JPH03213370A - Page printer - Google Patents

Abstract

PURPOSE:To obtain a normal printing result by making printing speed alterable according to the data transfer speed of a host computer. CONSTITUTION:When a CPU 11 detects the empty state of an image memory 14 to issue the request command of image data for a host computer 13, the host computer 13 transmits the image data of one page to a printer. The CPU 11 receives the image data to begin to store the image data in an image memory 14 and performs printing processing through a mechanism control circuit 17 after the completion of the storing of the image data. When the image memory is in an empty state and the storing of the image data is not completed, the CPU 11 discharges paper at that time and outputs a speed indication signal S2 to the mechanism control part 17 so as to decrease printing speed to the speed considered to be in time for the data transmission of the host computer 13 and also requires the re-transmission of the image data of one page presently processed with respect to the host computer 13. By this constitution, the timing of data transfer speed is matched with that of printing speed to obtain a normal printing result.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a page printer, such as a laser printer, that prints on a page-by-page basis.

(Prior Art) For example, page printers such as laser printers have the advantage of low noise and high image quality, but have the disadvantage of being expensive. This is because printing is done page by page at once.
This is because it requires a large amount of memory. Generally, a page printer is equipped with an image memory (page memory) that stores at least one page worth of image data (dot image data), and prints while storing data page by page in this image memory. .

Here, as one method for reducing the price, there is a method of printing by reducing the amount of data stored in the image memory. This receives part of the image data for one page from the host computer and prints it, and before the data necessary for printing runs out, it receives the next data and continues printing. Finally, the printing result for the entire page is obtained. According to this method, the memory capacity is 1
If you use the data alternately for data reception and printing to improve efficiency, you can use it twice. 1 will suffice.

By the way, in a page printer, unlike other printers, it is not possible to interrupt the printing operation in the middle of printing one page. Therefore, when using the above method, the host computer transfers the same amount of next data before the data currently stored in the image memory finishes printing, so as not to interrupt the printing operation. There must be.

However, if there is a delay in the data transfer from the host computer due to, for example, complicated editing of transferred data, the printing speed of the printer has traditionally been fixed, so the timing between the printing speed and the data transfer speed cannot be determined. There was a problem in which the printer went awry, making it impossible to obtain normal printing results.

(Problem to be solved by the invention) As described above, conventionally, when an image memory with a small capacity is used and one page of image data is printed in a predetermined unit, the data transfer speed of the host computer There is a problem in that a timing error with the printing speed of the printer makes it impossible to obtain normal printing results.

The present invention was created in view of the above points, and it is possible to match the timing of data transfer speed and printing speed without limiting the processing speed of the host computer even if a small capacity image memory is used. The object of the present invention is to provide a page printer that can obtain normal printing results.

[Structure of the invention] (Means and actions for solving problems) That is, in the present invention, printing is performed page by page.

In a page printer, the printing speed can be changed according to the data transfer speed of the host computer.
The image data for a page is printed in a predetermined unit. Thereby, it is possible to obtain normal printing results by matching the timing of the data transfer speed and the printing speed.

(Embodiment) Hereinafter, a page printer according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the circuit configuration thereof.

In FIG. 1, the CPU II is in charge of controlling the entire apparatus, and here executes printing speed control processing and the like as shown in FIG. 5. The interface 12 exchanges data with the host computer 13.

The host computer 13 transfers one page of image data (dot image data) to the printer in predetermined units.

The image memory 14 sequentially stores image data transferred from the host computer 13 in predetermined units.

The video signal generation circuit 15 converts the image data stored in the image memory 14 into a video signal S1 to the mechanism control circuit 17.
Output to. The input/output boat 16 performs input/output control with the mechanism control circuit 17, and here, the CPU
The speed instruction signal S2 from II is output to the mechanism control circuit 17. Mechanism control circuit 17 controls the printing mechanism based on video signal S1 and speed instruction signal S2. The speed control circuit 18 drives the motor drive circuit 19 under the control of the mechanism control circuit 17, and directly controls the rotation speed of the paper feed motor 20.

FIG. 2 is a conceptual diagram showing the configuration of a printing mechanism section of a page printer. In FIG. 2, a paper feed roller 21 feeds each sheet of paper to a photosensitive drum 22. The photosensitive drum 22 is
A latent charge image is formed using a light beam such as a laser. The light beam scanner 23 scans the photosensitive drum 22. A developing process 24 causes charged toner to adhere onto the photosensitive drum 22 to form an image. The transfer roller 25 transfers the toner from the photosensitive drum 22 onto the paper fed by the paper feed roller 21 . The cleaner 26 scrapes off excess toner from the photosensitive drum 22. The charging electrode 27 is
A uniform charge is applied to the photosensitive drum 22 to clear the image.

Fixing roller 28 fixes the toner onto the paper.

Further, the paper feed motor 20 is a motor for driving a paper feed mechanism including the photosensitive drum 22.

FIG. 3 is a diagram showing the scanning direction of the light beam.

With respect to the paper 31 being conveyed at a constant speed in the direction of arrow A, the optical beams 32a, 32b, 32cm are applied in this order.
The paper 31 is scanned.

FIG. 4 is a diagram showing a method of storing data in the image memory 14. For example, the image memory 14 has two sets of memories 14a,
14b, the image data for one page of the paper 31 conveyed in the direction of arrow A is stored in the memory 1 in predetermined units.
4g and 14b alternately.

By the way, as shown in FIG. 2, a page printer is an electrophotographic printing device that transfers a latent image scanned by a first beam onto a photosensitive drum 22 onto a sheet of paper using a developing process 24. In this method, information for one page is printed at one time on sheets of paper that are transported one by one at a constant speed, so printing cannot be interrupted midway. Therefore, is it usually necessary to prepare one page of image data for printing?If the data transfer from the host computer is faster than the paper conveyance speed (printing speed), it is necessary to prepare the entire page of image data for printing. No covering image memory is required. That is, if one page's worth of image data is sequentially processed in predetermined units, an image memory with a small capacity is sufficient.

However, the processing on the host computer side is diverse and cannot always match the processing speed on the printer side, and in such a case, a timing error will occur in an image memory with a small capacity. Therefore, the present invention is characterized in that the printing speed on the printer side is made variable so that data transfer from the host computer can keep up with the printing speed without imposing a limit on the processing speed on the host computer side.

The operation of this embodiment will be described below with reference to the flowchart shown in FIG.

First, the CPU II requests image data from the host computer 13 by detecting the empty state of the image memory 14 (step Sl). In response to this request, the host computer 13 sends one page of image data to a predetermined C.
It is transferred to the printer at position P (step S2). C.P.U.I.
By receiving this image data through the interface 12, I starts storing the image data in the image memory 14 (step S3). When the storage of this image data is completed (step S4), the CPU II
The printing process is executed through the mechanism control circuit 17 (step S5). Thereafter, until printing for one page is completed,
The CPU 11 repeats the above process (step S6).
.

Here, in step S4, if storage of the image data is not completed even though the image memory 14 is empty, the CPU II determines that there is a timing error between the data transfer of the host computer 13 and the printing speed of the printer. It is determined that this has occurred, and the paper at that time is immediately ejected (step S7).

Then, the CPU 11 sends a speed instruction signal S2 to the mechanism control circuit 17 so as to reduce the printing speed to a speed at which the data transfer of the host computer 13 is considered to be in time.
(step S8), and requests the host computer 13 to resend the one page of image data currently being processed (step S9). As a result, printing is resumed on a new sheet of paper at a speed slower than the speed at which the timing error occurred.

In this way, printing can be performed by matching the printing speed of the printer to the data transfer speed of the host computer 13. Therefore, even if a configuration is used to print one page of image data in predetermined units using a small-capacity image memory, for example, it is possible to obtain normal printing results without limiting the processing speed of the host computer. can.

In this embodiment, when a timing error occurs during a printing operation, the printing speed is changed, but if, for example, the data transfer speed of the host computer 13 is found to be slower than the printing speed of the printer. If this is the case, you can set the printing speed accordingly before starting printing.

Further, as a specific method for changing the printing speed, for example, several types of speed levels are set and a speed level corresponding to the data transfer speed of the host computer 13 is selected from among them. do.

[Effects of the Invention] As described above, according to the present invention, the printing speed can be changed according to the data transfer speed of the host computer, so even if a small capacity image memory is used, the processing on the host computer side can be It is possible to obtain normal printing results by matching the timing of the data transfer speed and printing speed without limiting the speed.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the circuit configuration according to one embodiment of the present invention, FIG. 2 is a conceptual diagram showing the configuration of the printing mechanism section of the same embodiment, and FIG. 3 is the scanning direction of the light beam of the same embodiment. A diagram showing
FIG. 4 is a diagram showing a data storage method in the image memory of the same embodiment, and FIG. 5 is a flowchart for explaining the operation of the same embodiment. 11... CPU, 12... Interface, 13...
...Host computer, 14...Image memory, 15
...video signal generation circuit, 16...input/output port,
17...Mechanism control circuit, 18...Speed control circuit, 19...Motor drive circuit, 20...Paper feed motor.

Claims (1)

[Scope of Claims] A page printer that prints page by page, comprising: a host computer that transfers one page of image data in predetermined units; a data storage unit that stores image data from the host computer; A page printer comprising: a printing means for printing based on image data stored in the means; and a speed control means for changing the printing speed of the printing means in accordance with the data transfer speed of the host computer. .