JPH06316120A - Printer - Google Patents

Abstract

PURPOSE: To reduce peak power requirements in a printer. CONSTITUTION: A density monitor 36 receives print data from a print data source 34 through a line 40 and a signal is sent to a servo control 38 for setting the rotating velocity of a drive motor 18 based on a raster image density. The density monitor 36 may be equipped with an independent microprocessor. The density monitor 36 decides appropriate timing for changing the velocity based on the print data in accordance with the position of a recording medium on a vacuum conveying belt 14. The density monitor 36 can select the appropriate velocity based on the value of a stored lookup table.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to reducing the peak power requirements of printers, and more particularly to printers having workstations that are powered on in an immediate response manner.

[0002]

2. Description of the Related Art Reprographic apparatuses of various types such as those using electrophotographic copying technology are used. Such devices incorporate a workstation that is maintained at a predetermined operating power level. A relatively constant speed sheet transport system is utilized to ensure good image quality. For this reason,
After the start-up condition has been achieved, the power input required by such devices tends to be relatively constant.

In recent years, thermal ink jet printing has been developed as an alternative to fused toner imaging technology utilized in electrophotographic devices and other hard copy imaging devices. Thermal inkjet printing is basically an immediate response system, which requires little power during idle conditions and high power at high speed and high image density (density) conditions. The advantage of inkjet printing is that the image quality does not deteriorate even if the processing speed is high compared to other methods.

Since it is necessary to boil the liquid component of the ink (usually water) twice, the ink is blown onto the recording medium by the first boiling, the ink is dried by the second boiling, and the ink is fixed on the recording medium. Power input excursion in the duty cycle of a thermal inkjet printer. In order to keep the total power consumption low, it is desirable to utilize an instant response dryer, such as a microwave dryer, which also has a wide range of power input requirements that are also dependent on copy speed and ink density. In an inkjet printer or marking engine that copies at a speed of 30 sheets per minute, approximately 25 is required when printing with high image quality using only black ink.
00 watts of power is required. A process color printer capable of copying 90 sheets per minute requires approximately 15,000 watts for high image quality. These power requirements tend to cause bursts. One burst occurs when the thermal inkjet printer bar is working,
The other burst occurs when the recording medium passes through a microwave dryer. This causes a significant peak power excursion over the printer duty cycle. However, from the viewpoint of user's acceptability, ordinary electric wires such as 1.5 kV ampere receptacle (outlet or socket) matching line, which are commonly used in offices and homes, are used as power sources for such printers. It is preferable to meet the requirements.
This saves the expense of installing special wires and provides flexibility in installing the device.

[0005]

One aspect of the present invention is a printing apparatus capable of printing with varying print density, which is provided on a base and on the base for moving a recording medium along a feed path. A movable support body, a printer provided along the feed path at a predetermined position for printing on a recording medium arranged in the feed path, a variable speed drive member for driving the movable support body, A control device for controlling the driving speed of a driving member; a means for supplying print data to the printer; a judging means for judging the print density of an image printed on the recording medium from the print data; and a judging means. The determination of the print density of the image printed on the recording medium is received, and the speed of the drive member is changed according to the print density of the image printed on the recording medium by the printer. A driving speed setting means for controlling the peak power requirements of the printer controls the urchin said control device, and a.

The object of the invention is achieved by a printing device in which the transport speed of the recording medium is inversely related to the density of the image printed on the recording medium. The support member that carries the recording medium along the transport path of the printing apparatus is driven by variable speed driving. The input power requirement is estimated by scanning the print data supplied to the printer to determine the density of the printed image or by evaluating the power level required to dry the ink in the dryer. Since the control system utilizes the predicted power demand to control the speed of the drive, the speed of the recording medium as it passes through the printer, the dryer, or both in high density images is Will be decelerated in proportion to. By controlling the residence time of the recording medium in the printing station and / or the drying station, the peak power requirement at each station can be dampened and the control is simplified.

Another aspect of the present invention is a printing apparatus,
Means for depositing a dry ink on the recording medium to form an image, a drying device having energy absorbing means for absorbing energy not consumed in drying the ink, and a drying device for passing through the drying device. A transport member for transporting the recording medium on which an image is formed, and an amount of energy absorbed by the energy absorbing means for determining energy consumed by the drying device for drying ink on the recording medium. And a means for controlling the speed of the conveying member according to the energy consumption determined by the determining means.

[0008]

DETAILED DESCRIPTION OF THE INVENTION Since thermal ink jet printers have a duty cycle with widely varying power requirements, the following description is in the context of thermal ink jet printers as a good example of the description. However, the present invention can be utilized in a variety of printer designs where peak power requirements are reduced to desirable levels.

According to FIG. 1, the printing device 10 has a housing 12 in which a conveyor belt 14 is arranged. Preferably, the belt 14 has small holes and the sheet S
Recording media such as ₁ and S ₂ are transferred to the transport areas 14a and 14a.
In b, it is associated with a vacuum source (not shown) that temporarily attaches to the belt 14 so that the sheet does not move or displace relative to the belt, which allows the sheet to pass through the device. Accurate positioning of the seat can be ensured.

The conveyor belt 14 is endless and is supported by a series of rollers 16. At least one roller 1
6a is driven by a variable speed drive motor 18. Also,
The belt 14 is also wound around a roller 24 a that drives the encoder 24. The encoder 24 may be a conventional optical encoder or an inductive encoder, but is preferably designed with a laser readable compact disc.

The printer 20 is disposed in the housing,
It is possible to have one full-width thermal inkjet printing bar 21a for printing monochrome documents. If color printing is required, the printer 20 has additional printer bars 21b, 21c, 21d commonly used for cyan, magenta, yellow or red, green and blue, respectively. Printer 2
Downstream of 0 is a dryer 26, preferably a microwave type.

Recording media such as the sheets S ₁ and S ₂ are supplied into the printer apparatus through the sheet inlet 28 and are placed on the conveyor belt 14. The sheet is conveyed to the printer 20 by the conveyor belt 14. The sheet beneath the print bar is partially supported by the plate 22. A configuration that has been found to be particularly useful is to place the encoder 24 under the plate 22 and the displaced portion of the belt is wrapped around the roller 24a of the encoder 24. In this configuration, a space is provided under the thermal inkjet bar to provide a maintenance station (not shown) for the injet bar that maintains the inkjet bar in the operating condition. Such maintenance stations are well known in the art and their detailed description is not considered necessary.

The encoder 24 provides signals indicating the position of the belt, which signals calculate the speed of the belt 14 to control the operation of workstations such as printer 20 and dryer 26, or otherwise the operation of the printer. Used to control the.

Drive motor 18 drives at least one roller 16 such as roller 16a, which in turn causes belt 14 on roller 16 to move. At the inlet 28, the sheets (S ₁ , S ₂ ) are fed onto the belt 14. The vacuum device associated with the belt holds each sheet on the belt so that it does not move laterally or longitudinally with respect to the belt after it is placed on the belt. The belt 14 carries the sheet to the printer station 20, where the ejected ink forms an image on the upper side of the sheet. Since the length of the support plate 22 is shorter than the supplied sheet length, the sheet always partially adheres to the belt and moves with the belt.
After passing through the printer 20, the sheet is directed into a dryer 26 where water or other liquid components of the ink deposited on the sheet are vaporized. The continuous movement of the belt 14 drives the sheet to the outlet 30, and the sheet is taken out or the next processing is performed. Therefore, the inlet 28,
The belt 14 and the outlet 30 form a supply path that penetrates the printing apparatus 10.

Generally, the printer 10 is controlled so that the processing speed can be changed instantly depending on the ink density being jetted and / or dried. In the case of low density (density) image formation (about 6% to 20% density), the motor 18 is driven at high speed. As the density increases, the speed of the drive motor 18 is correspondingly reduced, so that the power required by the printer and / or the power required by the dryer is maintained below a predetermined level. In this way, each sheet can be passed through the printer with varying speed rates depending on the print density in each area of the sheet.

FIG. 2 schematically illustrates one embodiment of a control system for printing device 10. Thermal inkjet print bars 21a, 21 for controlling image formation on a recording medium by a source 34 of print data such as a video source
Print data is provided to b, 21c, and 21d. The data may be in the bitmap data format and is supplied line by line in the conventional raster system. In the illustrated embodiment,
The density monitor 36 receives the print data from the line 40 and sends a signal to a servo control 38 which sets the speed of the drive motor 18 based on the raster pixel density. Concentration monitor 3
6 can have a stand-alone microprocessor or can be implemented within the microprocessor that controls the printer. From the print data, the density monitor determines an appropriate timing for changing the speed according to the position of the recording medium on the vacuum conveyance belt 14. Based on the values in the stored look-up table, the density monitor can select the appropriate speed. These values are empirically determined for the printer. That is, the table correlates the range of density levels and the copy speed at each density level that keeps the power consumption of the printing station 20 and / or the dryer 26 below a predetermined power level.

Alternatively, the density monitor 36 can output a speed control signal by detecting the current of the print head and send it to the servo controller 38. The above-mentioned concentration determination configuration can be realized by a fixed programming technique. Therefore, detailed description of the density monitor 36 is unnecessary.

Instead of monitoring print data, microwave dryer 26 can be monitored to provide speed control information. Ideally, a microwave dryer such as dryer 26 should be operated at a constant power output. This output partially combines with the ink as it heats and dries the ink. Electric power that exceeds the electric power required to dry the ink is absorbed by the dummy load.
At the quasi load, the excess microwave power is converted to heat and this heat is dissipated. The amount of power dissipated in the pseudo load is directly related to the ink density on the recording medium and the speed at which the recording medium moves through the dryer. If the dummy load absorbs little power, this indicates that the dryer is operating at a rate that is almost optimal for print density during drying. The higher the power dissipated in the dummy load, the less ink is dried, which is due to the lower speed and / or density of the recording medium. Under these conditions, the speed of the belt 14 can be increased, so that more ink can be fed into the dryer per unit time. In FIG. 2, the dotted line 40 ′ shows the connection between the concentration monitor 36 and the microwave dryer 26 as another control configuration. Dotted line 40 'has a signal indicative of the power dissipated in the pseudo load of microwave dryer 26, and further concentration monitor 36 sends a control signal to servo control 38 which controls drive monitor 18 so that it is dissipated in the pseudo load. The amount of power generated is minimal.

Since the print density can be determined from the print data supplied to the printer or the power usage of the dryer, the control system can anticipate or determine the need for speed changes. Further, since the width of the dry area is finite in the processing direction, the dry area is affected by the integrated shift effect. By changing the processing speed, the residence time of each sheet or a part of the sheet in the dryer 26 can be controlled.
Thus, the dryer can operate in a timed on / off mode, eliminating the need for a variable energy power supply, which reduces the cost of the dryer unit.

In a typical design, with an 800 watt microwave dryer, the drive speed required for image densities between 6% and 20% is about 45 sheets (81/2 x 11 inches) / minute. This is the drive speed at which it is generated, and the speed drops to 11 sheets / min for 100% highlight color and 5 sheets / min for 230% process color. These are all peak power requirements of less than 1.5 kilovolt amps. Generally, the speed of copying can be increased by accelerating in the blank areas at the front and rear edges of the sheet. That is, if an unprinted area of the recording medium is located at the printing station 20 or dryer 26, the speed of the belt 14 is immediately increased as determined by the density monitor 36, so that the unprinted portion of the recording medium is removed. You can cross workstations quickly.

[Brief description of drawings]

FIG. 1 is a schematic side view of a printer using the present invention.

FIG. 2 is a diagram of a motor control system for the printer illustrated in FIG.

[Explanation of symbols]

 10 Printer 14 Conveyor Belt 16 Roller 18 Variable Speed Drive Motor 20 Printer 24 Encoder 38 Servo Control Device

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Frederick A. Donahue United States New York 14568 Walworth Fosdick Road 5176

Claims (2)

[Claims] 1. A printing apparatus capable of printing with varying print density, comprising: a base, a movable support provided on the base for moving a recording medium along a feed path, and arranged on the feed path. A printer provided along the feed path at a predetermined position for printing on a recording medium, a variable speed drive member for driving the movable support, and a control device for controlling the drive speed of the drive member, A unit for supplying print data to the printer; a judgment unit for judging the print density of an image printed on the recording medium from the print data; and a print density of an image printed on the recording medium from the judgment unit. Is received, the control device controls the controller to change the speed of the drive member according to the print density of the image printed on the recording medium by the printer. A driving speed setting means for controlling the peak power requirements of the printer, the printing device comprising. 2. A drying device having means for adhering a dry ink on a recording medium for forming an image, an energy absorbing means for absorbing energy not consumed in drying the ink, and the drying device. A transport member for transporting the recording medium on which an image is formed so as to pass therethrough, and energy to be consumed by the drying device for drying the ink on the recording medium is determined and absorbed by the energy absorbing means. A printing unit comprising: a determining unit that includes a unit that detects the amount of energy that is stored; and a unit that controls the speed of the transport member according to the energy consumption determined by the determining unit.