Patent Application
20060007274
The present invention relates to mechanisms for use in printers. More particularly, the present invention relates to mechanisms for controlling ink supply in a printer.
Generally in inkjet printing, ink is supplied in four different colors in the “CMYK” scheme. These colors are cyan, magenta, yellow and black. Cyan, magenta and yellow are the subtractive primary colors, rather than the additive primary colors of red, green and blue. This means that colors must be subtracted in order to obtain white (the color of the paper), rather than adding colors to obtain white.
It is possible to create black from a combination of the three subtractive colors, by removing all red, blue and green. However, this results in high use of all three color inks, and so the fourth color, black, is added to print cartridges to reduce use of the other three colors.
In general, during home printing, the consumption of black ink is higher than the consumption of the other colors. Therefore, the black ink supply will generally run out first. Once one of the ink colors has run out, generally the black ink supply, the ink cartridge (containing all ink colors) must be replaced. This is because, once one supply is exhausted, air will be drawn from the empty reservoir into the printhead. The printhead can be damaged if too much air is drawn through it. Therefore, when the black ink supply is low, before the supply runs out completely and the cartridge has to be replaced, the printer will enter “limphome” mode. In this mode, the printer does combine the cyan, magenta and yellow colors to produce a black color. In this way, the black ink supply is conserved and the life of the cartridge is extended until one of the color ink reservoirs is empty. However, even in limphome mode, the black ink reservoir of the cartridge is still functioning, and so air may still travel into the printhead when the black ink level is low.
In brief, the invention provides a mechanism for controlling at least one ink transmission module, which controls a supply of ink using received control rotation. The mechanism includes an input, to receive control rotation. The mechanism also includes an output, to selectively transfer the control rotation to the ink transmission module. A control system is also provided to control the selective transfer of the output. The mechanism is moveable into a disengaged configuration by the control system, in which the output does not transfer rotation of the input to the ink transmission module, by a first predetermined sequence of rotations of the input, and into an engaged configuration, in which the output transfers rotation of the input to the ink transmission module, by a second predetermined sequence of rotations of the input.
Embodiments of the invention will now be described, purely by way of example, with reference to the accompanying drawings, in which:
a shows a mechanism for controlling an ink supply apparatus according to an embodiment of the invention;
b shows a part of an ink supply apparatus for a printer including a mechanism according to an embodiment of the invention;
a shows detail of the mechanism of an embodiment of the invention in a first configuration;
b shows an exploded view of a part of the mechanism shown in
c shows parts from the view of
d shows a part from the view of
e shows detail of the mechanism of
f shows detail of the mechanism of
The detailed description set forth below in connection with the appended drawings is intended as a description of exemplary embodiments of the present invention and is not intended to represent the only embodiments in which the present invention can be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced without these specific details.
Referring to
b shows a part of an ink delivery system of a printer according to an embodiment. In the delivery system, four different reservoirs, one for each of the CMYK colors, are provided. In
Three color transmission modules 115, 117, (not shown), made up of three pairs of cams 114, 116, (not shown), and gears 124, 126, (not shown), are mounted on the color ink control shaft 110. In the present embodiment, the colour ink transmission modules do not have idler gears.
An encoder disc 130 is also attached to the color ink control shaft 110, and an encoder disc reader 132 is provided, which accurately reads the rotational position of the encoder disc 130 and outputs information representing the rotational position of the color ink control shaft 110. The color ink control shaft 110 is rotated by a motor 134, mounted transversely to the color ink control shaft 110 and coupled to the color ink control shaft 110 by a belt drive and a worm gear to turn the axis of rotation, through 900, to that of the color ink control shaft 110.
The system also has an actuator 136, for each reservoir, for opening and closing each reservoir. Looking only at the black ink reservoir 102, the reservoir 102 is activated by rotation of the cam 112 on the black ink control shaft 111, which moves the actuator 136 towards the reservoir 102. This movement provides pressure to a pressure valve (not shown) inside the ink reservoir 102, which opens the reservoir ink supply. The valve is open for as long as the cam 112 is positioned to push the actuator 136 towards the reservoir 102. The other reservoirs are opened and closed in the same way.
The color ink control shaft 110 is attached directly to the motor 134. A first set of transmission modules 115, 117, (not shown), each having one cam 114, 116, (not shown) and one gear 124, 126, (not shown) controls the three color reservoirs. The reservoirs are controlled as described above. A second set of transmission modules, in this embodiment the transmission module 113 for the black ink supply, is mounted on the black ink control shaft 111, which is not directly connected to the motor 134.
The black ink transmission module 113, and therefore the black ink control shaft 111, is coupled to the color ink control shaft 110, and therefore the motor 134, by a selective engagement mechanism 140. The selective engagement mechanism 140 has an input in the form of a toothed input gear 142, which is engaged with the toothed gear 124 of a transmission module 115 mounted on the color ink control shaft 110. The mechanism 140 has an output in the form of a toothed output gear 144 that is movable into and out of engagement with the second idler gear 122B of the black ink transmission module 113 as the selective engagement mechanism 140 is moved between an engaged configuration and a disengaged configuration. The output gear 144 selectively transfers the rotational movement received by the input gear 142 from the color ink control shaft 110 to the black ink transmission module 113. The mechanism 140 also has a control system 145, for controlling the engagement and disengagement of the output gear 144.
When the selective engagement mechanism 140 is in the engaged configuration, the output gear 144 is engaged with the second idler gear 122B of the black ink transmission module 113, and rotation of the motor 134, causes the color ink control shaft 110 and the black ink control shaft 111 to rotate in the same direction by the same angle. The black ink reservoir 102 is therefore opened and closed during rotation of the motor 134. However, when the selective engagement mechanism 140 is in the disengaged position, the output gear 144 is disengaged from the second idler gear 122B of the black ink transmission module 113. While the mechanism 140 is in the disengaged position, rotation of the motor 134, while causing rotation of the color ink control shaft 110, does not cause any rotation of the black ink control shaft 111. The black ink control shaft 111 remains in the rotational position in which it was when the output gear 144 of the selective engagement mechanism 140 was disengaged. Therefore, if the black ink reservoir 102 is closed when the output gear 144 is disengaged, the reservoir 102 remains closed, despite rotation of the motor 134. The black ink reservoir 102 remains closed until the mechanism 140 is reengaged, as described below, and the output gear 144 reengages with the transmission module 113 of the black ink supply.
In the present embodiment, the mechanism 140 and ink transmission modules are arranged so that when the mechanism 240 is engaged, one revolution of the color ink control shaft 110 corresponds to one revolution of the black ink control shaft 111.
a shows a part of a selective engagement mechanism 240 according to an embodiment, having corresponding function to the mechanism shown in
The input gear 242 and output gear 244 are engaged to each other via the intermediate gear 246, which is toothed and which forms part of the control mechanism 245. Because of the coupling, the input 242 and output gears 244 rotate in the same sense, with the intermediate gear 246 rotating in the opposite sense between them.
The axis of rotation of the input gear 242 is fixed relative to the axis of rotation of the intermediate gear 246. The output gear 244 is coupled to the intermediate gear 246 by the connector 248 so as to allow rotation of the axis of rotation of the output gear 244 about the axis of rotation of the intermediate gear 246, while retaining engagement of the teeth of the gears 244, 248. The axis of rotation of the output gear 244 is then free to rotate about the intermediate gear 246, and the output gear 244 can move into and out of engagement with the second idler gear 222B. In this way, the output gear 244 moved into and out of engagement with the black ink transmission module (not shown).
The connector 248 is biased into frictional engagement with the intermediate gear 246 by the spring (not shown) and the spring retainer 250. The connector 248 is able to rotate relative to the intermediate gear 246 about the common axis of rotation. However, the frictional engagement causes the connector 248 to rotate with the intermediate gear 246 unless the connector 248 is constrained from moving, in which case the intermediate gear 246 rotates while the connector 248 does not.
The connector 248 also includes an engaging arm 251 on the opposite radial side of the output gear 244. The engaging arm 251 interacts with the locking arrangement 252 as described below.
The locking arrangement 252 is mounted in the mechanism 240. The locking arrangement 252 includes a toothed control gear 254, the axis of rotation of which is fixed in position relative to axes of rotation of the intermediate 246 and input gears 242. The control gear 254 is engaged with the intermediate gear 246 and rotates in the opposite sense to it, i.e. in the same sense as the input and output gears 242, 244. The locking arrangement 252 also includes a first cam 256 and a second cam 260, each mounted coaxially with the control gear 254, the first cam 256 being arranged between the control gear 254 and the second cam 260.
b shows an exploded view of the locking arrangement 252 of
c shows the first and second cams 256, 260 and the control shaft 258 of
d shows the second cam 260, of the locking arrangement 252 shown in
The first and second flanges 266, 268 of the first cam 256 shown in
As shown in
e and 2f show the mechanism 240, and second idler gear 222B of
The operation of the control system of the mechanism of an embodiment will now be explained. Referring back to
In order to reset the mechanism 240, the input gear 242 is rotated anti-clockwise by more than one complete revolution. This ensures that the mechanism 240 is in the reset position where the second cam 260 is being rotated by abutment of the tooth of the second cam 260 with the second flange of the first cam 256 and where the two cams 256, 260 are therefore rotating together.
When the input gear 242 is rotated anti-clockwise, the intermediate gear 246 of the control system 245 is rotated clockwise, and the output gear 244 is urged towards the second idler gear 222B of the transmission module, so the output gear 244 will engage, if currently disengaged, and will then remain engaged. The input gear 242 is then rotated clockwise. The intermediate gear 246 rotates anti-clockwise, which urges the connector 248 to also rotate anti-clockwise.
However, the two cams 256, 260 are not aligned and the engaging arm 251 of the connector 248 cannot enter the recesses in the cams 256, 260, to disengage the output gear 244. The control gear 254 of the control system 245 is rotated clockwise by the intermediate gear 246, and the first cam 256 also rotates clockwise, due to the frictional contact with the control gear 254. The second cam 260 remains still, as the second flange of the first cam 256 is no longer abutting the tooth of the second cam 260, until the first flange of the first cam 256 comes into contact with the tooth of the second cam 260, and the second cam 260 then rotates with the first cam 256. At this point, the two cams 256, 260 are still not aligned, and continued clockwise rotation will result in transmission of the clockwise rotation from the color ink control shaft (not shown) to the black ink control shaft (not shown), for as long as the only rotation is clockwise. The color ink control shaft (not shown) may be stopped and restarted, and the mechanism 240 will remain engaged.
When a gear (not shown) coupled to the input gear 242 is rotated anti-clockwise, it rotates the input gear 242 of the mechanism 240 clockwise. The rotation of the input gear 242 causes the intermediate gear 246 to rotate anti-clockwise. The connector 248 cannot rotate anticlockwise with the intermediate gear 250 because the engaging arm 251 is abutting the locking arrangement 252. As the intermediate gear 246 rotates, the control gear 254 rotates the locking arrangement 252 as a single unit. Therefore, the arm 251 cannot extend into the recesses of the cams 256, 260 of the control system 245 because they are not aligned, and, rotating as one, will not become aligned. The output gear 244 is kept in engagement with the second idler gear 222B of the transmission module.
Therefore, when the gear (not shown) coupled to the input gear 242 is rotated anti-clockwise (causing clockwise rotation of the input gear 242), with the mechanism 240 engaged, the output gear 244 rotates clockwise, which rotates the second idler gear 222B anti-clockwise.
In order to disconnect the mechanism 240, after the resetting anti-clockwise rotation of the input gear 242, the input gear 242 is rotated clockwise, until the second cam 260 is rotating in clockwise, as described above. However, instead of continuing the clockwise rotation of the input gear 242, the input gear 242 is rotated clockwise by a predetermined angle that engages the second cam 260 to rotate clockwise, and then stops the rotation when the recess of the second cam 260 is aligned with the engaging arm 251 of the connector 248.
The input gear 242 is then rotated anti-clockwise again, which rotates the control gear 254 anticlockwise, together with the first cam 256, again due to the frictional contact between the two. The second cam 260 does not rotate, as the tooth of the second cam 260 is not abutting the first flange of the first cam 256. Before the second flange rotates around on the first cam 256 and abuts the tooth on the second cam 260, the first cam 256 passes the position in which it is aligned to receive the engaging arm 251 of the connector 248 in the recess. The rotation is stopped at this point.
The rotation is then reversed once more. The rotation of the input gear 242 in the clockwise direction causes the intermediate gear 246 to rotate anti-clockwise, and the connector 248 also rotates anticlockwise due to the frictional engagement of the two. The engaging arm 251 of the connector 248 therefore enters the aligned recesses of the first and second cams 256, 260, and the mechanism 240 disengages.
Now when the clockwise rotation of the input gear 242 is continued, the connector 248 is always rotated anti-clockwise, so pushing the engaging arm 251 of the connector 248 into the aligned recesses of the first and second cams 256, 260, and keeping the mechanism 240 in the disengaged configuration. When the mechanism 240 is in the disengaged configuration, the first and second cams 256, 260 do not rotate as they are held in position by the engaging arm 251 of the connector 248. The first cam 256 therefore slips against the control gear 254, overcoming the frictional engagement with it.
In the present embodiment, the gears of the mechanism 240 are sized so that, when used in the system of
The invention has been described above purely by way of example and modifications, omission, additions and substitutions can be made, which fall within the scope and spirit of the invention, the invention also extending to individual integers and groups of integers and their equivalents.
