JPH0764091B2 - Electrophotographic printer - Google Patents

Description

The present invention relates to an electrophotographic printer that develops a toner image on the surface of a photosensitive drum based on print data and transfers the toner image onto a medium.

[Conventional technology]

The electrophotographic printer receives data from the host device,
There is a control unit that processes received data and stores the data in a data buffer, and a printing unit that controls the printing process and performs printing.

FIG. 3 is a schematic side view showing a configuration example of a printing section of a conventional example of this type of electrophotographic printer.

In the figure, 1 is a photosensitive drum having a property of storing electric charges on the surface and releasing the electric charges by light irradiation, 2 is a charger for uniformly charging the photosensitive drum 1, and 3 is an arbitrary surface of the charged photosensitive drum 1. LED head for exposing an optical image of the photosensitive drum 1 to form an electrostatic latent image on the surface of the photosensitive drum 1, 4 is a developing unit for developing the electrostatic latent image from charged powder called toner, and 5 is a surface of the photosensitive drum 1. A transfer unit for transferring the developed toner image onto the printing paper, a fixing unit 7 for fixing the toner image transferred onto the paper to the paper, and a toner remaining on the surface of the photosensitive drum 1 even after the transfer onto the paper. , A cleaning unit for removing electric charges respectively, 8 is a neutralization unit, 9
Is a paper feed mechanism that conveys printing paper in accordance with the rotation of the photosensitive drum 1, and 10 is each of the above blocks including a sensor, a timer, a CPU,
A print control unit that controls a printing process using a memory or the like.

The operation of the electrophotographic printer will be described below.

When the control unit receives the data from the host device, the control unit edits the data according to the attribute of the data, and sequentially stores the character code in the data buffer in which the video data is expanded based on the character generator.

When one page of video data is available in the data buffer, the control unit instructs the printing unit to start printing.

The print control unit 10 receives this, rotates the photosensitive drum 1, and, by using the LED head 3 to the surface of the photosensitive drum 1 uniformly charged by the charger 2, the video in the data buffer of the control unit. Create an electrostatic latent image based on the data.

This electrostatic latent image is developed with toner using the developing device unit 4.

The transfer unit 5 transfers the toner image onto the printing paper running at the same speed as the photosensitive drum 1 by the paper feeding mechanism 9.

After that, the printing paper is fixed in the fixing unit 6 and the printing process is completed.

After the transfer of the photosensitive drum 1, the toner and the electric charge remaining on the surface of the photosensitive drum 1 are removed by the kunning unit 7 and the static elimination unit 8.

This printing operation is continuously performed by rotating the photosensitive drum 1.

By the way, in the cleaning unit 7, since the toner remaining on the photosensitive drum 1 is wiped off by the roller-shaped sponge, the surface of the photosensitive drum 1 is constantly in contact with the sponge.

Therefore, if the photosensitive drum 1 is continuously rotated for a long period of time, the surface of the photosensitive drum 1 is abraded due to friction. This abrasion disturbs the electrostatic latent image formed on the surface of the photosensitive drum 1 and adversely affects the print quality. The deterioration of the print quality due to the abrasion of the photosensitive drum 1 becomes the life of the photosensitive drum 1.

Therefore, in order to effectively utilize the life of the photosensitive drum 1, it is necessary to stop the photosensitive drum 1 except during printing.

However, if the rotation speed of the photosensitive drum 1 does not match the traveling speed of the paper, the image of the printed matter is distorted due to the difference in speed between the photosensitive drum 1 and the paper during transfer.

For this reason, printing cannot be performed unless the photosensitive drum 1 is stably rotated in accordance with the sheet traveling speed. Therefore, when performing printing from the stopped state of the photosensitive drum 1, the photosensitive drum 1
Requires a so-called start-up time until the target rotates at a desired speed.

Therefore, in the case of printing a number of sheets continuously, if the photosensitive drum 1 is stopped every time one sheet is printed, the throughput is lowered due to the startup time of the photosensitive drum 1.

However, if the photosensitive drum 1 is kept rotating, the life of the photosensitive drum 1 is wasted.

Therefore, in this conventional example, the fixed timer of the print control unit 10
After the page printing is completed, the photosensitive drum 1 is kept in a rotating state for a certain period of time, and if there is a print start command of the next page from the control unit within the time, the print is promptly performed and the print start command of the next page must be issued within the time. For example, control is performed to stop the photosensitive drum 1.

[Problems to be solved by the invention]

However, according to the conventional technique with the above configuration, when it takes time to receive the data of the next page from the host device, the control unit edits the data of one page while the photosensitive drum is driven,
Unfolding does not finish and the command to start printing cannot be issued.

For this reason, the photosensitive drum is stopped, printing of the next page needs to be restarted, and there is a problem that the throughput of printing of the next page is reduced.

In view of the above problems, the present invention solves the problem that even if there is unprocessed print data in the control unit, the photosensitive drum is stopped unless a command to start printing is received. After a lapse of time, the rotation of the photosensitive drum is stopped, and when the next page is printed, the photosensitive drum is continuously rotated and waits even after editing the print data, without shortening the life of the photosensitive drum. An object is to provide an electrophotographic printer having high printing throughput.

[Means for solving problems]

In order to achieve the above object, the present invention determines the presence or absence of print data for the next page in the control unit, and thereby determines whether to continue or stop driving the photosensitive drum.

That is, according to the present invention, a control unit that receives print data by a higher-level device, edits and expands the video data and stores the print data, and a toner image is developed on the surface of the photosensitive drum based on the video data stored in the control unit. Then, in an electrophotographic printer having a printing unit for transferring the toner image to a medium, a data buffer in the control unit is provided with a flag indicating the presence or absence of unprinted video data in the control unit,
The printing unit is provided with a variable timer that manages the passage of time after the completion of one printing operation and sends a signal to notify the control unit when a predetermined period of time has passed. In response to this, the control unit judges whether or not the flag is present. If there is no video data, the photosensitive drum is stopped, and if there is video data, an instruction to start printing the next page with the photosensitive drum being rotated. It is characterized by waiting for.

[Action]

With the above-described configuration, according to the present invention, when one printing is completed, the variable timer manages the elapsed time from the end, and when a predetermined fixed time elapses, a signal is transmitted to notify the control section, and the control section Upon reception of the signal, the control unit checks the flag indicating the presence or absence of unprinted video data,
If there is no video data, the photosensitive drum is stopped to prevent abrasion of the photosensitive drum. If there is video data, wait for a command to start printing of the next page while rotating the photosensitive drum, and then receive from the host device. Printing of the next page, which was delayed, can be started.

〔Example〕

 Embodiments will be described below with reference to the drawings.

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

Since the mechanical structure of the printing unit is the same as that of the device described with reference to FIG. 3, the description thereof will be omitted and the reference numerals will be used as they are.

In FIG. 1, 11 is a control unit, 12 is a main control unit that controls each block in the control unit 11, 13 is an interface control unit that controls an interface, and 14 is an editing / expanding device that edits / expands data. The expansion control units 15 and 16 are data buffers for accumulating video data for each page. By providing two data buffers in this way, this device can keep unused data buffers during printing of the first page. Using,
It is possible to receive data from a host device and develop / edit it.

Reference numerals 17 and 18 denote flags indicating the presence or absence of unprinted data in the data buffers 15 and 16, and reference numerals 19 and 20 denote switching control units for switching the data buffers 15 and 16.

Reference numeral 21 is a printing unit similar to the configuration shown in FIG. 3, and the printing unit 21 has a photosensitive drum 1, other printing mechanism unit 22, and a printing control unit 23.

Further, reference numeral 24 is a variable timer which sets a predetermined fixed print start waiting time at the end of one printing and sends a signal to the control unit 11 when the print start waiting time has elapsed.

The operation of this embodiment having the above configuration will be described.

When print data is sent from the host device, the interface control unit 13 receives the print data, and the edit / expansion control unit 14 converts the print data into video data.

This video data is stored in the data buffer 15 or 16 selected by the switching control unit 19, and the flag 17/18 of the data buffer selected at the same time indicates that unprinted data exists in the data buffer 15/16. Display the flag that indicates.

Hereinafter, it is assumed that the video data of the first page is stored in the data buffer 15.

As data is being received from the host device, the data buffer 15
When the video data for one page is completed, the main controller 12
Instructs the print control unit 23 to start printing.

Upon receiving this command, the print control unit 23 activates the photosensitive drum 1 and notifies the main control unit 12 of the printable state after the startup time has elapsed. After confirming this notification, the main control unit 12 switches the switching control unit 20 to the data buffer 15 side, sends data from the data buffer 15, and prints one page.

When the printing of one page is completed, the state of the flag 17 displays a flag indicating that there is no unprinted data in the data buffer 15.

FIG. 3 shows the print control unit 23 from the end of printing the first page to the printing of the next page in this embodiment.
It is a flowchart which shows the process of.

In the print control unit 23, the print start command from the main control unit 12 is processed as an interrupt. Therefore, after the printing of one page is completed, the print control unit 23 receives the print start command during any process. If any, printing will start immediately.

When the printing of one page is completed, the print control unit 23 sets a certain value in the variable timer 24 in S1. Then, while rotating the photosensitive drum 1, the timer value is decreased by "1" in S2, and the processing of S2 is repeated until the timer value becomes "0" in S3.

When the timer value becomes "0", the main control unit 12 is notified in S4 that the timer value has become "0". This notification means that the print control unit 23 continued to wait for a command to start printing with the photosensitive drum 1 kept rotating for a certain period of time, but there was no command within the time.

The print control unit 23, which has issued the notification in S4, waits for a response from the main control unit 12 in S5.

The main control unit 12 that has received the notification determines whether or not there is unprinted video data for the next page in each of the data buffers 15 and 14. As described above, the presence / absence of data in the data buffers 15 and 16 is displayed in the flags 17 and 18, so the main control unit 12
Refers to the flags 17 and 18, determines the presence or absence of data, and notifies the print control unit 23 of it.

The print control unit 23, which has received the notification from the main control unit 12, proceeds to S1 if there is unprinted data in S5 and S7 if there is no print data.
Proceed to. If you proceed to S1, the timer is set again,
While continuing to rotate the photosensitive drum 1, the printing of the next page is kept waiting.

When the process proceeds to S7, the print control unit 23 stops the photosensitive drum 1 and waits for printing of the next page.

Now, when the print control unit 23 finishes printing the first page,
A certain value is given to the variable timer 24, and during this time the photosensitive drum 1
It waits for an instruction to start printing of the next page from the main control unit 12 while rotating. If there is an instruction to start printing within the time, printing is promptly performed, but if there is no instruction within the time, the fact is notified to the main control unit 12. Upon receiving this notification, the main control unit 12 refers to the flags 17 and 18, determines whether or not there is video data for the next page in each of the data buffers 15 and 16, and notifies the print control unit 23 of it.

Upon receiving this, the print control unit 23 stops the photosensitive drum 1 when there is no data. But if you have the data,
The variable timer 24 is reset, and the photosensitive drum 1 is kept rotating to wait for a command to start printing the next page.

〔The invention's effect〕

As described in detail above, according to the present invention, a control unit that receives print data by a host device, edits and expands the video data, and stores the print data; and a photosensitive drum based on the video data stored in the control unit. Develop a toner image on the surface of
In an electrophotographic printer having a printing unit for transferring the toner image to a medium, a buffer indicating the presence / absence of unprinted video data in the control unit is provided in a buffer in the control unit, and one printing is performed in the printing unit. A variable timer that manages the passage of time after completion and sends a signal to notify the control unit when a predetermined fixed time has passed, and sends a signal when the fixed time has passed by the variable timer, receives this Since the control unit judges the presence or absence of the flag, if there is no video data, the photosensitive drum is stopped, and if there is video data, the photosensitive drum is rotated and waits for a command to start printing of the next page. The presence / absence of print data for the next page in the control unit is determined, and it is possible to determine whether to continue or stop driving the photosensitive drum.

This makes it possible to stop the rotation of the photosensitive drum after a certain period of time when there is no printing of the next page, and to continue waiting for the rotation of the photosensitive drum even when the editing of print data is delayed when there is printing of the next page. Therefore, it is possible to provide an electrophotographic printer having high printing throughput without shortening the life of the photosensitive drum.

[Brief description of drawings]

FIG. 1 is a block diagram showing a control configuration of an embodiment of the present invention, FIG. 2 is a flow chart showing an operation of a main part of the embodiment, and FIG. 3 is a schematic side view showing a mechanism of a printing unit of a conventional example. is there. 1 ... Photosensitive drum, 11 ... Control unit, 12 ... Main control unit, 13
...... Interface control unit, 14 ...... Editing / expansion control unit, 15,16 ...... Data buffer, 17,18 ...... Flag, 21 ...
... Printing unit, 22 ... Printing mechanism unit, 23 ... Printing control unit, 24 ...
… Variable timer

Claims (1)

[Claims] 1. A control unit which is connected to a higher-level device via an interface, receives print data from the higher-level device, edits / decompresses the video data, and stores the video data, based on the video data stored in the control unit. In an electrophotographic printer that has a printing unit that develops a toner image on the surface of the photosensitive drum and transfers the toner image to a medium, a flag indicating the presence or absence of unprinted video data is provided in the control unit, and one printing is completed. A variable timer is provided for managing the subsequent passage of time and transmitting a signal when a predetermined fixed time has passed and notifying the control unit of this. Part determines the presence or absence of the flag,
An electrophotographic printer characterized in that if there is no video data, the photosensitive drum is stopped, and if there is video data, the photosensitive drum is rotated and waits for a command to start printing the next page.