JP2001113683A - Ink jet recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet recorder in which a recording head can be sustained constantly in a state suitable for recording, while shortening the recording time, by controlling the transition timing of a recording head to recording state at the start of recording and controlling the transition timing of the recording head to protection state at the end of recording. SOLUTION: Each recording head has at least two states including a protection state of head part and a recordable state where the head part is not protected. The number of drive pulses of a carriage is counted and when a predetermined count is reached, each recording head is switched from protection state to recordable state and when a count corresponding to the length of recording data is reached, each recording head is switched from recordable state to protection state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording apparatus, and more particularly to an ink jet recording apparatus for protecting a recording head during non-recording.

[0002]

2. Description of the Related Art In recent years, a recording apparatus which performs recording with a recording head in which a plurality of recording elements are arranged has become widespread.

[0003] Such recording apparatuses can be classified into an ink jet type, a wire dot type, a thermal transfer type and the like according to a recording method. Among these, an ink jet type recording apparatus performs recording by discharging ink droplets from a discharge port, which is a recording element, onto a recording medium. As a method of ejecting ink droplets, a thermal energy generating element is provided in an ink path near an ejection port, and is driven to generate air bubbles in the ink, and the ink droplets are ejected by the generation pressure of the air bubbles. Alternatively, a method is used in which a piezoelectric element such as a piezo element is used as an ejection energy generating element, and ink is ejected using pressure generated when the piezoelectric element is deformed.

In such an ink jet recording apparatus, since the size of ink dots can be made relatively small, a high-definition image can be recorded, and color recording using multi-color ink can be easily performed. In recent years, it has been rapidly spreading because of its advantages.

In such an ink jet recording apparatus, a recording head having a length corresponding to the width of the recording medium is provided. In addition, full-line types that record data are also widely used. The full line type can perform printing for one line length of the printing medium by one ejection operation, so that the printing is performed in comparison with the serial type which scans the printing medium and prints one line. It has the advantage that the time can be reduced.

As described above, the ink jet recording apparatus performs recording by discharging ink droplets from the fine discharge ports. Therefore, after the recording operation is completed, the discharge ports are kept in a recording state, that is, in a state where they are exposed to air. If it is left as it is, the ink near the discharge port evaporates and the ink thickens, and dust in the air adheres. Such a state of the recording head causes a recording failure such as a shift in the ejection direction of the ink droplet at the time of recording or an inappropriate amount is not ejected.

Therefore, at the time of non-printing, the ejection port array portion is covered with a recovery tub to protect the print head from drying and dust. Further, there is a type in which a recovery process such as suction is performed to remove dust that has already adhered.

The recording head is protected at the time when the recording of one image data sent from the host computer is completed. Specifically, the time is when the recorded recording medium is discharged.

[0009]

However, in the above-described conventional ink jet recording apparatus, if the recorded image is a very small area on the recording medium, the conveyance state of the recording medium is monitored even after the recording in this area is completed. Then, it is not determined that the recording is completed until the recording medium is discharged, and the recording head is left in the recording state.

Further, in the case where a recording head is provided for each color of ink ejected corresponding to color recording, all recording heads do not perform a recording operation depending on image data. It will be in the recording state,
The recording head of the ink color not used for recording is left unprotected in the recording state until the recording of the image data is completed.

As described above, if the recording head is not protected in spite of the fact that recording is not performed, the recording head may be in a state unsuitable for recording depending on how long it has been left.

When a plurality of recording heads are arranged in parallel with respect to the transport direction of the recording medium, even if the recording head on the upstream side in the transport direction starts recording, the recording head on the most downstream side performs recording. It is not facing the medium and is in a state of waiting for a recording operation. Nevertheless, the recovery tubs of all the print heads are simultaneously removed in accordance with the operation timing of the upstream print head, and the downstream print heads are waiting in an unprotected state. . Similarly, even when recording is completed, the recording medium shifts to the protection state at the timing when the recording medium is ejected. Therefore, even if recording is completed, if the downstream recording head is recording, the upstream recording head is The recording head will be left unprotected. As described above, when there are a plurality of recording heads, the recovery tub is attached and detached at the same timing even though the recording heads in the standby state are generated due to the conveyance state of the recording medium. Depending on the position where the ink is ejected, the time during which the ink is left undisturbed becomes longer, which promotes the evaporation of the ink near the ejection port.

When a plurality of image data are continuously sent from the host computer, the recording head is protected each time recording of one image data is completed, and a transition to a recording state is performed. This is an efficient process. For example, despite the image data being continuously sent from the host computer, every time the recording medium on which recording is performed is ejected, the recording head is covered with a recovery tub, or after performing suction processing, In the processing method of recording the next image data, it takes a considerable time to complete the recording of all the image data.

The present invention has been made in view of the above-mentioned conventional problems, and provides a timing at which a recording head is shifted to a recording state at the start of recording.
It is an object of the present invention to provide an ink jet recording apparatus that controls the timing at which a recording head is shifted to a protection state at the end of recording, thereby always keeping the recording head in a state suitable for recording and shortening the recording time. .

[0015]

According to the present invention, there is provided an ink jet recording apparatus which conveys a recording medium and discharges ink droplets from a plurality of recording heads arranged opposite to the recording medium to perform recording. In the device,
Measuring means for measuring a conveyance distance from a predetermined position of the recording medium, and control means for setting each of the plurality of recording heads to a recordable state according to the conveyance distance measured by the measurement means. Features.

According to the above arrangement, the recording head is switched from the protection state to the recording state at the first timing when the transport distance of the recording medium reaches the first value to execute the recording operation. Is further measured, and the time when the image data to be recorded is conveyed by the length in the conveyance direction is set as a second timing, and the recording head is protected from the recording state at the second timing. By shifting to, the recording head can always be kept in an optimal state.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment to which the ink jet recording apparatus of the present invention is applied will be described with reference to the drawings.

(Embodiment 1) FIG. 1 is a perspective view of a printer to which an ink jet recording apparatus of the present invention is applied.

The printer 101 has four recording heads 102 for ejecting inks of different colors.
The image data sent from the host computer is expanded for each color, and the image data for each color is stored in an image temporary recording memory (hereinafter, also referred to as “VRAM”) for each color. At the time of recording, the recording head 102 performs recording on a recording medium (hereinafter, referred to as “recording paper”) 104 fed from a paper feeding unit 103 to a predetermined position based on the image data. When the recording is completed, the transport unit 105 transports the recording paper 104 to the loading unit 106, and the recording paper 104 on which the recording is completed is loaded on the loading unit 106.

A control unit (not shown) for controlling the operation of each of these operating units in accordance with a command from a host computer or a user's operation command is provided, and each operating unit operates according to a control signal from this control unit. .

As described above, a state in which ink is ejected from the recording head, an image is formed on the recording paper, and the recording paper is loaded on the loading section 106 is referred to as a “recording state”. . On the other hand, a state in which such a recording operation is not performed is referred to as a “protection state”. Basically, the recording state is switched from the recording state to the protection state when all the image data recording is completed and no image data is sent from the host computer.

FIG. 2 is a schematic front view of the recording head.

The recording head 102 has four recording heads, one for discharging cyan (C) ink, one for discharging magenta (M) ink, one for discharging yellow (Y) ink, and one for discharging black (K) ink. is there. Hereinafter, when distinguishing the recording head of each color, C,
Add M, Y, K. Each recording head 102 is connected to an ink tank (not shown) via a tube.
Ink is supplied from this ink tank.

Each recording head 102 has an ejection port array (not shown) in which a plurality of ejection ports are arranged, and the length of the ejection port array corresponds to the width of the recording paper. Further, each recording head 102 is connected to an ink tank (not shown) storing ink of each color via a tube (not shown), a tube connector (not shown), and a tube station (not shown). ing. The ink in the ink tank is supplied to the recording head 102 via this tube.

A common liquid chamber for storing the ink supplied through the tube 107 is provided inside the recording head 102. The common liquid chamber communicates with each discharge port via an ink path, and the ink is usually filled in the discharge port and the ink path. Heating heaters are provided in the ink path corresponding to the respective ejection ports. When ejecting ink,
By causing the heating heater to generate heat rapidly, film boiling occurs in the ink, and bubbles are instantaneously generated. Ink droplets are ejected from each ejection port using the pressure at which the bubbles are generated. The method of ejecting ink droplets is not limited to such a bubble jet method, but may be a method using a piezoelectric element such as a piezo element.

Further, a recovery unit 2 is provided to protect the ejection port array portion of the recording head 102 during non-printing.

As shown in FIG. 3A, the recovery unit 2
Includes a recovery tub 201 that covers the ejection port array 110 of each recording head 102. When not recording, the recovery tub 201
Covers the entire surface of the recording head 102 having the ejection port array so that the ejection ports are not exposed to the outside air. further,
An absorber 202 is provided at a portion facing the discharge port of the recovery tub 201.
When the recovery tub 201 covers the discharge port array 110, the absorber 202 comes into close contact with the discharge port array 110. Then, while absorbing excess ink attached to the discharge port portion, the contact between the discharge port portion and the outside air is cut off, and the evaporation of the ink in the discharge port is prevented.

On the other hand, at the time of recording, the recording head 102 is moved in the direction of arrow p (FIGS. 2 and 3) as shown in FIG.
(See (a)) to be separated from the recovery tub 201.
That is, the clutch 107 corresponding to each recording head 102 is rotated by the driving of the head drive motor 108, and the recording head 102 is lifted up in the vertical direction and separated from the recovery tub 201 by this rotation. On the other hand, in the recovery tub 201, the clutch 203 corresponding to each recovery tub 201 is rotated by the drive of the tub drive motor 204, and the recovery tub 201 is moved in the direction of the arrow p. When the recovery tub 201 moves a predetermined distance, the clutch 107 of the recording head 102 rotates in the reverse direction, and the recording head 102 reaches the recording position (the state shown in FIG. 3B). The operation of the four recording heads 102 may be performed simultaneously, or only those necessary for recording may be performed.

In the printer 101 having such a configuration, in order to properly protect the recording head 102 and efficiently execute the recording operation, the present invention employs a recording operation corresponding to the amount of image data and the ink used. I do.

Next, the recording operation will be described.

FIG. 4 is a schematic sectional view of the printer.

FIG. 5 is a flowchart showing the operation flow.

It is assumed that the host computer sequentially transmits image data for a plurality of recording sheets to the printer 101 in the data arrangement order. When all the image data has been transmitted, the host computer finally transmits a data transmission end signal.

The control unit converts the image data sent from the host computer (not shown) into a VR for each ink color.
Deploy to AM (step 1). At this time, the control unit identifies a print head used for printing and a print head not used. When the development of the image data for one sheet of recording paper in the VRAM is completed (step 2), the transport unit 105 is operated (step 3). Further, of the recording heads 102 protected by the recovery unit 2, only the recording head used for recording is detached from the recovery tub 201, moved to a predetermined recording position, and brought into a recordable state (step 4).
FIG. 6A shows a printable state when printing is performed using all printheads 102. Paper feed unit 1
03 is operated, and the recording paper 104 is transported one sheet at a time.
5 (step 5).

As described above, when the recording head 102 is set in the recordable state, the recording is performed by discharging ink from each recording head at the following timing (step 6).

The recording paper 104 sent to the transport section 105 moves on the transport section 105 in the direction of arrow q at a constant speed according to the operation of the transport section 105. The entrance TOF sensor 111, which is a photo interrupter,
When the leading end of the conveyed recording paper 104 is detected, the detection signal is sent to the control unit. The control unit counts the number of operation pulses of the conveyance motor (not shown) of the conveyance unit 105 using the detection signal as a timing. When the number of operation pulses reaches a predetermined value P1, the recording paper 104 moves in the direction of arrow q. It is determined that the sheet has been conveyed to a position facing the black recording head 102K disposed at the most upstream side, and ink droplets are ejected from the black recording head 102K. Further, when the number of operating pulses of the transport motor reaches a predetermined value P2, ink droplets are ejected from the cyan recording head 102C. Thus, according to the number of operating pulses of the transport motor,
The recording heads 102 are sequentially operated from the upstream in the direction of the arrow q to form an image on the entire recording paper 104.

When the number of operating pulses of the transport motor reaches a value corresponding to the length of the recording paper in the direction of the arrow q, that is, when recording of one recording paper is completed, each recording head 102 The ink ejection ends. And FIG.
As shown in (a), the apparatus stands by in a recordable state.

When there is image data expanded in the VRAM, that is, when there is image data to be recorded on the next recording sheet, the recording head 102 repeats the above recording operation. In other words, the transport unit 105 transports the next recording sheet to a predetermined position.
The number of operating pulses of the transport motor is started to be counted with the detection signal 11 as a timing, and the recording head 102 performs an ejection operation according to the number of pulses.

On the other hand, if there is no image data expanded in the VRAM and there is no new image data transmitted from the host computer, that is, if a data transmission end signal has been transmitted from the host computer (step 7), The control unit determines that all recording is completed, and
As shown in (b), the recovery unit 2 is connected to the recording head 102 to be in a protection state (step 8). Further, when the recording paper 104 on which recording is completed is loaded on the loading unit 106, the transport unit 105 and the paper feeding unit 103 are stopped, and the recording operation is completed (step 9).

As described above, if the control unit issues an operation command to the recovery unit 2 after confirming the status of data stored in the VRAM and the transmission end signal of the host computer, it is unnecessary to print the recording head. Is no longer in a protected state, so that the recording time can be shortened as compared with the related art.

(Embodiment 2) In Embodiment 1, the inlet TO
When a predetermined time elapses after the F sensor detects a recording sheet, the recording sheet is simultaneously detached from the recovery tub regardless of the arrangement order of the recording heads, and is set in a recordable state. However, when the transport speed of the recording paper is slow, it may take a considerable time from when the recording head on the upstream side in the transport direction starts the recording operation to when the recording head on the most downstream side starts the recording operation. . In such a case, if the most downstream print head is detached from the recovery tub at the same timing as the upstream print head, the ink in the ejection port portion may evaporate during the print standby state, and may not be suitable for printing. . In the present embodiment, a method for preventing such a situation will be described.

FIG. 7 is a perspective view of a printer for performing recording on roll-shaped recording paper.

The recording paper 104 on which the label with the label attached is rolled is fixed to the roll holder 112 such that the end of the recording paper 104 is on the transport unit 105. And the transport unit 1
When the recording sheet 105 is operated, the end of the recording sheet 104 is conveyed in the direction of the arrow p, and the roll is rotated in accordance with the operation of the conveying section 105, and the recording sheet is sequentially moved to the conveying section 105 and fed. The mechanism is that it is. The labels are of uniform size and are attached to the backing paper at predetermined intervals.

The structures of the recording head 102 and the recovery unit 2 are the same as in the first embodiment.

FIG. 8 is a schematic sectional view of the printer shown in FIG.

FIG. 9 is a flowchart showing the recording operation.

It is assumed that image data for a plurality of labels is sequentially transmitted from the host computer to the printer 101 in the data arrangement order. When all the image data has been transmitted, the host computer finally transmits a data transmission end signal.

The control unit converts the image data sent from the host computer (not shown) into VR for each ink color.
Develop to AM (step 91). At this time, the control unit identifies a printhead used for printing and a printhead not used.

At the time when the image data for one label has been developed in the VRAM (step 92), the roll holder 11
2 and the transport unit 105 are operated (step 93).

When the roll holder 112 and the transport unit 105 are operated, the recording paper 104 is fed, and when the leading end reaches the entrance TOF sensor 111, the entrance TOF sensor 111 detects the recording paper 104 (FIG. 8). (A) Middle point). The control unit counts the number of drive pulses of the transport motor with the timing when the entrance TOF sensor 111 detects the recording paper 104 as timing. When the number of pulses reaches a predetermined value T4, the black recording head 102K
Is removed from the recovery tub 201 and moved to a predetermined recording position to be in a recordable state (middle point in FIG. 8A) (step 94). When the black recording head 102K is not used for recording, the protection state may be maintained. T4 is a value obtained by subtracting the pulse number T2 required for the recording head 102 to shift from the protection state to the recordable state from the pulse number T1 required for the recording paper 104 to reach the black recording head 102K. .

Further, when the pulse number reaches T1 (the middle point in FIG. 8A), the black recording head 102K starts discharging (step 95).

At the timing when the black recording head 102K becomes recordable, that is, at the point where the pulse number reaches T4, the pulse number starts counting again, and when the pulse number reaches a predetermined value T3, the cyan recording head 10K is started.
The 2C is detached from the recovery tub 201, moved to a predetermined recording position, and brought into a recordable state (the middle point in FIG. 8A). Further, when the pulse number reaches T5 (FIG. 8)
(A) Middle point), the cyan recording head 102C starts discharging.

FIG. 8B is a diagram showing a state of the recording head when the recording paper 104 reaches a point. Black recording head 102K and cyan recording head 102C
Performs the ejection operation, but the magenta recording head 102M and the yellow recording head 102Y, to which the recording paper has not yet arrived, remain in the protected state.

Each of the magenta recording head 102M and the yellow recording head 102Y shifts to a recordable state and discharges when the number of drive pulses of the transport motor reaches a predetermined value in the same manner as described above. Then, the number of drive pulses of the transport motor is newly counted at the timing when each recording head starts the discharging operation. The counted pulse number is referred to as “recording pulse number”.

After starting the recording operation in this way,
That is, when the number of pulses after the recording paper reaches the point (see FIG. 8), that is, the number of pulses at the time of recording coincides with the vertical size of the recorded image, that is, the recording of black developed in the VRAM is completed. At this point, the black recording head 102K stops the ejection operation and enters a recordable state. Similarly, the other recording heads stop the ejection operation when the number of recording pulses matches the vertical size of the recorded image.

When recording the next label, the pulse of the transport motor is counted after the next label is detected by the entrance TOF sensor as described above.
When the number of pulses reaches a predetermined value, a recording operation is performed in the same manner.

At the time when each recording head stops the ejection operation, the control unit receives no data developed in the VRAM corresponding to the recording head and further receives a data transmission end signal from the host computer (step S1). 96),
It is determined that the recording is completed, the recovery unit 2 is moved, and each recording head 102 is set in the protection state (step 97).

FIG. 10A shows the point in time when the black recording head enters the protection state. In this way, the recording heads that have completed recording sequentially shift to the protection state. FIG.
(B) shows a point in time when all the recording heads are in the protection state.

Then, the transport unit 105 and the roll holder 1
12 is stopped (step 98), and the recording operation ends.

As described above, by setting the respective recording heads to the recordable state after the recording paper reaches the predetermined position, the ejection ports are not unnecessarily exposed to the air.
The discharge port can always be maintained in a good state.

Further, depending on the image data, there is image data having colors not used for recording among the four colors. For example,
In the case of image data formed in a single color of black, cyan, magenta, and yellow recording heads are not used for recording. The printing operation in the present embodiment in the case of one color black will be described below.

FIG. 11B is a schematic cross-sectional view of the printer during a printing operation in one color of black.

In the same manner as in the above-described processing sequence, the control unit expands the data sent from the host computer in the VRAM for each ink color, and identifies printheads used for printing and printheads not used. .

When the image data for one label has been developed in the VRAM, the roll holder 112 and the transport unit 105
Is operated to feed the recording paper 104. Recording paper 10
4 is detected by the entrance TOF sensor 111 (FIG. 1).
1 (a)), the control unit counts the number of drive pulses of the transport motor, and when the count reaches a predetermined value T4, moves the black recording head 102K from the protection state to the recording state, and When the time reaches T3, the ejection of the ink is started. In this case, since only black is used for recording, the cyan, magenta, and yellow recording heads 102C, M, and Y maintain the protected state.

When the ejection operation is started in this way and the number of recording pulses reaches the vertical size of the recorded image, the black recording head 102K stops the ejection operation and becomes ready for recording. Further, when there is no data developed in the VRAM and a data transmission end signal is received from the host computer, the recovery unit 2 is moved and the black recording head 1 is moved.
02K is placed in a protection state. Then, a paper discharging operation is performed, and the recording operation ends.

As described above, since the recording head that is not used can maintain the protection state, it is possible to prevent the deterioration of the ink and the like.

As described above, the timing of the recording state transition of the recording head is controlled for each color, and the timing of the recording head transition to the protection state is also controlled for each color.
It is possible to maintain the protection state of the recording head other than during recording, prevent deterioration of the quality of the recorded image, and minimize the protection of the recording head during recording, thereby shortening the recording time. .

(Embodiment 3) In the second embodiment, a printer having a recording head of four colors has been described. In the present embodiment, a printer having a recording head of six colors in which two more colors are added will be described. .

FIG. 12 is a perspective view of the printer.

The recording heads 102 are arranged in the order of black, cyan, light cyan, magenta, light magenta, and yellow in this order from the front in the conveying direction of the recording paper. The recording state and the protection state of each recording head are determined by attaching and detaching the recovery unit as in the first and second embodiments.

Further, in this embodiment, the recording paper 104
Use cut paper. Cut paper is paper that is long in the transport direction.

FIGS. 13 and 14 are sectional views of the printer of FIG.

FIG. 15 is a flowchart showing the recording process.

As in the first and second embodiments, the control unit expands the data sent from the host computer in the VRAM for each color of ink, and identifies printheads used for printing and printheads not used. . At the point in time when the recording image for one color has been developed (step 1501), the sheet feeding unit 1
03 and the transport section 105 are operated to transport the recording paper (step 1502). When the entrance TOF sensor 111 detects the leading edge of the conveyed recording paper (point in FIG. 13), the detection signal is sent to the control unit. The control unit starts counting the number of operating pulses of the transport motor using the detection signal as a timing, similarly to the first and second embodiments. Note that the recording paper 104 is long and has a margin before the recording area as shown in FIG. Therefore, the recording operation is started after the recording paper is conveyed by the margin.
Specifically, it is as follows.

When the number of pulses, which has started counting after the leading edge of the sheet is detected by the entrance TOF sensor 111, reaches a predetermined value P3 (point in FIG. 13), the black recording head 102K is separated from the recovery tub 201. Is moved to a predetermined recording position to be in a recordable state (step 15).
03). Here, P3 is determined from the time T1 during which the recording paper 104 travels the distance from the entrance TOF sensor 111 to the black recording head 102K, from the black recording head 102K.
Is a value obtained by adding a pulse number P2 for conveying the distance from the leading end of the sheet to the upper margin portion to a numerical value P1 obtained by subtracting a time T2 from the protection state to the recording state by converting the time into a pulse number.

Then, in accordance with the black recording image developed in the VRAM, the black recording head 102K starts discharging ink (middle point in FIG. 13B) (step 1504). When the number of drive pulses of the transport motor further reaches the predetermined value P4 (point in FIG. 13) from the timing when the number of pulses reaches the predetermined value P3 (point in FIG. 13), the cyan recording head 102C goes out of the protection state. The state shifts to the recording state, and the ejection of ink is started in accordance with the recording image developed in the VRAM (point in FIG. 13). Here P4
Is the time T during which the recording paper 104 travels the distance from the black recording head 102K to the cyan recording head 102C.
3 is a value converted into the number of pulses.

Thereafter, similarly, the light cyan recording head 102L
C, the magenta recording head 102M, the light magenta recording head 102LM, and the yellow recording head 102Y also sequentially shift to the recording state and start ink ejection.

When the recording of the predetermined area is completed, a recording end process is performed.

When the number of drive pulses of the transport motor, which starts counting from the timing (point in FIG. 13) at which the black recording head 102K starts recording, becomes the vertical size of the recorded image, that is, the black color developed in the VRAM When the recording of one recording image is completed, the black recording head 102K shifts from the recording state to the protection state (see FIG. 14A). Thereafter, the recording heads of cyan, light cyan, magenta, light magenta, and yellow also sequentially shift to the protection state similarly (step 1505). When all the recording heads have shifted to the protection state (see FIG. 14B),
The recording paper 104 is discharged, and the paper supply unit 103 and the transport unit 105
Is stopped and the recording is terminated (step 1506).

As described above, the recording state transition timing of the recording head is controlled for each color, the number of recording pulses is counted for each recording head, and the protection state transition timing is also controlled for each color. Can always be maintained in an optimal state.

(Others) It should be noted that the present invention includes a means (for example, an electrothermal converter or a laser beam) for generating thermal energy as energy used for discharging ink, particularly in an ink jet recording system. An excellent effect is obtained in a recording head and a recording apparatus of a type in which the state of ink is changed by the thermal energy. This is because according to such a method, it is possible to achieve higher density and higher definition of recording.

The typical configuration and principle are described in, for example, US Pat. Nos. 4,723,129 and 4,740.
It is preferable to use the basic principle disclosed in the specification of Japanese Patent No. 796. This method is a so-called on-demand type,
Although it can be applied to any type of continuous type, in particular, in the case of the on-demand type, it can be applied to a sheet holding liquid (ink) or an electrothermal converter arranged corresponding to the liquid path. By applying at least one drive signal corresponding to the recorded information and giving a rapid temperature rise exceeding the nucleate boiling, heat energy is generated in the electrothermal transducer, and film boiling occurs on the heat acting surface of the recording head. Liquid (ink) corresponding to this drive signal on a one-to-one basis.
This is effective because air bubbles inside can be formed. The liquid (ink) is ejected through the ejection opening by the growth and contraction of the bubble to form at least one droplet. When the drive signal is formed into a pulse shape, the growth and shrinkage of the bubble are performed immediately and appropriately, so that the ejection of a liquid (ink) having particularly excellent responsiveness can be achieved, which is more preferable. As the pulse-shaped drive signal, those described in US Pat. Nos. 4,463,359 and 4,345,262 are suitable. Further, if the conditions described in US Pat. No. 4,313,124 relating to the temperature rise rate of the heat acting surface are adopted, more excellent recording can be performed.

As the configuration of the recording head, in addition to the combination of the discharge port, the liquid path, and the electrothermal converter (linear liquid flow path or right-angled liquid flow path) as disclosed in the above-mentioned respective specifications, U.S. Pat. No. 4,558,333 and U.S. Pat.
A configuration using the specification of Japanese Patent No. 59600 is also included in the present invention. In addition, Japanese Unexamined Patent Application Publication No. 59-123670 discloses a configuration in which a common slit is used as a discharge portion of an electrothermal converter for a plurality of electrothermal converters, and an aperture for absorbing a pressure wave of thermal energy is provided. The effect of the present invention is effective even if the configuration is based on JP-A-59-138461, which discloses a configuration corresponding to a discharge unit. That is, according to the present invention, recording can be reliably and efficiently performed regardless of the form of the recording head.

Further, the present invention can be effectively applied to a full line type recording head having a length corresponding to the maximum width of a recording medium on which a recording apparatus can record. Such a recording head may have a configuration that satisfies the length by a combination of a plurality of recording heads, or a configuration as one integrally formed recording head.

It is preferable to add a recording head ejection recovery unit, a preliminary auxiliary unit, and the like as the configuration of the recording apparatus of the present invention since the effects of the present invention can be further stabilized. If these are specifically mentioned, the recording head is heated using capping means, cleaning means, pressurizing or suction means, an electrothermal transducer, another heating element or a combination thereof. Pre-heating means for performing the pre-heating and pre-discharging means for performing the discharging other than the recording can be used.

The type and number of recording heads to be mounted are not limited to those provided only for one color ink, for example, and for a plurality of inks having different recording colors and densities. A plurality may be provided. That is, for example, the printing mode of the printing apparatus is not limited to a printing mode of only a mainstream color such as black, but may be any of integrally forming a printing head or a combination of a plurality of printing heads. The present invention is also very effective for an apparatus provided with at least one of the recording modes of full color by color mixture.

In addition, in the embodiments of the present invention described above, the ink is described as a liquid. However, an ink which solidifies at room temperature or lower and which softens or liquefies at room temperature may be used. In general, the ink jet method generally controls the temperature of the ink itself within a range of 30 ° C. or more and 70 ° C. or less to control the temperature so that the viscosity of the ink is in a stable ejection range. Sometimes, the ink may be in a liquid state. In addition, in order to positively prevent temperature rise due to thermal energy by using it as energy for changing the state of the ink from a solid state to a liquid state, or to prevent evaporation of the ink, the ink is solidified in a standing state and heated. May be used. In any case, the application of heat energy causes the ink to be liquefied by the application of the heat energy according to the recording signal and the liquid ink to be ejected, or to start to solidify when reaching the recording medium. The present invention is also applicable to a case where an ink having a property of liquefying for the first time is used. In such a case, the ink
JP-A-54-56847 or JP-A-60-7
As described in Japanese Patent Publication No. 1260, a form may be adopted in which the liquid sheet or the solid substance is held as a liquid or solid substance in the concave portion or through hole of the porous sheet and faces the electrothermal converter. In the present invention, the most effective one for each of the above-mentioned inks is to execute the above-mentioned film boiling method.

In addition, the form of the ink jet recording apparatus of the present invention is not limited to those used as image output terminals of information processing equipment such as computers, copying apparatuses combined with readers and the like, and facsimile apparatuses having a transmission / reception function. It may take a form.

[0089]

According to the present invention, the recording head is switched from the protection state to the recording state at the first timing when the transport distance of the recording medium reaches the first value, and the recording operation is executed. By further measuring the transport distance, the time when the image data to be printed is transported by the length in the transport direction is defined as the second timing, and the recording head is shifted from the recording state to the protection state at the second timing. The timing at which the recording head is shifted to the recording state at the start of recording and the timing at which the recording head is shifted to the protection state at the end of recording are controlled so that the recording head is always kept in a state suitable for recording, and the recording time is shortened. Can be achieved.

[Brief description of the drawings]

FIG. 1 is a perspective view of a printer according to a first embodiment of the present invention.

FIG. 2 is a perspective view showing a recording head and a recovery unit.

FIG. 3A shows a protection state of a recording head, and FIG.
FIG. 3 is a side view of a recording head showing a recording enabled state of the recording head.

FIG. 4 is a sectional view of the printer according to the first embodiment.

FIG. 5 is a flowchart illustrating a recording process.

6A is a cross-sectional view illustrating the printer in a recordable state, and FIG. 6B is a cross-sectional view of the printer in a protected state.

FIG. 7 is a perspective view illustrating a printer according to a second embodiment.

8A is a cross-sectional view illustrating a point in time when the leading edge of the recording sheet reaches an entrance TOF sensor, and FIG. 8B is a cross-sectional view of the printer in FIG. 7 illustrating a point in time when a recording operation is started.

FIG. 9 is a flowchart illustrating a recording process according to the second embodiment.

FIG. 10A is a cross-sectional view showing a state in which the state shifts from a recording state to a protected state after printing is completed, and FIG. 10B is a cross-sectional view of the printer shown in FIG.

11A is a cross-sectional view showing a point in time when the leading edge of the recording paper reaches an entrance TOF sensor, and FIG. 11B is a cross-sectional view of the printer of FIG. 7 showing only a black recording head performing a recording operation. It is.

FIG. 12 is a perspective view illustrating a printer according to a third embodiment.

13A is a cross-sectional view illustrating a point in time when the leading edge of the recording sheet reaches an entrance TOF sensor, and FIG. 13B is a cross-sectional view of the printer in FIG. 12 illustrating a point in time when a recording operation is started.

14A is a cross-sectional view showing a state in which the recording state is shifted to a protected state after recording is completed, and FIG. 14B is a cross-sectional view of the printer in FIG. 12 showing a protected state.

FIG. 15 is a flowchart illustrating a recording process according to a third embodiment.

[Explanation of symbols]

 Reference Signs List 101 Printer 102K Black recording head 102C Cyan recording head 102LC Light cyan recording head 102M Magenta recording head 102LM Light magenta recording head 102Y Yellow recording head 103 Paper feed unit 104 Recording medium (recording paper) 105 Transport unit 106 Loading unit 107 Tube 108 Tube connector 109 tube station 110 discharge port array 111 inlet TOF sensor 2 recovery unit 201 recovery tub 202 absorber

Claims (7)

[Claims] 1. An ink jet recording apparatus which conveys a recording medium and ejects ink droplets from each of a plurality of recording heads arranged to face the recording medium to perform recording, wherein the recording medium is conveyed from a predetermined position. An ink jet recording apparatus comprising: a measuring unit for measuring a distance; and a control unit for setting each of the plurality of recording heads to a recordable state in accordance with the transport distance measured by the measuring unit. 2. Each of the recording heads has at least two states: a protected state in which a head unit is protected, and a recordable state in which the head unit is not protected, and transport of the recording medium measured by the measuring unit. At a first timing when the distance reaches the first value, the control unit switches each of the recording heads from the protection state to the recordable state, and the conveyance distance of the recording medium measured by the measurement unit reaches the second value. 2. The ink jet recording apparatus according to claim 1, wherein the control unit switches the recording heads from a recordable state to a protected state at the second timing. 3. The method according to claim 1, wherein the first timing is a point in time before the recording head starts recording by a time required for the recording head to transition from the protection state to the recording enabled state. The inkjet recording apparatus according to claim 2. 4. The method according to claim 1, wherein the second timing is a point in time when the printhead has conveyed a distance corresponding to a length of image data to be recorded in a conveying direction of the recording medium from a point in time when the recording head starts recording. 4. The printing apparatus according to claim 2, wherein, at the second timing, when there is no more image data to be recorded, the recording head is switched from a recordable state to a protected state.
3. The ink jet recording apparatus according to claim 1. 5. The measuring unit counts the number of drive pulses of a transport motor that drives a transport unit that transports the recording medium in a predetermined direction at a constant speed, and counts the first timing and the first timing in accordance with the number of pulses. 5. The ink jet recording apparatus according to claim 2, wherein two timings are obtained. 6. The ink jet recording apparatus according to claim 2, wherein said measuring means obtains said first timing and said second timing for each recording head. 7. The ink jet recording apparatus according to claim 1, wherein the recording head generates bubbles in the ink by thermal energy, and discharges ink droplets by the pressure of the generated bubbles. .