Recording apparatus having a pivotable member to maintain a constant distance and angle between a recording head and a recording medium

A recording apparatus for recording on a recording medium includes a conveyor rotating member rotatable for imparting a conveying force to the recording medium; a follower rotating member driven by rotation of the conveyor rotating member; and a recording area located downstream of the conveyor rotating member and the follower rotating member as viewed in the direction of conveyance of the recording medium for recording on a surface of the recording medium with which said follower rotating member comes into contact, wherein the position of the follower rotating member is fixed and the position of the conveyor rotating member is rockable. The recording apparatus can always maintain a recording device and a recording surface of a recording medium at constant distance and angle even if the thickness of the recording medium is changed, and perform an excellent recording.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a recording apparatus for recording images 
on a recording medium by using recording means while supporting the 
recording medium in a recording area. 
2. Description of the Related Art 
Conventionally, a recording apparatus for recording on a recording medium 
by using recording means, such as a recording head, has been provided with 
a conveyor roller located upstream of a recording position of the 
recording head as viewed in the direction of conveyance of the recording 
medium, and a press-contact member pressed into contact with the conveyor 
roller so that the recording medium is nipped and conveyed by the 
press-contact member and the conveyor roller. And, the position of the 
conveyor roller is fixed, while the press-contact member is rockably 
pressed into contact with the conveyor roller. That is, the position of 
the surface of the recording medium conveyed by the conveyor roller is 
always fixed, and a surface of the press-contact member with respect to 
the recording medium is rocked. 
Therefore, when the thickness of the recording medium is changed, the 
distance between the recording head and the recording surface of the 
recording medium is changed. In the case of a thick recording medium, such 
as an envelope, as compared with a thin recording medium, such as a cut 
paper, the distance between the recording head and the recording surface 
of the recording medium becomes a short distance so that recording quality 
may be changed and the recording medium may be caught by a carriage when a 
main scanning is performed with the cartridge. 
Thus, a mechanism for maintaining the recording head and the recording 
surface of the recording medium at a constant distance as shown in FIGS. 8 
and 9 has been conventionally introduced. FIG. 8 is a sectional view taken 
along a plane perpendicular to a main scanning direction of a so-called 
serial-type printer in which the recording head scans in the main scanning 
direction; and FIG. 9 is a partial view of the carriage viewed from the 
direction of arrow A as shown in FIG. 8. 
Referring to these drawings, there are shown a carriage 101 having a 
recording head and scanning in the main scanning direction, a carriage 
shaft 102, a roller 103, a roller lever 104 holding the roller 103, a rail 
105 provided parallel to the carriage shaft 102, a conveyor roller 106 for 
conveying the recording medium, a press-contact member 107 for pressing 
the recording medium into contact with the conveyor roller 106 to generate 
a conveying force, and a spring 108 provided between the roller lever 104 
and the carriage 101. 
By the action of the spring 108, the roller lever 104 and the roller 103 
are pressed against the rail 105. By the reaction thereof, the carriage 
101 receives a force of rotating clockwise in FIG. 8 about the carriage 
shaft 102. The carriage 101 is provided with a projection 101a, and the 
projection 101a is always kept in contact with the press-contact member 
107 by the rotating force of the carriage 101 toward the press-contact 
member 107. For this reason, the recording head (not shown) mounted on the 
carriage 101 and the press-contact member 107 are always maintained at not 
less than the constant distance. 
Therefore, since between the recording surface of the recording medium and 
the carriage 101, and further, the recording head are always maintained at 
not less than the constant distance even if the thickness of the recording 
medium is changed, the main scanning is always performed with the carriage 
101 because the recording medium is not caught by the carriage 101. 
However, in the conventional recording apparatus as described above, the 
distance between the carriage 101 rotating about the carriage shaft 102 
and the press-contact member 107 is maintained by means of the projection 
101a provided on the carriage 101. Thus, a rotation amount of the carriage 
101 rotating counterclockwise in FIG. 8 about the carriage shaft 102 is 
changed when the thickness of the recording medium is changed. For this 
reason, the angle of the carriage 101, and the angle of the recording head 
with respect to the recording surface of the recording medium are changed 
although the amount of change is slight. Therefore, although a change in 
the thickness of the recording medium does not substantially affect 
recording to a recording medium of the same thickness, the recording 
position of the recording head with respect to the recording medium is 
slightly changed in accordance with the change of the thickness of the 
recording medium. 
In addition, since the position of the projection 101a is closer to the 
carriage shaft 102 than the recording position of the recording head, 
variations in the length of the projection 101a are expanded so as to 
appear as variations in the distance between the recording head and the 
recording surface. For this reason, a predetermined distance between the 
recording head and the recording surface might be changed for each 
apparatus to vary recording quality for each apparatus. 
Further, in order to maintain the predetermined distance between the 
recording head and the recording surface for the purpose of avoiding the 
above variations, the length of the projection 101a must be carefully 
managed. This leads to an increase in cost of the apparatus. 
Still further, since the projection 101a is always pressed into contact 
with the holding member, it is worn out by friction when the main scanning 
of the carriage is repeated. As a result, the distance between the 
recording head and the recording surface might be changed during the use 
thereof for a long period of time. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a recording apparatus 
which can always maintain recording means and a recording medium at 
constant distance and angle even if the thickness of the recording medium 
is changed, and perform an excellent recording. 
It is another object of the present invention to provide a recording 
apparatus wherein a recording means and a recording medium are always 
maintained at a constant distance and angle because a position of a 
follower rotating member in regard to the recording means is fixed, 
although the conveyor rotating member is rocked when the thickness of the 
recording medium is changed. 
It is further object of the present invention to provide a recording 
apparatus for recording on a recording medium which comprises a conveyor 
rotating member rotatable for imparting a conveying force to the recording 
medium; a follower rotating member driven by rotation of the conveyor 
rotating member; and a recording area located downstream of the conveyor 
rotating member and the follower rotating member as viewed in the 
direction of conveyance of the recording medium for recording on a surface 
of the recording medium with which the follower rotating member comes into 
contact, wherein the position of the follower rotating member is fixed and 
the position of the conveyor rotating member is rockable.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
A first embodiment of a recording apparatus according to the present 
invention will now be described with reference to the accompanying 
drawings. FIG. 1 illustrates a construction of a main part of the 
recording apparatus; FIG. 2 is a perspective view which illustrates a 
section around a carriage including a recording area; FIG. 3 illustrates a 
rocking structure of conveyor rollers; and FIG. 4 illustrates a driving 
force transmission mechanism. 
Taking an ink jet recording apparatus as an example of the recording 
apparatus according to the present invention, an overall construction of 
the apparatus will be first described, and a rocking structure of the 
conveyor rollers will be next described. 
(Overall construction of the apparatus) 
The recording apparatus is of a ink jet recording method. A cassette 1 is 
detachably mounted to the bottom of the apparatus, and a plurality of 
recording mediums 2 are stacked and held on a pressure plate 1b which is 
urged by a pressing spring 1a of the cassette 1. The recording mediums 2 
are separated and fed one at a time by a feed roller 3 and a separator lug 
1c provided on the upper portion of the tip of the cassette 1, and are 
reversed and conveyed by a reverse roller 4 and a press-contact roller 6 
which is pressed into contact with the roller 4 by means of a plate spring 
5. Then, the recording mediums 2 are nipped by a conveyor roller 7, which 
is a first conveyor rotating member to be driven for rotation, and a first 
follower roller 8, driven by rotation of the conveyor roller 7 so as to be 
conveyed to a recording position located downstream of the nipped position 
as viewed in the direction of conveyance of the recording medium. 
In a recording area R (in this embodiment, a space where ink ejected from a 
recording head 9 is allowed to fly) where recording is performed on the 
recording medium, the recording head 9 constituting recording means is 
mounted on a carriage 11 together with an ink tank 10 at a position 
opposite to the recording medium. The carriage 11 is reciprocable in a 
main scanning direction along two carriage shafts 12 provided parallel to 
each other in the direction crossing the conveyance direction of the 
recording medium, for example, in the direction crossing the conveyance 
direction of the recording medium substantially at right angles (the 
vertical direction of a plane of FIG. 1). The recording head 9 ejects ink 
in response to an image signal when the carriage 11 reciprocates to 
perform a predetermined recording on the recording medium 2. 
An ink ejection structure of the recording head 9 of the ink jet method 
used in this embodiment includes commonly a fine liquid ejection ports 
(orifices), a liquid path, an energy active section provided in a portion 
of the liquid path, and energy generation means for generating liquid 
droplet-forming energy which is acted on the liquid in the active section. 
Examples of energy generation means for generating such energy include an 
electrical-mechanical conversion member such as piezoelectric element, 
energy generation means for generating heat by irradiation with 
electromagnetic wave such as laser, and for ejecting liquid droplets by 
the action of heat generation, and energy generation means for ejecting 
liquid by heating the liquid with an electrical-thermal conversion member 
such as a heating element having a heating resistor. 
A recording head used in an ink jet recording method in which liquid is 
ejected by thermal energy can arrange orifices for ejecting recording 
liquid droplets in high density. Therefore, high-resolution recording can 
be performed. Particularly, the recording head using the electro-thermal 
conversion member has the following advantages. The recording head can be 
easily reduced in size. The recording head can sufficiently utilize recent 
advanced technology in the field of semiconductor, and advantages of IC 
technology and microtechnology in which reliability is remarkably 
increased. The recording head can be easily mounted in high density. And, 
the recording head can be manufactured at a low cost. 
In this embodiment, the recording head has a lot of nozzles. 
Electro-thermal conversion elements provided in the nozzles selectively 
generate heat, so that ink is ejected from orifices formed at the tip of 
the nozzles by a film-boiling pressure generated in the ink to from an ink 
image on the recording medium 2. 
Further, in this embodiment, not only a serial-type recording apparatus in 
which a carriage as the head mounting section is serially moved, but also 
a recording apparatus in which a recording head of so-called a full line 
type having recording elements (such as orifices and heating elements) 
over the entire width of a recording medium in the direction of 
intersecting the conveyance direction of the recording medium may be 
employed. 
The recording medium 2 on which an image is recorded by the recording head 
9 is nipped and conveyed by a second conveyor roller 13 and a second 
follower roller 14 to be discharged to a discharge stacker 15. The second 
conveyor roller 13 is a second conveyor rotating member which is located 
downstream of the recording position of a rocking member surface 19b in 
regard to the head in the recording area R of the recording medium as 
viewed in the direction of conveyance of the recording medium. The second 
follower roller 14 is driven by rotation of the roller 13. 
The first follower roller 8 is rotatably mounted to a first holding member 
16, and the second follower roller 14 is rotatably mounted to a second 
holding member 17. The first and second holding members 16 and 17 are 
fixed to a chassis 18, and the carriage shafts 12 are also fixed to the 
chassis 18. Therefore, the positions of the first and second follower 
rollers 8 and 14 in the heightwise direction of the apparatus are always 
constant with respect to the recording head 9. 
On the other hand, the first and second conveyor rollers 7 and 13 are 
rockably mounted in the heightwise direction of the apparatus with respect 
to the recording head 9. 
(Rocking structure of the conveyor rollers) 
The rocking structure of the first and second conveyor rollers 7 and 13 
will now be described. FIG. 3 is a right side view in which a chassis side 
plate 18a supporting a roller shaft 4a shown in FIG. 2 is removed. As 
shown in FIG. 3, a rocking member 19 is pivotably mounted about the roller 
shaft 4a of the reverse roller 4, and a roller shaft 7a of the conveyor 
roller 7 is fitted into a reversed U-shaped groove 19a which is formed in 
the rocking member 19. A tension spring 20 as an elastic member is locked 
between both ends of the roller shaft 7a and the first holding member 16. 
As a result, the rocking member 19 is urged to pivot counterclockwise 
about the reverse roller shaft 4a, and the first conveyor roller 7 is 
pressed into contact with the first follower roller 8. The spring 20 may 
be provided at several sections of the portion in the direction of the 
length of the first conveyor roller 7 other than an area through which 
paper passes. 
In addition, the second conveyor roller 13 is mounted to the rocking member 
19 and abuts against the second follower roller 14 when the rocking member 
19 is urged counterclockwise as described above. 
The first and second conveyor rollers 7 and 13 are driven by rotation so as 
to impart a conveying force to the recording medium 2. A driving force 
transmission mechanism is constructed as shown in FIG. 4. 
Referring to FIG. 4, a motor gear 22 attached to a drive shaft of a motor 
21 is meshed with an idler gear 23, which is a first driving force 
transmission member, and the idler gear 23 is meshed with a roller gear 24 
attached to the roller shaft 7a of the first conveyor roller 7, so that 
driving force of the motor 21 is transmitted to the first conveyor roller 
7. 
In addition, as shown in FIG. 1, a transmission roller 25, which is a 
second driving force transmission member, is pressed into contact with the 
first and second conveyor rollers 7 and 13 by means of a spring (not 
shown). A driving force of the first conveyor roller is transmitted to the 
second conveyor roller 13 through the transmission roller 25. 
The motor 21, idler gear 23 and transmission roller 25 are mounted to the 
rocking member 19 so that the driving force can be transmitted even if the 
first and second conveyor rollers 7 and 13 are rocked by the action of the 
rocking member 19. 
In such a construction as described above, as represented by the following 
equation, a value of a press-contacting force at a press-contacting 
position can be obtained by dividing a difference between a moment around 
the rocking center (i.e., reverse roller shaft) 4a of the rocking member 
19 due to the resilient force of the spring 20 and a moment around the 
rocking center 4a of the rocking member 19 due to weight of each member 
mounted to the rocking member 19 by a distance between the rocking center 
4a and a press-contacting point of the first conveyor roller 7 and the 
first follower roller 8. 
##EQU1## 
Therefore, by selecting the resilient force of the spring 20 fitted to both 
right and left ends of the rocking member 19 in consideration of the 
position of the member, such as a motor, to be mounted to the rocking 
member 19, the press-contacting force which is most suitable for conveying 
the recording medium can be set while maintaining a balance between the 
right and left portion of the rocking member 19. 
In addition, if the resilient force of the spring 20 is set within its 
allowable stress, a desired press-contact force can be obtained for a long 
period of time without deformation of the spring itself. 
In the construction as described above, when a thick recording medium 2 is 
conveyed (see FIG. 6), as compared with conveying of a thin recording 
medium 2 (see FIG. 5), the first conveyor roller 7 moves substantially 
downwards in the direction of arrow B, and the second conveyor roller 13 
is also moved in this direction because the rocking member 19 is caused to 
pivot downwards around roller shaft 4a when the first conveyor roller 7 so 
moves. As a result, the recording medium 2 is securely nipped and conveyed 
by the first and second conveyor rollers 7 and 13 and the first and second 
follower rollers 8 and 14 even if the thickness of the recording medium 2 
is changed. At this time, the positions of the first and second follower 
rollers 8 and 14 which come into contact with a recording surface of the 
recording medium 2 are fixed, and the positions are not changed with 
respect to the carriage shaft 12. For this reason, the recording surface 
of the recording medium 2 and the recording head 9 mounted on the carriage 
11 are always maintained at constant distance and angle even if the 
thickness of the recording medium 2 is changed, whereby an image of high 
quality can be recorded. 
In addition, the recording head 9 and the recording surface of the 
recording medium 2 are not positioned by members relating to the main 
scanning as in the conventional recording apparatus. Therefore, a problem 
concerning durability does not arise, thereby always obtaining an 
excellent image for a long period of time. 
Further, the distance between the recording head 9 and the recording 
surface of the recording medium 2 can be easily set by merely positioning 
the holding members 16 and 17 which hold the first and second follower 
rollers with respect to the chassis 18. 
Still further, the position of the first follower roller 8 located in 
regard to the recording head 9 with the recording medium therebetween is 
fixed, and the first conveyor roller 7 located substantially opposite the 
recording head 9 is movable. Thus, the diameter of the first follower 
roller 8 can be freely selected because it does not directly affect on the 
degree of conveyance accuracy as would the first conveyor roller 7. 
Therefore, by selecting a first follower roller 8 of a smaller diameter, 
the distance between the recording head 9 and the recording surface of the 
recording medium 2 can be located at a position nearer to the recording 
head, so that the distance accuracy between the recording head and the 
recording surface of the recording medium 2 can be further increased. In 
addition, the recording medium 2 is held by the press-contacting point of 
the first follower roller 8 and the first conveyor roller 7 while 
obtaining the effect of maintaining the distance between the recording 
head 9 and the recording medium 2, thereby increasing a recordable area. 
In addition, the diameter of the first conveyor roller 7, located at the 
substantially opposite area to the recording head 9 with the recording 
medium 2 therebetween is not limited. Thus, that and more diameter can be 
selected for the preferred degree of conveyance accuracy, so that the 
conveyance accuracy can be further increased. Therefore, it is also 
possible to record a higher-quality image. 
FIG. 7 illustrates a second embodiment of a recording apparatus according 
to the present invention. In the recording apparatus of this embodiment, a 
spring seat 19c is provided on the opposite side to the first conveyor 
roller 7 with the reverse roller shaft 4a (i.e., the center of pivoting of 
the rocking member 19) therebetween, a compression spring 26 as an elastic 
member is provided between the spring seat 19c and the opposing section 
16a of the first holding member 16 to allow the first conveyor roller 7 to 
be pressed into contact with the first follower roller 8. This differs 
from the construction of the first embodiment in which the first conveyor 
roller shaft 7a and the driven roller holding member 16 are connected by 
the tension spring 20 to allow the first conveyor roller 7 to be pressed 
into contact with the first follower roller 8. 
The construction as described above offers the same advantages as those of 
the construction of the first embodiment. 
Although the ink jet recording method is described in the above 
embodiments, the recording method is not limited thereto, and other 
recording methods may be employed. In addition, the conveyor rotating 
members and driven rotating members are not limited to roller-like members 
as in described in the embodiments. Even if a rotation belt or the like is 
used as the above rotating member, the same advantages as those of the 
embodiments can be provided. 
As described above, according to the embodiments, the positions of the 
follower rotating members, for example rollers which come into contact 
with the recording surface in regard to the recording means are fixed, and 
the positions of the conveyor rotating members, for example rollers, are 
movable. Therefore, even if the thickness of the recording medium is 
changed, the recording means and the recording surface of the recording 
medium are always maintained at constant distance and angle. Accordingly, 
even by a recording apparatus like a recording apparatus of an ink jet 
recording method, which requires an accurate setting of the positions of 
the recording medium and the recording means, a high-quality image can be 
obtained. 
While the present invention has been described with respect to what is 
presently considered to be the preferred embodiments, it is to be 
understood that the invention is not limited to the disclosed embodiments. 
To the contrary, the invention is intended to cover various modifications 
and equivalent arrangements included within the spirit and scope of the 
appended claims. The scope of the following claims is to be accorded the 
broadest interpretation so as to encompass all such modifications and 
equivalent structures and functions.