JPH0338356A - Varying method of resolution in laser printer - Google Patents

Abstract

PURPOSE:To print with the printing quality corresponding to the resolution of an input data by changing the outputting number of dots per one pixel of said input data in accordance with the resolution of said input data. CONSTITUTION:When the resolution of an input data is 240DPI, one pixel of a printed image is expressed by the pattern of 5X5 dots. When the information of the 240DPI resolution is developed to an output buffer 16, the information of the output buffer 16 is output one line by one line as a laser modulating signal through an output interface 18, thereby modulating the strength of outputs of a semiconductor laser in a laser unit. The outputting timing at this occasion is controlled by an address controller 20. Since the information corresponding to the input data is developed in the output buffer 16 as an information of five lines, the optical scanning is conducted five times to print one line of the input data. Thus, one line of the input data is written by the optical scanning of five lines. This process is repeated per every one line of the input data. The resolution of the printed image can be adjusted in accordance with the resolution of the input data.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for varying resolution in a laser printer.

[Background Art] Recently, a wide variety of data and document processing systems such as personal computers and word processors have been put into practical use. Laser printers are widely used as output devices for such systems.

In these systems, there is generally no problem if the data transferred to the printer is limited to text codes, but in reality, the data transferred to the printer often includes dot image data, and the resolution of the output printer is limited to the printer. On the other hand, the resolution of data handled by various systems varies.

[Problems to be Solved by the Invention] Conventional laser printers have been unable to handle data that does not match the printer's inherent resolution.

The present invention has been made in view of the above-mentioned circumstances, and aims to provide a method for varying the resolution of a laser printer so that the same laser printer can process multiple types of data with different resolutions.

[Means to solve the problem] The present invention will be explained below.

The method of the present invention is based on ``the possible resolution of multiple types of input data nl Z p 112 g + + t m i y
+ + y m 11, in a laser printer that has a common multiple M of these resolutions as the address control accuracy, the resolution can be increased by changing the number of output dots corresponding to the input data ↓ pixel according to the resolution of the input data. ``how to adapt.''

This method includes an accumulation step, a production step, a development step, and a discharging step.

The accumulation process is a process of "accumulating input data in an input buffer via an input interface".

The generation step is a step of ``generating a dot array pattern in the pattern generator according to the resolution of input data.'' The pattern generator has a predetermined value of 1 at the output according to the resolution mi (i=1 to k) of the input data.
A pixel dot array pattern Pi (i=1 to k) is stored.

The expansion process is a process of ``expanding the input data accumulated in the input buffer into the output buffer according to the dot array pattern generated by the pattern generator.''

The output process is the process of ``outputting the information developed on the output sofa as a laser modulation signal via the output interface.''

The dot array pattern Pi prepared in the pattern generator is not limited to one type, but a plurality of types can be selected according to each resolution ml of input data.

[Operation] As described above, in the resolution variable method of the present invention, the laser printer adjusts the resolution m, (i
It is assumed that the address control accuracy is a common multiple M of =1=k). "Address control accuracy" is a measure of how many dots can be arranged without gaps per unit length, and is determined by the scanning beam spot diameter. For example, address control accuracy is r1200API (Addre
ss per inch) means that 1,200 addresses can be specified per inch, or in other words, 1,200 dots can fill each inch.

In the present invention, when the resolution of input data is given, a pattern generator generates a dot array pattern for representing one pixel at this resolution as a set of dots. Then, the information for each pixel of the input data accumulated in the input buffer is expanded to the output buffer as the presence/absence array of the above-mentioned dot array pattern, and the information expanded to this output buffer is transmitted dot by dot via the output interface to the laser. Output as a modulated signal.

The print quality required of a printer only needs to be commensurate with the target resolution, and there is no need for individual dots to be guaranteed.Therefore, using the above method, the print quality commensurate with the resolution of the input data can be achieved. It is possible to print.

[Example] Hereinafter, embodiments will be described with reference to the drawings.

FIG. 3 schematically shows an example of a laser printer to which the present invention is applied.

A photoconductive photoreceptor 30 formed in a belt shape is uniformly charged by a charger 32 while being rotated in the direction of the arrow.
Image information is written by the laser unit 34. As a result, an electrostatic latent image corresponding to the image information is formed on the photoreceptor 30.

The electrostatic latent image is subjected to magnetic brush type dry development by a developing device 36 and is made into a visible image.

The visible image thus obtained is transferred onto the transfer paper S by the transfer device 38, then fixed by the fixing device 40, and discharged from the apparatus.

The photoreceptor 30 after the visible image has been transferred is cleaned by a cleaner 42 . The above is an overview of the printing process.

The laser unit 34 uses a semiconductor laser as a light source, collimates the light beam from the light source with a collimating lens, deflects it with a rotating polygon mirror, and exposes the deflected light beam through an fθ lens, a plane mirror, and a long cylinder lens. body 30
, and is imaged as a spot on the surface by the action of an fθ lens and a long cylinder lens.

The printing speed of this laser printer is fast enough to print 8 A4 size sheets per minute.

The address control precision M is 1200 API, and the target resolutions that can be supported are 240, 300, 400, 600D.
There are four types of PI. Address control accuracy is a common multiple of these four types of resolution.

In addition, the rotating polygon mirror used in the laser unit 34 is 1
It has a rotation speed of 3680 RPM, 10 reflective surfaces, a scanning frequency of 2268)1z, and a scanning beam spot optimized for a maximum resolution of 600 DPI.

FIG. 1 shows a block diagram of the 1-resolution variable processing section.

The input buffer 12, pattern generator 14, and output buffer 16 are controlled by an address controller 20. That is, a clock generated by a clock generator 22 and a synchronization signal for optical scanning in the laser unit (generated once for each scan) are input to the address controller 20.

When the address controller 20 receives the synchronization signal, the address controller 20 controls the input buffer 12 at a predetermined timing according to the clock.
．． Controls the pattern generator 14 and output buffer 16. Since the clock guarantees address accuracy in main scanning, a clock with the necessary accuracy is used.

Now, the input data is data representing the presence or absence of one pixel, and if one pixel is present, it is "1", and if one pixel is absent, it is "0", then it is "1".

It is array data of rQJ and is temporarily stored in the input buffer 12 via the input interface IO.

The input buffer 12 is composed of a RAM and has enough memory to store one line of information at the highest resolution, that is, 600 DPI. Therefore, data for one line is accumulated in the input buffer every - degree.

The pattern generator 14 is composed of a ROM, and stores a dot array pattern corresponding to the resolution of input data.

FIG. 2 shows an example of a dot array pattern stored in the pattern generator 14.

Figure 2 (I) shows the dot array pattern corresponding to the input data resolution of 240 DPI, and Figure 2 (II), (I
II) and (IV) are the resolution of input data 300, respectively.
It shows dot array patterns corresponding to DPI, 400DPI, and 600DPI.

At each time in FIG. 2, the first square represents one dot recorded by the scanning beam spot. Therefore, when the resolution of the input data is 240 DPI, one pixel in the print image is represented by a 5.times.5 dot pattern as shown in FIG. 2(I). Similarly, the resolution of the input data is 300, 400.600
When using DPI, one pixel in the printed image is
It will be expressed as a pattern of 4x4, 3x3, and 2x2 dots.

The pattern generator 14 responds to whether the resolution of the input data is 240, 300, 400, or 600 DPI.
), (generate m dot array patterns.

A dot array pattern corresponding to the input data is developed in the output buffer 16. For example, the resolution is 24
The case of input data of 0DPI will be explained.

In this case, the arrangement of the dot arrangement pattern shown in FIG. Therefore, in this case, the memory capacity of the output buffer 16 (consisting of RAM) is
Requires memory for 5 lines.

In other words, the memory of the output buffer 16 requires a capacity necessary to expand one line of input data with the minimum resolution.

Now, when the information with 5 resolution and 240 DPI is expanded to the output buffer 16 as described above, the information in the output buffer 16 is output line by line as a laser modulation signal via the output interface 18, and the semiconductor laser in the laser unit is outputted as a laser modulation signal. Intensity modulates the output. Needless to say, the output timing is controlled by the address controller 20 at this time.

Information corresponding to the input data is stored in the output buffer 16 at 5
Since the information is developed into lines, five optical scans are performed to print one line of input data, and one line of input data is written by five lines of optical scan.

Printing is performed by repeating this process ψ for every l line of input data.

In this way, the resolution of the print image can be adjusted according to the resolution of the input data.

The dot array pattern that represents one pixel of input data is
It is not limited to the one shown in FIG. For example, in response to input data resolutions of 240, 300, 400, and 800 DPI.

For example, the dot array patterns generated by the pattern generator are shown in Fig. 4 (I), (u), (o■),
(rv) may be selected. Adoption of such a dot array pattern has the effect of correcting the print image to be somewhat thicker than the input image. - In order to adopt such a dot arrangement pattern, it is necessary to increase the memory capacity of the output sofa compared to the case of the pattern shown in FIG.

Further, the dot array pattern to be stored in the pattern generator need not be limited to one type for one resolution, and a plurality of types of dot array patterns may be prepared for each resolution.

Figure 5 (I), (II), (III), (m
The dot array patterns shown in 2 are examples of those prepared for input data resolution of 3000 PI. By using these dot array patterns properly for input data with 1 resolution of 300 DPI, it is possible to print images. The apparent print density can be changed.

Each of the dot array patterns shown in FIGS. 6(I), (II), (III), and (IV) also has a resolution of 3000
Another example of what is provided for PI is shown. For input data with a resolution of 300 DPI, it is possible to express a print image thicker than the input image by appropriately using these toad array patterns.

[Effects of the Invention] As described above, according to the present invention, a novel method for varying resolution in a laser printer can be provided. Since this method is configured as described above, it is possible to perform printing that is compatible with input data of various resolutions.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment system for carrying out the method of the present invention, FIG. 2 is a diagram showing an example of a dot arrangement pattern according to the resolution of input data, and FIG. 3 is a diagram showing an embodiment of the system. FIG. 4 is a diagram showing another example of a dot arrangement pattern according to the resolution of input data, and FIGS. 5 and 6 are the same diagrams. FIG. 6 is a diagram showing examples of various dot array patterns representing one pixel of resolution input data.

Claims (1)

[Claims] 1. Possible resolutions of multiple types of input data are m_1, m
_2,. ．． ,m_i,. ．． , m_k, in a laser printer that has a common multiple M of these resolutions as the address control accuracy, the resolution is adapted by changing the number of output dots corresponding to one pixel of input data according to the resolution of the input data. The method comprises the steps of accumulating input data in an input buffer via an input interface, and determining in advance a one-pixel dot array pattern P_i( i
= 1 to k) is stored in the pattern generator to generate a dot array pattern according to the resolution of the input data; A method for varying resolution in a laser printer, comprising the steps of: expanding the information to an output buffer; and outputting the information expanded to the output buffer as a laser modulation signal via an output interface. 2. In claim 1, the dot array pattern P_i corresponds to each resolution m of input data.
A method for varying resolution in a laser printer, characterized in that a plurality of types are selectable according to ___i.