JP3054269B2 - Image forming method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming method and apparatus capable of enlarging an image.

[0002]

2. Description of the Related Art In a laser beam printer or the like,
Character information sent from a connected host computer or the like is developed as a bit image and stored in an internal bit map memory. Thereafter, the bit image is read and converted into a serial video signal. Then, the on / off of the laser beam is controlled by the video signal and output on a recording medium. When performing enlargement printing in such a conventional laser beam printer, it is necessary to enlarge and re-expand the bit image enlarged in the memory or to output a video signal with a reduced dot density. did not become.

[0003]

However, in the above conventional example, the bit map memory for storing the original bit image before the enlargement in the memory and the bit map memory for storing the bit image after the enlargement Two bitmap memories of the memory are required, which is expensive. Further, since enlargement processing for enlarging the original bit image is required, there is a problem that the processing takes time. In the method of lowering the dot density when outputting a video signal, for example, when enlarging the print data of A4 to A3, two types of video clock frequencies are prepared, and the frequency of the video clock is set at the time of normal printing. Switches the time of enlargement printing. However, since a fixed video clock frequency is used by switching, a plurality of transmitters are required and there is a problem that it is impossible to cope with enlargement of an arbitrary magnification.

[0004] The present invention has been made in view of the above-mentioned problems, and it is possible to enlarge an arbitrary magnification by a single transmitter by changing the interval of a video clock at a timing corresponding to a set enlargement ratio. In addition to making it possible, a bitmap memory for storing the enlarged bit image is not required, and a high-quality enlarged image can be obtained.
And to provide an image forming method and apparatus that.

[0005]

An image forming apparatus according to the present invention for achieving the above object has the following arrangement.
That is, an image forming apparatus having means for outputting image data in synchronization with a video clock, wherein: a setting means for setting an enlargement rate when outputting the image data; and an enlargement rate set by the setting means. a timing signal generating means for generating a timing signal based on the video clock, the video upon occurrence of said timing signal
Subtract the clock for two clocks and execute the decimation.
A clock obtained by inverting the phase of the video clock
And changing means for changing the interval of the video clock by inserting one clock .

Further, an image forming method according to the present invention for achieving the above object has the following arrangement. That is, an image forming method including a step of outputting image data in synchronization with a video clock, wherein: a setting step of setting an enlargement rate when outputting the image data; and an enlargement rate set by the setting step. A timing signal generating step of generating a timing signal based on the video clock; and
Is subtracted for two clocks, and at the place where
One clock is obtained by inverting the phase of the video clock.
Changing the video clock interval by inserting a clock.

[0007]

With the above arrangement, a timing signal for changing the interval of the video clock is generated based on the enlargement ratio and the video clock set by the setting means. When this timing signal is generated, the video clock is
The video is removed at the place where the
Insert 1 clock with inverted clock phase
By doing so, the interval of the video clock is widened and the image is enlarged.

[0008]

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

First, the configuration of a laser beam printer to which the present embodiment is applied will be described with reference to FIG.

FIG. 1 is a sectional view showing the internal structure of a laser beam printer (hereinafter abbreviated as LBP) according to an embodiment.
The BP can register a character pattern and a partner format (form data 9) from a data source (not shown).

In the figure, 100 is an LBP main body,
While inputting and storing print information (character codes, etc.), form information, macro instructions, etc., supplied from an externally connected host computer, create a corresponding character pattern, form pattern, etc. according to the information, An image is formed on a recording paper as a recording medium. 3
Reference numeral 00 denotes an operation panel on which switches for operation and an LED display are arranged, and 101 denotes a printer control unit that controls the entire LBP 100 and analyzes character information supplied from a host computer. The printer control unit 101 mainly converts character information into a video signal having a corresponding character pattern and outputs the video signal to the laser driver 102.

The laser driver 102 is a semiconductor laser 10
3 for driving the laser light 1 emitted from the semiconductor laser 103 in accordance with the input video signal.
The laser beam 104 for turning on and off the laser beam 104 is swung right and left by a rotary polygon mirror 105 to scan and expose an electrostatic drum 106. As a result, an electrostatic latent image of a character pattern is formed on the electrostatic drum 106. This latent image is developed by a developing unit 107 provided around the electrostatic drum 106 and then transferred to a recording sheet. A cut sheet is used as the recording paper, and the cut sheet recording paper is stored in a paper cassette 108 mounted on the LBP 100, taken into the apparatus by a paper feed roller 109 and transport rollers 110 and 111, and Supplied to

FIG. 2 is a block diagram showing a schematic configuration of a printer control unit of the laser beam printer. In the figure, reference numeral 200 denotes a central processing unit (CPU), which controls the entire laser beam printer. 20
A ROM 1 stores various processing programs and data executed by the CPU 200. A RAM 202 temporarily stores various data necessary for the CPU 200 to execute various processes. An interface 203 receives print data from the host computer 207. Reference numeral 204 denotes a bitmap memory, in which print data received by the interface 203 is developed into image data and stored. Reference numeral 205 denotes a video controller which takes in image data from a bitmap memory, converts it into a video signal, and
Output to 6. The video controller 205 will be described later. Reference numeral 21 denotes a data bus, which is a bus for performing direct memory access (DMA) transfer from the bitmap memory 204 to the video controller 205. 2
Reference numeral 06 denotes a printing unit that executes recording output on a recording medium by a laser beam method. The operation panel 300 includes operation keys and the like for setting an enlargement ratio. Each of the above components is connected to the system bus 208 so that data can be exchanged with each other. The system bus 208 has a data bus 12 described later.

Next, the video controller 205 will be described. FIG. 3 is a block diagram of the video controller 205 capable of enlarging image data in the laser beam printer. Reference numeral 1 denotes an enlargement ratio setting register, which stores the enlargement ratio set by the operation panel 300 in the CPU 200.
From the data bus 12. Enlargement ratio setting register 1
Is input to the adder 2. The addition result storage register 3 outputs the video clock signal 15 from the output 22 of the adder 2.
Is latched. Further, the output 23 of the addition result storage register 3 becomes an input of the adder 2, and the output 23 is cleared to 0 by a clear signal 27 according to a command from the CPU. The value set in the enlargement ratio setting register 1 is added by the above-described enlargement ratio setting register 1, adder 2, and addition result storage register 3 every time the video clock signal 15 is input. When the result of the addition by the adder 2 is 1 or more, the value of the addition result storage register 3 latched by the video clock 15 is added, and when the result is 1 or more, the carry signal 25 is output.

Reference numeral 13 denotes a basic video clock.
The input of the circuit 7 and the input of the inverter 4. The flip-flop 5 outputs the carry signal 25 to the inverter 4
, Ie, at the falling edge of the basic video clock. The output 17 of the flip-flop 5 becomes “L” when the carry signal 25 is sampled, and becomes “H” when the carry signal 25 is not sampled.
Input to the ND circuit 7. Output 1 of flip-flop 5
1 is an operation opposite to that of the output 17 described above.
Input. The flip-flop 6 samples the output of the AND circuit 20 at the rise of the basic video clock 13. The AND circuit 8 outputs the basic video clock 1
The logical product of the inverted signal of 3 and the output 14 of the flip-flop 6 is calculated. The OR circuit 9 outputs the output 26 of the AND circuit 7
And the output 18 of the AND circuit 8 is ORed, and the output video clock 15 becomes the latch signal of the addition result storage register 3 and the clock signal of the P / S converter 10.
In the P / S converter 10, data is taken in through the data bus 21 from the bitmap memory 204, converted into a serial signal in synchronization with the video clock 15, and output as a video signal 19.

Next, the operation of the video controller 205 having the above configuration will be described in more detail with reference to FIGS. FIG. 4 is a timing chart for explaining the present embodiment, and FIG. 5 is a view for explaining data to be transferred. FIG. 6 is a diagram illustrating a setting state of the enlargement ratio in the enlargement ratio setting register 1.

First, at the timing of S0 in FIG.
The CPU 200 first outputs a clear signal 27 to clear the contents of the addition result storage register 3 to 0. Then, the addition result storage register 3 is cleared to "0". Next, the CPU 200 sets the enlargement ratio in the enlargement ratio setting register 1 via the data bus 12. Here, the format of the data to be set is a fixed-point format, which is shown in FIG. Here, for example, assuming that the enlargement ratio is 1.25, it is set as shown in FIG. In the adder 2, the values of the enlargement ratio setting register 1 and the addition result storage register 3 are added, and the value is 0.25 here.
+ 0 = 0.25.

In the initial state, the flip-flops 5 and 6 are in the reset state, and the output 11 of the flip-flop 5 is "L". Therefore, the output 28 of the AND circuit 20 becomes "L". The output 17 of the flip-flop 5 becomes "H". Output 14 of flip-flop 6
Is "L", the output 18 of the AND circuit 8 is "L".
It is.

Next, at the timing of S1, when printing becomes possible, the basic video clock 13 is output, and AN
The output 26 of the D circuit 7 follows the basic video clock 13.
On the other hand, since the output 18 is “L”, the video clock 15 output from the OR circuit 9 is the same as the basic video clock 13. Therefore, at this timing (S1) when the basic video clock rises, the video clock 15 also becomes “H”, and the output value 0.25 of the adder 2 is latched in the addition result storage register 3. At this time, the image data to be transferred from the bitmap memory 204 is P /
The bit data at the position of number 0 shown in FIG. 3A is output as a video signal.

Next, at the timing of S2, the carry signal 25 of the adder 2 is sampled at the falling edge of the basic video clock 13. At this timing, the carry signal is "L". The output of the flip-flop 5 remains unchanged. Next timing (S
Also in 3), the carry signal 25 is not output, so that the output of the flip-flop 5 does not change.

At the timing of S4, the carry signal 25 becomes "H", and at the timing of S5,
At the falling edge of the basic video clock 13, the carry signal 25 is sampled by the flip-flop 5. Therefore, the outputs 11, 17 of the flip-flop 5 are inverted at this timing (S5). Therefore, the output of the AND circuit 7 is always “L”, and the output 28 of the AND circuit 20 is “H”.

Next, at the timing of S6, the flip-flop 6 samples the level "H" of the output 28 of the AND circuit 20, and the output 14 thereof becomes "H". At the timing of S7, the basic video clock 1
The logical product of the inverted signal of C.3 (ie, the output of inverter 4) and the output 14 of flip-flop 6 is output 1 of AND circuit 8
It becomes 8. Therefore, the video clock 15, which is the output of the OR circuit 9, becomes "H" at the timing S7. At the timing S7, that is, at the falling edge of the basic video clock, the data of the number 3 shown in FIG.
2 is latched in the addition result storage register 3, and the carry signal 25 of the adder 2 is not output (becomes "L").

At the timing of S8, the "L" of the carry signal 25 is sampled by the flip-flop 6, and the output 14 thereof becomes "L". Therefore, AN
The output 18 of the D circuit 8 becomes “L” and the video clock 1
5 also becomes "L". At the timing of S9, "L" of carry signal 25 is sampled in flip-flop 5, and output 17 thereof becomes "H". At the timing of S10, since the output 17 of the flip-flop 5 is at "H", the output 26 of the AND circuit 7 becomes "H" and the output video clock 15 of the OR circuit 26 is output.
Becomes “H”. Thereafter, the operations at the timings of S1 to S10 described above are repeated.

As described above, according to the laser beam printer of this embodiment, the bit image data expanded in the bit map memory is transmitted as a video signal while being expanded, so that the expanded bit image data is stored. No bitmap memory is required. Furthermore, 1
Since any number of oscillators can cope with an arbitrary enlargement ratio, it is effective in cost reduction. In addition, there is an effect that data processing for enlargement processing is not required, and processing time is shortened.

Also, at the time of enlargement, data of one pixel is simply
Since the enlargement process is executed by changing the interval of the video clock instead of printing continuously for the number of pixels, 1.5 times pixels are printed together with adjacent pixels. For this reason,
There is also an effect that the quality of printing is improved.

Although the data bus 12 of the CPU 200 and the data bus 21 of the image memory have been described separately,
It goes without saying that the same bus can be used. At that time, the CPU 200 sets the bitmap memory 204 by itself.
The image data may be transmitted more, or the image data may be transmitted by DMA (direct memory access).

The present invention may be applied to a system constituted by a plurality of devices or to an apparatus constituted by a single device. Needless to say, the present invention can be applied to a case where the present invention is achieved by supplying a program to a system or an apparatus.

[0028]

As described above, according to the image forming method and apparatus of the present invention, by changing the interval of the video clock at a timing corresponding to the set magnification, a single transmitter can be used. In addition to the possibility of enlargement at an arbitrary magnification, there is an effect that data processing for image enlargement and a bitmap memory for storing the enlarged bit image are not required. In addition, two video clocks
Video at the place where the thinning was performed, with the lock mined
Insert one clock with inverted clock phase
To change the video clock interval,
It is possible to obtain a high-quality enlarged image.

[0029]

[Brief description of the drawings]

FIG. 1 is a sectional view showing the internal structure of a laser beam printer according to an embodiment.

FIG. 2 is a block diagram illustrating a schematic configuration of a printer control unit of the laser beam printer.

FIG. 3 is a block diagram of a video controller in the laser beam printer.

FIG. 4 is a timing chart illustrating the operation of the video controller according to the present embodiment.

FIG. 5 is a diagram illustrating data to be transferred.

FIG. 6 is a diagram illustrating a setting state of an enlargement ratio in an enlargement ratio setting register.

[Explanation of symbols]

 Reference Signs List 1 enlargement ratio setting register 3 addition result storage register 5, 6 flip-flop 13 basic video clock 15 video clock 10 P / S converter 19 video signal

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B41J 2/485 B41J 2/00 G06F 3/12 H04N 1/387

Claims (3)

(57) [Claims] 1. An image forming apparatus comprising: means for outputting image data in synchronization with a video clock, wherein the setting means sets an enlargement ratio when outputting the image data; and Timing signal generating means for generating a timing signal based on an enlargement ratio and the video clock;
In addition to subtracting the clock minutes,
One clock with inverted video clock phase
Changing means for changing an interval of the video clock by inserting the video clock. 2. The image processing apparatus according to claim 1, further comprising a recording unit that records the image data output in synchronization with the video clock on a recording medium by a laser scan method.
An image forming apparatus according to claim 1. 3. An image forming method having a step of outputting image data in synchronization with a video clock, wherein: a setting step of setting an enlargement factor when outputting the image data; and A timing signal generating step of generating a timing signal based on an enlargement ratio and the video clock;
In addition to subtracting the clock minutes,
One clock with inverted video clock phase
Changing the video clock interval by inserting the video clock.