JPH07149010A - Image forming apparatus - Google Patents

Abstract

PURPOSE:To shorten the standby time of paper by starting clocking when a pre-feed command is sent from an image data source and sending out paper from a supply source based on the faster time between clocking completion time and the time receiving the printing start command sent from an image data source. CONSTITUTION:In an image forming apparatus, the surface of the photosensitive drum 11 positioned between a charge corotron 12 and a developing device 13 is scanned by laser beam 18 outputted corresponding to image data from a semiconductor laser 17 through an optical system 19 composed of an ftheta lens or a polygon mirror to form an electrostatic latent image. In this case, when a command starting the pre-feed of paper is issued to the image forming apparatus, pre-feed is stated after a first time T1 is elapsed and paper is set to a temporary stop state when the paper reaches the place of a resist roller. When a printing start command arrives, the resist roller is rotated after the elapse of a second time T2 to resume the supply of paper. By this constitution, a standby time is shortened.

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 for forming an image using print data such as bit map data sent from an image information source such as a host computer, and more particularly to a cassette tray before starting printing. The present invention relates to an image forming apparatus in which a sheet is preliminarily fed from a sheet supply source and the time required for printing is shortened.

[0002]

2. Description of the Related Art In a certain type of host computer, image data of characters or figures to be printed is expanded into bitmap data inside, and this is sent to an image forming apparatus such as a laser printer as print data to form an image. Is to be done. Many of such image forming apparatuses employ a xerographic recording method for forming an image. An image forming apparatus that employs a recording method using xerography is characterized by quieter sound and a clearer image reproduction on plain paper than an impact type printer.

FIG. 8 shows an outline of the configuration of an example of such an image forming apparatus. This image forming apparatus uses a photoconductor drum 11 as a photoconductor for forming an electrostatic latent image. Around the photosensitive drum 11, a charge corotron 12 for imparting a uniform charge to the drum surface, and a developing device 13 for developing an electrostatic latent image.
Further, a transfer corotron 15 for transferring the toner image formed by development onto the paper 14 and a cleaning device 16 for removing the toner remaining without being transferred from the surface of the photoconductor drum 11 are arranged. The drum surface located between the charge corotron 12 and the developing device 13 is scanned by a laser beam 18 output from a semiconductor laser 17 according to image data by an optical system 19 including an fθ lens and a polygon mirror. The above-mentioned electrostatic latent image is formed.

In such an image forming apparatus, one or a plurality of paper cassettes (only one is shown in the figure for simplicity) 21 is set as a paper supply source. It is normal. The sheets 14 of a predetermined size stacked in the sheet cassette 21 are fed one by one by the feed roller 22, pass through the registration roller 23, and pass between the photosensitive drum 11 and the transfer corotron 15. At this time, the toner image is transferred to the paper 14. The paper 14 on which the toner image is transferred is then
After passing between the heat roller 24 and the pressure roller 25, thermal fixing is performed. After that, the sheet is discharged onto a discharge tray (not shown). In this figure, the arrow 26 indicates the rotation direction when the photosensitive drum 11 rotates at a constant speed.

Generally, in the image forming apparatus, the paper cassette 2
From the exposure position on the photoconductor drum 11 by the optical system 19 to the transfer position of the toner image by the transfer corotron 15 rather than the length of the conveying path until the paper 14 sent out from 1 passes directly above the transfer corotron 15. Often the length along the drum surface is shorter. In particular,
In the case of an image forming apparatus in which a plurality of paper cassettes 21 are arranged, since the transport path is often complicated and long, this relationship tends to be established. In the image forming apparatus having such a relationship, at the stage when the irradiation of the laser beam 18 on the photosensitive drum 11 is started, the paper cassette 21
If the paper 14 is sent from the paper 14, the toner image cannot be transferred from the front end of the paper 14.

Therefore, in the conventional image forming apparatus, the paper cassette 21 is expected to start printing.
The sheet 14 is first sent out from the sheet, and when the leading edge of the sheet 14 reaches the registration roller 23, the conveyance is temporarily stopped. Then, the photosensitive drum 11
The rotation of the registration roller 23 is started at a predetermined timing after the irradiation of the laser beam 18 is started, and when the leading edge of the sheet 14 reaches a position just above the transfer corotron 15, the photosensitive drum 11 The starting position of the above image is exactly the same.

FIG. 9 is a diagram for explaining the contents of control performed by the host computer side and the image forming apparatus in order to enable such image registration in which the leading edge of the image is positioned on the leading edge of the sheet. is there. In the figure, the horizontal axis represents the passage of time. The host computer sends a pre-feed command to the printer at time t ₁ when the adjustment of print data has progressed to some extent. When the printer receives the pre-feed command, the paper 14 is sent out from the predetermined paper cassette 21 shown in FIG. At the time t ₂ when the time T ₁₁ has elapsed, the sheet 14 is conveyed to the registration roller 23 at its leading edge, and is put in a standby state here. The host computer adds a certain allowance time to the time T ₁₁ in consideration of the transfer distance and the transfer speed to the registration rollers in various printers, and outputs a print start command at a predetermined time t ₃ after the time T ₁₁ has elapsed.

When the printer receives the print start command, it starts to form an image on the photosensitive drum 11, and at the above-mentioned predetermined timing, the registration roller 23 at the time t _4.
To start the rotation. As a result, when the leading edge of the sheet 14 reaches the position just above the transfer corotron 15, the transfer of the toner image corresponding to the sheet on the photosensitive drum 11 is started.

In the conventional image forming apparatus, the
The paper pre-feed is opened when the feed command is received.
Start printing and start printing when the print start command is received.
It was supposed to be. Therefore, the leading edge of the paper 14
Time t₂After reaching the registration roller 23 at time t_Four
Is the time T until the registration roller 23 starts to rotate. ₁₂
It was supposed to be held in a waiting state only. This waiting state
During this period, a print start command may arrive at any time.
Therefore, in order to be able to respond to printing immediately,
In the image forming apparatus of FIG.
The rotation of the photosensitive drum 11 is started from the time when the end arrives.
The charge corotron 12
Other printing such as discharge and rotation of polygon mirror of optical system 19
Preparation work was also started at the same time.

Therefore, in such a conventional image forming apparatus, the photosensitive drum 11 is exposed and developed even in a time other than the time required for printing, which causes the life of the photosensitive drum 11 to be shortened. The same applies to other circuit components. Further, since the leading edge of the sheet 14 draws a loop at the position of the registration roller 23, the sheet 14 may have a loop-shaped habit when the state continues for a long time. In this case, the conveyance of the sheet 14 and the storage after printing may be adversely affected.

In order to solve such a problem, in the image forming apparatus disclosed in Japanese Patent Laid-Open No. 4-29256, the print start command comes after the pre-feed command shown in FIG. It was decided that the print operation would be stopped if some trouble occurred in the host computer itself or in communication with the host computer when the time up to the normal time was exceeded.

[0012]

However, when the printing operation is stopped, it is practically impossible to reversely convey the paper 14 once sent to the registration roller 23 to the paper cassette 21 in the reverse direction. Therefore, in the proposed apparatus, the sheet 14 that has been sent out halfway is conveyed in a blank state and discharged to the above-mentioned discharge tray. The paper sheet 14 that has passed through the transport path once is highly likely to be wrinkled or jammed (paper jam), and thus is often not reused for printing. Therefore, not only is the paper wasted, but if the host computer side stops the printing operation while image processing is in progress, the work is wasted and communication must be started from the beginning. There was a problem of disappearing.

Therefore, an object of the present invention is to pre-feed a sheet of paper prior to the start of printing, to temporarily stop the sheet at a predetermined location, to wait it, and then to feed it to the printing location.
An object of the present invention is to provide an image forming apparatus capable of relatively shortening the standby time.

[0014]

According to the first aspect of the present invention, (a) when a pre-feed command for instructing the start of sheet conveyance is sent prior to image data transmission, this is received. Pre-feed command receiving means, (b)
A print start command receiving means for receiving a print start command for instructing the start of printing for the same image data from the sending side of the pre-feed command, and (c) receiving the pre-feed command First means for timing a predetermined first time after the means receives the pre-feed command
And (d) paper conveyance for feeding the paper from its supply source at the earlier of the time when the first time measuring means measures the first time or the time when the print start command is received. Start control means, (e) paper temporary conveyance stop means for temporarily stopping the paper conveyed by the paper conveyance start control means at a predetermined position before the printing position, and (f) print start command A second means for measuring another predetermined second time after the receiving means receives the print start command
And (g) paper transport resuming means for releasing the transport stop of the paper temporary transport stop means and sending the paper to the printing position at the time when the second clock means measures the second time. It is provided in the image forming apparatus.

That is, according to the first aspect of the invention, when the pre-feed command is sent from the image information source such as the host computer, the first time is counted from this time, and the time end time and the image information source are sent. The paper is sent out from the supply source at an earlier time than the print start command. As a result, the time during which the sheet waits at the sheet temporary conveyance stopping means is reduced as compared with the conventional case in which the feeding of the sheet is started immediately after the pre-feed command arrives. The sheet temporarily stopped to be conveyed by the sheet temporary conveyance stopping means is resumed to be fed out when another predetermined second time has elapsed after receiving the print start command.

According to the second aspect of the present invention, (a) pre-feed command receiving means for receiving a pre-feed command for instructing the start of sheet conveyance prior to image data transmission, and pre-feed command receiving means. (B) A print start command receiving means for receiving a print start command for instructing the start of printing for the same image data after the sending of the pre-feed command, and (c) Selection information receiving means for receiving selection information for selecting one of a plurality of first time candidates having a predetermined time length prior to transmission of image data; and (d) using this selection information. First time selecting means for selecting a first time by
(E) First time measuring means for measuring the first time selected by the first time selecting means after the pre-feed command receiving means receives the pre-feed command, and (f) the first time measuring means. Paper feed start control means for feeding the paper from its supply source at the earlier time of measuring the first time or the time when the print start command is received,
(G) A paper temporary conveyance stop means for temporarily stopping the paper conveyed by the paper conveyance start control means at a predetermined position before the printing position, and (h) a print start command receiving means for starting printing. Second timing means for timing the second time after receiving the command, and (i) canceling the conveyance stop of the paper temporary transportation stop means at the time when the second timing means measures the second time. Then, the image forming apparatus is provided with a sheet transport resuming means for sending the sheet to the printing position.

That is, according to the second aspect of the present invention, when the pre-feed command is sent from the image information source such as the host computer, the first time is counted from now on, and the time end time and the image information source are sent. The paper is sent out from the supply source at an earlier time than the print start command. Here, for the first time, a plurality of candidates are prepared in advance on the image forming apparatus side, and the selection information receiving means receives the information for selecting one of them. As a result, not only is the time for the paper to wait in the paper temporary conveyance stopping means reduced compared to the conventional case in which the paper is immediately started to be sent out when the pre-feed command arrives, but also the image of the host computer or the like is reduced. The first time can be set to an optimum one according to the situation of the information source and the like, and the waste of the waiting time can be reduced accordingly. Also in the invention according to the second aspect, the sheet whose conveyance is temporarily stopped by the sheet temporary conveyance stopping means is sent out at a time point when another predetermined second time has elapsed after receiving the print start command. Will be resumed.

According to the third aspect of the invention, (a) pre-feed command receiving means for receiving a pre-feed command for instructing the start of sheet conveyance prior to image data transmission, and pre-feed command receiving means. (B) A print start command receiving means for receiving a print start command for instructing the start of printing for the same image data after the sending of the pre-feed command, and (c) Second clocking means for timing a second time after the print start command receiving means receives the print start command, and (d) the prefeed command receiving means receives the print start command after the prefeed command is received. A third time measuring means for measuring a third time as the time until it is measured for each image data, and (e)
Prediction means for predicting the time from the reception of the pre-feed command by the pre-feed command receiving means to the reception of the print start command based on the past time measured by the third time measuring means, ) Paper feed start control means for setting the timing at which the pre-feed command receiving means receives the pre-feed command based on the prediction result of the predicting means, and then feeds the paper from its supply source; Paper temporary conveyance stop means for temporarily stopping the paper whose conveyance has been started by the control means at a predetermined position before the printing position, and (h) at the time when the second timing means measures the second time. The image forming apparatus is provided with a paper transport resuming means for releasing the paper transport stop of the paper temporary transport stop means and sending the paper to the printing portion.

That is, according to the third aspect of the invention, the time from the reception of the pre-feed command to the reception of the print start command is counted as the third time for each image data, and the past data is used as the basis. Then, the third time in the present printing work is predicted. Then, after the pre-feed command receiving means receives the pre-feed command based on the prediction result of the predicting means, the timing for sending out the paper from the supply source is set. Accordingly, even if the image information source such as the host computer does not transmit the information regarding the sheet feeding timing to the image forming apparatus, the image forming apparatus can adjust the timing.

[0020]

EXAMPLES The present invention will be described in detail below with reference to examples.

FIG. 1 shows a main part of a circuit configuration of an image forming apparatus according to an embodiment of the present invention. The mechanical structure of this image forming apparatus is the same as that of FIG. 8, and this figure will be used as it is in this embodiment. The image forming apparatus of this embodiment is a CP for controlling each part of the apparatus.
A U (central processing unit) 31 is installed. The CPU 31 is connected to various circuit devices in the device through a bus 32 such as a data bus. Of these, the ROM 33 is a read-only memory that stores various control programs. RA
M34 is a random access memory that temporarily stores various data required for control. The non-volatile memory (NVM) 35 is a memory backed up by a battery (not shown) and stores data to be held even when the power of the image forming apparatus is turned off. The communication controller 36 communicates with the host computer 38 via the communication cable 37.
Print data and control data are transmitted from the host computer 38 to the image forming apparatus. Here, the control data includes a command and a sync signal. The image forming apparatus transmits the internal status of the apparatus to the host computer 38.

On the bus 32, in addition to this, a paper control unit 41,
The fixing device temperature control unit 42, the high pressure control unit 43, the optical system control unit 44, and the drum drive unit 45 are also connected. Here, the sheet control unit 41 is configured to control the driving of the rollers such as the feed roller 22 and the registration roller 23 shown in FIG. 8 to control the conveyance of the sheet 14. Fixing unit temperature control unit 42
Controls the temperature of a heater (not shown) built in the heat roller 24 shown in FIG. The high voltage control unit 43 is adapted to perform control for applying a high voltage to a high voltage application portion such as the charge corotron 12 shown in FIG. The optical system controller 44 controls rotation of the polygon mirror of the optical system 19 shown in FIG. 8 and ON / OFF control of the semiconductor laser. The drum control unit 45 controls the drive of a main motor (not shown) to rotate the photosensitive drum 11 shown in FIG. 8 at a constant speed.

By the way, in this embodiment, after the pre-feed command is received, the paper 14 is actually fed from the paper cassette 21.
The time that is a candidate for the time before performing the pre-feed (hereinafter referred to as the first time) is determined as shown in Table 1 below and stored in the non-volatile memory 35. As described above, various values are prepared whether the image data processed by the host computer 38 side is data already developed into an image, or a graphic which needs to be developed into bitmap data by calculation processing. This is because, depending on the type of the original data such as whether the data is the same or the like, the ratio of the data to the page, etc., there is a considerable length in the time until the data is expanded into the bitmap data and transmitted. In this embodiment, as shown in Table 1, three candidates are prepared for the first time, but one of these values is preferentially used when the host computer 38 does not make a particular designation. It is set as the value to be selected (default value). In Table 1 below, the signal "1" indicates a candidate for which a default value is set.

[0024]

[Table 1]

FIG. 2 shows the operation of setting the first time by the image forming apparatus of this embodiment. The image forming apparatus receives set value data as control data from the host computer 38 shown in FIG. 1 (step S10).
1; Y), decoding which one of these corresponds to Table 1 is performed and the first time is set to that value (step S10).
2). In the initial state where such set value data does not arrive, the time for which the default value is set in Table 1 is initially set as the first time (step S103).

On the side of the host computer 38, the person who transmits the image data selects one of the first to third candidates in Table 1 in relation to the content of the image data before starting the transmission. , And is sent to the image forming apparatus as set value data. However, the image forming apparatus side may be configured to be able to input information for setting the first time from the operation panel as necessary. This is because an operator who is familiar with the operation status of the image forming apparatus has a possibility to empirically set the first time.

FIG. 3 shows a state of control until the image forming apparatus of this embodiment starts sheet feeding according to an instruction from the host computer. The image forming apparatus monitors the arrival of the pre-feed command and the print start command (steps S201 and S202). Normally, the host computer 38 (FIG. 1) first issues a pre-feed command and then a print-start command, but depending on the situation and the type of device, it may issue a print-start command without issuing a pre-feed command. . When the print start command is suddenly sent (step S202; Y), the print start flag is set to ON (step S203). Such a flag can be stored in a predetermined area of the RAM 34. When the print start flag is turned on, prefeed of the paper 14 is started from the paper cassette 21 shown in FIG. 8 (step S204).

In contrast to this, in a normal case, the pre-feed command comes first (step S201; Y). When the pre-feed command arrives, the CPU 31 (FIG. 1) starts the timer (step S205). Although the timer can be configured as a dedicated circuit like this, the RAM
It can also be realized by sequentially writing clocks in a predetermined area of 34. Unless the print start command arrives on the way, the timer (step S206;
N), count up until the first time shown in Table 1 is measured (step S207). When the first time is measured (Y), the process proceeds to step 204 and the paper cassette 2
The pre-feed of the paper 14 is started from 1.

On the other hand, when the print start command arrives on the way (step S206; Y), the time counting operation of the timer is stopped (step S208), and the print start flag is set to ON (step S203). ), Step 20
The process proceeds to step 4 to start pre-feeding the paper 14 from the paper cassette 21.

FIG. 4 shows a state of the printing work after the paper pre-feed is started in this way. When the feed roller 22 is rotated by the control of the sheet controller 41 shown in FIG. 1 and the uppermost sheet 14 stacked in the sheet cassette 21 starts to be fed, the CPU 41 is provided in the sheet controller 41. The detection output of the sensor is monitored to detect the time when the leading edge of the sheet 14 reaches the registration roller 23 (step S301). Such a sensor can be arranged as a photo sensor immediately before the registration roller 23, for example. Registration roller 2
If you place such a sensor right after 3,
The registration roller 23 must first rotate in order to grip the paper 14, but this rotation stops when the leading edge of the paper 14 is detected. As a result, the front end of the pre-fed paper 14 is stopped by the registration roller 23 and curls in a loop.

In this state, the CPU 31 checks whether the print start flag is on (step S30).
2). If it is on (Y), the timer is reset (step S303), the print start flag is turned off (step S304), the photosensitive drum 11 is rotated, and the on / off control of the semiconductor laser 17 is started. The printing operation of is started (step S305). If the print start flag is not turned on (step S302;
N), waiting until the print start command arrives (step S306), and when it arrives, the control from step 303 onward is performed.

When the printing operation is started in this way, C
The PU 31 restarts the timer timing operation (step S307). Then, when the second time is measured (step S308), the rotation of the registration roller 23 is started to convey the paper 14 to a position just above the transfer corotron 15 (step S309). Here, the second time is the timing at which the position of the photosensitive drum 11 is directly above the transfer corotron 15 after the printing of the leading position for one page is started, and the front end of the paper 14 is at this position. It is the adjustment time that is set so that Therefore, when the registration roller 23 is very close to the image transfer position, the second time is lengthened accordingly.

When the driving of the registration rollers 23 is started, the timer is reset again (step S310). The control after this is the same as the control performed in a normal image forming apparatus such as a copying machine, and the description thereof will be omitted.

FIG. 5 corresponds to FIG. 9 and shows timing control for enabling image registration in this embodiment. In the figure, the horizontal axis represents the passage of time. The host computer sends a pre-feed command to the printer at time t ₁₁ when the adjustment of print data has progressed to some extent. After receiving the pre-feed command, the printer measures the first time T ₁ , and at the end time t ₁₂ , the paper 14 is sent out from the predetermined paper cassette 21 shown in FIG. The paper 14 is about time T _11.
At time t ₁₃ when the time elapses, the leading end of the sheet is conveyed to the position of the registration roller 23, and the waiting state is set there. A print start command is sent from the host computer 38 at time t ₁₄ when a relatively short time has elapsed, and rotation of the registration roller 23 is started at time t ₁₅ when the second time T ₂ has elapsed. As a result, when the leading edge of the sheet 14 reaches the position just above the transfer corotron 15, the transfer of the toner image corresponding to the sheet on the photosensitive drum 11 is started.

As described above, in the embodiment of the present invention, the first time is set by the instruction of the host computer 38, etc., and in principle, even if the pre-feed command arrives, the paper 14 is fed.
No pre-feeding was performed, and pre-feeding was performed when the first time had elapsed. Therefore, these embody the contents of claims 1 and 2.

Modification

Next, as a modified example of the present invention, an image forming apparatus embodying the contents of claim 3 will be described.

FIG. 6 shows the initial work contents on the image forming apparatus side in this modified example, and corresponds to FIG. In this modification, the image forming apparatus waits for a request for update registration of the set value from the host computer 38 (step S401). Here, the request for updating and registering the set value is a request for instructing to automatically correct the value when the first time in the previous embodiment is not suitable for the image forming apparatus. Such a request is issued by the host computer 38 or the operator of the image forming apparatus.
However, the same request may be input from the operation panel on the image forming apparatus side to the apparatus side. When a setting value update registration request is input to the image forming apparatus (step S401; Y), R
The update registration flag assigned to the predetermined area of the AM 34 is set to the ON state (step S402). In the state before this request comes (step S401; N), the update registration flag is set to the off state (step S).
403).

FIG. 7 shows a state of the printing work after the start of the pre-feed of the paper in this modification.
This FIG. 7 corresponds to FIG. 4 of the previous embodiment. Since the control shown in FIG. 3 is similarly performed in this modification,
Description and illustration of these are omitted. The control of steps S501 to S503 in FIG. 7 is also performed in step S30 of FIG.
Since the control is the same as that of 1 to S303, the description thereof will be omitted. In this modification, in step S504, it is checked whether the update registration flag is turned on. If this is turned on, that is, if it is agreed to adjust the first time, the currently registered set value of the first time and the previous pre-feed command arrival time The average value of the time until the print start command arrives (third time) is calculated by adding the measured values of the timers and dividing by the number of measurements (step S505). Then, the present value registered in the non-volatile memory 35 as the first time is replaced with this calculation result (step S506). Instead of taking the whole average value and replacing it, the latest plural average values may be taken and replaced.

When the above processing is completed, and when the update registration flag is off in step S504,
Next, the timer is reset (step S507),
Subsequently, the print start flag is also turned off (step S50).
8). Thereafter, the update registration flag is turned off (step S509) and printing is started (step S511).
Subsequent steps S511 to S514 are the same as steps S307 to S310 in FIG. 4, so description thereof will be omitted.

In the modification described above, when the set first time is too short and the waiting time at the registration roller 23 is disproportionately long, this is sequentially corrected with the actual measurement time. be able to. Therefore, this waiting time can be corrected to an appropriate value.

Although the image forming apparatus using the photoconductor drum has been described in the embodiment, the present invention can be similarly applied to the case where another photoconductor such as a photoconductor belt is used. According to the first and second aspects of the present invention, when the second time measuring means measures the second time, the paper temporary carrying stopping means releases the carrying stop and the paper is sent to the printing portion. However, if the position for temporarily stopping the conveyance of the sheet is appropriately set by the sheet temporary conveyance stopping means, the time measurement of the second timing means is set to "0".
That is, it is also possible to virtually omit the timing operation of the second timing means.

[0043]

As described above, according to the first and second aspects of the present invention, when the pre-feed command is sent from the image information source such as the host computer, the first time is measured from this time, and this time measurement is performed. The paper is sent from the supply source at an earlier time between the end time and the print start command sent from the image information source. Therefore, the time for the paper to stand by in the paper temporary conveyance stop means becomes shorter than in the conventional case in which the paper is immediately started to be sent out when the pre-feed command arrives, and the life of the photoconductor is extended by that much. Not only that, there is an effect that jam due to curling of the leading edge of the paper is reduced.

Further, according to the second aspect of the invention, the first time can be set to an optimum one according to the situation of the image information source such as the host computer, so that the waiting time of the paper is wasted. Can be reduced, and the effect of extending the life of the photoreceptor and the like can be correspondingly increased.

According to the third aspect of the invention, the time from the reception of the pre-feed command to the reception of the print start command is counted as the third time for each image data, and these past data are recorded. Based on the above, the third time in the present printing work is predicted. Then, after the pre-feed command receiving means receives the pre-feed command based on the prediction result of the predicting means, the timing for sending out the paper from the supply source is set. As a result, there is an effect that this timing can be adjusted on the image forming apparatus side without imposing a burden on the image information source such as the host computer.

[Brief description of drawings]

FIG. 1 is a block diagram showing a main part of a circuit configuration of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a flowchart showing an operation of the image forming apparatus of the embodiment for setting a first time.

FIG. 3 is a flow chart showing a state of control until the image forming apparatus of the embodiment starts sheet feeding according to an instruction from the host computer side.

FIG. 4 is a flowchart showing a state of a printing operation after the paper prefeed is started in the image forming apparatus of the embodiment.

FIG. 5 is a timing explanatory diagram showing a command sent from the host computer side and the corresponding operation on the image forming apparatus side in the embodiment.

FIG. 6 is a flowchart showing an initial work content on the image forming apparatus side in a modified example.

FIG. 7 is a flow chart showing a state of a printing operation after starting pre-feeding of paper in a modified example.

FIG. 8 is a schematic configuration diagram showing an outline of the configuration of an example of an image forming apparatus.

FIG. 9 is a timing explanatory view showing a conventional instruction sent from the host computer side and the corresponding operation on the image forming apparatus side.

[Explanation of symbols]

11 ... Photosensitive drum, 17 ... Semiconductor laser, 21 ... Paper cassette, 23 ... Registration roller, 31 ... CPU, 33
... ROM, 34 ... RAM, 35 ... communication control unit, 38 ... host computer, T ₁ ... first time, T ₂ ... second time

Claims (3)

[Claims] 1. A pre-feed command receiving means for receiving a pre-feed command for instructing the start of sheet conveyance prior to transmission of image data, and a pre-feed command sending side. After this transmission, when a print start command for instructing the start of printing for the same image data is sent, the print start command receiving means receives the print start command, and the pre-feed command receiving means receives the pre-feed command. A first time measuring means for measuring a predetermined first time from, and a time point when the first time measuring means measures the first time or a time point when the print start command is received, whichever is earlier. The paper transport start control means for sending the paper from its supply source at, and the paper started to be transported by the paper transport start control means at a predetermined position before the printing position. A paper temporary conveyance stopping means for temporarily stopping, a second time measuring means for measuring another predetermined second time after the print start command receiving means receives the print start command, and the second time measuring means. An image forming apparatus comprising: a paper transport resuming means for releasing the transport stop of the paper temporary transport stop means and sending the paper to a printing position at the time when the clock means measures the second time. . 2. A pre-feed command receiving means for receiving a pre-feed command for instructing the start of sheet conveyance prior to image data transmission, and a pre-feed command sending side. A print start command receiving means for receiving a print start command for instructing the start of printing for the same image data after the sending, and a plurality of times prepared in advance before sending the image data. Selection information receiving means for receiving selection information for selecting one of the long first time candidates; first time selecting means for selecting the first time using this selection information; First time measuring means for measuring the first time selected by the first time selecting means after the pre-feed command receiving means receives the pre-feed command; and the first time measuring means for measuring the first time. A paper conveyance start control means for feeding the paper from its supply source at the earlier time of measuring the time of 1 or the time when the print start command is received, and the paper conveyance start control means starts the conveyance. A paper temporary conveyance stopping means for temporarily stopping the formed paper at a predetermined position before the printing position; and a second time for measuring a second time after the print start command receiving means receives the print start command. And a paper feed resuming means for releasing the paper feed stop of the paper temporary feed stop means and sending the paper to the printing position when the second time feed means measures the second time. An image forming apparatus comprising: 3. A pre-feed command receiving means for receiving a pre-feed command for instructing the start of sheet conveyance prior to the transmission of image data, and a pre-feed command sending side. After this transmission, when a print start command for instructing the start of printing for the same image data is sent, the print start command receiving means receives the print start command, and the print start command receiving means receives the print start command. A second time measuring means for measuring a second time from, and a third time as a time from the reception of the pre-feed command by the pre-feed command receiving means to the reception of the print start command for each image data. Based on the past time measured by the third time measuring means and the third time measuring means, and the pre-feed command receiving means receives the pre-feed command. A predicting means for predicting the time from the start of receiving the print start command, and based on the prediction result of the predicting means, the pre-feed command receiving means receives the pre-feed command and then feeds the paper from its supply source. A paper conveyance start control means for setting a timing for causing the paper conveyance, a paper temporary conveyance stop means for temporarily stopping the paper whose conveyance is started by the paper conveyance start control means at a predetermined position before the printing position, An image comprising: a paper transport resuming means for releasing the transport stop of the paper temporary transport stop means and sending the paper to the printing position when the second timing means measures the second time. Forming equipment.