JPH07154557A - Image forming system - Google Patents

Abstract

PURPOSE:To save toner consumption without causing disturbance in a print form by outputting picture data while saving unit element data outputted to a print engine side. CONSTITUTION:A control circuit 25 including a frequency divider circuit 27 and sending a data enable signal used to set to allow unit element data depending on either one of shift registers 23a-23d of a conversion circuit 22 based on a horizontal synchronizing signal selects a data enable signal for one frequency division to send only data of a unit element line to an LED head circuit. Thus, number of times of lighting LED elements in each dot position is reduced to reduce a diameter of latent image dots or a potential level and the toner consumption is reduced without causing disturbance in a print form.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a laser printer and LE.
To reduce the toner consumption on the print engine side in an image forming apparatus that forms a matrix-shaped dot image such as an electrophotographic recording apparatus applied to a D printer or other page printer, a facsimile, or a digital copying machine. The present invention relates to an image forming method characterized by the following.

[0002]

2. Description of the Related Art Conventionally, a dot-matrix pixel pattern is formed by repeatedly scanning a laser beam modulated based on video data serially output from an image controller along a generatrix of a photosensitive drum in a main scanning direction. Laser printers for forming a laser are known. Further, the array-shaped pixel forming means arranged in one row in the main scanning direction is arranged in a matrix on the photosensitive drum which relatively moves in the sub-scanning direction while controlling lighting for one line simultaneously or in block units based on video data. L forming a pixel pattern
ED printers are also known.

In this type of page printer, after the dot latent image written on the photosensitive drum is visualized with toner, the toner image is transferred to a transfer paper, and then the fixing device is used to perform the above-mentioned operation. Although the toner image is fixed, in such a printer, the consumption amount of the toner largely affects the running cost, and the page printer is 300 dpi or 600 dpi.
Since the print quality is extremely high, as in the case of, for example, when checking the print format or checking the created document, it may be necessary to suppress the toner consumption rather than the print quality. .

As such a toner-saving type image forming system, a dot thinning or line thinning type image forming system has been proposed in the past, but if, for example, odd dots or odd lines are thinned, As a result, horizontal stripes or vertical stripes in the form of fine line prints are not preferable. Therefore, there is also a technique in which, for example, odd-numbered lines and even-numbered lines are made different in thinning-out dots, and odd-numbered dots are thinned out in odd-numbered lines and even-numbered dots are thinned out in even-numbered lines, without uniformly thinning out dots. (Japanese Patent Laid-Open No. 62-227771)

[0005]

However, in such a method, since the thinning control is performed regardless of the shape of the print font, the print shape may be disturbed. Therefore,
A technique is also being studied in which dots in a stepped portion on the boundary line of printing are detected and dots in the stepped portion are not thinned out, and other dots are thinned out based on a predetermined rule. However, since all the toner saving methods are methods of thinning out dots forming a font, it is unavoidable that the print shape is disturbed.

In view of the above-mentioned drawbacks of the prior art, the present invention reduces the diameter or potential level of the latent image dots so that the print shape is not disturbed and the toner consumption can be reduced. The purpose is to provide a method.

[0007]

The present invention is disclosed in, for example, Japanese Unexamined Patent Publication No.
No. 16432 or the like, specifically, the original image data is divided into a plurality (M) of unit elementary data in the sub-scanning direction, and the unit elementary data is multiplied by M times the original image video clock. By using an image forming apparatus that is configured to be able to output serially to the print engine side in synchronization with the video clock set to, the unit data to be output to the print engine side in the toner saving mode is reduced while reducing the image data. It is characterized by reducing the toner consumption on the print engine side by performing the output.

[0008]

According to such a technical means, the one-dot latent image (corresponding to the original image data) written on the photosensitive drum corresponds to the unit elementary data a plurality of times in the sub-scanning direction such as the LED element and the modulation laser. Since it is obtained by optically outputting the exposure element, in other words, as shown in FIG. 1A, the exposure element is turned on a plurality of times for each scanning line and the latent image potential corresponding to the normal mode is obtained. If the image forming apparatus is configured so that the dot diameter can be obtained (in this case, the number of lighting times of the exposure element corresponding to the normal mode is not necessarily M times corresponding to the division unit element and is M times or less. In the toner saving mode, as shown in FIG. 1B, by controlling the controller side so as to reduce the number of times the exposure element is turned on, the diameter or potential level of the latent image dot is reduced. There is something to do , Thereby those to reduce the toner consumption by reducing the amount of toner adhering to the latent image dots.

Therefore, according to such a technique, the dots themselves are left by controlling the unit elements and the number of dots forming the original image, instead of thinning out all the dots corresponding to the original image data as in the prior art. As a result, the amount of toner adhering to the dots is reduced, so that the print shape is not disturbed and the toner consumption can be reduced. In this case, as shown in FIG. 2A, if the remaining reduced element, in other words, the unit pixel data position to be printed is always constant, there is a pattern in which the line width of one dot line becomes thin and faint. In such a case, as shown in FIG. 2B, the unit element data position to be printed can be appropriately changed and output to the print engine side to solve the problem. The boundary data of the original image data is detected, and the unit element data corresponding to the boundary data is output to the print engine side without reduction even in the toner saving mode as shown in FIG. 2C. This is preferable because the shadow of the print can be made clear.

[0010]

Embodiments of the present invention will now be illustratively described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative positions and the like of the components described in this embodiment are not intended to limit the scope of the present invention thereto, but are merely examples, unless otherwise specified. Not too much. Figure 3
Is applied to the original image data in the sub-scanning direction by M
This is a time-division LED head circuit in which unit element data obtained by dividing a pixel into individual unit element data is taken and the LED elements are sequentially driven and controlled in units of n bits. 1 is an n-bit LED element 1a Embedded LED chips 1A ...
LED array 10 in which the LEDs are arranged in a row is a drive IC of the LED array 1, and a shift register 11 having a memory capacity of a number corresponding to the number n of LED elements for each chip,
It is composed of a latch circuit 12 and a switch circuit 13 including a number of switch elements corresponding to the number n of LED elements, and the LED elements 1a of the chip 1A and the switch elements are connected via a matrix-shaped wiring pattern.

Reference numeral 4 denotes the switch element 13 and L for each transfer control of the unit element to the shift register 11 side by n bits.
It is a block designating circuit for selectively selectively switching the connection with the ED chips 1A.

To briefly explain the operation of the head circuit, first, the first n-bit unit pixel data is serially fetched and stored in the shift register 11 from the image control device (see FIG. 5) based on the clock. After that, based on the latch signal from the control circuit 5, the n-bit unit elementary data is latched in parallel by the latch circuit 12, and the output signal based on the latch data is transferred to the switch circuit 13 side to cope with it. The drive control of each LED element 1a of the LED chip 1A is performed.

Then, after the data is transferred to the latch circuit 12 in the shift register 11, the next n-bit unit prime data is continuously stored serially, and after the n-bit data is stored, the latch circuit is based on the latch signal. The data is latched on the side of 12 and a switching signal is sent from the control circuit 5 to the block designating circuit 4 to switch the connection of the switch circuit 13 to the next LED chip 1B.
The respective LED elements 1a of the LED chip 1B are driven and controlled, and thereafter, the same operation is repeated m times to output the unit elementary data for one scanning line.

Thereafter, the LED chips 1A to 1M are similarly processed.
By performing the drive control of (m × 4) times, the light output from the LED element is imaged on the photosensitive drum via the optical system, and the unit element is divided into four in the sub-scanning direction as shown in FIG. The latent image group is written, and the unit element latent image group is integrated to form a dot latent image corresponding to one original image data. Even in the normal mode, the smoothing process may be appropriately omitted without printing all four unit element lines for each main scanning line. (Refer to the unit element data of (P ₁ , 1) in the enlarged view of FIG. 4)

FIG. 5 is an overall configuration diagram showing an image control device of a toner saving mode / normal mode switching type according to an embodiment of the present invention used in the LED printer, and FIG. 6 is a time chart diagram thereof.

In the figure, for example, original image data video-developed in an image RAM (not shown) or the like is 300 dpi.
Is transferred serially to the shift register 21 in synchronism with the video clock corresponding to, and every time the original image data for one main scanning line is stored in the shift register 21, the conversion unit 22
In parallel to the first to fourth shift registers 23a ... (Hereinafter, the respective shift registers 23a
The data transferred to ... is the unit prime data. On the other hand, in the conversion unit 22, first, based on the horizontal synchronizing signal RES of 1200 dpi, the unit element data stored in the first shift register 23a is first read at a speed four times as high as that of the video clock (1200d).
pi) Serial transfer by clock, and then sequentially 120
The line counter 26 is driven by the horizontal synchronizing signal RES of 0 dpi.
While incrementing, the unit element data stored in the second, third and fourth shift registers 23b ... Are serially transferred to the side of the control circuit 25 based on the quadruple speed clock. On the other hand, the control circuit 25 includes a frequency dividing circuit 27 for transmitting a data enable ENA signal for setting which one of the shift registers 23a ... If the signal from the mode setting register 28 is in the normal mode, select the data enable ENA4 of 4 division,
The unit element data of the first to fourth shift registers 23a ... Are sequentially transmitted to the LED head circuit side. When the toner saving mode is selected, the data enable E
By selecting NA1 and transmitting only the data of one unit element line to the LED head circuit side, as shown in FIG.
As shown in, it is possible to reduce the number of times the LED elements are turned on at each dot position to reduce the diameter or potential level of the latent image dot, thereby reducing the amount of toner adhering to the latent image dot. It is possible to reduce the toner consumption.

Further, a unit element data selection circuit 31 consisting of a ring counter is provided on the exit side of the control circuit 25 to select the data enable ENA2 of frequency division by 2 from the frequency dividing circuit, and the unit element of the first shift register 23a. Regarding data, only the odd number data is selected by the data selection circuit 31 and transmitted to the LED head circuit side. For the unit elementary data of the second shift register 23b, the data selection circuit based on the horizontal synchronizing signal RES of 1200 dpi. 31 is counted up, only even data is selected and transmitted to the LED head circuit side. As a result of this LED
The unit element data position to be transmitted to the head circuit side can be appropriately changed by the first and second shift registers 23a and 23b and can be transmitted to the LED head circuit side. As a result, as shown in FIG. 2B, L at each dot position
It is possible to reduce the diameter or potential level of the latent image dot while appropriately changing the lighting position of the ED element, and it is possible to eliminate the faint pattern in which the line width of one dot line becomes thin. On the other hand, as shown in FIG. 2C, when the toner is saved while detecting the step, the mode setting register 2
8 selects the data enable ENA4 divided by 4 according to the signal for step detection, and the first to fourth shift registers 23a
The unit element data of ... Are sequentially transmitted to the data selection circuit 31 side, and the selection control of the unit element data is performed on the data selection circuit 31 side.

That is, at the same time as the parallel transfer from the shift register 21 to the conversion unit 25, a step detecting circuit 24 for detecting the step position by taking the AND of adjacent data in the main scanning direction is provided, and the step detecting circuit 24 is provided. The presence / absence of a step in each original image data is detected by and is sent to the data selection circuit 31 side. In the data selection circuit 31, for the unit prime data of the first shift register 23a, only the odd data is selected by the data selection circuit 31 and the LED is selected.
For the unit element data of the second shift register 23b, which is transmitted to the head circuit side, the data selection circuit 31 counts up based on the horizontal synchronization signal RES of 1200 dpi, selects only even data, and the LED head circuit side To the third and fourth shift registers 23c,
The unit element data of 23d is configured not to be transmitted. However, when the boundary position of the original image data is detected by the step detection circuit 24, the detection signal is transmitted to the data selection circuit 31 so that the unit selection data corresponding to the boundary position is selected by the data selection circuit 3.
The boundary unit elementary data of the first to fourth shift registers 23a is selected without inhibiting on the 1st side and transmitted to the LED head circuit side. As a result, as shown in FIG. 2C, it is preferable that even in the toner saving mode, the shadow of printing can be made clear by outputting to the print engine side without reduction.

[0019]

As described above, according to the present invention, the print shape is disturbed in order to reduce the toner consumption by reducing the diameter or potential level of the latent image dot without thinning out the dots corresponding to the original image. It is possible to obtain a toner-saving type image forming method without causing the problem. It has various remarkable effects.

[Brief description of drawings]

FIG. 1 shows the relationship between the number of times an exposure element is turned on and the latent image dot diameter and potential, (A) showing a normal mode and (B) showing a toner saving mode.

FIG. 2 shows various forms of toner saving mode, (a)
Shows that the unit element lines are uniformly reduced, (b) shows that odd unit element data and even unit element data are alternately selected,
(C) shows the detected boundary data of the original image data.

FIG. 3 shows a time division type LED head circuit to which the present invention is applied.

FIG. 4 shows a unit element latent image group divided into four in the sub-scanning direction.

FIG. 5 is an overall configuration diagram showing a toner saving mode / normal mode switching type image control device 5 according to an embodiment of the present invention used in the LED printer.

FIG. 6 is a time chart diagram of FIG.

[Explanation of symbols]

21 shift register 22 conversion unit 23a, 23b, 23c, 23d first to fourth shift register 26 line counter 25 control circuit 27 frequency divider circuit 28 mode setting register

Claims (3)

[Claims] 1. A plurality of original image data in the sub-scanning direction (M
The image forming apparatus is configured so that it can be serially output to the print engine side while being synchronized with a video clock set to M times the original image video clock. In the toner saving mode, the image data is output while reducing the unit element data to be output to the print engine side, thereby reducing the toner consumption on the print engine side. 2. The image forming method according to claim 1, wherein the unit element data position output to the print engine side is appropriately changed and output to the print engine side. 3. The boundary data of the original image data is detected, and the unit element data corresponding to the boundary data is
The image forming method according to claim 1, wherein the toner is output to the print engine side without reduction even in the toner saving mode.