JPH0412946A - Image forming device - Google Patents

Abstract

PURPOSE:To simultaneously realize preliminary transport in a plurality of paper feed parts by providing a preliminary transport means for paper sheets so that paper sheets supplied from all paper feed parts to be able to feed paper are once stopped for stand-by in proximity to the confluence and at a prescribed point on the upper stream side of resist means. CONSTITUTION:At preliminary transporting, paper sheets supplied from paper feed parts 1,2 are controlled so that the extreme parts of them are once stopped on this side of the confluence 14 in a paper sheet transport passage on the upper stream of a resist roller 15. The position on this side of the confluence 14 on the upper stream of the resist roller 15 is set as the stop position of preliminary transport. Preliminary transport can be simultaneously completed as for a plurality of paper feed parts 1,2 regardless of execution order of preliminary transport, and a paper sheet on any paper sheet transport passage is equally selected and sent to an image forming part 16,17.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image forming apparatus such as an electrostatic recording type printer, and particularly relates to an improvement in paper feed control means.

[Prior Art] Generally, in this type of image forming apparatus, a predetermined image forming process is executed in response to an image forming start command signal called a print signal. That is, the apparatus is configured to perform a series of operations such as forming a latent image and a toner image on an image carrier and transferring and fixing the toner image to a sheet of paper. At this time, the paper is sent to the transfer point at a predetermined timing that is synchronized with the image forming process.

Note that in conventional image forming apparatuses, a common method is to start transporting paper from a selected paper feed section based on the print signal. Also, it takes a certain amount of time to perform image signal processing such as expanding data received from the host computer into the image memory, but before the image signal processing is completed, the print signal (
Alternatively, a method has been devised in which paper is preliminarily conveyed from a paper feeding section to a predetermined position by generating a paper feeding command signal. Furthermore, if the paper feed section is configured to be able to carry out preliminary transport, the print signal (
Alternatively, there is also a structure in which preliminary conveyance is carried out regularly, regardless of the paper feed command signal.

By the way, in any of the above-mentioned preliminary conveyance systems, the paper sent out from the paper feed section is stopped with the leading edge of the paper abutting the registration roller provided upstream of the transfer point. There is. Note that the opening timing of the registration rollers generally has a delicate timing relationship with the image forming process. In other words, the release of the registration rollers becomes the basis for timing control in the image forming process. The purpose of preliminary conveyance is to artificially shorten the paper feeding distance and improve printing speed as a result. Therefore, when trying to make the pre-conveyance distance as long as possible in order to obtain the maximum effect, it is extremely difficult to set the paper stop position for pre-conveyance at the registration roller position due to the physical configuration of this type of printer. This seems to be a reasonable method.

[Problems to be Solved by the Invention] As described above, in the prior art, preliminary conveyance is performed up to the registration roller position. However, in an image forming apparatus having a so-called multistage paper feeding means, in which a plurality of paper feeding units and a plurality of paper transport paths corresponding to each paper feeding unit are provided, the plurality of paper transport paths are connected to the registration rollers. They are positioned so that they meet upstream. For this reason, if the pre-fi conveyance is performed to the position of the registration rollers, inconveniences may occur.

That is, since it is assumed that only one sheet of paper must be stopped at the position of the registration roller, preliminary conveyance can only be completed for one sheet feeding section. In other words, it is necessary to control the paper so that the paper that has been preliminarily conveyed to the immediate vicinity is subsequently carried into the image forming section. Therefore, the start of preliminary transport also means that the paper to be printed next has been selected.
In addition, the form of control is limited so that preliminary conveyance is performed based on a paper feed command signal such as a print signal.

Therefore, an object of the present invention is to be able to simultaneously establish preliminary transport in a plurality of paper feed sections, to significantly shorten the distance between the transport paths, and as a result, An object of the present invention is to provide an image forming apparatus equipped with a preliminary conveyance control means capable of improving the lint speed.

[Means for Solving the Problems] In order to solve the above problems and achieve the objectives, the present invention takes the following measures as basic means.

The openings at the downstream ends of the plurality of conveyance paths are arranged so that they merge into one on the upstream side of the image forming means, and the sheets sent out from all the paper feeding units capable of feeding paper are transferred to the merging point. and a means for preliminarily conveying the paper so as to temporarily stop and wait at a predetermined point upstream of the registration means and near the registration means.

[Effects] By taking the above measures, the following effects occur. When preliminary conveyance is performed, the paper sent out from the paper feed section is controlled so as to stop when the leading end of the paper comes before the confluence of the paper conveyance paths upstream of the registration rollers.

Since the preliminary conveyance stop position is set upstream of the registration rollers and before the merging point, the above-mentioned problem is solved.

Furthermore, since the preliminary conveyance can be completed for a plurality of paper feed units at the same time, the sheets on any paper conveyance path are equally selected and sent to the image forming unit, regardless of the order in which the preliminary conveyance is performed. Furthermore, there is no need to wait for the generation of a paper feed command signal such as a print signal before executing the preliminary conveyance.

Therefore, it can be controlled independently of the host computer and the image signal processing section of the printer.

[Example] FIG. 1 is a diagram showing the configuration of an embodiment of the present invention.

This embodiment is configured so that upper and lower paper feed cassettes 1 and 2 and an elevator feeder 3 having a relatively large paper loading capacity and having an elevating mechanism can be attached. The sheets placed on the paper feed cassettes 1, 2 and the elevator feeder 3 are pressed against the pickup roller 4.degree. 5.6 by a paper feed spring (not shown).

When the big-heat rollers 4, 5.6 are rotationally driven by a drive system (not shown), the sheets are moved one by one to the retard rollers 7.
Transported towards 8.9. Retard roller 7.8.9
The paper is completely separated one by one and continues to be transported. Paper detection sensors 10, 11, and 12 are provided downstream of the retard roller 7.8°9. Retard roller 7
．． 8.9 The leading edge of the paper passes through the paper detection sensor 10, 1.
When detected at 1.12, the pickup rollers 4, 5, 6 are stopped from rotating at a predetermined timing calculated based on this detection time. Thus, the paper is temporarily stopped. In the above timing, the leading edge of the paper is in the paper feed cassette 1.
．． 2 and the elevator feeder 3 are generated so as to be located in front of the merging point 14 of the three paper feeding paths provided corresponding to the elevator feeder 2 and the elevator feeder 3.

As described above, preliminary conveyance of paper is appropriately carried out for the paper feed portions of the paper feed cassettes 1 and 2 and the elevator feeder 3 that are ready for feeding. Therefore, in the case of this embodiment, up to three sheets of paper can be stopped at the same time in front of the merging point 14 by preliminary conveyance.

By the way, the format controller 24 in FIG.
When the rask image data has been developed in the rask image processor 23, a print signal, which is a start signal for the image forming operation of the engine, is sent to the engine controller 25 via the engine I/F. At this time, one of the sheets of paper that has completed the preliminary conveyance described above is selected based on a transmission command from the host computer 21 and input data from the printer operation panel.

Of course, it is also possible to select a sheet of paper, for example, in a paper feed cassette, which has not finished its preliminary conveyance, but in that case, the print speed performance will be reduced by the time required for preliminary conveyance.

Now, when the print signal is transmitted, the engine controller 25 resumes conveyance of the only paper selected to perform the following image forming process.

That is, in FIG. 3, when a print signal is transmitted as shown by numeral 33, one of the big-up ports 4 and 5.6 begins to rotate again as shown by 34, and paper conveyance is resumed. be done. Then, when the paper detection sensor 13 disposed immediately before the registration roller 15 detects the leading edge of the paper as shown by reference numeral 35, a raster image is sent from the format controller 24 via the recording head drive circuit 26 based on the detection signal. Data is recorded in recording head 2
Transferred to 8. This forms a latent image on the drum 16.

On the other hand, after a predetermined period of time has passed since the paper detection sensor 13 detects the leading edge of the paper, the pickup rollers 4, 5.6 stop as indicated by reference numeral 36.

As a result, the paper is slightly loosened and then stopped. This slight slack corrects the paper skew.

Next, the registration roller 15 begins to rotate as indicated by reference numeral 37 in synchronization with the position of the developed toner image on the drum 16. Therefore, the paper is conveyed toward the drum 16. When the paper is fixed on the drum 16 and passes over the transfer unit 17 in synchronization, the toner image on the drum 16 is transferred to the paper due to the corona discharge of the transfer unit 17. Thereafter, the paper is separated from the drum 16, the toner image is fixed on the paper by a fixing unit (not shown), and then the paper is ejected from the printer.

By the way, the preliminary conveyance may be carried out by the engine controller 25 alone when the paper feeding unit becomes ready to feed paper, as described above, or alternatively, as shown in the fourth factor, the format controller 24 and the engine controller 25
A system may also be used in which the process is performed at the time 41 when a paper feed signal is sent to the paper feed signal.

In this case, the paper feed signal may be sent by providing a dedicated signal line, or may be set as a command in a host interface such as R5232C.

Control when performing preliminary transport in this method is entrusted to the Rusk image processor 23.

At this time, based on the print command from the host computer 21, the Rusk image processor 23 sends a paper feed signal to the engine controller 25 to first instruct preliminary transport, and upon completion of the rask image data development process, the Rusk image processor 23 sends the paper feed signal to the engine controller 25 to print the paper. It is configured to send out signals.

Regardless of the preliminary transport method, the paper is preliminarily transported from the paper feed cassette etc. to a predetermined position before sending the print signal from the format controller 24 to the engine controller 25, so that the transport distance of the paper can be simulated. As a result, printing speed can be improved.

Note that the present invention is not limited to the embodiments described above, and it goes without saying that various modifications can be made without departing from the gist of the present invention.

[Effects of the Invention] As described above, according to the present invention, when performing preliminary conveyance,
Since the paper sent out from the paper feed section is controlled to stop before the meeting point upstream of the registration rollers, preliminary conveyance can be achieved at the same time in multiple paper feed sections, and as a result, the printing speed can be reduced. The big benefit is improved performance.

[Brief explanation of the drawing]

Figures 1 to 4 are diagrams showing one embodiment of the present invention. Figure 1 is a diagram showing the configuration of the device, Figure 2 is a block diagram showing the configuration of the control system, and Figure 3 is a diagram showing the operation timing. FIG. 4 is a diagram showing the timing of another example of operation. 1.2...Paper feed cassette, 3...Elevator feeder, 4,5.6...Pickup roller, 7,89...
・Retard roller, 1o, 11.12...Paper detection sensor, 14...Paper feed merging point, 15...Register roller,
16...Drum, 17...Transfer unit. Applicant's agent Patent attorney Atsushi Tsuboi

Claims (1)

[Scope of Claims] An image comprising an image forming means, a plurality of paper feed sections for conveying paper to the image forming means, and a plurality of paper conveyance paths provided corresponding to each of these paper feed sections. In the forming apparatus, the openings at the downstream ends of the plurality of conveyance paths are arranged so as to merge into one on the upstream side of the image forming means, and the paper is sent out from all paper feeding units capable of feeding paper. Image forming means for preliminary transporting the paper so that the paper is temporarily stopped and waited at a predetermined point near the merging point and upstream of the registration means. Device.