JPH0567423B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for supplying ink and dampening water to an offset printing press.

Normally, in offset printing, the supply of dampening water is sequentially carried from a water source roller to a water transfer roller and a dampening roller, and finally the dampening water is applied from the dampening roller to the printing plate surface.

Thereafter, an ink applicator roller in the ink supply device applies ink to the image area of the plate.

At this time, if the amount of dampening water from the dampening roller is less than the appropriate amount, ink will adhere to areas other than the image areas of the plate, resulting in stains.

Similarly, even if the amount of dampening water is constant, if the amount of ink supplied to the printed area is greater than the appropriate amount, there is a drawback that stains may occur.

In addition, if the amount of dampening water is large, the ink tends to emulsify, resulting in a decrease in the density and gloss of the printed matter, and furthermore, there is a drawback that the paper expands and contracts, resulting in poor registration.

The above phenomenon occurs even when the amount of dampening water is constant but the amount of ink supplied to the printed area is less than the appropriate amount. As mentioned above, in order to produce printed matter of excellent quality, it is necessary to keep the balance of ink and water within an appropriate range.

Conventionally, dampening water is controlled by an operator who periodically visually observes the finished state of the printing book and controls the increase and decrease of dampening water and ink.

Therefore, the quality is greatly influenced by the skill level of the operator, and it is difficult to maintain a constant quality level, and the current situation is that it is easy to produce defective printed matter such as insufficient density or lack of gloss.

Recently, in an attempt to produce printed matter of a certain quality, as shown in FIG. 1a, a large number of areas A, B,
After dividing into C...E and F and calculating the picture area ratio for each area, attach the offset printing plate to the cylinder of the offset printing machine as shown in Figure 1b and calculate the picture area ratio for each area. There is a device that presets the ink supply amount before printing based on a preset appropriate ink supply amount. Here, the preset appropriate ink supply amount means that the correspondence between the pattern area ratio and the ink supply amount is determined in advance for each printing machine, and the ink supply amount is determined in advance according to the value of the pattern area ratio. The amount of supply is determined.

By using this device, the amount of ink supplied is controlled by the image area ratio for each area of the plate.

That is, if the picture area ratio of a certain area is large, the amount of ink supplied to that area will be large, and conversely, if the picture area ratio of a certain area is small, the amount of ink supplied to that area will be small.

However, even if the ink supply amount is controlled, if the dampening water is not controlled, as mentioned above, it will not be possible to maintain an appropriate supply balance of ink and dampening water, and it will be difficult to maintain high quality printed matter in terms of density, gloss, etc. It will no longer be possible to manufacture Even if dampening water is controlled, if a constant amount of dampening water is supplied from the water source roller of the dampening water device, the following problems will occur.

In other words, since the plate is divided into many areas in the vertical direction and the ink supply amount is controlled in proportion to the image area ratio of each area, there is no problem with plates where the image area ratio of each area is almost equal. In the case of plates with large area ratios, if a uniform amount of dampening water is supplied to each area, the amount of dampening water may be insufficient in areas with large image area ratios, and stains are likely to occur. Furthermore, in areas where the pattern area ratio is small, a large amount of dampening water is applied, resulting in a state where insufficient density and insufficient gloss are likely to occur.

It is impossible to satisfy both of these requirements, and the current situation is to use a large amount of dampening water to avoid stains, even at the cost of insufficient density and gloss.

The present inventor focused on the above points and tried the following method as a method of controlling the supply amount of ink and dampening water by utilizing the picture area ratio of the printing plate.

That is, according to the above method, the printing plate is divided into a large number of areas in the vertical direction, the pattern area ratio of each area is measured, and the ink supply amount for each area is determined using an ink adjusting means such as an ink key based on the data. At the same time, the rotational speed of the water head roller is controlled based on the picture area ratio of the entire printing plate obtained from the picture area ratio of each area and a preset appropriate ink supply amount, and the picture area ratio of each area is controlled. The number of rotations of the divided roller, which is installed on the water transfer roller and is divided into each area, is controlled by the pre-printing machine, and the amount of dampening water is preset in accordance with the image area ratio of each area, and the ink is applied to each area. A well-balanced amount of dampening water can be supplied with respect to the supply amount.

However, with the above method, although the balance between ink and dampening water can be maintained for each area during printing, fluctuations during printing, such as changes in ink viscosity due to increases in printing machine temperature and evaporation rate of dampening water, etc. It is difficult to maintain a consistent supply balance.

Therefore, it is not possible to always produce printed matter of constant quality during printing.

The present invention aims to improve the above-mentioned drawbacks and provide a method and apparatus for producing printed matter of constant quality by always maintaining a constant balance of ink and dampening water from the start of printing to the end of printing.

The ink and dampening water control method according to the present invention includes:
At the same time as printing starts after performing the presetting as proposed above, the concentration of ink supplied to the ink supply amount measuring marks formed in the margins of each area of the printing plate or the concentration of ink transferred from the marked portions to the printing substrate is determined. The ink supply amount is detected for each zone based on the ink concentration, and based on the detection data of the ink supply amount, the ink source is adjusted so that the ink supply amount is constant with respect to the preset appropriate amount. The number of revolutions of the roller and the interval between the ink key and the ink source roller are controlled, the amount of dampening water supplied to each area on the dampening roller is detected, and based on the detection data of the amount of dampening water supplied, By controlling the rotational speed of the dampening water source roller and the rotational speed of the divided rollers so that the dampening water supply amount is constant with respect to the set appropriate amount, the dampening water supply amount is always constant from the start of printing to the end of printing. It maintains the balance between ink and dampening water.

Next, the present invention will be explained in more detail with reference to the drawings.

FIG. 2 is an explanatory diagram of the apparatus of the present invention, in which first the number of revolutions of the ink source roller 14 is controlled in order to control the overall amount of ink supplied to the plate 20.

This control is performed by integrating the picture area ratio measured by the picture area ratio measuring device 41 for each area divided in the vertical direction as shown in FIG. The area ratio is calculated and the measurement data of the pattern area ratio of each area and the pattern area ratio of the entire plate is output to a magnetic card. Although the area width varies depending on the machine, it is often about 30 mm.
The data recorded on this magnetic card is read by a card reader 1 and input to an ink and dampening water supply control device 3 that controls the overall amount of ink and dampening water to the plate 20. is input to a second ink and dampening water supply control device 2 which controls the amount of ink and dampening water for each zone.

Signals from the ink and dampening water supply control device 3 enter a source roller speed control circuit 5 of the inking device.

The speed control circuit 5 inputs a control signal for controlling the rotation speed of the ink source roller 14 to the motor 8, drives the motor 8, and controls the rotation speed of the ink source roller 14. Through the above steps, the amount of ink required for the entire plate 20 is set.

Next, the pattern on the printing plate 20 is divided into regions in the vertical direction as shown in FIG. 1, and the amount of ink supplied is adjusted for each region. This is done as follows.

The image area ratio data for each area read by the card reader 1 as described above is input to the ink and dampening water supply control device 2. The ink and dampening water supply control device 2 calculates the ink supply amount and dampening water supply amount for each area based on the picture area ratio for each area and a preset appropriate ink supply amount. Among these, the ink supply amount data is transmitted from the ink and dampening water supply control device 2 to the rotational position control device 4.
to go into.

The rotational position control device 4 inputs a control signal to the motor 7 to rotate the eccentric bearing ring 13 divided into the sections.
is driven to adjust the distance between the ink source roller 14 and the eccentric bearing ring 13 for each area.

Therefore, ink corresponding to the picture area ratio of each area of the plate 20 is adjusted and supplied to each area from the ink 27 stored in the ink reservoir of the inking device.

If the pattern area ratio of a certain area is large, the distance between the ink source roller 14 and the eccentric bearing ring 13 of that area is increased to increase the amount of ink supplied to that area.

Conversely, if the picture area ratio in a certain area is small, the interval is made smaller to reduce the amount of ink supplied to that area. In this way, the necessary amount of ink is supplied to the entire plate 20 depending on the rotation speed of the ink source roller 14, and the supply amount is controlled for each area according to the picture area ratio of each area of the plate 20, and the ink source roller 1
4, different ink film thicknesses are transferred to the ink feed roller 15 that contacts the ink source roller 14 in each divided area.

The different amounts of ink for each area are sequentially conveyed to the ink reciprocating roller 16, the ink kneading roller 17, and the ink reciprocating roller 18, and finally to the ink forming roller 19.
The required amount of ink is transferred to the plate 20 for each area. Further, the supply of dampening water 26 is controlled in order to maintain a balance with the ink supply amount. This control is performed as follows.

As described above, the overall moisture required is determined based on the image area ratio of the entire plate read by the card reader 1 and input into the ink and dampening water supply control device 3 and the appropriate dampening water supply amount set in advance. The amount of fresh water is calculated and this signal is input to the speed control circuit 10. Here, the preset appropriate dampening water supply amount is the correspondence relationship between the pattern area ratio and the dampening water supply amount that has been determined in advance for each printing machine, and is based on the numerical value of the pattern area ratio. The dampening water supply amount is determined accordingly.

The speed control circuit 10 inputs a control signal for controlling the rotation speed of the water head roller 21 to the motor 11, drives the motor 11, and controls the rotation speed of the water head roller 21.

As described above, the amount of dampening water required for the entire plate 20 is set.

Next, using the measurement data of the pattern area ratio for each area of the plate 20, the supply amount of dampening water is adjusted for each area. This adjustment is performed as follows.

The image area ratio for each area read by the card reader 1 as described above is input to the ink and dampening water supply control device 2. The ink and dampening water supply control device 2 calculates the amount of dampening water supplied for each area based on the image area ratio data for each area, and this data is input to the speed control circuit 6.

The speed control circuit 6 inputs a control signal for controlling the rotation speed of the divided roller 24 to the motor 9, drives the motor 9, and controls the rotation speed of the divided roller 24 divided into each area.

The dampening water 26 is supplied to the water transfer roller 22 in an amount necessary for the entire plate 20 by the rotation speed of the water source roller 21 which is controlled based on measurement data of the image area ratio of the entire plate. and the dampening water 26 on the water transfer roller 22.
is divided by the next dividing roller 24 into ink area widths e. As shown in FIG. 3, the dividing roller 24 is in contact with the water transfer roller 22 with a certain nip width, and is divided into ink area widths e. The divided rollers 24 are arranged such that the upper and lower parts are in contact with each other alternately. The divided rollers 24 are overlapped with a certain width a to eliminate gaps between the rollers. This overlap width a is suitably 1 to 2 mm, but is not limited to this value. The reason for this overlap is that if there is a gap between the rollers, a larger amount of water will be supplied during this gap, and the lines will appear as water marks on the printed matter, so the adjacent divided rollers will overlap to eliminate the water marks.

Further, both end rollers of the divided roller 24 protrude from the water transfer roller 22 by a certain width b to prevent excess dampening water from transferring from the ends of the water transfer roller. This protrusion width is usually about 10 mm, but is not limited to this value.

In this way, from the water base roller 21 to the water transfer roller 2
The amount of dampening water supplied to the ink area 3 is distributed and supplied by the dividing roller 24 in proportion to the pattern area ratio for each ink area width e. Here, when the pattern area ratio of each area is extremely different, the amount of dampening water is different at the boundary as shown in FIG. 4a. If printed in this state, the boundary line will appear as water marks on the printed matter as described above, which is not preferable. Therefore, in this embodiment, the boundaries are smoothed by overlapping the dividing rollers. FIG. 4b shows the amount of dampening water in this case. However, this alone does not completely remove the water, so the next swing width d of the reciprocating roller 25 is used to even out the distribution of dampening water in the boundary area as shown in FIG. 4c to prevent the water.

This reciprocating roller 25 rotates in contact with the water transfer roller 22 with a certain nip width. The swing width d of this reciprocating roller 25 is suitably about 5 mm, but is not particularly limited to this value. Further, both ends of the reciprocating roller protrude beyond the water transfer roller by a certain width c to prevent excess dampening water from transferring from the end of the water transfer roller. This protrusion width is usually about 10 mm, but is not limited to this value. The dampening water 26 leveled by the reciprocating roller 25 is conveyed to the bathing roller 23, and the required amount of dampening water 26 is transferred to the plate 20 for each area.
Further, there is no problem even if the divided rollers are arranged alternately so that they overlap each other by a certain width a value, and the adjacent rollers do not come into contact with each other. Also, this reciprocating roller 25
There is no problem in shaking the divided rollers 24 as a whole without providing them, or shaking the water transfer roller.

The explanation above has been based on the case where the divided rollers are provided alternately on the upper and lower sides, but as shown in Fig. 5, the divided rollers 24
It is also possible to arrange them in a straight line. As the split roller, a hollow pipe with a rotating mechanism inside can be used. An example of the mechanism will be explained with reference to the circumferential cross-sectional explanatory diagram of the dividing roller 24 in FIG. 10 and the axial cross-sectional explanatory diagram of the dividing roller 24 in FIG. Bearings 51 at both ends
A ring of permanent magnets 48 consisting of N and S poles is fitted through the ring, a roller member 47 is provided on the outer periphery of the permanent magnet 48, and wiring (not shown) is provided inside the hollow pipe 50 to supply electricity. The opposite has happened. In this case, although a slight gap is created between adjacent rollers, it is smoothed out by the next reciprocating roller, so no particular problem occurs.

The divided roller 24 controls the amount of dampening water supplied to each area by transferring a portion of the water film formed on the water transfer roller 22 to the dividing roller and leaving the other portion on the water transfer roller 22. As the number of rotations of the divided rollers increases, the amount of dampening water remaining on the water transfer roller 22 decreases, and the amount of dampening water supplied to the plate decreases.

In this case, the water transferred to the dividing roller 24 is removed from the dividing roller 24 by evaporation or the like, but if the removal is not sufficient, the water returning rollers 32, 33, 34, etc. are removed as shown in FIG. It may also be forcibly removed using

As described above, using the data of the image area ratio of the plate,
The ink and dampening water supplies are preset before printing, and then printing begins.

However, the thickness of the water film on the plate surface and the amount of ink supplied vary due to fluctuation factors during printing, such as changes in ink viscosity due to increases in printing machine temperature and changes in the evaporation rate of dampening water. It becomes impossible to maintain water balance, and it is necessary to adjust the supply amount of dampening water and ink supply. Therefore, according to the present invention, in order to maintain the supply balance of ink and dampening water that follows the fluctuation factors during printing, the ink is supplied to the ink supply amount measurement marks formed in the margins of each area of the printing plate. The ink supply amount is detected for each area based on the ink density transferred from the marked portion or the ink density transferred from the mark portion to the printing substrate, and based on the detection data of the ink supply amount, the ink supply amount is determined according to the preset appropriate amount. , the rotation speed of the ink source roller and the interval between the ink key and the ink source roller are controlled so that the ink supply amount is constant, the amount of dampening water supplied to each area on the dampening roller is detected, and the dampening water is Based on the detection data of the dampening water supply amount, the rotation speed of the dampening water source roller and the rotation speed of the divided roller are controlled so that the dampening water supply amount is constant with respect to the preset appropriate amount. By doing so, a constant balance of ink and dampening water is always maintained from printing to the end of printing, and the balance of ink and dampening water can be maintained well even during printing.

In order to reduce fluctuations in the dampening water supply amount during printing and keep it within a certain range, the dampening water supply amount is detected for each area on the dampening roller, and this dampening water supply amount data is used. This method provides feedback to the water base roller and the divided rollers, and by controlling the rotational speed of the water base roller and the divided rollers during printing using the feedback data, the amount of dampening water supplied can be kept within a certain range. .

Methods for detecting the amount of dampening water include capacitance, electrical conductivity,
Although there are various methods such as reflectance of infrared rays, in this embodiment, a method using reflectance of infrared rays will be described.

According to this method, two or more infrared rays of different wavelengths are irradiated onto the water forming roller, and the water film thickness is measured by detecting the difference in the amount of light reflected by the two or more infrared rays from the plate surface. The amount of dampening water can be detected.

Next, a case will be described in which the water film thickness of the water forming roller is detected and the rotation speed of the water base roller is controlled based on this data.

FIG. 7 is an explanatory diagram of the dampening water supply amount detection mechanism that detects the dampening water supply amount as described above, and the dampening water supply amount detector 12 is provided parallel to the dampening water application roller 23. It is attached to a bar 43 and can be moved left and right, and its position is set manually. Once the position of the dampening water supply amount detector 12 is set as described above, it can be synchronized by interlocking with the rotary encoder 28 attached to the plate cylinder and always measure the water film thickness at the same location. good. Water film thickness is 0.5~
It is common to adjust the thickness to be in the range of 2.5μ, but it is preferable to keep it within the range of 0.7 to 1.2μ.

The water film thickness data thus enters the speed control circuit 44. The speed control circuit 44 is connected to the water head roller 21.
A control signal for controlling the rotation speed of the water head roller 2 is inputted to the motor 45 to drive the motor 45.
The rotation speed of 1 is controlled to keep the water film thickness of the non-image area of the plate constant. The water base roller 21 is controlled by the motor 11 that drives the water base roller 21 during presetting before printing and the data from the detector 12 during printing.
A switch 46 is used to switch between the motor 45 that drives the motor 45 and the drive motor 45 .

Above, we have explained the method of installing a dampening water supply amount detector on the swimsuit roller to measure the water film thickness on the swimsuit roller and controlling the rotation speed of the water fountain roller based on the data. A dampening water supply amount detector is installed on the swimsuit roller for each zone, the water film thickness on the swimsuit roller is measured for each zone, and the rotation speed of the divided roller divided for each zone is determined based on the data. It may be controlled, and by doing so, even more precise control becomes possible.

Furthermore, both the dividing roller and the water head roller may be controlled. Split roller 2 during presetting before printing
Switching between the motor 9 that drives the roller 4 and the motor 45 that drives the dividing roller 24 based on data from the detector 12 can also be performed by a switch as described above.

Furthermore, in the present invention, the ink supply amount during printing is constantly detected, and the ink supply amount is controlled based on this detection data so that the ink supply amount during printing is constant. The amount of ink supplied can be obtained by measuring the ink density on the printing plate or the ink density printed on the printing material using a reflection densitometer.

Next, a method of constantly detecting the ink supply amount during printing and controlling the ink supply amount during printing will be described.

First, as shown in Figure 9a, mark 3 for measuring ink supply amount is placed at one place on the margin of the offset printing plate.
0 is set, a number of reflective densitometers corresponding to the detection points are provided, and the ink density on the plate surface of the mark or the representative surface of the printing medium is measured, and based on the data, the ink is transferred from the ink forming roller to the detection point. Measure and detect the amount of ink supplied.

The mark has 300 lines/to improve detection accuracy.
It is better to use thin parallel horizontal lines of inch. However, the mark is not limited to this.

The density at which an appropriate ink film is applied to the mark is stored in advance in the memory of the ink supply control circuit 36. The density value from the ink density measuring device 35 enters the ink supply control circuit 36 and is compared with the data stored in the memory.

Based on the density difference data, the ink supply control circuit 36 issues a control signal to drive the motor 37. This control signal drives the motor 37 to change the rotational speed of the ink source roller 14 to control the amount of ink supplied to the entire plate.

In the above explanation, a mark was placed in one place on the margin of the printing plate to measure the amount of ink supplied.
When marks 30 for measuring the amount of ink supplied are provided in each ink key area as shown in FIG. 9b, the number of ink concentration measuring devices 35 corresponding to the marks are provided.

Ink density measuring device 35 for each ink key area
The individual density values on the printing plate or paper surface are input to the ink supply control circuit 36 and compared with the value already stored as the proper density value. A control signal is issued for each area to drive the individual motors 37 that rotate the divided eccentric bearer rings 13. Based on this control signal, the motors 37 divided into sections are driven to drive the eccentric bearing ring 13.
change the rotation angle.

Therefore, by measuring the ink concentration for each ink key area, it is possible to control the ink supply amount for each ink key area. Further, the ink density measuring device 35 is a rotary encoder 2 attached to the plate cylinder.
Synchronization is achieved using a pulse signal such as 8, so that the same location is always measured.

The ink concentration measuring device 35 is attached to a support bar provided parallel to the printing plate surface or to a support bar provided parallel to the printing medium, as in the case of the dampening water supply amount detector. In this case, as shown in FIG. 9a, the ink supply amount measurement mark 30
When the ink density measuring device 35 is provided at one location, the ink density measuring device 35 is movable along the support bar, and the ink density measuring device 35 can be manually set at the location of the mark 30. can do. Further, when the ink supply amount measurement mark 30 is provided for each area as shown in FIG.
They are installed one by one.

The attachment state of the ink concentration measuring device to the support bar and the flow of the detection signal from the ink concentration measuring device are similar to those in FIGS. 7 and 8 showing the control mechanism for the amount of dampening water supplied. Therefore, it is omitted here. However, in the case of controlling the ink supply amount, in the case corresponding to Fig. 7, it is the ink source roller that is controlled by feedback from the detection data, and in the case corresponding to Fig. 8, the ink source roller is controlled by feedback from the detection data. Needless to say, it is the eccentric bearing ring that is fed back and controlled by data.

As explained above, according to the present invention, after presetting the supply amount of ink and dampening water before printing, the thickness of the water film on the printing plate or swimsuit roller is measured during printing, and the rotation speed of the dividing roller is determined. In addition, the amount of ink supplied during printing is measured to control the rotation speed of the ink source roller and/or the distance between the ink source roller and the ink key, so the pattern area ratio for each ink area is controlled from the start of printing to the end of printing. The appropriate supply balance of ink and dampening water is maintained, making it possible to easily and stably produce printed matter of constant quality.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of an offset printing plate divided into many areas in the vertical direction, FIG. 2 is an explanatory diagram of the apparatus of the present invention, FIGS. 3 and 5 are explanatory diagrams of the dividing roller, and FIG. The figure is an explanatory diagram of the distribution of the dampening water supply amount, Figure 6 is an explanatory diagram of the water return roller, Figures 7 and 8 are explanatory diagrams of the dampening water supply amount detection mechanism, and Figure 9 is an explanatory diagram of the ink supply. FIGS. 10 and 11 are explanatory diagrams of the quantity measuring marks, respectively, and are explanatory diagrams of cross-sections in the circumferential direction and axial direction of the divided roller of FIG. 5, respectively. 1... Card reader, 2, 3... Ink and dampening water supply control device, 4... Rotation position control device,
5... Ink source roller control circuit, 6, 10, 44
...Speed control circuit, 7, 8, 9, 11, 37, 4
5... Motor, 12... Detector, 13... Bearer ring, 14... Ink source roller, 15...
Ink feed roller, 16, 18... Ink reciprocating roller, 17... Ink kneading roller, 19... Ink forming roller, 20... Plate, 21... Water base roller, 22... Water transfer roller, 23... Water Application roller, 24...Divided roller, 25...Water reciprocating roller, 26...Mountain water, 27...Ink, 28...
Rotary encoder, 32, 33, 34...
Water return roller, 35... Ink concentration measuring device, 36
...Ink supply control circuit, 43 ... Support bar, 4
6...Switch, 47...Roller member, 48...
Permanent magnet, 49...Coil member, 50...Hollow pipe, 51...Bearing.

Claims (1)

[Scope of Claims] 1. Divide the offset printing plate into a large number of areas in the vertical direction, determine the image area ratio of each area and the image area ratio of the entire offset printing plate, and calculate the image area ratio and the preset ink supply. In the ink and dampening water supply method, which controls the ink and dampening water supply amount based on the appropriate amount of the ink and dampening water supply amount, before printing starts, the image area ratio of the entire offset printing plate and the aforementioned Determining the rotational speed of the ink source roller and the water source roller, which control the overall supply amount of ink and dampening water, based on the preset appropriate amounts of ink supply amount and dampening water supply amount, and determining the interval between the ink key and the ink source roller to control the ink supply amount for each area based on the picture area ratio for each area and the preset ink supply amount and dampening water supply amount; Rotation of a divided roller divided into each area, which controls the amount of dampening water supplied to each area based on the picture area ratio and the preset appropriate amounts of ink supply and dampening water supply. The number of ink and dampening water during printing is balanced based on the determined rotation speeds of the ink source roller, water source roller, and split roller and the distance between the ink key and the ink source roller, and the ink and dampening water are balanced during printing. Ink supply to each area is determined based on the ink concentration supplied to the ink supply amount measuring mark formed in the margin of each area of the printing plate or the ink concentration transferred from the mark area to the printing substrate. Based on the detection data of the ink supply amount, the rotation speed of the ink source roller, the ink key, and the ink source roller are adjusted so that the ink supply amount is constant with respect to the preset appropriate amount. , the dampening water supply amount for each area on the dampening roller is detected, and based on the detection data of the dampening water supply amount, the dampening water is adjusted to the preset appropriate amount. By controlling the rotational speed of the dampening water source roller and the rotational speed of the divided rollers so that the amount of dampening water supplied is constant, a constant balance of ink and dampening water is always maintained from the start of printing to the end of printing. A method for supplying ink and dampening water, characterized by: