickness detecting unit, the thickness of the sheet is detected, and the sheet passes through the transfer section 4 by the registration roller pair 13 and is conveyed to the fixing section 5 on the downstream side in the conveying direction.

As shown in FIG. 2, the thickness detecting means is a thickness detecting sensor 28 which is an optical reflection displacement sensor, an LED 32 which is a light emitting element, a lens 33, a position detecting element (PSD).
Has 34. The LED 32 irradiates light to the measurement target 36, and the reflected light from the measurement target 36
It is focused on D34. The center of gravity of the collected reflected light
(A, B) changes according to the distance to the measurement target 36.

As shown in FIG. 3, the output signals (output currents) I1 and I2 from the PSD 34, the distance X from the center of the PSD 34 to the center of the reflected light, and the total length L of the PSD 34 include (I1 +
I2) = 2X / L. FIG. 4 shows this equation in a block diagram of an electronic circuit.

As shown in FIG. 5, a guide 29 is provided on a conveyance path facing the thickness detection sensor 28, and the guide 29 is configured to sandwich a transfer material. Thickness detection sensor
The transfer material S transported to the transfer material 28 is suppressed from fluttering by the guide 29, and the thickness detection sensor 28 accurately detects the distance to the transfer material S that is the transported measurement object.

(Transfer Unit) The transfer unit 4 includes photosensitive drums 14Y, 14M, 14C, and 14K for each station arranged in parallel for developing colors, and injection charging units 15Y, 15M, 15C, and 15 as primary charging units.
K, developing units 16Y, 16M, 16C and 16K, toner cartridges 21Y, 21M, 21C and 21K, and an intermediate transfer member 22.

The photosensitive drums 14Y to 14K are formed by applying an organic photoconductive layer to the outer periphery of an aluminum cylinder, and the driving force of a drive motor (not shown) is transmitted to transfer the intermediate transfer body 22 in accordance with an image forming operation. It rotates to transport the material S. The scanner units 20Y, 20M, 20C, and 20K are photosensitive drums 14Y to 14K.
By selectively exposing the surface of the photosensitive drum 14Y
To K, an electrostatic latent image is formed.

The injection chargers 15Y to 15K are provided with sleeves 18Y, 18
M, 18C and 18K to charge the photosensitive drums 14Y to 14K.

The developing devices 16Y to 16K are developing means for visualizing the electrostatic latent image, and are sleeves 19Y, 19M, 19C, 19C.
K, yellow (Y), magenta for each station
(M), cyan (C) and black (K) are developed. Each developing unit is detachably attached.

The intermediate transfer member 22 is in contact with the photosensitive drums 14Y to 14K, rotates with the rotation of the photosensitive drums 14Y to 14K during color image formation, and receives a visible image.

Further, the intermediate transfer body 22 superimposes and transfers a color visible image onto the transfer material S while nipping and transporting the transfer material S with a transfer roller 17 described later during image formation. The transfer roller 17 is in contact with the intermediate transfer member 22 while the color visible image is being transferred onto the transfer material S in a superimposed manner.
Separate from.

The cleaning means 27 is for cleaning the toner remaining on the intermediate transfer member 22, and the waste toner after transferring the four color visible images formed on the intermediate transfer member 22 to the transfer material S. In a cleaner container to prepare for the next transfer.

(Fixing Unit) The fixing unit 5 fixes the transferred color visible image while transporting the transfer material S, and as shown in FIG.
And a pressure roller 24 for pressing the transfer material S against the fixing roller 23.

The fixing roller 23 and the pressure roller 24 are formed to be hollow, and have heaters 25 and 26 therein, respectively.
That is, the transfer material S holding the color visible image is conveyed by the fixing roller 23 and the pressure roller 24, and the toner is fixed on the surface by applying heat and pressure.

(Ejection Unit) The transfer material S after fixing the visible image is ejected outside the image forming apparatus 1 by the ejection roller pair 35, and the image forming operation is completed.

The operation of the image forming apparatus 1 having the above configuration will be described.

When a print instruction is transmitted, the thickness detection sensor 28 outputs the output current I with no transfer material on the conveyance path.
1. I2 is acquired (S1: see FIG. 6). The output currents I1 and I2 at this time indicate the distance to the transport path.

Thereafter, feeding is started from the designated manual feed tray 7 or feeding cassette 8 (S2: see FIG. 6), and the fed transfer material S reaches the position of the thickness detecting sensor 28 on the transport path. (S3: see FIG. 6).

When it is determined that the transfer material S has reached the thickness detection sensor 28, the transfer of the transfer material S is temporarily stopped (S4: see FIG. 6), and the transfer of the transfer material S is performed without the flutter of the transfer material S. The output currents I1 and I2 are obtained (S5: see FIG. 6), and the transfer of the transfer material S is started again, and the registration roller pair 1
The sheet is transported to the temporary standby position 3 (S6: see FIG. 6).

Thereafter, the output currents I1, I2 (S1, S5: see FIG. 6) when the transfer material S is on the transport path and when it is not present are compared to detect the thickness of the transfer material S (S7: see FIG. 6). ).

The image forming conditions such as the transfer high voltage, the temperature of the fixing device, and the image forming operation speed during the image forming operation are changed in accordance with the calculated thickness of the transfer material S to be optimum for the type of the transfer material to be used. Set image forming conditions (S8: see FIG. 6)
Then, an optimum image is formed based on the thickness information (S
9: See FIG. 6).

As described above, when the transfer material S reaches the thickness detection sensor 28, the transfer of the transfer material S is temporarily stopped, and the thickness of the transfer material S is detected accurately by detecting the thickness of the transfer material S. This makes it possible to form an optimal image according to the thickness of the transfer material.

The thickness detecting means detects the thickness of the transfer material S by irradiating the transfer material S with light by the LED 32. However, as shown in FIG.
Alternatively, the lower transport roller 31 may be irradiated with light to detect the distance from the upper transport roller 30.

When the upper transport roller 30 and the lower transport roller 31 are used, the transfer material S is provided between the upper transport roller 30 and the lower transport roller 31.
, The upper transport roller 30 is lifted by the thickness of the transfer material S. Therefore, the thickness of the transfer material S can be detected by reading the fluctuation of the upper transport roller 30 with the thickness detection sensor 28. The upper transport roller 30 and the lower transport roller 31
As a result, the fluttering of the transfer material S during conveyance can be suppressed, and an accurate thickness can be detected.

Second Embodiment Next, a second embodiment of the image forming apparatus according to the present invention will be described with reference to the drawings. FIG.
5 is a flowchart illustrating the operation of the image forming apparatus. The image forming apparatus according to the present embodiment has the same structure as the image forming apparatus 1 according to the first embodiment. The same parts as those in the first embodiment will be denoted by the same reference numerals, and description thereof will be omitted.

As shown in FIG. 8, the image forming apparatus 1 of this embodiment temporarily stops the transfer of the transfer material S performed in the first embodiment, and outputs the output currents I1, I2 of the thickness detection sensor 28.
Are repeated a plurality of times, and the average value is used as the output currents I1 and I2 of the thickness detection sensor.

First, the operations of S1 to S5 are performed to obtain the output currents I1 and I2 of the thickness detection sensor 28. Here, it is determined whether or not the output currents I1 and I2 of the thickness detection sensor 28 for the required number (a plurality of times) have been obtained (S21), and the output currents I1 and I2 of the thickness detection sensor 28 for the required number of times have been obtained. If it is determined that the transfer has not been performed, the transfer of the transfer material is restarted again, and after the transfer for a predetermined time or a predetermined distance, the transfer of the transfer material S is temporarily stopped again (S22), and the process returns to S5.

If it is determined that the output currents I1 and I2 of the thickness detection sensor 28 have been obtained for the required number of times, the output currents I1 and I2 of the thickness detection sensor 28 are averaged (S23), and the transfer of the transfer material S is performed again. After starting, the transfer material is transported to the temporary standby position of the registration roller (S6).

Thereafter, the operations of S7 and S8 are performed, and an optimum image is formed (S9).

As described above, the operation of obtaining the output currents I1 and I2 is repeated a plurality of times, and the average value is used as the output currents I1 and I2, whereby the influence of the thickness unevenness of the transfer material S can be reduced. It is possible to accurately detect the thickness of the transfer material, and it is possible to perform optimal image formation according to the thickness of the transfer material.

[Third Embodiment] Next, a third embodiment of the image forming apparatus according to the present invention will be described with reference to the drawings. FIG.
5 is a flowchart illustrating the operation of the image forming apparatus. The image forming apparatus according to the present embodiment has the same structure as the image forming apparatus 1 according to the first embodiment. The same parts as those in the first embodiment will be denoted by the same reference numerals, and description thereof will be omitted.

As shown in FIG. 9, the image forming apparatus 1 of this embodiment temporarily stops the transfer of the transfer material S performed in the first embodiment, and outputs the output currents I1, I2 of the thickness detection sensor 28.
Is obtained, the output currents I1 and I2 are obtained by lowering the transport speed of the transfer material S instead of the operation of obtaining the output currents I1 and I2.

First, the operations from S1 to S3 are performed, and when it is determined that the transferred transfer material S has reached the thickness detection sensor 28, the driving speed of the transfer roller pair 12 is switched to a low speed to transfer the transfer material S. At a low speed (S4), the output currents I1 and I2 of the thickness detection sensor are acquired in a state where the influence of the flutter of the transfer material or the swing of the transport roller is reduced (S5). Here, it is determined whether or not the output currents I1 and I2 of the thickness detection sensor 28 for the required number (a plurality of times) have been obtained (S32), and the output currents I1 and I2 of the thickness detection sensor 28 for the required number of times have been obtained. If it is not determined that
Return to 5.

When it is determined that the output currents I1 and I2 of the thickness detection sensor 28 have been acquired for the required number of times, the output currents I1 and I2 of the thickness detection sensor 28 are averaged (S33), and the driving of the transport roller pair 12 is performed again. The speed is switched to the normal speed, and the transfer material S is transported to the temporary standby position of the registration roller pair 13.
(S6).

Thereafter, the operations of S7 and S8 are performed, and an optimum image is formed (S9).

As described above, by lowering the driving speed of the conveying roller pair 12 to lower the conveying speed of the transfer material S,
It reduces the effects of the transfer material fluttering and the swinging of the transport roller, enabling accurate detection of the transfer material thickness.
Optimum image formation according to the thickness of the transfer material can be performed.

[0045]

As described above, when the transfer material reaches the detecting portion of the transfer material thickness detecting means, the transfer of the transfer material is temporarily stopped, or the transfer speed of the transfer material is switched to a low speed. By detecting the thickness of the transfer material, it is possible to reduce the effects of fluttering of the transfer material and the swing of the transport roller, and to detect the correct thickness of the transfer material. Image formation can be performed.

Further, the operation of detecting the thickness of the transfer material is repeated a plurality of times, and the average value is used as the thickness of the transfer material. It is possible to detect the thickness,
Optimum image formation according to the thickness of the transfer material can be performed.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an image forming apparatus.

FIG. 2 is an explanatory diagram of a thickness detecting means.

FIG. 3 is an explanatory diagram of a thickness detecting means.

FIG. 4 is a block diagram of an electronic circuit that detects position information from an output of a thickness detection sensor.

FIG. 5 is a diagram illustrating transfer of a transfer material and detection of a thickness.

FIG. 6 is a flowchart illustrating an operation of the image forming apparatus.

FIG. 7 is an explanatory diagram of a thickness detecting means.

FIG. 8 is a flowchart illustrating an operation of the image forming apparatus.

FIG. 9 is a flowchart illustrating an operation of the image forming apparatus.

[Description of Signs] I1, 2 ... output current L ... full length S ... transfer material X ... distance 1 ... image forming apparatus 2 ... feeding section 3 ... transport section 4 ... transfer section 5 ... fixing section 6 ... discharge section 7 ... manual feed Tray 8: Feeding cassette 9: Pickup roller 11: Feeding roller 12: Transport roller pair 13: Registration roller pair 14Y-K: Photosensitive drum 15Y-K: Injection charger 16Y-K: Developing device 17: Transfer roller 18Y- K ... Sleeve 19Y-K ... Sleeve 20Y-K ... Scanner unit 21Y-K ... Toner cartridge 22 ... Intermediate transfer member 23 ... Fixing roller 24 ... Pressurizing rollers 25 and 26 ... Head 27 ... Cleaning means 28 ... Thickness detecting sensor 29 … Guide 30… Upper transport roller 31… Lower transport roller 32… LED 33… Lens 34… Position detection element (PSD) 35… Discharge roller pair 36… Object to be measured

Continued on front page F term (reference) 2H027 DC02 DE07 DE10 EA03 EA12 ED16 EE03 EF06 2H032 AA01 BA13 BA23 BA25 CA12 CA13

Claims (4)

[Claims] An image forming apparatus in which a transfer unit transfers an image to a transfer material based on an image information signal sent from the outside to form an image, wherein a transfer unit for transferring the transfer material and a thickness of the transfer material are detected. A thickness detection unit that is located upstream of the transfer section in the transport direction of the transfer material, and that when the transfer material reaches the detection position of the thickness detection unit, the transport unit conveys the transfer material. An image forming apparatus, wherein the thickness of a transfer material is detected in a state where the state has been changed. 2. The image forming apparatus according to claim 1, wherein when the transfer material reaches a detection position of the thickness detecting means, the transfer of the transfer material is temporarily stopped to detect the thickness of the transfer material. . 3. When the transfer material reaches the detection position of the thickness detecting means, the transfer speed of the transfer material is reduced, and the thickness of the transfer material is detected while the transfer speed is low. 2. The image forming apparatus according to 1. 4. The image forming apparatus according to claim 1, wherein an operation of detecting the thickness of the transfer material is repeated a plurality of times, and an average value thereof is used as the thickness of the transfer material.