Manual printing device

A manual printing device for printing on a recording medium when scanned over the recording medium in a print direction, the manual printing device comprising: an ink tank filled with ink; a recording unit in formed with an ink ejection aperture in fluid connection with the ink tank, the recording unit ejecting ink supplied from the ink tank through the ink ejection aperture onto the recording medium; and a recovery unit for applying pressure to the ink in the ink tank to eject ink from the ink ejection aperture.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a manually operated printing device which 
a user manually scans across a recording medium, such as paper to print 
predetermined patterns on the recording medium. 
2. Description of the Related Art 
Nozzles of a recor4ding head can become clogged with dust or filled with 
air bubbles. These can result in defective printing. Conventional printing 
devices are provided with purge type recovery units for returning the 
recording head to good operating condition. The purge type recovery unit 
is connected with the nozzle plate of the recording head and used to suck 
ink, and consequently the dust and air bubbles, out of the nozzles of the 
head. 
SUMMARY OF THE INVENTION 
However, conventional suction-type recovery devices have a large size and a 
complicated configuration and so are difficult to incorporate into the 
body of a manual printing device. Therefore, a special recovery device 
independent from the body must be provided for manual printing devices. 
Also, suction force is not always reliably transmitted from the recovery 
unit to the recording head, so purge operations are often insufficient. 
It is an objective of the present invention to overcome the above-described 
problems and to provide a manual printing device requiring no special 
independent recovery device for recovering printing quality of the 
recording head and wherein recovery operations can be sufficiently 
performed without use of a complicated configuration. 
In order to achieve the above-described objectives, a manual printing 
device according to the present invention is for printing on a recording 
medium when scanned over the recording medium in a print direction, and 
the manual printing device includes: an ink tank filled with ink; a 
recording unit formed with an ink ejection aperture in fluid connection 
with the ink tank, the recording unit ejecting ink supplied from the ink 
tank through the ink ejection aperture onto the recording medium; and a 
recovery unit for applying pressure to the ink in the ink tank to eject 
ink from the ink ejection aperture. 
With this configuration, purge operations are performed by ejecting ink 
from the nozzles. Therefore, the recording head can be returned to a good 
printing condition more effectively than when purged using suction force. 
According to another aspect of the invention, the recovery unit includes: a 
piston mechanism having a piston for applying pressure to the ink in the 
ink tank when pressed against; and a pressing mechanism connected with the 
piston of the piston mechanism so that the pressing mechanism presses 
against the piston when moved in a pressing direction. With this 
configuration, by pushing the piston down using the pressing mechanism, 
pressure is applied to ink in the ink tank, whereupon a recovery operation 
is performed by ejecting ink from the nozzles of the head. Therefore, 
recovery operations can be performed with a simple mechanism and without 
wasting ink. 
When the ink tank is connected to atmosphere by a through hole formed in 
the pressing mechanism, the pressure in the ink tank will be maintained 
equal to atmospheric pressure. Therefore, a negative pressure can be 
prevented from building up in the ink tank while ink consumed from the ink 
tank. 
By arranging the pressing mechanism so that its top portion is exposed to 
the outside of the manual printing device, recovery operation can be 
performed by a user pressing down the top of the push-down mechanism with 
his or her finger. Therefore, there is no need to provide a drive source 
for driving the pressing mechanism so that the manual printing device can 
be made lighter and in a more compact size. Because an air hole is opened 
through the upper portion of the push-down mechanism, ejection purge can 
be effectively performed by pushing the push-down mechanism down while 
covering the opening with the user's finger. 
According to a different aspect of the present invention, the recovery 
device is incorporated into the body of the manual printing device so that 
no special recovery device needs to be provided separately. The manual 
printing device can therefore be made in a more compact size.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
A manual printing device according to a preferred embodiment of the present 
invention will be described while referring to the accompanying drawings 
wherein like parts and components are designated by the same reference 
numerals to avoid duplicating description. 
FIG. 1 is an external view showing a manual printing device according to 
the present embodiment of the present invention. A body 1b of a manual 
printing device 1 is formed in a square shape so as to be easy for a user 
to hold by hand. A roller 2 is rotatably provided to the lower tip of the 
body 1b. A purge button 3 for applying pressure to ink in an ink tank 8 
(see FIG. 2) is provided to the upper tip of the body 1b. A switch 4 for 
turning a power source on and off and for selecting a printing mode of the 
manual printing device 1 is provided to the body 1b. An interface portion 
20 (see FIG. 5) for performing infrared transmission with an external 
device to transmit and receive a variety of data, such as print data, is 
also provided to the upper tip of the body 1b. 
An ink jet recording head 5 serving as a recording unit is provided near 
the roller 2 of the body 1b. The roller 2 is supported by a frame 1c 
having a protrusion portion 1d. The protrusion portion 1d is formed from a 
material, such as a resin material, having good sliding characteristics. 
In order to print the print data or other data inputted from an external 
device and the like onto a recording medium P, such as a print sheet, a 
user holds the body 1b by hand and scans the body 1b in a direction 
indicated by an arrow X in FIG. 1 across the surface of the recording 
medium P while maintaining the roller 2 and the protrusion portion 1d in 
contact with the upper surface of the recording medium P. During printing, 
the roller 2 and the protrusion portion 1d maintain the upright 
orientation of the body 1 and fix the distance from the surface of the 
recording medium P to the ink jet recording head 5. Printing of a 
predetermined image is performed by using, in a manner to be described 
later, rotation of the roller 2 to detect relative position (i.e., 
movement) between the ink jet recording head 5 and recording medium P. 
FIG. 2 is a cross-sectional view showing internal configuration of the 
manual printing device 1. Next, an explanation will be provided for the 
internal configuration of the manual printing device 1 while referring to 
FIG. 2. The roller 2 is provided to the lower tip of the body 1b on a 
shaft 7 so as to be freely rotatable around the shaft 7. To prevent the 
roller 2 from smudging freshly printed images, the ink jet recording head 
5 is disposed to the rear of the roller 2 in regards to the scanning 
direction X of the manual printing device 1. The ink tank 8 for supplying 
ink to the ink jet recording head 5 is disposed above the ink jet 
recording head 5. 
A pulley 9 is fixed to the shaft 7 of the roller 2 so as to rotate around 
the shaft 7 in association with rotation of the roller 2. An encoder 11 
having a rotation disk 12 is disposed near the center of the body 1b. A 
belt 10 is suspended between the pulley 9 and the rotation disk 12 so that 
rotational force generated by the pulley 9 in association with rotation of 
the roller 2 is transmitted to the rotation disk 12 of the encoder 11. 
Slits are provided around the periphery of the rotation disk 12 at a 
predetermined interval. A photointerrupter 13 of the encoder 11 is turned 
on and off by rotation of the rotation disk 12. The photointerrupter 13 
converts the rotational speed of the roller 2, that is, relative position 
between the ink jet recording head 5 and the recording medium P, into an 
intermittent electric pulse signal. The signal is inputted to a control 
portion 14 to be described later. The photointerrupter 13 also detects the 
rotational direction of the roller 2. 
The control portion 14 for controlling recording operations of the ink jet 
recording head 5, detection operation of the photointerrupter 13, and an 
interface portion provided for receiving print data is provided in the 
upper portion of the body 1b. A power source 15 for supplying power to 
electrical components of a control system (to be described later) is 
provided near the control portion 14. The power source 15 includes a small 
power supply portion, such as, a dry cell battery, and a device for 
stabilizing supply of the power. 
FIG. 3 is a different cross-sectional view from FIG. 2 showing the internal 
configuration of the manual printing device 1, particularly a recovery 
device incorporated in the manual printing device 1. A purge piston 16 and 
a purge cylinder 17 for applying pressure to ink in the ink tank 8 are 
disposed above the ink tank 8. The inside of the ink tank 8 and the inside 
of the purge cylinder 17 are in fluid connection via a connection line 8A. 
A purge button 3 is provided to the top of the purge piston 16 so as to 
protrude upward exposed to the outside of the body 16. A spring 18 for 
urging the purge button 3 upward is provided between the upper portion of 
the purge piston 16 and the purge cylinder 17. The spring pushes the purge 
button 3 back up after the purge button 3 is pressed downward. An air hole 
19 for maintaining air pressure in the ink tank 8 at a fixed level is 
formed through the purge button 3 and the purge piston 16 and provides 
fluid connection between the ink tank 8 and atmosphere. It should be noted 
that the ink tank 8 is exchangeable and is detachably mounted between the 
ink jet recording head 5 and the purge piston 16. 
FIG. 4 is a view showing the underside of the ink jet recording head 5 and 
the roller 2 of the manual printing device 1. Next, an explanation will be 
provided for the positional relation between the ink jet recording head 5 
and the roller 2 while referring to FIG. 4. A plurality of nozzles 5a are 
aligned on the surface of the ink jet recording head 5 to a widest width 
L, which determines the widest recording width of the print region, 
extending in a direction perpendicular to the scanning direction X. As 
described above, the roller 2 is rotatably supported by the shaft 7 and 
the pulley 9 at both sides. A portion M where the roller 2 contacts the 
recording medium P is set to a width narrower than and within the width L. 
The protrusion portion id is likewise formed to a width narrower than and 
within the width L. 
FIG. 5 is a block diagram showing a control system of the manual printing 
device 1. The control portion (CPU) 14 performs overall control of the 
manual printing device 1 and is connected to a host computer 21 via the 
interface portion 20. The control portion 14 is also connected to a 
variety of other components including a ROM 22 storing a control program 
for controlling each function block according to a predetermined program; 
a RAM 23 for storing print data inputted from the host computer 21 via the 
interface 20; a head driver 33 for driving the ink jet recording head 5; 
and an operation panel 24 including the switch 4 and the like. Pulses from 
the encoder 11 for detecting rotational speed and rotational direction of 
the roller 2 are inputted to a speed detection circuit 25 and a position 
detection circuit 26, which are connected to the CPU 14. Speed of the 
manual printing device 1 and relative position between the manual printing 
device 1 and the recording medium P are detected by the speed detection 
circuit 25 and the position detection circuit 26, and then a detection 
signal is inputted to the control portion 14 accordingly. These electrical 
components are incorporated into the body 1b of the manual printing device 
1. 
Next, an explanation will be provided for printing operations of the manual 
printing device 1 with the above-described configuration. The manual 
printing device 1 is operated according to a predetermined program stored 
in the ROM 20. Input of print data is performed by the control portion 14 
when the switch 4 is set to an input mode. The print data is inputted from 
the host computer 21 via the interface 20 by using an infrared signal. The 
inputted print data is first temporally stored in the RAM 23. When a user 
manipulates the switch 4 to transmit a print start signal to the control 
portion 14, the control portion 14 receives the signal, confirms that the 
print data is stored in the RAM 23, and then goes into a print standby 
condition. 
At this point, the control portion 14 determines whether or not the 
rotation disk 12 of the encoder 11 is rotating. When it determines that 
the rotation disk 12 is rotating, the control portion 14 controls drive of 
the ink jet recording head 5 to print on the surface of the recording 
medium P by controlling output of the print data in association with 
rotational amount of the roller 2. In this way, the control portion 14 
controls output of the print data to match the rotational amount of the 
roller 2 so that printing can be constantly performed on the recording 
medium P as predetermined regardless of whether the scanning speed of the 
body 1b across the surface of the recording medium P is uniform or not. 
Next, an explanation will be provided for operation of the recovery device 
of the manual printing device 1 having the above-described configuration. 
A user performs a recovery operation of the ink jet recording head 5 
before using the manual printing device 1, when he or she notices poor 
performance of the print head, or otherwise when necessary. In order to 
perform the recovery operation, the user pushes the purge button 3 down 
while covering the air hole 19 with his or her finger. By this operation, 
pressure is applied to ink in the ink tank 8 and consequently ink is 
ejected from the nozzles of the ink jet recording head 5. At this time, 
dust and air in the nozzles are also pushed out with the ink. Afterward, 
the user releases his finger from the purge button 3 so that the purge 
button 3 is pushed back up by the spring 18. Therefore, the user can 
repeatedly perform the operation if necessary. Further, when ink in the 
ink tank 8 is consumed during printing, air will enter the ink tank 8 
through the air hole 19 so that air pressure in the ink tank 8 is 
maintained at a fixed level. Therefore, a negative pressure will not build 
up in the ink tank 8 when the level of ink decreases so that printing can 
be always performed properly. 
While the invention has been described in detail with reference to specific 
embodiments thereof, it would be apparent to those skilled in the art that 
various changes and modifications may be made therein without departing 
from the spirit of the invention, the scope of which is defined by the 
attached claims.