JP2775767B2 - Printing device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a printing device such as a liquid crystal printer, an LED printer, a laser beam printer, and the like.

[Conventional technology]

2. Description of the Related Art In a printing apparatus that prints on a sheet according to print data output from an external device such as a liquid crystal printer or an LED printer, an image is created on the sheet as follows.

B) First, when print data is output from an external device such as a host computer, the printing device temporarily writes the print data into a reception buffer, and then sequentially reads out the print data from the reception buffer to read pattern data corresponding to the print data. And store it in the image memory.

B) When pattern data for one page of paper is stored in the image memory, an instruction to carry out the paper stored in the paper cassette is issued, and the paper is carried into the printing device.

C) Thereafter, the paper conveyed into the printing apparatus is temporarily stopped by the standby roll, and at the same time, the pattern data is sent from the image memory to the print head to start forming an image on the photosensitive drum.

D) The sheet once stopped by the standby roll is re-fed at the timing of printing the image (electrostatic latent image) on the photosensitive drum at a predetermined position on the sheet, and forms an image on the sheet.

E) Further, when the same image is printed on a plurality of sheets (hereinafter, referred to as copy printing processing), the next sheet is carried out from the sheet cassette, and the pattern data stored in the image memory is copied in the same manner as described above. Perform processing to print on the next paper.

[Problems of the prior art]

However, in the above-described printing apparatus, after the processing shown in (a), that is, the processing of once writing the print data into the receiving buffer, then converting the print data into pattern data and writing the one-page pattern data into the image memory, is completed. First, the processing of (b), that is, the processing of instructing the paper to be carried out to the paper cassette and carrying the paper into the printing apparatus is executed. Therefore, it takes time until the paper is carried into the printing apparatus, and the printing process on the first paper cannot be performed at high speed.

When performing the copy printing process, as described in the above process (e), after the printing process on the previous sheet (preceding sheet) is completed, the next sheet (subsequent sheet) is set in the printing apparatus. Carry in. Accordingly, the start of the printing process on the next sheet is delayed, and the printing process on the succeeding sheet requires a long time as described above, and the printing process cannot be performed at high speed.

[Object of the invention]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described conventional drawbacks, and has as its object to provide a printing apparatus capable of performing printing processing at high speed.

[Gist of the invention]

In order to achieve the above object, the present invention provides a receiving buffer for temporarily storing print data received from an external device, a developing means for developing print data input to the receiving buffer into image data to be printed, An image memory for storing image data stored therein, and printing means for performing print output on paper conveyed from a paper storage unit by a paper supply unit based on the data stored in the image memory. Trailing edge detecting means disposed downstream of the leading edge of the paper stored in the paper transport path by a predetermined distance in the paper transport path and detecting that the trailing edge of the paper has passed, the receiving buffer, the image memory, and the The data to be printed in any of the data processing steps, and the trailing edge detection sensor detects the presence of paper on the sensor. And paper feed start control means for controlling the start of the paper feed operation by the paper feed means, wherein the interval between the trailing edge of the preceding paper and the leading edge of the succeeding paper during continuous printing is maintained substantially at the predetermined distance. The paper is continuously fed.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 2 is a configuration diagram of a printing apparatus according to one embodiment. In FIG. 1, the printing apparatus includes an image forming section 1 for forming a toner image on a sheet, and a transport mechanism 3 for transporting the sheet P from a sheet cassette 2 and transporting the sheet P into the printing apparatus.

The image forming section 1 includes a photosensitive drum 4, a charger 5, a print head 6, a developing device 7, and a transfer device 8 which are sequentially arranged near the peripheral surface of the photosensitive drum 4. Charger 5 is indicated by arrow A
The print head 6 is a device that applies an initial charging voltage to the photosensitive surface of the photosensitive drum 4 that rotates in the direction. The print head 6 is a device that exposes the photosensitive surface based on print data. The electrostatic latent image formed on the surface is converted into a toner image, and the transfer unit 8 is a device that transfers the toner image to a sheet P conveyed in the direction of arrow B.

The transport mechanism 3 rotates the paper feed roller 9 to rotate the paper cassette 2.
It comprises a standby roll 10 for transporting the paper carried out of the printer, a fixing roll 11, a transport roll (not shown), a transport guide plate (not shown) for forming a paper transport path 12, and the like.

The standby roll 10 is a roll that temporarily stops the conveyance of the sheet by bringing the leading end of the sheet into contact with the sheet, rotates the sheet P at a predetermined timing described later, and conveys the sheet P between the photosensitive drum 4 and the transfer unit 8. Fixing roll 11 is transferred to paper P by transfer device 8
A roll that fixes the unfixed toner transferred thereon to the paper P and conveys the paper P to the paper discharge unit 13. Also,
A paper trailing edge detection sensor 14 for detecting the passage of the trailing edge of the paper is provided in the paper transport path 12 between the paper cassette 2 and the standby roll 10, and detects that the leading edge of the paper abuts on the standby roll 10. The standby switch 15 is provided below the standby roll 10.

A control circuit having a block configuration shown in FIG. 1 is provided on a substrate (not shown) in the printing apparatus having the above-described mechanism configuration. However, a host computer 17 shown in the figure is an external device that outputs print data to a printing device. The circuit inside the printing device consists of the interface control unit 18 and the printing unit.
It is composed of 19.

The interface control unit 18 is a circuit that controls the conversion of the character code output from the host computer 17 into pattern data (image data), a CPU (central processing unit) 20, a host interface (hereinafter, referred to as host I / F) 21 , A ROM 22, a RAM 23, a reception buffer 24, an image data generator 25, and an image memory 26.

The printing unit 19 is a circuit that controls output of pattern data when actually printing on paper, conveyance of the paper P, and operation control of each unit constituting the above-described image forming unit 1. , And a printer controller 27. The print unit 19 and the above-described interface control unit 18 are connected by a PR interface 28. The host computer 17 is a circuit that outputs a character code and print control data to the host I / F 21.

The CPU 20 controls each unit according to a program stored in the ROM 22.

The image data generating unit 25 stores character pattern data corresponding to the character code. When the character code once stored in the receiving buffer 24 is read out to the image data generating unit 25 under the control of the CPU 20, the corresponding character pattern is read. This circuit outputs data to the image memory 26. The image memory 26 is a memory for storing pattern data for one page or a plurality of pages. The print head 6 drives a printing element such as a liquid crystal shutter or an LED (not shown) in accordance with the pattern data to expose the photosensitive surface as described above.

The printer controller 27 transmits and receives control data to and from the CPU 20 described above, controls the rotation of the feed roller 9 and the standby roll 10, and controls the charging device 5, the developing device 7, the transfer device 8, and the fixing roll.
This is a circuit for performing drive control such as eleven.

In the printing apparatus having the above-described configuration, an operation of printing on a sheet will be described with reference to the flowcharts of FIGS.

3A shows the processing on the interface control unit 18 side, and the flowchart in FIG. 3B shows the processing on the printing unit 19 side.

First, the CPU 20 in the interface control unit 18
Monitors whether data such as a character code has been input into the reception buffer 24. If no data has been input into the reception buffer 24, the paper feed start (PFS) output is reset (step (hereinafter referred to as S) 1) N, S2). In this state, it waits for data such as a character code to be output from the host computer 17, and when data such as a character code is output from the host computer 17, this data is input to the reception buffer 24 via the host I / F 21. .

The CPU 20 creates the above-described PFS signal immediately after data such as a character code starts to be input to the reception buffer 24, and transmits this PFS signal to the printer controller 27 of the printer unit 19 via the RR interface 28 (S1 is Y , S3). Thereafter, the CPU 20 determines whether there is an empty area for writing pattern data in the image memory 26 (S4), and if there is a write area, sequentially outputs the character codes in the reception buffer 24 to the image data generator 27, and After conversion to pattern data to be performed, the pattern data is written to the image memory 26 (S4 is Y, S
Five).

On the other hand, the printer controller 27 executes the sheet feeding operation based on the PFS signal output from the CPU 20 while performing the above-described pattern data creation operation on the interface control unit 18 side (ST1 is Y, ST2 (here, ST means a step, and ST is used to distinguish it from the process S on the interface control unit 18))). When the PFS signal is input, the printer controller 27 sends a rotation instruction signal to the paper feeding roller 9 to rotate the paper feeding roller 9 and carry out the paper P from the paper cassette 2. When the paper P carried into the printing apparatus reaches the standby roll 10 through the paper transport path 12, the standby sensor 15 is turned on. After determining that the refeeding flag described later is not “1”, the printer controller 27 stops the rotation of the feeding roll 9 when confirming that the standby sensor 15 is on (ST3 to ST5). As described above, the interface control section is provided on the print section 19 side.
While the pattern data is being written into the image memory 26 on the 18 side as described above, the sheet P is unloaded from the sheet cassette 2, fed to the position of the standby roll 10, and temporarily stopped. The time chart showing the feeding timing of the sheet P is the first half of FIGS. 4 (a) to 4 (c).

Thereafter, on the interface control unit 18 side, when the writing of the above-described pattern data to the image memory 26 is completed (S6: Y), the CPU 20 issues a write completion signal (I
DR signal) to the printer controller 27 (S7).
When the printer controller 27 receives the IDR signal (rising), if the above-described paper P feeding process is completed, the printer controller 27 transmits a data transmission permission signal (VSYN) to the CPU 20 as a confirmation (ST6 is Y, ST7). When the CPU 20 receives the VSYN signal,
The pattern data written in the image memory 26 is transmitted to the printing unit 19 together with the valid signal (VAL) (S8 to S8).
10) The exposure according to the pattern data is performed by the print head 6 (ST8 is Y, ST9). The time charts showing the respective signal output timings correspond to the first half of FIGS. 4 (d) to 4 (g).

Thereafter, when the transmission of the pattern data is completed in the interface control unit 18 frame, the CPU 20 stops outputting the valid signal and the transmission of the pattern data, decrements the number counter, and the CPU 20 executes the number counter provided in the RAM 23, for example. It is determined whether it is "0" (S11-S14). The determination of the count value of this number counter is performed in the copy printing process for two or more sheets, and does not become “0” even when the printing process on the first sheet is completed as described above (“1”). "(K) in FIG. 4), the CPU 20 returns to the above-described processing (S7).

On the other hand, in the printing section 19, after the exposure operation is started in the printing section 6 as described above, for example, a timer provided in the printer controller 27 is started (ST10). This timer is used to make the image formed on the photosensitive surface coincide with the leading edge of the paper P. While the timer expires (ST11 is N), the image forming operation of the print head 6, the developing device 7, and the like is performed. A process is performed to form an image on the photosensitive surface, develop an image, and the like (ST12). Thereafter, when the timer times out, the timer is reset, the standby roll 10 is driven, and the refeed flag is set to “1” (ST11 is Y, ST
13, ST14, ST15). By this processing, the sheet P is conveyed to the transfer unit 8 side, the toner image is transferred onto the sheet P, and the toner image is fixed on the sheet P by the fixing unit 11. After that, the printer controller 27 continues the sheet conveyance and continues to execute the above-described image forming process (ST12). In the meantime, it is determined whether the trailing edge of the sheet P is detected by the sheet trailing edge detection sensor 14 (ST16). Before the trailing edge of the sheet P is detected by the trailing edge detection sensor 14 (N in ST16), the process (ST3) is executed to determine whether the refeed flag “1” and the standby switch are OFF (ST3 is Y). , ST17 is N), the above processing (ST6
→ ST7 → ・ ・ ・) is repeated.

Thereafter, when the trailing edge of the sheet P is detected by the sheet trailing edge detection sensor 14 (ST16 is Y), the process returns to the process (ST1), and if the input of the PFS signal is determined and input, the (ST1 is Y). Then, the paper feed roller 9 is driven to rotate to execute the carry-out processing of the next paper P '(ST2). That is, the preceding paper P is still in the standby roll 10
Then, while the image forming process is being performed on the paper P (ST3 → ST17 → ST6 → ST7 →...), The next paper P ′ is carried into the printing device. FIGS. 4A and 4B show the above processing timings in the latter half of FIG.
(H) to (j).

Thereafter, when all of the bull P is sent from the standby roll 10 to the transfer device 8 side, the standby switch 15 is turned off (Y in ST17),
The printer controller 27 stops the rotation of the standby roll 10, and sets the refeed flag to "0" (ST18, ST19).
During this time, the next sheet P 'is being transported on the sheet transport path 12, and immediately after the standby roll 10 stops rotating, the next sheet P' is
Abuts on the standby roll 10 and turns on the standby switch 15.
That is, it is determined that the refeed flag is set to “0” (ST
3) becomes N, and the standby switch 15 is turned on again by the sheet P 'conveyed at an interval of, for example, about 10 mm on the sheet P. Therefore, the feeding of the sheet P 'is temporarily stopped by this process (ST3 → ST5). At this time, the IDR signal is transmitted from the CPU 20 to the printer controller 27 as described above, and printing is performed in the same manner as described above in accordance with the pattern data written in the image memory 26 (ST6 → ST7 →...).
・). That is, when the printing process on the previous sheet P is completed, the next sheet P 'has already been sent to the standby roll 10, and the printing process on the next sheet P' can be executed immediately. Then, when printing on the last sheet is completed, the number counter becomes “0”, so that the CPU 20 stops outputting the IDR signal and ends the printing process (S15).

〔The invention's effect〕

As described in detail above, according to the present invention, during the creation of image data, the first sheet is carried in to a predetermined position of the printing apparatus, and printing can be performed simultaneously with the completion of creation of the image data. During the printing process of the preceding sheet, the sheet is carried into a predetermined position in the printing apparatus and can be processed immediately, so that the printing process can be performed at high speed.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram of a printing apparatus according to one embodiment, FIG. 2 is a configuration diagram of the printing apparatus according to one embodiment, FIG. 3 is a flowchart illustrating the operation of the printing apparatus according to one embodiment, and FIG. 5 is a time chart illustrating an operation of the printing apparatus according to the embodiment. 9: paper feed roller, 10: standby roll, 14: paper trailing edge detection sensor, 15: standby switch, 20: CPU, 27: printer controller.

Claims (1)

(57) [Claims] 1. A receiving buffer for temporarily storing print data received from an external device, a developing means for developing print data input to the receiving buffer into image data to be printed, and storing and storing the developed image data. And a printing device that prints out a sheet carried out from a sheet storage unit by a sheet supply unit based on data stored in the image memory. A sheet trailing edge detecting means disposed downstream of the leading edge by a predetermined distance in the sheet transporting path to detect the passage of the trailing edge of the sheet; and any one of the reception buffer, the image memory, and a data processing process between the two. If the data to be printed is recognized and the trailing edge detection sensor does not detect the presence of paper on the sensor, Paper feed start means for controlling the start of the paper feed operation by continuous paper feed processing. The interval between the trailing edge of the preceding paper and the leading edge of the succeeding paper during continuous printing is maintained substantially at the predetermined distance. A printing device characterized by being performed.