JPH0619255A - Printer - Google Patents

Abstract

(57) [Summary] [Structure] First-side printing, second-side printing in double-sided printing,
The operation duration of the photosensitive drum, the fixing roller 55, and the scanner motor 15 after printing is changed according to each printing mode such as single-sided printing. [Effect] Especially, in double-sided printing, by setting the operation continuation time after printing on the first side to be long, the start-up time at the time of printing on the second side is shortened, thereby shortening the life of the apparatus and increasing the power consumption. Throughput can be improved without incurring such problems.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing device which is preferably implemented when it has a double-sided printing function.

[0002]

2. Description of the Related Art Conventionally, in a printing apparatus having an electrophotographic double-sided printing function, regardless of single-sided printing or double-sided printing, various functions related to the printing process are operated only during a printing operation in order to extend the life of the apparatus and reduce power consumption. (Hereinafter, this state is referred to as a printing state.) When the printing operation is not performed, it is stopped, or the load is maintained at a level lower than that during the printing operation (hereinafter, this state is referred to as a standby state).

[0003]

However, in the above-mentioned conventional example, since the printer is in the standby state even after the printing operation for the first side of the double-sided printing is completed, the following problems occur.

That is, when the printing operation for the second side is performed, each printing process condition is reset to the printing state. Therefore, if there is a device that takes time to start up, the start of the printing operation on the second side is delayed by that amount.

In order to avoid such a problem, before the printing operation for the first side is completed, that is, while each printing function is operating in the printing state, the operator, the external device, etc.
The preparation for printing the first side (for example, setting the original in the case of a copying machine, developing the image data in the case of a printer) must be completed and a print start instruction must be input, which imposes an excessive burden on the operator and external equipment. It will be.

An object of the present invention is to solve such problems, perform double-sided printing at high speed without increasing power consumption and shortening the life of the apparatus, and without imposing an excessive burden on the operator and external equipment. It is an object of the present invention to provide a printing device that can perform printing.

[0007]

According to the present invention, in a printing apparatus having a double-sided printing function, printing on only one side, printing on the first side of double-sided printing, printing on the second side of double-sided printing. By having a print control means for changing the operation duration time at the end of image formation in such a print mode, the next print start instruction can be input immediately after the print operation for the first side of double-sided printing is completed. If it is expected, by continuing the operation state at the end of printing, you can immediately enter the next printing operation at the same time as inputting the printing instruction, such as printing on only one side or printing on the second side of double-sided printing. If it is uncertain whether or not the next print instruction will be input immediately, by immediately shifting to the standby state, it is possible to eliminate increase in power consumption due to useless driving and reduction in device life. Those were.

[0008]

【Example】

(Embodiment 1) Embodiment 1 of the present invention will be described below with reference to the accompanying drawings.

FIG. 2 is a sectional view of the laser beam printer 1.

As shown in FIG. 2, the laser beam printer 1 has an upper cassette 49u, and is provided with a pickup roller 50u for taking out recording paper from the upper cassette 49u and a feed roller 51u for sending out the taken out paper. The laser beam printer 1 also has a lower cassette sheet feeding mechanism including a lower cassette 49l, a pickup roller 50l, and a feed roller 51l, which has a mechanism similar to this upper cassette sheet feeding mechanism. A registration roller pair 53 that conveys the recording paper in synchronism with the image formation in the image forming unit 54, which will be described later, is disposed downstream of the feed rollers 51u and 51l. A pre-registration sensor 32 for detecting is provided. Further, on the downstream side of the registration roller pair 53, an image forming unit 5 that forms an image by laser light from the laser unit 52.
4 are provided. Further, a fixing roller 55 is provided downstream of the image forming section 54, and a fixing paper discharge sensor 34 is provided immediately after the fixing roller 55.

A conveying roller 56 is arranged downstream of the sensor 34, and a double-sided flapper 57 is arranged immediately after it. The double-sided flapper 57 is a flapper that sorts the recording paper into a double-sided conveyance mechanism and a conveyance path to the sheet discharge port, which will be described later. The recording paper is the double-sided flapper solenoid 2.
When 8 is pulled, it is sent to the double-sided transport mechanism side, and when it is returned, it is sent to the paper exit side. A conveying roller 58 is arranged downstream of the sheet discharge side conveying path of the double-sided flapper 57, and a FU (face-up) flapper 59 is arranged downstream of the roller 58. The FU flapper 59 is a flapper that sorts the recording paper into a conveyance path to the two ejection openings, the FD (face down) ejection opening 61 and the FU ejection opening 63. When the FU flapper solenoid 30 is pulled, the recording paper is pulled out. When it is returned to the FU side, it is ejected to the FD side. An FD paper ejection port 61 is provided downstream of the flapper 59 on the FD side, and a paper ejection roller 60 and a paper ejection port sensor 36 are arranged in the FD paper ejection port 61 to eject recording paper to an FD tray 62. It is like this.

The double-sided transport mechanism 4 is a mechanism for reversing the recording paper on one side of which is printed for double-sided printing and feeding it again to the registration roller pair 53.
5, double-sided sensor 42, reversing roller 66, re-feeding roller 6
8 and a re-feed sensor 40. First, double-sided rollers 64 and 65 are arranged downstream of the double-sided flapper 57, and a double-sided sensor 42 for detecting the presence / absence of paper is arranged between the double-sided rollers 64 and 65. Further, a reversing roller 66 is arranged downstream of the double-sided roller 42.

On the other hand, the control configuration of the laser beam printer 1 is shown in FIG. The laser beam printer 1 includes a main controller 5, and the main controller 5 is connected to an external device 3 via an external device interface 2. The main control unit 5 has a microprocessor for controlling the entire apparatus, a ROM storing a control program, and an R storing data.
A printing control unit 6 configured by an AM, a gate element, and the like, which functionally controls printing of an image on a sheet, and a sheet of paper that stores various kinds of information regarding sheet conveyance (sheet feed port, destination, conveyance state, etc.) The transport information storage unit 9 and the external device communication unit 10 that controls communication with the external device 3 are included.
The print control unit 6 includes a paper transport control unit 7 that controls the transport of paper and a print process control unit 8 that controls the print process.
It consists of

The main control section 5 includes a main motor 1 for driving each paper transport mechanism downstream of the pair of registration rollers 53.
1 is a main motor control circuit 12, the laser unit 1
3 is a laser light amount control circuit 14, a high voltage unit 15 for outputting various high voltages related to image formation of the image forming section 54 is a high voltage output control circuit 16, a scanner motor 17 is a scanner motor control circuit 18, and a fixing unit 19 is a fixing heater control. The circuit 20, the pickup rollers 49u and 49l, and the paper feed motor 21 that drives the feed rollers 51u and 51l are connected via a paper feed motor control circuit 22.

Further, the sensors 32, 34 and 36 for the pre-registration, fixed sheet discharge and sheet discharge ports are connected to the main control section 5 through input circuits 31, 33 and 35, respectively, and the pickup roller 17u. , A pickup mechanism 24 for turning on and off the drive of a cam mechanism (not shown) for moving up and down 17l, a driver 23, a registration roller solenoid 26 for turning on and off the drive to the registration roller pair 53, a driver 25, and the double-sided flapper. The double-sided flapper solenoid 28 for turning ON / OFF the drive of 57 turns ON / OFF the drive of the driver 27 and the FU flapper 59.
FU flapper solenoids 30 are connected to each other via a driver 29.

Also in each part of the double-sided transport mechanism 4, a reversing motor 47 for driving a reversing roller 66 is provided with a reversing motor control circuit 46, refeeding and double-sided sensors 40, 42.
The input circuits 39 and 41, and the re-feed roller solenoid 38 that turns on / off the drive of the re-feed roller 68. The re-feed roller solenoid 38 turns on the drive of the driver 37 and the double-sided rollers 64 and 65.
Double-sided roller clutches 45 that perform F are connected to each other via a driver 43.

The main motor control circuit 12 includes a main controller 5
When the main motor drive signal is received from the main motor 11
Is controlled to rotate at a predetermined speed, and the main motor 1
When 1 reaches a predetermined rotation speed, a main motor ready signal is sent to the main controller 5.

Similarly, when the scanner motor control circuit 18 receives a scanner motor drive signal from the main control section 5, it controls the scanner motor 17 to rotate at a predetermined speed, and the scanner motor 17 reaches a predetermined rotation speed. At that time, a scanner motor ready signal is sent to the main control unit 5.

When the paper feed motor control circuit 22 receives the paper feed motor drive signal from the main control unit 5, the paper feed motor control circuit 22 drives the paper feed motor 21 at a predetermined rotation speed and sends a main paper drive motor driving signal to the main control unit 5. .

The reversing motor control circuit 46, upon receiving the reversing roller drive signal from the main control section 5, controls the reversing motor 47 so that the reversing roller 66 operates once for normal rotation and three times for reverse rotation as described later. During driving of the reversing roller, a driving signal is sent to the main controller 5.

When the laser light quantity control circuit 14 receives the laser light quantity adjustment signal from the main control section 5, the laser light quantity control circuit 14 controls the laser unit 13 by a known procedure to perform the laser light quantity adjustment APC.
Adjustment is made so as to output a predetermined amount of laser light. During the light amount adjustment, a light amount adjusting signal is sent to the main control unit 5.

When the high voltage output control circuit 16 receives an output signal relating to each high voltage from the main control section 5, the high voltage output control circuit 16 raises the corresponding high voltage. As for the transfer high voltage, a high voltage of the type instructed by the main controller 5 is output. The types of transfer high voltage referred to here are a print bias output during image formation, a sheet-to-sheet bias output between paper sheets during continuous printing, a reverse bias output when the main motor is idle, and the like. . Further, when a transfer high voltage adjustment request is received from the main control unit 5, the transfer high voltage output adjustment ATVC is performed by a known procedure to adjust the values of the print bias and the inter-sheet bias. During the transfer high voltage adjustment, a transfer high voltage adjusting signal is sent to the main control unit 5, and after the adjustment is completed, the output of the transfer high voltage is set to the inter-sheet bias.

The fixing heater control circuit 20 controls the fixing device temperature of the fixing device unit 19 to a value designated by the main controller 5 and sends a feedback value of the fixing device temperature to the main controller 5.

Further, the interface 2 has an RDY signal for informing the external device 3 that the main control unit 5 is ready to print, and a PRNT signal for instructing the main control unit 5 to start printing by the external device 3, The main control unit 5 requests the external device 3 to output a vertical direction (sub scanning direction) synchronization signal VSYNC for image output, a vertical direction (sub scanning direction) synchronization signal VSYNC for image output, and main control The horizontal direction (main scanning direction) synchronization signal BD of the image output that the unit 5 outputs to the external device 3 and the external device 3 are
An image signal VDO for serially transmitting a dot image is transmitted in synchronization with the VSYNC signal and the BD signal, and has a handshake type serial communication line, and the external device 3 is connected by the serial communication line. Transmits various commands (designation of paper feed port, designation of destination, etc.) to the main control unit 5, and the main control unit 5 transmits various information (fault information, etc.) to the external device 3 regarding the state of the laser beam printer 1. Can be told.

Reference numeral 48 in the drawing is a low voltage power supply unit for converting a commercial AC voltage into a predetermined DC voltage.

With the above-mentioned configuration, the laser beam printer 1 is provided with a print instruction (PRNT signal tr) from the external device 3.
ue), each process system is started up, and recording paper is fed from a predetermined paper feed port to perform printing.

FIG. 6 shows a flow chart of the printing process control means 8 of the conventional laser beam printer 1.

Wait until the laser beam printer 1 receives a print instruction (PRNT signal true) from the external device 3 (S
301), the print process control means 8 upon receiving the print instruction
Proceeds from S301 to S302 and the main motor control circuit 1
2 outputs the main motor drive signal, the scanner motor drive circuit 14 outputs the scanner motor drive signal, sets the fixing heater control circuit 20 to the fixing device control temperature at the printing temperature, and starts the respective startups. To do.

Further, in step S303, a high voltage output control circuit 16 is instructed to transfer high voltage (ATVC), and in step S304 a laser light amount adjustment (APC) instruction is issued to the laser unit control circuit 14 to start each adjustment. Establish the above process conditions. Then, in S305, the high voltage output control circuit 16
The start of each high voltage other than the transfer high voltage, and S3
At 06, the process waits until each process condition becomes ready. That is, after waiting for the high voltage rise time, the ready signals are returned from each control circuit for the main motor and scanner motor, the adjusting signal from each control circuit for the laser light amount and transfer high voltage becomes false, and the fixing device temperature is controlled. When the temperature monitor value from the circuit reaches the printing temperature, the process proceeds to S307. In step S307, the paper conveyance control unit 7 is notified of the print start permission. In step S308, the process waits until the paper conveyance control unit 7 notifies that the print conveyance is in progress. When the print start is notified in S308, the high voltage output control circuit 1 is sent in S309.
6 is instructed to set the transfer high-voltage print bias. Thereafter, in S310, the printing state is continued while the paper conveyance control unit 7 informs that printing is in progress. When the end of printing is notified in S310, each high voltage is stopped in S311 (the transfer high voltage is set to the inter-paper bias), and the process waits until the paper transfer control unit 7 notifies the end of paper transfer in S312. Meanwhile, PR in S314
If the NT signal becomes true and the next printing is started, S305
Return to high-voltage startup. When the paper conveyance control means 7 notifies the end of the paper conveyance in S312, the scanner motor and the main motor are stopped in S313, the fixing device is lowered to the standby temperature, the transfer high voltage is set to the stop bias, and the process returns to S301.

FIG. 4 shows a flow chart of paper feed control of the paper feed control means 7, and FIG. 5 shows a flow chart of print feed control.

First, in the paper feed / conveyance control of FIG.
Then, the external device 3 waits until the print signal is set to true, and when the print signal becomes true, the process waits in S102 until a sufficient space is obtained between the sheet and the sheet being previously conveyed. S102
If it is time to make a sufficient space between the previous sheet and
In step 103, the paper feed information storage unit 9 stores the paper feed port and the destination designated by the external device at that time as the information of the paper to be fed, and then the information of the paper being fed is transferred to the external device in S104. In step S105, the above-described paper feed mechanisms are controlled to feed the recording paper from the designated paper feed port. When the recording sheet is conveyed to the registration roller pair 53, VSREQ is set to true in S106, and S10 is set.
Wait until VSYNC becomes true at 7. When VSYNC is set to true from an external device, VSREQ is set in S108.
Set false and return to S101.

In the print conveyance of FIG. 5, first, in S201
Wait until the external device sets VSYNC to true
When YNC becomes true, the registration roller 53 is driven at a predetermined timing in S202, and printing of the recording paper fed to the registration roller is started by the paper feed / conveyance control. S20
In 3, printing is performed according to a known process. During this time, the printing process control means 8 continues to be informed of printing. S2
In 04, the destination is checked by the paper conveyance information of the recording paper, and if the destination is the FD or FU discharge port, S205
On the other hand, if the double-sided printing is designated, the process proceeds to S206. In step S205, the paper discharge port (FD) specified by the FU flapper 59 is specified.
Or, after allocating the recording paper to the FU paper exit) and discharging it, S
Proceed to 207. Further, in S206, the double-sided unit 4 is controlled, the recording paper printed on one side is reversed, the paper is re-fed to the registration roller pair 53, and then the process proceeds to S207. After notifying the print process control means 8 of the end of paper conveyance in S207, S2
Return to 01.

When printing is performed using the laser beam printer 1, the external device 3 must set the PRNT signal to true after the development of the image data of the page is completed. Because the PRNT signal true causes the laser beam printer 1 to start up each drive system and the registration roller 53.
If the external device 3 has not prepared image data at the time when the paper feeding is completed, VSREQ
Even if the signal becomes true, the external device 3 tr
I can't ue. During this time, the laser beam printer 1 continues to idle each drive system, which adversely affects the life of each drive system, particularly the life of the photosensitive drum.

Therefore, when the external device 3 prints on both sides of one sheet of recording paper of the upper cassette and discharges it to the FD discharge port, if the image development on the first surface is completed, the upper stage is first sent through the serial communication I / F. Laser beam printer 1 with PRNT signal set to true after cassette feeding and double-sided designation
Waits for the VSREQ signal to go true. VSREQ
When the signal becomes true, the VSYNC signal is set to true, and the image signal is output from the VDO signal line at a predetermined timing to print the image on the first surface. Under the control described above, the laser beam printer 1 reverses the recording sheet by the duplex unit and re-feeds it to the registration roller 53. If the external device 3 has only the image data storage area for one surface, the external device 3 outputs the image data for the first surface,
When the image data for the second side is ready, serial communication I
After the double-sided paper feed and the FD discharge port designation are specified through / F, the image on the second side is printed by the same control as the first side.

According to the conventional print process control as shown in FIG. 6, each drive system is stopped and the standby state is entered as soon as the paper conveyance is completed in S312 regardless of the print mode. However, in such control, it takes time for the external device 3 to develop the image on the second side of double-sided printing, and when the re-feeding of the recording paper on which the printing on the first side is completed is completed, a print start instruction for the second side is issued. If it is not performed (PRNT signal is not true), the state immediately shifts to the standby state. Therefore, when a print start instruction for the second side is issued, each print process condition must be raised again.

When the external device carries out double-sided printing, there should normally be an image on the second side that is paired with an image on the first side. As described above, image formation is completed when the re-feeding is completed. In most cases, the printing start command for the second side is issued after waiting for a while even if the printing has not ended. In such a case, even if each drive system is continuously driven until the PRNT signal becomes true, there is almost no effect on the life of each drive system in consideration of the time for stopping and then restarting. It can be said that there is no.

Therefore, in the present invention, the control of the print process control means 8 after the completion of the paper conveyance is changed according to the print mode as described below.

FIG. 3 is a flow chart showing the control of the printing process control means 8 of the laser beam printer 1 embodying the present invention. S001 to S011 are the same as S301 to S311 of the conventional control of FIG. 6, and if the paper conveyance is not completed in S012, the process proceeds to S014 to wait for the completion of the paper conveyance while monitoring the PRNT signal. 6 is the same as the conventional control S312, S314 of
When the end of the paper conveyance is notified from the paper conveyance control unit 7 in S012, it is determined in S013 from the paper conveyance information whether the paper is in the re-feeding state or ejected outside the machine, and in the re-feeding state, it is waiting. If so, the process proceeds to S015 and waits until the PRNT signal becomes true. That is, in the case of the re-feeding state, the drive of each drive system is continued even after the paper conveyance is completed. On the other hand, if the sheet is not in the re-feeding state in S013 (if it is discharged to the FD or FU sheet discharge port), the process proceeds to S014, and after stopping each drive system, S0 is performed.
Return to 01.

With the control as described above, in the case of double-sided printing, even if the external device takes time to develop the image on the second side, the drive system is not stopped and the second side is printed immediately when the PRNT signal becomes true. You will be able to start.

(Embodiment 2) In the embodiment 1, when performing double-sided printing,
In the case of re-feeding, the drive system continues to drive forever until the external device issues a print start instruction for the second side, but if for some reason the external device does not immediately issue a print start instruction for the second side. , The drive system continues to rotate idly, which adversely affects the service life. Therefore, in such a case, in order to protect the device in such a case, it is necessary to continue the drive of each drive system for a certain period of time after the completion of refeeding, and control each drive system to stop if a print start instruction is not issued during that time. You can also

FIG. 7 shows a block diagram of the control configuration of the second embodiment. Although the configuration is substantially the same as that of the first embodiment (FIG. 1), a drive continuation control means 49 is newly added in the print control means 6. In the present embodiment, the paper conveyance control means 7 is the same as the first embodiment.
The same control as shown in FIGS. 4 and 5 is performed.

Here, the drive continuation control means 49 changes the drive continuation of each drive system after the end of paper conveyance according to the print mode. FIG. 8 shows a flowchart of the control of the drive continuation control means 49. In step S401, the process waits until the paper conveyance control unit 7 notifies the end of paper conveyance. If the end of the paper conveyance is notified, the process proceeds to S402, it is determined whether the recording paper is ejected to the FD or FU or is in the re-feeding state based on the paper conveyance information,
If it is discharged to the outside of the machine, the process proceeds to S404, and the print process control means is instructed to end the driving. On the other hand, if the sheet is in the re-feeding state, the process proceeds to S403 and waits for a predetermined time while continuously instructing the printing process control unit to continue driving. The waiting time here is set to an optimum value in consideration of the image development ability of the external device and the life of each drive system. After that, the process proceeds to S404, and the print process control unit is instructed to end the driving.

The printing process control means 8 performs the control shown in the flowchart of FIG. Steps S501 to S512 are the same as steps S001 to S012 in FIG. 3 in the first embodiment, but in step S513, the drive continuation information from the drive continuation control unit is monitored. If the drive continuation control means instructs the drive continuation in S513, the process proceeds to S515 to continue the drive of each drive system. During this time, the PRNT signal is true
If so, the process advances to step S505 to continue printing. If the end of driving is instructed in S513, the process proceeds to S514 and after stopping each drive system, the process returns to S501.

By the control as described above, during normal double-sided printing, double-sided printing can be continuously performed even if it takes time for the external device to develop an image, and for some reason, the external device issues a printing instruction for the second side. If not present, it is possible to prevent the drive system from stopping in a predetermined time and adversely affecting the life of the device.

(Third Embodiment) In the first and second embodiments, the driving of each drive system is always continued in the re-feeding state. However, when the life of the apparatus is important, the paper is conveyed. It is advantageous to stop each drive system in the state in which is completed. If the print image is simple for the external device and the image development is completed before the re-feeding is completed, the above function is not necessary. Takes a considerable amount of time from the completion of image development to the end of image development, and it is meaningless to continue driving each drive system, and even if the disadvantage to the life of the device is rather large, the above function is not necessary Is. The above-described function is most effective in the case of double-sided printing in which the image development of the second side of the external device cannot be completed in time by the completion of re-feeding.

Therefore, as a third embodiment, means for selecting and instructing to continue driving the drive system from an external device is provided, and more effective control can be performed by the instruction.

Although the device configuration is the same as that of the second embodiment (FIG. 7), a drive continuation instruction command and a drive continuation cancellation command are provided in the command from the external device 3 for serial communication to the laser beam printer 1. Further, an area for drive continuation instruction information is provided in the paper transport information storage means 9.

When receiving the drive continuation instruction command from the external device 3, the external device communication means 10 sets the drive continuation instruction in the paper conveyance information storage means 9, and when the drive continuation instruction command is received, the external device communication means 10 operates. Cancel the drive continuation instruction.

FIG. 10 shows a flow chart of the control of the drive continuation control means 49 in the third embodiment. S601, S6
02 is the same as S401 and S402 in FIG. 8 in the second embodiment, but if the sheet is in the re-feeding state in S602, S6
In step 03, the drive continuation instruction information in the paper conveyance information 9 is checked. If the drive continuation instruction is not set, the flow advances to step S605 to instruct the print process control means 8 to end the drive. On the other hand, if the drive continuation instruction is not set, the process proceeds to S604 and waits for a predetermined time as in S403 of FIG. 8 in the second embodiment, and continues to instruct the print process control unit 8 to continue the drive.

The control of the printing process control means 8 in this case is the same as that of FIG. 9 in the second embodiment.

By the above control, the external device 3 can select continuation of driving at the time of re-feeding according to the image data of the second side.

[0052]

As described above, by changing the operation continuation time at the end of image formation according to the print mode in a printing apparatus having a double-sided printing function, double-sided printing can be performed without sacrificing the life of the apparatus. Throughput can be improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing a control configuration of the present invention.

FIG. 2 is a cross-sectional view of a laser beam printer embodying the present invention.

FIG. 3 is a flowchart showing control of print process control means in the first embodiment.

FIG. 4 is a flowchart illustrating sheet feeding / conveying control according to the first embodiment.

FIG. 5 is a flowchart showing print conveyance control according to the first embodiment.

FIG. 6 is a flowchart showing control of a conventional print process control means.

FIG. 7 is a block diagram showing a control configuration of the second embodiment.

FIG. 8 is a flowchart showing control of drive continuation control means 49 in the second embodiment.

FIG. 9 is a flowchart showing the control of the print process control means in the second embodiment.

FIG. 10 is a flowchart showing control of drive continuation control means 49 in the third embodiment.

[Explanation of symbols]

 1 Laser Beam Printer 2 External Device Interface 3 External Device 6 Print Control Means 7 Paper Conveyance Control Means 8 Printing Process Control Means 9 Paper Conveyance Information Storage Means 10 External Equipment Communication Means

Claims (4)

[Claims] 1. A printing unit for printing on a sheet material, a unit for designating a printing mode in the printing unit, and when a print start instruction is input, image formation is completed according to the printing mode designated by the designating unit. And a print control unit for changing the duration of the preparatory operation in the print unit afterwards. 2. The printing apparatus according to claim 1, wherein the printing unit is capable of double-sided printing, and the printing control unit is designated by the designation unit to designate a printing mode for printing on the first side of double-sided printing. In this case, after the printing operation on the first side is completed, the printing device is kept in the preparatory operation state at the end of image formation until an instruction to print on the second side is issued. 3. The printing apparatus according to claim 1, wherein the printing unit is capable of double-sided printing, and the printing control unit is designated by the designation unit to designate a printing mode for printing on the first side of double-sided printing. In this case, the printing apparatus is controlled such that after the printing operation on the first side is completed, the preparation operation state is maintained for a longer duration than other printing modes. 4. The printing apparatus according to claim 1, further comprising means for selecting and instructing whether the duration of the preparatory operation after the image formation is changed according to the print mode or is constant regardless of the print mode. Characteristic printing device.