JP3058440B2 - Ink jet recording device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink-jet recording apparatus, and more particularly, to a method for detecting a distance between a recording medium and a recording head by using a detection unit such as an optical sensor. The present invention relates to an ink jet recording apparatus that can be adjusted to a minimum.

[Prior Art] Among non-impact recording apparatuses, a so-called ink jet apparatus is capable of high-speed recording, and has advantages such as being able to perform recording on plain paper without requiring a special fixing process and being quiet. And has attracted attention as an extremely powerful recording apparatus.

In such a recording apparatus, it is desirable to provide a means for maintaining a constant distance between the recording medium and the recording head and a means for detecting the presence or absence of the recording medium. The distance between the recording medium and the recording head is kept constant by contacting the holding mechanism of the recording medium with some means, and as the latter, the presence or absence of the recording medium is detected by a position detection sensor or the like. And the like are known.

[Problems to be Solved by the Invention] However, the following problems are involved in a mechanism provided in a conventional ink jet printing apparatus for maintaining a constant distance between a print medium and a printhead for high-precision printing. There was a point.

That is, in order to keep the distance between the recording medium and the recording head constant, the position where the carriage is brought into contact with the holding mechanism of the recording medium by some means is limited. In addition, the carriage that maintains contact vibrates with the movement, and the vibration is transmitted to the recording head, whereby the ejection state becomes unstable, and there is a possibility that image unevenness may occur.

Further, even when the carriage is not brought into contact with the holding mechanism of the recording medium, the following problem occurs.

That is, in the case of the conventional carriage, the positional accuracy when the carriage is stationary and when it is driven depends on the attitude accuracy of the carriage itself and the linearity of the rail along which the carriage moves. The rail may warp due to fluctuations and the like. Further, the platen, which is a mechanism for holding the recording medium, may be warped, and the distance between the recording medium and the recording head may fluctuate slightly, resulting in a disadvantage that a high impact point accuracy cannot be obtained. In addition, there is also a problem that the recording head is too close to the recording medium and comes into contact with the recording medium to stain the recording medium. Furthermore, excessive pursuit of linearity of the rails resulted in high costs.

Further, the conventional sensor for detecting the presence or absence of the recording medium detects a position different from the recording position on the recording medium, and whether the recording object actually exists at a position facing the recording head. However, it is not possible to detect whether the recording medium is torn or not. For example, when the recording medium is torn, there is an adverse effect such that recording is performed on a portion having no recording medium.

Further, there is a waste that a sensor is specially attached to detect the presence or absence of the recording medium.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-described conventional problems by performing control in real time to always maintain a constant distance between a recording medium and a recording head with high accuracy in real time. It is an object of the present invention to provide an ink jet apparatus which can improve the position accuracy and can realize a mechanism for controlling the position at low cost.

Means for Solving the Problems In order to achieve the above object, the present invention uses an ink jet recording head to discharge ink onto a recording medium that is arranged on a platen and moves relatively to the ink jet recording head. In the ink jet recording apparatus that performs recording by using a light source, a half mirror, and a condensing lens in order to determine whether the distance between the ink jet recording head and the recording medium disposed on the platen is a predetermined distance. And a plurality of light receiving elements, a first optical path through which the irradiation light emitted from the light source reaches the recording medium via the half mirror and the condenser lens, and a reflection of the irradiation light from the recording medium. After the reflected light reaches the half mirror via the condensing lens in the opposite direction through the first optical path, the reflected light changes its path in a direction different from the first optical path, and A second optical path extending in the direction of a number of light receiving elements, a detecting means for issuing a signal for optically detecting the distance based on a state of the reflected light reaching the plurality of light receiving elements, and the ink jet. Supporting means for movably supporting the recording head and the detecting means in a direction approaching and separating from the platen; and setting the distance to the predetermined distance based on the signal from the detecting means. Control means for moving the support means.

[Operation] According to the present invention, the distance between the recording head and the recording medium is detected by the optical detecting means, and when the distance deviates from the predetermined distance, the control means supports the distance based on the signal from the detecting means. Since the recording head supported by the means is moved so as to be maintained at a predetermined distance, a high-quality recorded image can be obtained by increasing the landing accuracy of ink droplets. Furthermore, by setting the first optical path and the second optical path between the half mirror and the recording medium to be the same optical path, it is possible to obtain a degree of freedom in the arrangement of the light source and the light receiving element, and it is generally said to be about 1 mm. The optical path can also be provided in the space between the inkjet recording head and the recording medium, so that the size can be reduced.

[Example] Hereinafter, an example of the present invention will be described in detail and specifically with reference to the drawings.

FIG. 1 shows an example of an ink jet recording apparatus capable of controlling a distance between a recording medium and a recording head as one embodiment of the present invention. In this figure, reference numeral 1 denotes an optical sensor unit having an optical sensor (not shown);
The driving source 4 for operating in the direction is a support for the optical sensor unit 1, the recording head 3, and the driving source 2, and these represent the main parts of the apparatus according to the present invention.

These main parts are mounted on a carriage 6 via a support 4 provided on a stage 5, and the carriage 6 is moved at a predetermined timing along a guide rail 7 by a driving means (not shown). Numeral 8 denotes a platen capable of holding the recording medium 9 at a recording position and feeding a sheet of the recording medium 9 by a drive motor (not shown). During the moving scan, ink is ejected toward the recording medium 9 to perform recording while being controlled so that a constant distance is always maintained by means described later.

FIG. 2 shows an example of the configuration of a control system according to the present invention, that is, a control system for controlling the distance between the recording medium 9 and the recording head 3 to be kept constant while monitoring the distance with the optical sensor unit 1. . Here, 10 is a light source using a miniature bulb, LED, laser, etc., 11 is a polarizing beam splitter, 12 is a collimating lens, 13 is a prism mirror, 14 is a focusing lens, 15 is a cylindrical lens, and 16 is a recording target as described later. It is a photodiode that receives light reflected from the light source from the body 9. The image on the photodiode 16 is analyzed by the control signal detection unit 20, and the drive source 2 drives the recording head 3 by a control signal output based on the analysis result, and moves the recording head 3 from the recording medium 9 to a predetermined position. Keep away.

Therefore, the distance between the recording medium and the recording head according to this embodiment is corrected as follows.

As described above, the deflection of the recording surface when the recording medium 9 is conveyed due to the warpage of the platen 8 or the fluctuation in the ink ejection direction when the recording head 3 moves due to the warpage of the guide rail 7. And so on, a deviation occurs from the focal point position of the light beam or the converged light, that is, the position where the distance between the recording medium 9 and the recording head 3 is an appropriate value. The magnitude and direction of the error are detected by the photodiode 16 and converted into a signal.
A signal for correcting the deviation (focus error) is converted into a current value as described later, and is controlled so as to be transmitted to the movement source 2 to move the recording head 3 in real time.

At the same time, the difference (change) in the amount of reflected light from the platen 8 and the recording medium 9 is used to detect the edge of the recording medium 9, thereby detecting the presence or absence of the recording medium 9 to perform recording. The driving state of the head 3 can be controlled.

Note that the diameter of the spot of the light beam or the converged light obtained from the light source 10 needs to be not too small so that a reaction as an optical sensor can be obtained with respect to the irregularities on the surface of the recording medium 9. In addition, it is necessary that the difference in the light amount of the focus diode 16 is only detectable and not too large, and is preferably about 100 μm to 500 μm.

Next, an optical detection operation when an astigmatism method is used as a specific method of detecting a control signal by the optical sensor unit 1 will be described with reference to FIG. 3A.

In FIG. 3A, the reflected light from the recording medium 9 (arrow)
Is configured to focus on the point Z when the recording medium 9 is correctly positioned at the focal point of the converging lens 14 (solid line).

In this case, the Z point does not change in the direction perpendicular to the paper surface due to the operation of the cylindrical lens 15, but the point at the P point becomes a perfect circle because the focus is on the X point in the direction parallel to the paper surface. So assuming that at a 4-division formation photodiode 16 of D ₁ to D ₄ to the position of the point P, the spot on the photodiode 16 is as shown in α of Figure 3B.

When the recording medium 9 and the recording head 3 approach each other as shown by a broken line, one focus Z similarly moves to the Z 'point or the X point moves to the X' point, and the spot at the P point becomes The direction perpendicular to the paper surface is thicker, and the direction parallel to the paper surface is thinner, and the spot on the photodiode 16 is a vertically long ellipse like β in FIG. 3B.

Conversely, when the distance between the recording medium 9 and the recording head 3 changes so that the recording medium 9 moves away from the converging lens 16, a horizontally long ellipse indicated by γ in FIG. 3B is obtained. Therefore, the calculation of the focus signal may be performed based on such a change in the shape of the ellipse.

FIG. 3C is a control signal detection unit for explaining a process until the recording head is actually controlled by a control signal obtained by receiving reflected light from the recording medium 9 into the four-division photodiode 16. FIG.

Here, when the reflected light as shown in FIG. 3A is received by the four-division photodiode 16, the output signal D _{1 at the} opposed position is received.
And D ₄ and D ₂ and D ₃ are input to two adders A and B, respectively. The outputs from the adders A and B are further input to the adder C and the subtractor D, thereby determining whether the distance between the recording medium 9 and the recording head 3 in the subtractor D is appropriate. The focus signal, which is an error signal, is output from the subtracter D to the drive source 2 by comparing the value with the appropriate value, and the focus is corrected by driving the drive source 2, that is, the above-described distance is corrected.

Further, by inputting the output of the adder C to the comparator F, it is determined whether or not the recording medium 9 is present relative to the recording head 3, and the output signal is sent to the head driver G to be output. If there is no recording medium 9, recording by the recording head 3 is not performed.

4A and 4B show a specific example of a drive mechanism for driving the recording head 3 for the above-described distance correction. 4A
In the figure, reference numeral 21 denotes a permanent magnet which is attached to the recording head 3 side and has a polarity formed on one end face thereof, 22 denotes a double electromagnetic coil fixed to the carriage 6 as shown, and 4 denotes In the case of the present example, the support member is constituted by a pair of parallel leaf springs made of metal and supports the recording head 3 via the stage 5 so as to be movable in the direction of arrow A. On the other hand, as shown in FIG. 4B, the double electromagnetic coil 22 has two coils 22A and 22B whose winding directions are opposite to each other, and the output signal from the subtracter D, that is, the recording medium 9 and the recording head 3 When the distance between them becomes too close to the initial set value, a current is supplied to the double electromagnetic coil 22 through the changeover switch H in a direction to attract the recording head 3.

When the output signal from the subtracter D is zero, the double electromagnetic coil 22 is not driven assuming that the above-mentioned distance is maintained at the initial setting position. Assuming that the distance between the recording head 3 and the recording head 3 is too large, a current in the opposite direction to that described above is supplied to the double electromagnetic coil 22 through the changeover switch H to repel the magnet 21 and Is brought closer to the recording medium 9. FIG. 5A shows a change in the above-mentioned distance at this time confirmed by an experiment. Here, a solid line represents a proper value (μm) of the distance, a broken line represents a change in the distance with the carriage movement when the control according to the present invention is not performed, and a solid line represents a change in the control result according to the present invention. Is shown.

As is clear from FIG. 5A, it has been found that the control has been performed so that the distance between the recording medium 9 and the recording head 3 is corrected with high accuracy. In addition, as a result of comparing the image recorded when performing the control according to the present invention and the image recorded without performing the control, the former image has much less image unevenness than the latter image, The present inventors confirmed that it was uniform.

In FIG. 3C as a second embodiment, when the output signal of the adder C is differentiated and input to the comparator F, the output becomes a peak value when the edge of the recording medium 9 is detected. Whether or not the recording medium 9 is always present can be detected. 3C, the output signal of the subtractor D is differentiated and, although not shown, the signal is input to the comparator F. Since the peak value is output, it is possible to simultaneously detect whether or not the recording medium exists at all times.

As a third embodiment, the control signal detecting means in the optical sensor unit 1 can be configured by using a wedge prism method using the apex angle of the prism 30 as shown in FIG.

That is, in this example, the reflected light from the recording medium 9 is obtained from _four photodiodes 16 (D _{1 to} D ₄ ) arranged as shown in FIG. Is an appropriate value, and when the reflected light from the surface of the recording medium is focused on the apex angle of the prism 30, the output relationship is D _{1 as} shown in FIG.
+ D ₄ = D ₂ + D ₃ , and when the distance between the recording medium 9 and the recording head 3 is smaller than an appropriate value, the output relationship is D ₁ + D ₄ > D ₂ + D _{3 as shown in FIG} . If it is large, the reverse is true.

Also in this example, a metal parallel plate spring is used as the structure of the support 4, and the head driving means as shown in FIGS. 4A and 4B is used, so that the recording medium 9 and the recording head 3 can be separated. The distance between the recording medium and the recording head 3 due to the movement of the carriage 6 can be corrected with high accuracy as shown in FIG. 5B. Was done. The respective lines in the following FIGS. 5B to 5E will be described later, but the description is omitted because it is based on the case of FIG. 5A.

FIG. 7 shows a fourth embodiment in which the control signal detecting means of the optical sensor unit 1 is irradiated with a light beam or convergent light to the recording medium 9 from an oblique direction. In this embodiment, the reflected light is detected by _two photodiodes 16 (D ₁ and D ₂ ), and the light is reflected in response to a slight change in the distance between the recording medium 9 and the recording head 3. from changing the reflection angle from the recording medium 9 of the beam or focused beam, and received by the photodiode D ₁ and D _2, detects that the change is the amount of light received both by its receiving position.

That is, the distance is a proper value between the recording head 3 and the recording medium 9, when the incident light is focused at the recording member surface becomes equal at the amount of light between D ₁ and D _2, and the recording amount of D ₂ is greater than the amount of D ₁ the distance between the body and recording head becomes smaller than the appropriate value. On the other hand, when the value is larger than the appropriate value, the opposite is true.

Such a detecting means is incorporated in the optical sensor unit 1 shown in the first embodiment to correct the distance between the recording medium 9 and the recording head 3. FIG. 5C shows the accompanying change in the distance between the recording medium and the recording head. Thus, also in the embodiment, the distance between the recording medium and the recording head could be corrected with sufficient accuracy. or,
The image also had less image unevenness and was more uniform than before.

FIG. 8 shows an example in which the critical angle method is used as the control signal detecting means of the optical sensor unit 1 as a fifth embodiment.

That is, in this embodiment, when the distance between the recording medium and the recording head is an appropriate value and the incident light is focused on the recording medium surface, the reflected light from the recording medium surface is parallel as indicated by a solid line. It utilizes the fact that the light, the reflected light is incident on and reflected by the reflecting surface of the prism 13 which is set to be critical angle bisected photodiode 16 (D ₁ and D _2). In the case of parallel light, the output of the photodiode 16 is D ₁ = D ₂ . When the distance between the recording medium and the recording head is smaller than an appropriate value, the reflected light from the recording medium surface becomes divergent light as shown by a broken line, and the incident angle to the reflection surface is on the left side with respect to the central ray (chain line). Is smaller than the critical angle, and transmitted light Lt is generated. Therefore, the output of the photodiode 16 is D ₁ <D ₂ .

When the distance between the recording medium and the recording head becomes larger than an appropriate value, the output of the photodiode 16 is reversed to D ₁
> The D _2.

In this example, the other mechanisms were subjected to the same experiment as in Example 1, and the change in the distance between the recording medium and the recording head due to the movement of the carriage 6 was corrected with high accuracy as shown in FIG. 5D. was gotten.

Also in this example, a uniform image was obtained with less image unevenness than in the prior art.

FIG. 9 shows a sixth embodiment of the present invention. In this embodiment, the control signal detecting means of the optical sensor unit 1 is configured in the same manner as in the second embodiment, and the recording head 3 is driven by the micrometer 41 and the motor 42. Is held movably in the direction of arrow B. Thus, FIG. 5E shows a change in the distance between the recording medium and the recording head due to the movement of the carriage as a result of performing the correction of the distance between the recording medium and the recording head as an experiment according to the present embodiment.

Also in this example, the distance between the recording medium and the recording head can be corrected with high accuracy, and a uniform image can be obtained with less image unevenness compared to the related art.

Next, the procedure of the recording head fine movement control operation by the control system according to the present invention will be described with reference to FIG.

First, in step S1, light irradiation is performed from the light source 10 toward the recording medium 9, and in step S2, the reflected light reflected from the recording medium 9 is received by the optical sensor unit.
The optical sensor unit outputs a control signal to a control signal detection unit in step S3 as a focus error detection system including a plurality of photodiodes 16. In step S4, it is determined whether the presence or absence of the recording medium 9 is detected or the distance between the head and the recording medium is corrected. In the former case, the process branches to step S5, where the operation results from the adder are compared. In step S6, it is determined whether or not the recording medium 9 is at a position facing the recording head 3. If it is determined that there is a recording medium, the process proceeds to step S7, and recording is permitted. If it is determined that there is no recording object, the process branches to step S8, and recording is prohibited.

If it is determined in step S4 that the distance between the recording head 3 and the recording medium 9 is to be corrected, the process branches to step S9, where whether or not the distance is appropriate is determined based on the output from the subtractor. Judge. Then, if appropriate, the process proceeds directly to step S11 to execute recording. On the other hand, if it is determined that the recording head 3 is not appropriate, the process branches to step S10, where the recording head 3 is finely driven by the drive source 2, corrected so that an appropriate value is obtained, and proceeds to step S11.

Although the control signal detecting means, the head support mechanism, and the head drive source of the optical sensor unit 1 shown in the above-described embodiment are the same as those of the first embodiment, a color that hardly reflects the color of the platen 8, for example, black Accordingly, when the recording apparatus is operated, the edge of the ordinary recording paper in the head scanning direction can be detected by the optical sensor unit 1 along with the movement of the carriage 6.

The control signal detecting means, the head support mechanism, and the head drive source of the optical sensor unit 1 are the same as those in the first embodiment, and the color of the platen 8 is also changed to a mirror glossy color that is easily reflected in the head scanning direction. The edge of the ordinary recording paper can be detected by the optical sensor unit 1.

(Others) The present invention brings about an excellent effect particularly in a recording head and a recording apparatus of a bubble jet system among ink jet recording systems. This is because according to such a method, it is possible to achieve higher density and higher definition of recording.

As for the representative configuration and principle, it is preferable to use the basic principle disclosed in, for example, US Pat. Nos. 4,723,129 and 4,740,796. This method can be applied to both the so-called on-demand type and the continuous type. In particular, in the case of the on-demand type, it is arranged corresponding to a sheet or a liquid path holding a liquid (ink). Applying at least one drive signal corresponding to the recording information and providing a rapid temperature rise exceeding nucleate boiling to the electrothermal transducer, thereby causing the electrothermal transducer to generate thermal energy, thereby causing the recording head to emit heat energy. This is effective because a film in the liquid (ink) corresponding to the driving signal can be formed one by one by causing film boiling on the heat acting surface. 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. U.S. Pat. No. 44
Those described in JP-A-63359 and JP-A-4345262 are suitable. Further, if the conditions described in US Pat. No. 4,313,124 relating to the invention relating to the temperature rise rate of the heat acting surface are employed, more excellent recording can be performed.

As a configuration of the recording head, in addition to a combination configuration (a linear liquid flow path or a right-angled liquid flow path) of a discharge port, a liquid path, and an electrothermal converter as disclosed in the above-mentioned specifications, A configuration using U.S. Pat. No. 4,558,333 and U.S. Pat. No. 4,459,600, which disclose a configuration in which is disposed in a bending region, is also included in the present invention. In addition, Japanese Unexamined Patent 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 opening 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.

In addition, even with the serial type printer as in the above example, the recording head fixed to the main unit or attached to the main unit enables electrical connection with the main unit and supply of ink from the main unit. The present invention is also effective when a replaceable chip type print head or a cartridge type print head having an ink tank provided integrally with the print head itself is used.

Further, it is preferable to add recovery means for the print head, preliminary auxiliary means, and the like provided as a configuration of the printing apparatus in the present invention since the effects of the present invention can be further stabilized. If these are specifically mentioned, capping means for the recording head, cleaning means, pressurizing or suction means, preheating means using an electrothermal transducer or another heating element or a combination thereof, Performing a preliminary ejection mode in which ejection is performed separately from printing is also effective for performing stable printing.

Regarding the type or number of print heads to be mounted, for example, in addition to one provided for single color ink, a plurality of print heads are provided corresponding to a plurality of inks having different print colors and densities. May be used. 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 extremely effective for an apparatus provided with at least one of full colors by color mixture.

In addition, in the embodiments of the present invention described above, the ink is described as a liquid. However, an ink that solidifies at or below room temperature and softens or liquefies at room temperature, or the ink itself in an inkjet method. In general, the temperature is controlled 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. I just need. In addition, the temperature rise due to thermal energy can be positively prevented by using it as energy for changing the state of the ink from a solid state to a liquid state, or ink that solidifies in a standing state to prevent evaporation of the ink can be used. In any case, the ink is liquefied by the application of the thermal energy according to the recording signal, and the ink is liquefied, and the liquid ink is discharged. The present invention is also applicable to a case where an ink that liquefies for the first time by energy is used. The ink in such a case is disclosed in
No. -56847 or JP-A-60-71260, while being held as a liquid or solid substance in a porous sheet recess or through hole, facing the electrothermal converter. It is good also as a form. 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 may be used as an image output terminal of an information processing apparatus such as a computer, a copying apparatus combined with a reader or the like, or a facsimile apparatus having a transmission / reception function. Or the like.

[Effects of the Invention] As described above, according to the present invention, the distance between the recording head and the recording medium is detected by the optical detecting means. Since the control means moves the recording head supported by the support means based on the signal so as to be maintained at a predetermined distance,
By improving the landing accuracy of ink droplets, recording quality is improved, and a high-quality recorded image is obtained. Furthermore,
By setting the first optical path and the second optical path between the half mirror and the recording medium to be the same optical path, the degree of freedom in the arrangement of the light source and the light receiving element can be obtained, and the inkjet recording head and the recording medium can be moved. The compactness can be achieved so that the optical path can be provided even in a narrow space.

Further, by providing the distance detecting means with a function of detecting the presence or absence of the recording medium, it is possible to eliminate a recording error in which recording is performed in a place where the recording medium does not exist.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an example of the configuration of the ink jet device of the present invention, FIG. 2 is a configuration diagram of a control system according to the present invention, and FIG. 3A is an example of a control signal detecting means of the optical sensor unit according to the present invention. FIG. 3B is an explanatory diagram showing an example of detection by the control signal detecting means in FIG. 3A, FIG. 3C is a circuit diagram of a recording head control signal detecting unit according to the present invention, and FIG. 4A is a diagram according to the present invention. FIG. 4B is an explanatory diagram of a drive source shown in FIG. 4A, and FIGS. 5A to 5E are first embodiment, third embodiment, and fourth embodiment of the present invention. FIG. 6 is a graph showing experimental results of control according to the embodiment, the fifth embodiment and the sixth embodiment. FIG. 6 is an explanatory diagram showing an optical configuration and principle of a control signal detecting means according to a third embodiment of the present invention. FIG. 7 is an explanatory view showing an optical configuration of a control signal detecting means according to a fourth embodiment of the present invention, and FIG. FIG. 9 is an explanatory view showing an optical configuration of a control signal detecting means according to a fifth embodiment of the present invention, FIG. 9 is a side view showing a configuration of a recording head drive control means according to a sixth embodiment of the present invention, and FIG. 9 is a flowchart of a recording head fine movement control operation according to the first embodiment. DESCRIPTION OF SYMBOLS 1 ... Optical sensor part, 2 ... Driving source, 3 ... Recording head, 4 ... Support body, 5 ... Stage, 6 ... Carriage, 8 ... Platen, 9 ... Recording object, 10 ... Light source, 16D _{1 to} D ₄ … Photodiode, 20… Control signal detector, 21… Permanent magnet, 22… Double electromagnetic coil, 30… Prism.

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B41J 25/308 B41J 2/01 B41J 11/20

Claims (4)

(57) [Claims] An ink jet recording apparatus which performs recording by discharging ink onto a recording medium which is arranged on a platen and relatively moves with respect to the ink jet recording head, using the ink jet recording head, comprising: A light source, a half mirror, a condenser lens, and a plurality of light receiving elements are used to determine whether or not the distance of the recording medium arranged on the platen is a predetermined distance. A first optical path that reaches the recording medium via the half mirror and the condensing lens, and reflected light due to reflection of the irradiation light from the recording medium passes through the first optical path in the opposite direction through the condensing lens. After reaching the half mirror, changing the course in a direction different from the first optical path and reaching the plurality of light receiving element directions; Detecting means for issuing a signal for optically detecting the distance based on the state of the reflected light reaching the optical element; and moving the ink jet recording head and the detecting means closer to and away from the platen. Ink jet recording, comprising: a support unit that movably supports in a direction; and a control unit that moves the support unit so that the distance is set to the predetermined distance based on the signal from the detection unit. apparatus. 2. The apparatus according to claim 1, wherein said control means moves said support means with respect to said platen such that said reflected light reaches a predetermined light receiving element among said plurality of light receiving elements. Item 2. An inkjet recording apparatus according to Item 1. 3. An ink jet recording apparatus according to claim 1, wherein said detecting means is capable of detecting the presence or absence of said recording medium at a position facing said ink jet recording head. 4. The ink-jet recording head according to claim 1, wherein said ink-jet recording head includes an electrothermal transducer, and discharges ink using thermal energy generated by said electrothermal transducer. apparatus.