JP2791186B2 - Image forming device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as an electrophotographic printer having a pre-feeding function. In the present specification, pre-feeding means feeding recording paper or the like from a paper feed cassette or the like to a predetermined position prior to a print request.

[Conventional technology]

Conventionally, this type of image forming apparatus has a configuration as shown in FIG. Hereinafter, each component will be described.

1 is a photosensitive drum of an electrostatic latent image carrier, 2 is a semiconductor laser serving as a light source, 3 is a laser beam, 4 is a polygon mirror for scanning the laser beam, and 5 is a photosensitive drum that is uniformly charged. A charging roller, 6 a developing device for developing a latent image, 7 a transfer roller for transferring a toner image onto paper, 8 a paper (recording medium), 9 a paper feed roller, 10 a paper presence / absence sensor,
Reference numeral 11 denotes a registration roller for correcting skew by abutting the paper, and synchronizing the paper conveyance and the start of image writing on the photosensitive drum, 12 a fixing unit for fusing toner transferred to the paper, and 13 a fixing device. This is a paper presence / absence sensor of the paper discharge unit.

The control system of the image forming apparatus having such a configuration is the seventh system.
Shown in the figure. The engine control unit 20 receives commands and returns the internal status of the printer with the printer controller 21, and receives image data and exchanges a synchronization signal of its output. Further, the paper transport unit 22 inside the printer engine 26, an optical system (laser scanner)
The drive unit 23 outputs a drive / stop command to the high-voltage drive units 24 for charging, development, and transfer.

FIG. 8 shows a flowchart of the paper transport sequence performed by the engine control unit 20 in this configuration.

First, the presence or absence of a print request from the printer controller 21 is checked (step S1). If there is no print request, the presence or absence of a pre-feed request is checked (step S2). If there is a pre-feed request, the pre-feed flag is set (step S3). If there is no pre-feed request, the flow returns to the print request check. If there is a print request, the paper feed roller is driven without setting the preliminary paper feed flag (step S4).

Thereafter, when the paper reaches the registration sheet presence sensor 10 (step S5), after the lapse of the time T ₁ (sec) for forming a predetermined loop abuts the registration roller 11 (step S6, S7), stops the paper feed roller (Step S8)
If the pre-feed flag is not set, a vertical synchronization request is output (step S13), and if a vertical synchronization signal is received (step S14), the output of image data is started (step S15). If the pre-feed flag is set in step S9, the process continues to wait for receiving a print request (step S10). The predetermined time T ₂ weight receives a print request (step S11), and outputs a vertical synchronization request (step S13), then performs control similar to that described above.

[Problems to be solved by the invention]

However, in the above-described conventional technique, the pre-fed paper 8 is pressed against the registration roller 11 and is kept on standby in a state where the paper 8 forms a loop. In this state, the image forming apparatus performs processing such as image expansion from input image data to image data. That is, pre-feeding is an indispensable technique for improving throughput by performing sheet feeding and image development processing in parallel.

Therefore, the pre-fed paper 8 is subjected to deformation force by the loop, the nip of the registration roller 11 and the pressurized portion of the paper feed roller 9.

In recent years, along with the complexity of recorded images, the time required for image development tends to be longer. In addition, as the paper 8, other than plain paper, second original drawing paper, transparencies, artificial paper, envelopes and the like are used, but all of them are thin sheets. Deflection (curl, etc.) occurs locally.

In that case, when the image is transferred by contacting the photosensitive drum 1, the adhesion of the portion becomes poor, resulting in poor transfer. That is, a phenomenon occurs in which the image is whitened because the toner is not partially transferred, or the image is blurred because the image is transferred without contact, thereby deteriorating the quality of the recorded image.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an image forming apparatus capable of improving the throughput without solving the above-mentioned technical problems and without increasing the cost or deteriorating the quality of a recorded image.

[Means and actions for solving the problem]

According to the present invention, there is provided a means for measuring the time during which the pre-fed paper stays in the transport path or the time during which the pre-feed is stopped, and furthermore, the dwell time and the like are set from among a plurality of predetermined times. If the printing time is exceeded, the staying paper is temporarily discharged outside the apparatus, and when a printing request is received next, paper is fed from a paper cassette or the like. Therefore, it is possible to prevent the pre-fed paper from staying for a long time and improve the reliability of the image quality. Moreover, the time until the sheet is adversely affected varies depending on the environment in which the sheet is placed, but according to the present invention, an appropriate time can be selected and set.

〔Example〕

1 to 3 show a first embodiment of the present invention. The mechanical configuration of this embodiment is the same as the configuration shown in FIG. 6, and a detailed description thereof will be omitted. As shown in FIG. 1, the control system according to the present embodiment is provided with a timer unit 25 as compared with the prior art. The timing section 25 is an engine control section.
20 receives the pre-feed request from the printer controller 26, conveys the sheet to a predetermined position, and counts the time from when the sheet is stopped in a print request waiting state. Reference numeral 27 denotes a temperature sensor such as a thermistor. Reference numeral 28 denotes a ROM that stores a residence time limit corresponding to each temperature,
The engine control unit 20 outputs to the timing unit 25 the retention time limit corresponding to the temperature detected by the temperature sensor 27 as the time T _3.
This time T ₃ is set.

FIG. 2 shows a flow chart of the engine control unit 20 in this embodiment. First, the engine control unit 20 sets the time T ₃ by the operation described above (step E0).

Next, the presence / absence of a print request from the printer controller 21 is checked (step E1). If there is no print request, the presence / absence of a pre-feed request is checked (step E2).
If there is a pre-feed request, the pre-feed flag is set (step E3), and if there is no pre-feed request at step E1, the process returns to the check for print request. When there is a print request, the paper feed roller is driven without setting the preliminary paper feed flag (step E4).

After that, when paper registration sheet presence sensor 10 reaches (step E5), abuts on the registration roller 11, after the lapse of the time T ₁ for forming a predetermined loop (s) (step E6, E7), i.e. a print request or When the paper feed is completed after the pre-feed request is received and the sheet is conveyed to reach the registration roller position, the paper feed roller is stopped (step E8),
The pre-feed flag is checked (step E9). If the pre-feed flag is OFF, a vertical synchronization request is output as in the conventional example (step E19). In the case of予給paper flag is ON, the residence restriction timer T ₃ to monitor the flight residence time of the sheet which is予給paper by excisional (step E10), the print request waiting state (step E11). The count of the print requests a checking and while residence time limit T ₃ is a checking whether completed (step E12). Retention time limit T ₃
If the count has received the print request prior to completion, and resets the residence restriction timer (step E15), and OFF the予給paper flag (step E16), after T ₂ sec wait (step E17, E18), and outputs a vertical synchronization request (step E19). Thereafter, the same processing as the conventional one is performed (steps E20 and E21). If the count of the dwell time limit T ₃ has not received the print request even if completed, the予給paper flag OF
F (step E13), the remaining paper is discharged out of the machine (step E14), and the process returns to the "start" process.

FIG. 3 shows these processes in a timing chart. In this timing chart, the first page is printed according to a normal printing request, and after receiving a pre-feed request for the next page and pre-feeding the sheet, the printing request is not received even after T ₃ (sec) has elapsed, so the automatic timing chart is used. This shows a case where the printer is set in the discharge mode, and after a print request is received after automatic discharge, paper is again fed from the paper cassette.

As described above, when the temperature is high, the sheet is easily curled, and when the temperature is low, the sheet is not easily curled. However, in the present embodiment, the temperature inside the apparatus is detected by the temperature sensor 27, and the retention time T ₃ is determined according to the temperature. Is set, it is possible to discharge the pre-fed paper only when an appropriate time has elapsed.

Further, as another embodiment of the present invention, a humidity sensor may be provided instead of the temperature sensor. In this case, although easy to paper curling as humidity is high, it is possible to set an appropriate residence time limit T ₃ in accordance with the humidity detected by the humidity sensor.

Further, both a temperature sensor and a humidity sensor are provided, and based on the detected temperature and the detected humidity, an appropriate residence time limit T ₃
May be set.

The plurality of times need not be stored in the ROM, but may be input from, for example, key input means and stored in the RAM.

[Other embodiments]

4 and 5 show a second embodiment of the present invention.

FIG. 4 shows an apparatus configuration in this embodiment. In the drawing, 14 and 15 are a second paper feed roller and a paper cassette.
Also, reference numeral 11 denotes a roller which corrects skew by abutting the end of one side of the sheet against the side surface of the conveyance path with a skew feeding roller, instead of a roller which corrects the skew by hitting the sheet. Thus, a loop is not formed in the registration roller portion unlike the method described above. However, since the conveyance path from the second paper cassette 15 to the registration sensor 10 has a certain curve, if the paper stays for a long period of time, the paper will still have a habit and adversely affect the subsequent paper conveyance. Exert. Therefore, in the present embodiment, the optimal control is to be performed by changing the paper retention time for each paper feed port. FIG. 5 is a flow chart showing the control.

First, in step P1, it is checked whether or not there is a print request from the printer controller 21. If no print request has been received, it is checked whether or not there is a pre-feed request (step P1).
P2). If a pre-feed request has not been received,
Return to P1 and check for print request. When a pre-feed request is received, the pre-feed flag is set (step
P3), and proceed to step P4 described below.

When a print request is received in step P1, the sheet feeding roller 9 and the conveying roller 11 are driven (step P4), and when the registration sensor 10 detects a sheet (step P5), the sheet feeding roller 9 and the conveying roller 11 are stopped. (Step P6). And
In step P7, it is checked whether or not the pre-feed flag is set.If the pre-feed flag is not set, the process proceeds to step P20 to be described later, a vertical synchronization request is output, and if the pre-feed flag is set. By reading data relating to the specification of the paper feed port from a RAM (not shown) or the like, the paper feed port designated to feed paper is set to the paper feed port of the first cassette 8a or the paper feed port of the second cassette 15. It recognizes whether it is (step P8), when a paper feed port of the first cassette 8a sets the T _L1 as residence time limit T ₃ (step P1
1), when a paper feed port of the second cassette sets T _L2 (step P10).

Then, while a checking whether a print request, the count of the dwell time limit T ₃ is a checking whether completed (step P12, P13). If the count of the dwell time limit T ₃ without receiving a print request is completed, and turns OFF the予給paper flag (step P14), and discharge the sheet in the residence to the outside (step P15), "start It returns to the process of "". In step P12, P13, when the count of the dwell time limit T ₃ receives a print request before the exit, the residence restriction timer was reset (step P16), and OFF the予給paper flag (step P17) , T ₂ sec after weight (Step P1
9, P20) Output vertical synchronization request. When the vertical synchronization signal is received (step P21), the output of the image data is started (step P22), and this sequence control ends.

As described above, in this embodiment, since there are two paper feed ports, when a pre-feed request is received, the designated paper feed port is read and the paper feed of the specified paper feed port is performed. Drive the rollers. After that, the paper arrives at the registration sensor 10 and waits for a print request and stops, and then reads from which paper supply port the paper is pre-fed, and sets the value of the retention limit timer corresponding to that paper supply port. . In the case of this embodiment, the first
Since the cassette paper path is straight and does not form a resist loop, the time limit may be long. However, the paper path of the second cassette has a curve and is set shorter than the time limit of the first cassette. That is, T _L1 > T _L2 . Thus, the paper feed port used will vary the time to adversely affect the paper, since the residence time limit T ₃ is set in accordance with the feed port, even when using any of the paper feed port Thus, image formation can be performed with an appropriate residence time limit.

In the above-described embodiment, the time after the pre-feed is measured as the staying time. However, the time after receiving the pre-feed request or starting the driving of the feed roller may be measured. . In this embodiment, the case where the present invention is applied to a laser printer has been described.
It can also be applied to D printers.

〔The invention's effect〕

As described above, by receiving the pre-feed request, the paper stays in the transport path, and sets an appropriate time limit for a state of waiting for a print request, and further automatically discharges the paper. Even if a print request is received next, normal printing can be performed without any image loss by re-feeding paper from the cassette again. It greatly contributes to.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of a control system of a laser printer according to an embodiment of the present invention. FIG. 2 is a flow chart for explaining the operation of an engine control unit 20 of the control system shown in FIG. FIG. 4 is a timing chart showing the processing operation of the control system shown in FIG. 1, FIG. 4 is a diagram showing the device configuration of a laser printer according to a second embodiment of the present invention, and FIG. 5 is an operation of the laser printer shown in FIG. FIG. 6 is a diagram showing the configuration of a general laser printer, FIG. 7 is a block diagram showing the configuration of a control system of a conventional laser printer, and FIG. 8 is a diagram of FIG. 3 is a flowchart for explaining the operation of the control system of FIG. DESCRIPTION OF SYMBOLS 1 ... Photosensitive drum 2 ... Semiconductor laser 4 ... Polygon mirror 6 ... Developing device 7 ... Transfer roller 8a, 15 ... Paper feed cassette 9 ... Paper feed roller 10, 13 ... Paper presence sensor 11 ... Registration roller 12 ... Fixing device 20 ... Engine Control unit 21 Printer controller 22 Paper transport unit 23 Optical drive unit 25 Clock unit 26 Printer engine 27 Temperature sensor

Continuation of the front page (51) Int.Cl. ⁶ Identification code FI G03G 15/00 518 G03G 21/00 510 21/00 510 H04N 1/00 108M H04N 1/00 108 B41J 3/00 D (72) Inventor Matsuo Shinpei 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Masaji Uchiyama 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Kazuo Yamada Tokyo 3-30-2 Shimomaruko, Ota-ku Canon Inc. (72) Inventor Makoto Takeuchi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (56) References JP-A-59-67071 (JP) JP-A-2-301359 (JP, A) JP-A-4-29255 (JP, A) JP-A-1-302273 (JP, A) JP-A-3-229996 (JP, A) 59-89349 (JP, U) JP 1-37736 (JP, B2) (58) Fields investigated (Int. Cl. ⁶ , DB name) G03G 15/00 510-534 G03G 21/0 0 370-540 G03G 15/00 140 B41J 11/42 B41J 13/00 H04N 1/00 108

Claims (4)

(57) [Claims] An electrostatic latent image is formed by irradiating a blinking light beam on an electrostatic latent image carrier based on image information, and then developed with toner, and the toner image is transferred to a predetermined sheet of paper. In an image forming apparatus that outputs a print image by fixing, a paper transport unit that feeds and transports paper to the electrostatic latent image carrier in response to a print request from an external device, and a paper that is transported by the paper transport unit Vertical synchronizing means for synchronizing the conveyance of the image information and the start of writing image information on the electrostatic latent image carrier, and after conveying the sheet to a predetermined position in the conveyance path prior to the print request, A pre-feeding means for conveying the paper to the predetermined position by receiving a pre-feeding request from an external device to stop and wait for a print request, and a pre-feeding means for conveying the paper to the predetermined position by the pre-feeding means. Start timing operation based on Time setting means for selectively setting one of a plurality of predetermined times, and printing from the external device until the time setting means finishes measuring the time set by the setting means. An image forming apparatus, comprising: a discharge unit configured to discharge the paper that has been pre-fed and stopped at a predetermined position to the outside when the request is not received. 2. An image forming apparatus according to claim 1, further comprising a plurality of paper feed ports, wherein said setting means selectively sets a time corresponding to a paper feed port to which paper is to be fed. Characteristic image forming apparatus. 3. The image forming apparatus according to claim 1, further comprising detecting means for detecting temperature or humidity, wherein said setting means sets a plurality of times based on the temperature or humidity detected by the detecting means. An image forming apparatus characterized by selectively setting one of the following. 4. An image forming means for forming an image on a recording sheet, a pre-feeding means for pre-feeding the recording sheet to a predetermined position, and a recording sheet stopped at the predetermined position being conveyed to the forming means. A conveying unit, a setting unit for selectively setting one of a plurality of times, and a stop state of the recording sheet at a predetermined position exceeding a time set by the setting unit. An image forming apparatus, comprising: a paper discharging means for discharging the recording paper.