JP3179803B2 - Operation control method of color recording apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an operation of a color recording apparatus such as a laser printer or a digital copying machine which is provided with one photosensitive member and one transfer member so as to obtain a plurality of color images. It relates to a control method.

[0002]

2. Description of the Related Art Conventionally, a color recording apparatus is provided with a plurality of photoconductors for each toner color (Y, M, C, BK) as disclosed in, for example, Japanese Patent Application Laid-Open No. 2-157868. There is a type in which a transfer paper is conveyed using a transfer belt common to these photoconductors, and an image on each photoconductor is sequentially transferred. However, it requires multiple photoconductors,
In addition to high costs, it is also easy to increase the size.

[0003] A toner image is sequentially formed on a photoreceptor by using a single photoreceptor and a single transfer member that winds and holds a transfer sheet in accordance with color-separated image signals of each color. In some cases, a color image is obtained by successively superimposing and transferring a toner image onto transfer paper on a transfer body.
According to this, only one photoconductor is required.

At this time, a writing operation and a transfer operation are controlled with reference to a photoconductor reference position signal obtained with the rotation of the photoconductor, so that a color image can be obtained by superimposed transfer.

[0005]

However, since the photosensitive member rotates while the transfer member is in contact with the photosensitive member, the photosensitive member may be subject to a load variation due to the transfer member. When a color image is obtained by superimposed transfer, image deterioration due to image position shift may occur.

[0006]

According to the first aspect of the present invention, one transfer member is provided for one photosensitive member so as to be able to freely contact and separate by a contact / separation mechanism, and is separated into each color on the photosensitive member. Color recording in which a color image is obtained by successively superimposing and transferring a toner image sequentially formed by color-specific image signals onto a transfer paper wound and held on the transfer body at a contact position between the photosensitive body and the transfer body. In the apparatus, after the transfer paper is wound and held on the transfer body, for each color, the photosensitive body is separated from the photosensitive body and the photosensitive body is rotated based on the photosensitive body reference position signal when the photosensitive body alone rotates. The operation timing of the writing operation on the body and the transfer operation by the transfer body is controlled.

In this case, according to the second aspect of the invention, the start timing of the writing operation and the transfer operation is set to a predetermined time after the generation of the photosensitive member reference position signal, and the first color photosensitive drum is exposed.
Measure the time from the generation of the body reference position signal to the start of the write operation.
Number, and write from the photoconductor reference position signal generation for the second and subsequent colors.
Time difference from the time until the start of
The transfer operation start timing for the second and subsequent colors
I tried to make it.

According to the third aspect of the present invention, the transfer member is brought into contact with the photosensitive member after the start of the transfer operation.

[0009]

[0010]

According to the first aspect of the present invention, the transfer member is temporarily separated from the photosensitive member, and writing is performed based on the photosensitive member reference position signal which is less affected by load fluctuations obtained in a state where the photosensitive member rotates alone. Since the transfer is controlled, a color image can be obtained by excellent transfer without color shift.

For example, based on the photoconductor reference position signal,
Start writing from a certain position with an encoder pulse.
The position of the photoconductor reference position signal and the encoder pulse.
If the phase difference is very small, the writing start
Ki can occur. Therefore, for each color image,
Transfer operation always performed at the same timing from the position signal
Then, a shift may occur in the superimposed image. this
According to the second aspect, the writing operation and the transfer operation are performed.
The crop is managed by time, and the photoconductor reference position of the first color
Count and hold the time from the input signal to the start of writing,
From the photosensitive member reference position signal for the second and subsequent colors to the start of writing
Calculate the time difference from the time, and start the transfer operation according to the time difference.
Changing the start timing later or earlier
The correction is based on the actual situation, making it possible to achieve superimposition transfer without color shift.
A color image is obtained. According to the third aspect of the present invention, the timing at which the transfer member is brought into contact with the photosensitive member is set to be after the start of the transfer operation, and the rotation state of the photosensitive member alone with a small load fluctuation becomes longer, A better color image can be obtained by overlapping transfer.

[0012]

[0013]

An embodiment of the present invention will be described with reference to the drawings. FIG. 2 shows a schematic configuration of a color recording apparatus to which the present invention is applied, in which an exposure beam 2 for optical writing can be applied to one drum-shaped photosensitive member 1 which is driven to rotate in the direction of an arrow. A developing device (preparing each color toner) 3 is arranged at a position after the writing. Also,
A drum-shaped transfer body 5 is provided at a transfer unit for transfer paper (not shown) fed from a paper feed unit 4 such as a paper feed cassette so that the transfer paper can be wound and held. . Here, the transfer member 5 can be freely moved toward and away from the photosensitive member 5 by a contact / separation mechanism 6, and the contact position is set to be the transfer position.

Here, from the photoreceptor 1, one for every rotation.
One photoconductor reference position signal (HP signal) and 3600 shots / encoder pulses are output. On the other hand, the transfer body 5 is set so as to be always stationary and waiting at the same rotation angle with respect to the photoconductor 1 by a home position sensor (not shown).

In such a schematic configuration, the basic operation of the system of the embodiment will be described. First, when a write instruction signal is received, the photoconductor 1 and the transfer body 5 are brought into contact with each other, and the paper is fed from the paper supply unit 4 to the transfer body 5, and the transfer paper is electrostatically wound. After the holding, the transfer body 5 is positioned. Thereafter, the transfer member 5 is separated from the photoreceptor 1, and
The photoreceptor 1 rotates alone, and after a lapse of a predetermined time from the photoreceptor reference position signal generated at this time, writing by the exposure beam 2 is started. The electrostatic latent image formed on the photoreceptor 1 by writing is visualized by the developing device 3, and the transfer member 5 and the photoreceptor 1 which start rotating after a predetermined time has elapsed from the generation of the HP signal after the writing is completed. And contact again while rotating at the same speed, and the toner image on the photoreceptor 1 is transferred to the transfer paper by a transfer charger (not shown). Such an operation is similarly repeated for each color image. After the transfer operation of the final color image is completed, the transfer body 5 is separated from the photoreceptor 1, and the transferred transfer paper on the transfer body 5 is separated from the transfer body 5 by a separation charger (not shown). The paper is discharged after the above operation.

FIG. 1 is a timing chart showing the operation control according to the method of this embodiment. First, when the transfer body 5 on which the transfer paper is wound has finished positioning, the photosensitive body 1 starts to rotate by itself, and the photosensitive body reference position signal HP is output every rotation. When this signal HP is output, a predetermined number of encoder pulses are counted, and when a predetermined time t ₀ has elapsed, writing is started. After the writing is completed, when the signal HP is output from the photoconductor 1 again, at a predetermined timing t ₁ , the transfer body is set at a predetermined timing t ₁ so that the top of the toner image on the photoconductor 1 coincides with the top of the writing area of the transfer paper. 5 starts rotating and comes into contact with the photoreceptor 1 to transfer the toner image to the transfer paper. By repeating such operation control for each color image in the same manner, a color image can be obtained by overlapping transfer.

When the phase difference between the signal HP and the encoder pulse is very small, there is a possibility that the writing timing may be shifted by one pulse at worst. According to FIG. 1, the timing t ₁ until the start of the transfer operation is the same. Therefore, there is a possibility that a shift occurs in the superimposed image. In this embodiment, this point is also improved, and is addressed by the following time management control. That is, the time t ₀ from the generation of the signal HP of the first color to the start of writing is counted and held, and the time from the generation of the signal HP of the second and subsequent colors to the start of writing and the held time t ₀ are calculated. Depending on the time difference of
The transfer operation start timing for the second and subsequent colors is changed. That is, for example, when the writing start timing of the second color is earlier than the held time t ₀ by the time t, the transfer start timing of the second color is advanced by t from the normal timing t ₁ to a timing of t ₁ −t, Conversely, for example, when the writing start timing of the third color is later by the time t, the transfer start timing of the third color is delayed by t from the normal timing t ₁ to be a timing of t ₁ + t.

The operation control based on such time management is executed by a circuit configuration as shown in FIG. 3 as shown in a timing chart of FIG. Note that, here, for simplicity of description, processes such as charging, charge elimination, and cleaning are omitted, and only writing and transfer operations will be described.

First, the time t ₀ from the generation of the signal HP of the first color to the start of the writing operation is counted by the counter 10.
The data is latched in the D-type flip-flop 11. Here, the clock CLK input to the counter 10 is higher than the write line frequency. The time t ₀ of the first color latched by the D-type flip-flop 11 is loaded into the up / down counters 12 and 13, and the second and subsequent colors are counted down from the generation of the signal HP for each color to the start of the writing operation. Time difference.

For example, when the second color is longer than the time t _{0 of the} first color by the time α (t ₀ + α), the up / down counter 12 outputs a ripple carrier RC, and the D-type flip-flop 14 outputs the ripple carrier RC. Up / down counter 1
The second counting mode is switched to the up mode when the transfer start time is counted. When the writing operation is completed and the next signal HP is output, the up-down counter 12 performs up-counting, and after counting the time α, outputs the ripple carrier RC again. Here, the timer 15 that counts the preset time t ₁ starts counting after the time α is counted by the D-type flip-flops 16 and 17, counts the time t _1, and outputs the transfer start signal. Output. Therefore, when viewed from the generation of the signal HP, (t ₁ + α)
After the lapse of time, the transfer operation is started.

Further, for example, the holding time t of the third color is the first color.
If it is shorter than ₀ by the time β, the AND gate 18
(As shown in FIG. 4, the signal output during the write end to the signal HP generator) signals S ₁ applied to the valid and up-down counter 13 and the timer 15 counts down. Here, the timer 15 is of a down type in which a preset time t ₁ is preset. Therefore, the timer 15 is set to the up-down counter 13
There counts down until the output ripple carrier RC against D-type flip-flop 19 to stop the count down the count enabling signal S ₂ generates in signal HP generated after completion of writing. In other words, by counting only the time β before the transfer start time is counted,
A transfer start signal is generated after a lapse of (t ₁ -β) from the generation of the signal HP, and the transfer operation is started.

In the circuit shown in FIG. 3, every time the transfer operation is completed, all the D-type flip-flops 11, 1
6, 17 and 19 are reset, and the up / down counters 12 and 13 load the time t _{0 of the} first color from the D-type flip-flop 11.

In this embodiment, the photosensitive member 1 and the transfer member 5
Although both are drum-shaped, the same can be applied to the case where a belt-shaped one is used.

[0024]

According to the present invention, the transfer member is once separated from the photosensitive member, and the load obtained in a state where the photosensitive member rotates alone is provided according to the first aspect of the present invention. Since the writing and the start of the transfer operation are controlled based on the photoconductor reference position signal having little influence of the fluctuation,
It is possible to obtain a good color image by superimposed transfer without color shift.

In particular, according to the second aspect of the present invention, after the photosensitive member reference position signal is generated, the operation is controlled by time management, so that a better color image can be obtained by superimposed transfer . Photoconductor reference position signal and encoder
If the phase difference from the
The start position may vary, so each color image
From the photoconductor reference position signal at the same time.
Doing so may cause the overlay image to shift.
The write operation and the transfer operation are managed by time.
Start writing from the photoconductor reference position signal of the first color
Count and hold the time until the photoreceptor base for the second and subsequent colors
Find the time difference from the quasi-position signal to the start of writing.
Therefore, the transfer operation start timing is delayed according to the time difference.
To change quickly, quickly,
This makes it possible to obtain a color image by color transfer without color shift . According to the third aspect of the present invention, the timing at which the transfer member is brought into contact with the photosensitive member is set to be after the start of the transfer operation, and the delay is as long as possible. Timing control, and a good color image can be obtained by superimposed transfer.

[0026]

[Brief description of the drawings]

FIG. 1 is a timing chart showing one embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a recording apparatus.

FIG. 3 is a block diagram.

FIG. 4 is a timing chart.

[Explanation of symbols]

 1 photoconductor 5 transfer body 6 contact / separation mechanism HP photoconductor reference position signal

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Norio Michiya 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (56) References JP-A-1-251047 (JP, A) JP-A-Hei 2-301790 (JP, A) JP-A-63-191169 (JP, A) JP-A-63-23173 (JP, A) JP-A-3-107797 (JP, A) (58) Fields investigated (Int. Cl ^7, DB name) G03G 13/01 G03G 15/01 -. 15/01 117 G03G 21/14

Claims (3)

(57) [Claims] 1. A transfer member is provided for one photosensitive member so as to be able to freely contact and separate by a contact / separation mechanism, and a toner image sequentially formed by color-separated image signals of each color on the photosensitive member is formed. In a color recording apparatus wherein a color image is obtained by sequentially superimposing and transferring a transfer sheet wound and held on the transfer body at a contact position between the photosensitive body and the transfer body, the transfer paper is wound around the transfer body. After the holding, for each color, the writing operation on the photosensitive member and the transferring operation by the transferring member are performed based on the photosensitive member reference position signal when the transferring member is separated from the photosensitive member and rotated by the photosensitive member alone. An operation control method for a color printing apparatus, wherein the operation timing is controlled. 2. The start timing of a writing operation and a transfer operation is set to a predetermined time after the generation of a photosensitive member reference position signal , and
From the generation of the photoconductor reference position signal for the color to the start of the writing operation
Is counted and held, and the photoconductor reference position signal for the second and subsequent colors
Find the time difference from the time from the occurrence to the start of the write operation,
The transfer operation for the second and subsequent colors is started according to the time difference.
2. An operation control method for a color printing apparatus according to claim 1, wherein the color is changed. 3. The operation control method for a color recording apparatus according to claim 1, wherein the transfer member is brought into contact with the photosensitive member after the start of the transfer operation.