JP2918268B2 - Color recording device - Google Patents

Description

Detailed Description of the Invention [Table of Contents] Overview Industrial application field Conventional technology (Figs. 11 and 12) Problems to be solved by the invention (Figs. 10 and 12) Means for solving the problems (1 (FIGS. 1 and 2) Function (FIGS. 1 and 2) Embodiment (FIGS. 3 to 9) Effects of the Invention [Summary] The images are exposed side-by-side, and color-separated images are formed and exposed based on the designated timing. A color recording apparatus, comprising: a photosensitive drum that transports recording paper provided with a gripper that sandwiches recording paper; and a recording device that sequentially performs superimposed recording on the recording paper transported by the transporting means to obtain a color image. To reduce the printing position shift between each color that occurs when printing each color on the printing paper due to the speed error of both the gripper and the paper feeder and the error of the mounting position of the gripper to the transport belt. For the purpose of An exposure timing information storage unit that stores predetermined exposure timing information relating to recording of one recording sheet created in association with each other, based on characteristics unique to each exposure drum, and detects a gripper arriving at each exposure drum; And an exposure signal generating section for reading out the exposure timing information from the exposure timing information storage section corresponding to the above, and generating an exposure timing signal based on the exposure timing information.

[Industrial applications]

The present invention relates to an electrophotographic recording apparatus, in which a plurality of photosensitive drums are arranged side by side, and a color-separated image is formed for each photosensitive drum. The present invention relates to an exposure control method for a color recording apparatus for obtaining an image.

Although this type of printing apparatus has the advantage of being able to perform high-speed color printing, the printing position between the colors tends to be misaligned, and alignment is an important issue.

[Conventional technology]

Conventionally, there has been a color recording apparatus as shown in FIG.
This apparatus shows an example of a color recording apparatus using four photosensitive drums 810, and includes a recording paper cassette 801, a feeding roller 802, a register roller 803, and a gripper 804.
And a belt 805 for transporting the gripper, and a drive pulley 806 for the belt 805. The gripper 804 is a conveyor belt 805
It is provided on the top at substantially equal intervals. Sensors 830, 803I to 830IV for detecting the arrival of the gripper include a rotatable lever 831 as shown in FIG. 11, a transmission type optical sensor 833 for detecting the movement of the lever 831, and a winding spring for applying a restoring force to the lever 831. Consists of 832. When gripper 804 arrives, gripper 804
As a result, the lever 831 rotates, and the normally blocked light on the light projecting side of the optical sensor 833 reaches the light receiving side. The sensor 830, 830I to 830IV outputs this change as a gripper detection signal and outputs a pulse to a control unit (not shown).

Further, the recording processes (I to IV) are constituted by the same members, respectively, and the photosensitive drum 810, the charger 811, the LE
Exposure system 812 using D array, developing device 813, transfer device 814
And a cleaner 815. These are 4 sets (I-IV)
They are arranged at equal intervals.

Next, the operation will be described. First, when the sensor 830 detects the arrival of the gripper 804, the control unit (not shown) starts supplying the recording paper 800, and the recording paper 800 is gripped at its leading end by the gripper 804, and the recording unit comprising the recording processes I to IV. Sent to In each recording unit, color toner images are superimposed and recorded on recording paper in the order of I to IV to perform color recording of a plurality of colors. After the four-color overlapping recording, the recording paper is sent to the fixing device 820, and the toner image is fixed on the recording paper by the heat and pressure given from the fixing roller 821 and the pressure roller 822, thereby completing a series of color recording processes. .

[Problems to be solved by the invention]

Incidentally, if there is a shift in the recording position on the recording paper between the colors recorded separately in the conventional overprinting, the image quality deteriorates. Therefore, it is necessary to match the recording positions of the colors. The recording position at the head of the recording paper is, for example,
As disclosed in JP-A-59-155870, the timing can be adjusted by detecting the arrival of the recording paper with sensors 830I to 830IV provided in front of each photosensitive drum and determining the exposure start timing. However, with respect to the recording position in the recording paper, the recording position is shifted between the colors due to the speed error of both the photosensitive drum and the gripper for feeding the paper. In particular, when a gripper is used, there is a tendency that an error due to a displacement of the gripper is likely to occur due to a state of attachment of the gripper to the transport belt.

As shown in FIG. 10, misalignment components can be broadly classified into low-frequency components due to shaft / gear eccentricity and the like and high-frequency components due to timing belt / gear tooth pitch errors and the like. Among them, the high-frequency component has a small amplitude and little influence on the displacement. However, the low frequency component has a large amplitude and a large influence on the displacement.

Although it is possible to prevent the recording position deviation by increasing the machining / assembly accuracy of the shaft / gear and reducing the fluctuation of the feed speed, there is a disadvantage that the cost is greatly increased.

In view of this, the present invention focuses on the reproducibility of the position shift method in relation to the unique characteristics of the gripper and each photosensitive drum, and based on the data of the position shift of each photosensitive drum with respect to the gripper and the gripper, for each recording color. The exposure timing that minimizes the deviation is obtained, the exposure timing is stored in a separate storage unit, and at the time of exposure, the image data is exposed based on the exposure timing information read from this storage unit, so that each color is exposed. The recording position is set to a substantially predetermined position, and the deviation of the recording position between colors is to be reduced.

[Means for solving the problem]

In order to solve the above technical problems, the first invention, as shown in FIG. 1, is arranged side by side, forms a color-separated image on each of the photosensitive drums 2 and is exposed based on a designated timing. And a transport means for transporting the recording paper, comprising a gripper 1 for holding the recording paper. In a color recording apparatus for sequentially superimposing and recording a color image on the recording paper transported by this transport means, a color image forming apparatus unique to the gripper 1 is provided. An exposure timing information storage unit 4 storing predetermined exposure timing information relating to recording of one recording sheet created in association with the characteristics, and a gripper 1 arriving at each photosensitive drum 2
And an exposure signal generating section 3 for reading out exposure timing information from an exposure timing information storage section 4 corresponding to the gripper 1 and generating an exposure timing signal based on the exposure timing information.

On the other hand, as shown in FIG. 2, the second invention forms a photosensitive drum 2 which is arranged side by side, forms color-separated images, and is exposed at a designated timing, and a gripper for nipping a recording sheet. And a transport unit for transporting the recording paper provided with the recording medium 1. The color recording apparatus obtains a color image by sequentially superimposing recording on the recording paper transported by the transport unit. An exposure timing information storage unit II6 storing predetermined exposure timing information related to recording on one recording sheet, which is created in association with each photosensitive drum 2, and an exposure timing information storage unit II6 corresponding to each photosensitive drum 2. An exposure signal generator II5 for reading out the exposure timing information and generating an exposure timing signal based on the exposure timing information is provided.

[Action]

The first invention of the color printing apparatus according to the present invention operates as follows. As shown in FIG. 1, the exposure signal generator 3 identifies the gripper 1 arriving at each photosensitive drum 2,
Exposure timing information storage unit 4 corresponding to the gripper 1
From, read out the exposure timing information recorded for each gripper in advance based on the unique characteristics of each gripper,
An exposure timing signal is generated based on the exposure timing information, and image data is exposed by the exposure timing signal.

On the other hand, the second invention operates as follows. As shown in FIG. 2, when controlling the exposure timing of each photosensitive drum in the exposure signal generating section II5, the exposure timing information storage section II6 corresponding to each photosensitive drum is used in advance based on the characteristic unique to each photosensitive drum. The exposure timing information recorded for each photosensitive drum is read, an exposure timing signal is generated based on the exposure timing information, and image data is exposed by the exposure timing signal.

〔Example〕

Subsequently, the embodiment according to the first invention and the second invention is described in the third embodiment.
This will be described in detail with reference to FIGS. Fig. 3 shows three grippers
FIG. 4 is an explanatory diagram of a color recording apparatus using 204 and four types of photosensitive drums 210. The gripper identification sensor 250 for identifying the gripper 204 in FIG. 3 includes a reflection type optical sensor for detecting a hole provided in the gripper as shown in FIG. When the gripper detection sensor 230 detects the arrival of the gripper 204, the gripper identification sensor 250 is installed at a position where each reflective optical sensor is below the hole position of the gripper. Further, a recording paper cassette 201, a feeding roller 202, a registration roller 203, a gripper 204, a belt 205 for conveying the gripper, and a belt driving pulley 206
, And the grippers 204 are provided on the belt 205 at substantially equal intervals.

FIG. 4 is a block diagram of the entire exposure control system. The control unit 31 performs processing based on the detection outputs of the gripper detection sensors 230 and 230I to 230IV and the gripper identification output of the gripper identification sensor 250, and each photosensitive drum 210 (I To (IV) to control the exposure, and an oscillator 36.

FIG. 5 is a block diagram of one exposure control system.
A counter section 41b for counting clocks output from the oscillator 36; ROM (read only memory) sections 42a to 42c (corresponding to the exposure timing information storage section 4) storing exposure timing for each gripper; A register unit 41c for reading data from the ROM units 42a to 42c in accordance with the clock from 36 (here, the control unit 31, the counter unit 41b, the register unit 41c, etc. correspond to the exposure signal generation unit 3 and the exposure signal generation unit II5); Image memory unit 44 that stores image data
And an LED driver unit 43 that reads image data for each line from the image memory unit 44 and drives an LED (light emitting diode) 45 as an exposure light source. In addition, each ROM section 42a
The output terminals of .about.42c are connected to a register unit 41c so that a corresponding ROM unit is selected by a switch 46 switched according to an instruction of the control unit 31.

Next, each of the ROM units 42a to 42c (and each of the other three ROM units (not shown) of the exposure control system (corresponding to the exposure timing information storage unit 4 and the exposure timing information storage unit II6)).
A method of creating the exposure timing information stored in the storage device will be described. First, a total of four types of photosensitive drums and three types of grippers
0.5 mm over the entire length of the recording paper for 12 combinations
A horizontal line pattern is recorded at a constant pitch. The density is measured with a microdensitometer as shown in FIG. 6 to measure the pitch of each line pattern. The measured line pitch is accumulated to obtain the waveform shown in FIG. A low-pass filter is provided on this waveform to leave only low-frequency components. From the data thus obtained, the exposure timing is determined so that the recording line is closest to the predetermined position. Here, the clock frequency of the oscillator 36 is twice the recording line clock. Information on the determined exposure timing
For example, in the case of Fig. 7 And so on in the ROM section. Perform this work for all 12 combinations of each color (photosensitive drum) and each gripper,
Each exposure timing information is stored in ROM of each LED exposure control system.
Write in the department.

 Next, the operation of this embodiment will be described.

When the gripper detection sensor 230 detects the arrival of the gripper 204, the control unit 31 issues a paper feed command and the feeding roller 202 takes out the recording paper 200 from the paper cassette 201. Further, the gripper identification sensor 250 identifies which of the three types of grippers 204 the incoming gripper 204 is, and outputs the identification signal to the control unit 31. Further, the taken out recording paper 200 is temporarily stopped by the registration roller 203, and the timing with the gripper 204 is taken.
Is sent out from the register roller 203 at a speed slightly higher than the feed speed of the register roller 203. When the leading edge of the recording paper enters the gripper 204, the gripper 204 closes and clamps the recording paper 200. Thereafter, the registration roller 203 returns to the constant speed rotation.

Next, a time chart in the recording process (I) will be described with reference to FIG. When the gripper detection sensor 230I detects the arrival of the gripper 204, after a predetermined time (Ty), the control unit 31 sends the LED exposure control system (I), that is, the counter unit 4
1b and an enable signal to the LED driver section 43,
The counting of the reference clock and the operation of the LED driver unit 43 are started. At the same time, the switch 46 is switched according to the type of the gripper 204 that has arrived. Here, the gripper 1 has arrived, the ROM section 42a is selected, an exposure timing signal is generated in the register section 41e based on the exposure timing information stored in the ROM section 42a, and the exposure of the image in the recording process I starts. Is done. In the exposure, the ROM section 42a
Exposure is performed based on the exposure timing information read from the printer, so that an error in the transport speed of the photosensitive drum 210 and the gripper 204 is removed, and an image is recorded at a predetermined position on the recording paper. II-IV are similarly recorded in other recording processes.

After the last recording process (IV) is overprinted, the recording paper
At 200, an image is fixed by a fixing device 220, and a series of color recording processing ends.

As described above, since the recording position in each recording process can be substantially the predetermined position, the positional deviation between the colors is greatly reduced.

Further, in the present embodiment, the case where the ROM unit that stores the exposure timing information for the type of the combination of the gripper and the photosensitive drum is used, but when the difference in the exposure timing for each photosensitive drum is smaller than that of the gripper, ROM that stores exposure timing information corresponding only to each gripper type
A unit may be used. This case corresponds to the embodiment of the first invention, and the same type of ROM unit as the type of gripper may be prepared. As for the error of each photosensitive drum, for example, a method of averaging all photosensitive drums can be considered.

Similarly, when the difference in the exposure timing of each gripper is smaller than that of the photosensitive drum, a ROM unit that stores exposure timing information corresponding only to the type of each photosensitive drum may be used. This case corresponds to the embodiment of the second invention, and the same ROM section type as the photosensitive drum type may be prepared. As for the error of each gripper, for example, a method of averaging all the grippers can be considered.

In this embodiment, the LED exposure system is used as the exposure means. However, a similar effect can be obtained in a color recording apparatus using a laser exposure system. In addition, the exposure start timing of each color is determined by the gripper detection sensors 230I to 230IV provided in front of the photosensitive drum by detecting the gripper 204, but the gripper detection sensors 230I to 230IV are omitted and the gripper detection sensor is omitted. Of course, the present invention can also be applied to a case where the timing of starting the exposure of each color is set based on the output of 230. Further, in this embodiment, only one identification sensor of the gripper 204 is used near the gripper detection sensor 230, but it may be provided in front of each photosensitive drum 210.

〔The invention's effect〕

As described above, in the present invention, the exposure timing at which the positional deviation between the colors caused by the unique characteristics of the photosensitive drum and the gripper for each color is reduced,
The exposure timing information is stored in a storage unit provided for each photosensitive drum and each gripper, and at the time of exposure, image data is exposed based on the exposure timing information read from the storage unit.

Therefore, even in a conveyance system in which the conveyance accuracy is not so high, high-quality color recording in which the positional deviation between colors is significantly reduced can be performed, and an excellent effect can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram of the principle of the first invention, FIG. 2 is a block diagram of the principle of the second invention II, FIG. 3 is an explanatory view of a driving section according to the embodiment, and FIG. Block diagram, fifth
FIG. 6 is a block diagram of one exposure control system, FIG. 6 is an explanatory diagram (1) relating to exposure timing information generation, FIG. 7 is an explanatory diagram (2) relating to exposure timing information generation, and FIG. 8 is a recording process (I). ) Time chart, FIG. 9 is an explanatory view of the gripper,
FIG. 10 is an explanatory diagram of a recording position shift, FIG. 11 is an explanatory diagram of a gripper detection sensor, and FIG. 12 is an explanatory diagram of a conventional example. 1,204: gripper 2,210: photosensitive drum 3 (31, 41b, 41c, 46): exposure signal generator (controller, counter, register, switch) 4 (42a-42c): exposure timing information storage (ROM
5) Exposure signal generation section II 6 Exposure timing information storage section II 36 Transmitters 37I to 37IV LED exposure control systems (I) to (IV) 43 LED driver section 44 Image Memory unit 45 LED 200 Recording paper 201 Recording paper cassette 202 Feeding roller 203 Registration roller 205 Gripper transport belt 206 Belt drive pulley 220 Fixing devices 230, 230I to 230IV Gripper detection sensor 250 …… Gripper identification sensor

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-192073 (JP, A) JP-A-1-116657 (JP, A) JP-A-63-151264 (JP, A) 103557 (JP, U) (58) Field surveyed (Int. Cl. ⁶ , DB name) G03G 13/01 G03G 15/01-15/01 117

Claims (2)

(57) [Claims] 1. A photosensitive drum (2) which is arranged side by side, forms color-separated images, and is exposed at a designated timing, and a gripper (1) for sandwiching recording paper.
And a transporting means for transporting the recording paper. The color recording apparatus sequentially superimposes recording on the recording paper transported by the transporting means to obtain a color image. An exposure timing information storage unit (4) storing predetermined exposure timing information relating to the recording of one recording sheet created by the above, and a gripper (1) arriving at each photosensitive drum (2) are detected. An exposure signal generation unit (3) for reading out exposure timing information from the exposure timing information storage unit (4) corresponding to 1) and generating an exposure timing signal based on the exposure timing information; A color recording apparatus, which comprises: 2. A photosensitive drum (2) which is arranged side by side, forms color-separated images, and is exposed at a designated timing, and a gripper (1) for sandwiching recording paper.
And a transport means for transporting the recording paper. The color recording apparatus sequentially superimposes the recording paper conveyed by the transport means to obtain a color image. An exposure timing information storage unit II (6), which stores predetermined exposure timing information relating to recording of one recording sheet, which is created in association with each photosensitive drum (2); An exposure signal generator II (5) for reading out exposure timing information from an exposure timing information storage unit II (6) to generate an exposure timing signal based on the exposure timing information, and exposing image data based on the exposure timing signal. A color recording apparatus.