JPH09152357A - Angle-of-rotation detection apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an angle-of-rotation detection apparatus whose production costs can be reduced and which can be miniaturized. SOLUTION: In an apparatus, a plurality of timing signals at every identical angle of rotation are generated with reference to one rotation or a rotating body, and the angle of rotation of the rotating body is detected on the basis of the timing signals. Then, one timing signal out of the respective timing signals is changed, its change position is made to correspond to the zero point of the rotating body, a detection circuit 81 which detects the change position is provided, and the detection timing of the change position is detected as the position of the zero point. In this case, a plurality of slits are formed on the rotating body at identical intervals in the circumferential direction, and the formation of one slit out of the slits is omitted. A signal output value is increased on the basis of beams of measuring light penetrating the slits when the beams of measuring light are blocked by the rotating body. The respective timing signals are formed in such a way that the signal output value is decreased when the beams of measuring light penetrate the slits. It is preferable that, when the output signal value is increased so as to reach a reference value, a zero-point detection signal is output.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotation angle detecting device for detecting a rotation angle of a rotating body. More specifically, the present invention relates to a rotation angle detection device capable of detecting a rotation angle and a zero point position of a rotating body based on one type of timing signal.

[0002]

2. Description of the Related Art As a rotation angle detecting device, a rotary encoder is attached to a rotary portion, and the position of a slit formed in the rotary encoder is converted into a pulse signal by an optical detecting means to detect it, thereby rotating the rotary portion. There are some that detect corners. Conventionally, in this type of rotation angle detection device, when simultaneously detecting the zero point position in addition to the rotation angle of the rotating part, a slit for detecting the rotation angle in the rotary encoder and a zero position for detecting the zero position The slit and the slit are formed separately, and the positions of these different types of slits are detected by dedicated optical detection means. For example, when detecting 1/90 rotation of the rotating unit and the zero position,
As shown in FIG. 15, the rotary unit, that is, the rotary encoder 1
A-phase slit 101 corresponding to 1/90 rotation of 03
And the Z-phase slit 102 corresponding to the zero point position are formed in the rotary encoder 103.

[0003]

However, in the above rotation angle detecting device, the A-phase slit 101 and the Z-phase slit 102 are formed separately, and these are detected by dedicated optical detecting means. Therefore, there is a problem that the number of constituent members and the number of manufacturing steps are increased, the production cost is increased, and the rotation angle detection device is increased in size.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a rotation angle detecting device in which the production cost is reduced and the size is reduced.

[0005]

In order to achieve the above object, the invention according to claim 1 generates a plurality of timing signals for each same rotation angle for one rotation of a rotating body, and based on the timing signals. A rotation angle detecting device for detecting a rotation angle of a rotating body by detecting one of the timing signals by changing one timing signal so that the changed position corresponds to the zero point of the rotating body and detecting the changed position. A circuit is provided, and the detection timing of the change position is detected as the zero point position.

Therefore, when the rotating body rotates, the detection circuit detects the changing position of the timing signal output with the rotation of the rotating body. Since this changed position corresponds to the zero point of the rotating body, the detection timing of the changed position becomes the zero point position, whereby the zero point of the rotating body is detected. On the other hand, since the timing signal is arranged for each same rotation angle, the rotation angle of the rotating body is detected based on the timing signal.

According to the second aspect of the present invention, a plurality of slits are formed in the rotating body at the same intervals in the circumferential direction, and one of the slits is omitted, and the slit is based on the measurement light passing through the slits. Each timing signal is formed to increase the signal output value when the measurement light is blocked by the rotating body and decrease the signal output value when the measurement light passes through the slit, and the output signal value increases. When it reaches the reference value, the zero point detection signal is output.

Therefore, the timing signal rises at a position outside the slit and falls at a position corresponding to the slit. That is, the timing signal has a waveform that periodically peaks in accordance with the rotation of the rotating body, but does not fall at the position where the slit formation is omitted and the signal value increases as it is and a large waveform, that is, other timing. Form an altered waveform for the signal. Therefore, the value of the timing signal does not become larger than the preset reference value at the position where the slit is formed, but becomes larger than the reference value at the position where the formation of the slit is omitted. It is possible to detect the changing position of the timing signal by comparing the value of 1 with the reference value. Then, when the value of the timing signal reaches the reference value and the change position is detected, the zero point detection signal is output.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below in detail based on the best mode shown in the drawings.

FIG. 1 shows a rotation angle detecting device according to the present invention, and shows an embodiment in the case of being used for controlling a rotating drum of an ink jet head and ink drops, for example. In addition,
Detailed description of the inkjet head will be given later.

The rotation angle detecting device is constructed by connecting a detecting circuit 81 to the optical detecting means 80. The optical detection means 80 is composed of, for example, a rotary encoder that is attached to a rotary drum of an inkjet head and rotates integrally with the rotary drum, and a photosensor that is arranged so as to sandwich the rotary encoder.

FIG. 2 shows an example of a rotary encoder that is a rotating body. The rotary encoder 17 has a plurality of slits 17a arranged at equal intervals in the circumferential direction. In this embodiment, in order to detect, for example, 1/90 rotation of the rotary drum, the entire circumference of the rotary encoder 17 is divided into 90 equal parts, and 89 slits 1 are provided at positions other than the zero point position 17b.
7a are formed. That is, at the zero point position 17b,
The formation of slits is omitted.

On the other hand, the photosensor is composed of, for example, a light emitting diode which emits measurement light and a light receiving element which receives the measurement light and outputs a signal. The output signal of this photosensor rises when the measurement light is blocked by each slit 17a and falls when it passes through each slit 17a. That is, the rotary encoder 17 is provided with a plurality of slits 17a at the same intervals in the circumferential direction, and the measurement light passes through the slits 17a, and when the measurement light is blocked by the rotary encoder 17, the signal output value is increased. The timing signals are formed by reducing the signal output value when the measuring light passes through the slit 17a.

The detection circuit 81 detects the position of the slit 17a and the position of the zero point position 17b based on the output signal of the photo sensor. The output signal from the photo sensor is pulled up by the resistor 82 and then amplified by the amplifier 83.
Supplied to In the amplification section 83, the output signals from the photosensor are separately amplified by the first and second buffer amplifiers 84 and 85.

The waveform of the signal amplified by the first buffer amplifier 84, that is, the output waveform at the position b in FIG. 1, rises at the position where it exits the slit 17a, while at the slit 17a, as shown by the waveform b in FIG. It is falling at the corresponding position. Therefore, the output waveform does not drop at the position corresponding to the zero point position (imaginary slit position) 17b, and its value becomes larger than the second reference voltage V2 described later. Then, the amplified signal is supplied to the A-phase comparator section 86 and the Z-phase comparator section 87, respectively. Each of the waves represented by the waveform b is a timing signal generated every 1/90 rotation of the rotary encoder 17. The wave that becomes larger than the second reference voltage V2 is the changed timing signal, and the position of this wave is the changed position.

The A-phase comparator section 86 compares the amplified signal with the first reference voltage V1 and outputs the waveform d as a signal. That is, the H signal is output when the amplified signal represented by the waveform b is smaller than the first reference voltage V1, and the L signal is output when the amplified signal is larger than the first reference voltage V1. Therefore, the output waveform at the d position corresponds to the H signal and the L signal corresponding to the position of the slit 17a.
It becomes a pulse that repeats with the signal. The first reference voltage V
1 is set to an optimum value by adjusting the first variable resistor 88.

Further, the Z-phase comparator section 87 compares the amplified signal with the second reference voltage V2 and outputs the signal represented by the waveform e. That is, when the amplified signal represented by the waveform b is smaller than the second reference voltage V2, the H signal is
If it is larger, the L signal is output. Therefore, the output waveform at the position e becomes a pulse that outputs the L signal corresponding to the change position of the timing signal, and the second reference voltage V2
By setting to the optimum value,
That is, the detection timing of the change position of the timing signal can be detected as the zero point position 17b. The second reference voltage V
2 is set by adjusting the second variable resistor 89.

The one-shot multivibrator section 90 which has received the pulse signal output from the Z-phase comparator section 87 triggers the falling edge of the output signal represented by the waveform e as represented by the waveform f. As a one-shot pulse, that is, a zero point detection signal is output. At this time,
The time constant t is set by the third variable resistor 91, and
By adjusting the time constant t and the second variable resistor 89, the waveform f
The trailing edge of the virtual waveform d'is matched with the trailing edge of the virtual waveform d '. Therefore, the output waveform at the f position is
It becomes a pulse showing the Z phase for detecting the zero point position 17b. Note that the value of the time constant t is the rotary encoder 17
Is adjusted to an optimum value according to the target rotation speed of. Further, the virtual waveform d'is a waveform obtained when it is assumed that the slit 17a is formed at the zero point position 17b.

On the other hand, the second buffer amplifier 8 of the amplification section 83
The signal amplified by 5 is supplied to the integral calculator 92, and then compared with the third reference voltage V3 in the rotation speed detector 93. Then, when the value of the signal is smaller than the third reference voltage V3, the L signal is output, and when the value is large, the L signal is output.
A signal is output. That is, the L signal is output when the rotation speed of the rotary encoder 17 is low, and the H signal is output when the rotation speed is sufficiently high. The third
The reference voltage V3 is set by adjusting the third variable resistor 94.

In the first gate section 95, the output signal of the one-shot multivibrator section 90 is passed according to the output signal of the rotation speed detecting section 93. That is, the output signal of the one-shot multivibrator unit 90 is output as an inverted signal only when the rotation speed of the rotary encoder 17 becomes sufficiently high. This prevents the Z-phase pulse signal represented by the waveform f from being output when the rotational speed of the rotary encoder 17 rises when the rotational speed is sufficiently lower than the target rotational speed. That is, due to the relationship between the second reference voltage V2 and the waveform of the output signal at the b position, the timing signals from all the slits 17a exceed the second reference voltage V2 when the rotation speed of the rotary encoder 17 is low. In this case, the rotary encoder 17, that is, the rotary drum 3 of the inkjet head 1 is servoed at a rotational speed lower than the target rotational speed by the combined signal (waveform i) of the Z-phase pulse signal and the signal represented by the waveform d. There is a risk that it will be affected. In order to prevent this, the integration calculation unit 92 smoothes the output waveform from the amplification unit 83, and compares this with the third reference voltage V3 of the rotation speed detection unit 93, until a constant rotation speed is reached. The Z-phase pulse signal is not output. Therefore, when the rotation angle detection device is incorporated in the inkjet head 1, a 1 μF electrolytic capacitor is used as the waveform integration capacitor 79 of the integration calculation unit 92.

The output signal of the first gate unit 95 is inverted in the second gate unit 96. Then, this inversion signal passes through the third and fourth gate sections 97 and 98, and A
It is combined with the output signal of the phase comparator unit 86, and the waveform of the signal becomes the i waveform. That is, the output signal at the i position is a combination of the Z phase for the zero point position 17b and the A phase for 1/90 rotation. Therefore, the zero point position 17b of the rotary encoder 17, that is, the Z phase can be known based on the pulse signal of the e position or the f position. In addition, the rotary encoder 17 is set to 1 based on the i-position pulse signal.
/ 90 rotations, that is, phase A can be known.

Reference numeral 99 in the figure denotes a PLL (Phase Locked Loop) circuit, and as will be described later, when the rotation angle detecting device according to the present invention is incorporated in an ink jet head, the rotation speed of the rotating drum. To maintain a predetermined value. Since the PLL circuit 99 is conventionally known, the description thereof will be omitted.

Next, as an application example of the rotation angle detection device according to the present invention, an embodiment in which the rotation angle detection device is incorporated in, for example, a full line type ink jet head will be described. 4 and 5 show an embodiment of a full line type inkjet head, and the inkjet head 1 is composed of an ink droplet generation unit and an ink droplet control unit.

The ink droplet generating section is for generating ink droplets that jump toward the recording medium by cutting off the flow of the ink that is continuously ejected in the form of filaments, and collecting the ink that is unnecessary for recording. This housing 2
The rotary drum 3 is rotatably housed therein, and the slit mechanism 4 is arranged below the rotary drum 3.

The rotary drum 3, as shown in detail in FIGS. 6 and 7, has an ink supply hole 7 through which ink is supplied.
a core drum 7 having an outer peripheral surface and a spiral groove 7b communicating with the ink supply hole 7a, and a gap 5 formed to have a larger diameter than the core drum 7 and absorbing a thermal expansion difference.
Covering the core drum 7 with the interposition of
A nozzle pipe 6 having a plurality of ink ejection holes 6a communicating therewith, and an elastic seal member 67 provided between the core drum 7 and the nozzle pipe 6 to close the gap 5.

The ink supply hole 7a of the core drum 7 and the spiral groove 7b are communicated with each other by a large number of communication holes 7c radially provided from the ink supply hole 7a. Spiral groove 7b
Are formed continuously from one end to the other end of the core drum 7 so that printing and drawing for one pitch can be performed by one rotation of the rotary drum 3.

The core drum 7 is made of resin, for example. That is, the core drum 7 is a pipe-shaped member obtained by, for example, extruding a phenol resin, and machining the spiral groove 7b and each communication hole 7c. When the core drum 7 is made of a resin that can be easily processed, the manufacturing cost can be reduced, and the weight and durability of the core drum 7 can be reduced. At both ends of the core drum 7, end plates 8 and 9 having shaft portions 8a and 9a are provided.
Are fixed by, for example, screws 72. An ink supply hole 8b is formed in the end plate 8 on one side, and the ink supply hole 8b communicates with the ink supply hole 7a in the core drum 7.

Further, as the nozzle pipe 6, an extremely thin nickel pipe having a thickness of, for example, about 40 μm is employed in order to form the ink ejection hole 6a capable of ejecting the ink in the shape of a thin thread that does not spread. The ink ejection holes 6a of, for example, about 35 microns are perforated at a predetermined pitch, for example, an axial pitch p corresponding to 300 DPI (dots per inch) so as to be the same lead as the spiral groove 7b of the core drum 7. . The nozzle pipe 6 having such a configuration is manufactured by, for example, an electroforming method, and a hole is formed by laser processing or the like. In some cases, the thin film material may be rolled and welded, and the seam portion may be removed by grinding.

The nozzle pipe 6 is formed to have a larger diameter than the core drum 7 and the end plates 8 and 9, and the thermal expansion difference is absorbed between the nozzle pipe 6 and the core drum 7 and the end plates 8 and 9. A gap 5 is formed. The nozzle pipe 6 is placed on the core drum 7 after being positioned such that the position of the spiral groove 7b and the position of each ink ejection hole 6a match.

The elastic seal member 67 is, for example, an O-ring. The O-ring 67 is arranged in annular grooves 7d, 7d formed at both ends of the outer peripheral surface of the core drum 7. Each O
The inner diameter of the ring 67 is smaller than the diameter of the bottom surface of each annular groove 7d, and the outer diameter is larger than the inner diameter of the nozzle pipe 6. Therefore, each O-ring 67 elastically deforms to close the gap 5, and the nozzle pipe 6 and the core drum 7 are frictionally engaged with each other to be integrated.

The shaft portions 8a and 9a of the end plates 8 and 9 are connected to the housing 2 via a bearing member such as a ball bearing 11.
It is supported rotatably. Each ball bearing 11
The side surface of is covered with a sheet-like elastic sealing member, and the gaps between the ball bearings 11 are liquid-tightly sealed to prevent ink leakage. Further, a coil spring 12 is arranged between the end plate 8 on one side and the ball bearing 11, and the rotary drum 3 has the ball bearing 1 on the other side.
Preloaded to 1. As a result, the ball bearings 11 can be appropriately used while applying a preload, and the rotary drum 3 can be positioned in the width direction of the recording paper 22 described later.

Here, when the ink jet head 1 is activated to start printing, the temperature of the rotary drum 3 becomes high. The coefficient of thermal expansion of phenol resin is significantly higher than that of nickel. Therefore, the expansion amount of the core drum 7 made of phenol resin is larger than the expansion amount of the nozzle pipe 6 made of nickel. In the rotating drum 3, since the gap 5 is interposed between the core drum 7 and the nozzle pipe 6, this gap 5 absorbs the difference in thermal expansion between the core drum 7 and the nozzle pipe 6, and the nozzle pipe 6 at the time of expansion.
Prevents deformation, rupture, and wrinkling during contraction. Each O-ring 67 includes a core drum 7 and a nozzle pipe 6.
Elastically deforms according to the thermal expansion of, and allows the gap 5 to absorb the difference in thermal expansion. In addition, the ink that has flowed into the gap 5 from the annular groove 7d through the communication holes 7c of the core drum 7 is
It is sealed by the ring 67 and does not leak from both ends of the rotary drum 3.

The shaft portion 9a of the end plate 9 on the other side projects outside the housing 2 and is connected to the drive motor 13 via a belt transmission mechanism. That is, the drive motor 13
A pulley 14 is attached to the output shaft 13a of the above, and a pulley 15 is attached to the shaft portion 9a, and the pulleys 14 and 15 are connected by a belt 16. Pulley 14 is pulley 15
Therefore, the rotation of the drive motor 13 is accelerated and transmitted to the shaft portion 9a.
The rotation speed of a reaches up to 9000 rpm, for example. As a result, the rotating drum 3 can be rotated at high speed without using an expensive high-precision motor for high-speed rotation. Further, when the rotary drum 3 is directly rotated by the motor for high-speed rotation without passing through the belt transmission mechanism, it is necessary to match the rotation centers with high accuracy. The head 1 does not require so high accuracy in aligning the rotation centers of the drive motor 13 and the belt transmission mechanism.

When the shaft portion 9a is rotated at a high speed in this way, the transmission of the rotational force by the belt 16 may cause slippage between the belt 16 and each of the pulleys 14 and 15, so that the drive motor 13 is driven. There is a possibility that the rotation angle and the rotation angle of the rotary drum 3 are not synchronized. Therefore, the inkjet head 1 includes the rotation angle detection device according to the present invention, detects the rotation angle of the rotary drum 3 every 1/90 rotation, and controls the ink droplets in synchronization with the rotation of the rotary drum 3. The rotary encoder 17 of the rotation angle detecting device is, for example, the shaft portion 9
a. The rotary encoder 17 is
The zero position 17b is attached to the shaft portion 9b so as to match the zero position of the rotary drum 3. On the other hand, at a predetermined position of the housing 2, a photo sensor 18 is attached so as to sandwich the rotary encoder 17.

The housing 2 has a square pipe 19 for accommodating the rotary drum 3, a pair of end plates 60 and 61 for liquid-tightly closing both ends of the square pipe 19, and a pair of support walls 20 for supporting the rotary drum 3. , 21. The square pipe 19 surrounds the rotary drum 3 at a predetermined interval, receives the ink continuously ejected in the form of threads from each ink ejection hole 6a of the rotary drum 3, and temporarily stores the ink at the bottom thereof. The inner peripheral surface of the square pipe 19 is provided with a liquid-permeable member (not shown) such as maltoprene as a lining, whereby the ink ejected from each ink ejection hole 6a is formed. It prevents atomization when it collides with the inner surface. Further, the ink attached to the maltoprene or the like flows down by its own weight and is collected at the bottom. An elongated rectangular cutout 19a for attaching the slit mechanism 4 is formed on the bottom surface of the square pipe 19.

The support walls 20 and 21 are arranged at a predetermined height while supporting the square pipe 19 at their upper half portions. Further, shaft holes 20a and 21a are provided in the upper half portions of the respective support walls 20 and 21, and rotatably support the rotary drum 3 via the bearings 11 and 11.

On the other hand, first windows 20b and 21b and second windows 20c and 21c are provided in the lower half portions of the support walls 20 and 21, respectively. The first windows 20b and 21b are the square pipe 1
The ink formed at the position facing the bottom surface of the nozzle 9 can collect the ink accumulated at the bottom of the square pipe 19. Also, the second window 20
The c and 21c are formed at positions facing a gutter 39, which will be described later, and can collect the ink collected by the gutter 39.

The outer side surfaces of the support walls 20 and 21 are covered with side covers 28 and 29 that define the ink flow paths 23 to 27. As shown in FIG. 8, the side cover 28 that covers the support wall 20 on one side is provided with a space between the side cover 28 and the support wall 20, and three ink flow paths 2 are provided.
Partition walls 28a defined by 3, 24, 25, an ink supply port 28b communicating with the first flow path 23, and all flow paths 23, 2
An ink recovery port 28c that communicates with ports 4 and 25 is provided. The ink supply port 28b is provided in the shaft hole 2 of the support wall 20.
It leads to 0a. Therefore, the ink supply port 28
The ink that has flowed into the side lid 28 from b is the shaft hole 20 a of the support wall 20, the end plate 8 and the ink supply holes 8 of the core drum 7.
The excess ink that has flowed into the rotary drum 3 through b and 7e but cannot flow into the rotary drum 3 and has overflowed from the shaft hole 20a passes through the first flow path 23 and the ink recovery port 28c. To fall. In addition, the second flow path 24 is the first
The ink communicating with the window 20b, and thus the ink collected by the square pipe 19, falls from the first window 20b through the second flow path 24 to the ink collecting port 28c. Furthermore, the third
The flow path 25 communicates with the second window 20c, so that the ink collected in the gutter 39 is transferred from the second window 20c to the third window 20c.
It drops through the flow path 25 to the ink recovery port 28c.

As shown in FIG. 9, the side cover 29 covering the support wall 21 on the other side has a fourth space between the support wall 21 and the side cover 29.
A partition wall 29a that defines the flow path 26 and the fifth flow path 27, and an ink recovery port 29b that communicates with the flow paths 26 and 27 are provided. The fourth flow path 26 communicates with the first window 21b of the support wall 21, so that the ink collected by the square pipe 19 passes through the fourth window 26 from the first window 21b to the ink recovery port 29b. To fall. In addition, the fifth flow path 27 communicates with the second window 21c, and therefore the ink collected in the gutter 39 drops from the second window 21c through the fifth flow path 27 to the ink recovery port 29b.

The first windows 20b and 21 for collecting the ink
b and the second windows 20c and 21c to the support walls 20 and 2 on both sides.
By forming the ink jet head 1 on each of the ink jet heads 1, the ink can be smoothly collected through the first and second windows of either one of the support walls even when the ink jet head 1 is installed at an inclination.

The slit mechanism 4 cuts the ink ejected from the rotary drum 3 in the form of filaments to form ink droplets, and is composed of a pair of partition members 30 and 31 arranged facing each other. The members 30 and 31 are divided into knife edge portions 68 and 69 that form the slit 2, and support portions 70 and 71 that are attached to the housing 2 side, that is, the square pipe 19 and that support the knife edge portions 68 and 69. There is.

The supporting portions 70, 71 have their base end sides fixed to the lower surface of the square pipe 19, and their leading ends penetrate into the square pipe 19 through the cutouts 19a in the bottom surface of the square pipe 19 to rotate the drum 3. It is projected toward. Each knife edge portion 68, 69 is formed into a flat plate shape, and each support portion 70,
It is fixed to the tip of 71. Each knife edge portion 68,
69 is a material that conducts electricity, for example, SUS304 material, SUS
It is made of a conductive material such as 316 material.

Since each partition member 30, 31 is divided into knife edge portions 68, 69 and support portions 70, 71, these knife edge portions 68, 69 and support portions 70, 71 are separated.
The shapes of 71 are simplified to simplify their manufacture.
Further, when each knife edge portion 68, 69 is subjected to a water repellent treatment such as Teflon coating and each support portion 70 is subjected to a hydrophilic treatment, it is possible to easily perform the treatment processing which is contrary to these properties.

The partition members 30 and 31 are the rotary drum 3
Is provided over a range of substantially the same length as, and is arranged parallel to the rotary drum 3. Then, the tips of the knife edge portions 68 and 69 are arranged facing each other with a predetermined gap therebetween to form the slit 32. The ink 46 continuously ejected like filaments from all the ink ejection holes 6a is
The slit 32 is cut by each knife edge portion 68, 69.
Ink droplets 47 that pass through are formed one after another. The width of the slit 32 is set to an appropriate value so that an ink droplet having a desired particle size can be formed.

Here, since the ink ejected in the form of filaments from the rotary drum 3 jumps out in the direction in which the centrifugal force and the rotary force of the rotary drum 3 are combined, each partition member 30 and 31 is placed directly below the center of rotation of the rotary drum 3. When installed, the traces of ink and ink droplets (indicated by the dotted lines in FIG. 4) greatly intersect the partition members 30 and 31. For this reason, in the partition members 30 and 31 having a simple shape, there is a risk that ink drops may contact the antinodes (portions inside the partition members 30 and 31 that are outside the housing 2) and atomize.
Therefore, in the case of the present embodiment, the pair of partition members 30, 31
Are arranged on the front side in the rotational direction with respect to the position directly below the center of rotation of the rotary drum 3. In this case, even if the shape of the partition members 30, 31 is simple, the partition members 30,
When the ink droplets pass through the gaps 31, the ink droplets have an angle at which they do not come into contact with the antinodes of the partition members 30 and 31, and it is not necessary to take measures to prevent the ink droplets from being atomized.

Further, the partition members 30 and 31 are provided with their rear surfaces (portions inside the housing 2) and the square pipe 1.
9 is provided so as to form a space for storing unnecessary ink. It is preferable that these spaces have a slight negative pressure, and when the negative pressure is applied to each space, the slit 3
Air is drawn from 2 to the rotating drum 3 side, and slit 3
It is possible to prevent unnecessary ink adhering to the periphery of 2 from being sucked into the square pipe 19 and dropping to the recording paper side.

The tips of the partition members 30 and 31 are
The partition member 31 on the back side is arranged at a lower position than the partition member 30 on the front side in the rotation direction of the rotary drum 3. By arranging the tip ends of the partition members 30 and 31 in the vertical direction in this manner, it is possible to prevent the slit 32 from being clogged by the surface tension of the ink droplet.

The ink droplet controller controls the ink so that only the necessary ink droplets of the ink droplets passing through the slit 32 between the partition members 30 and 31 collide with the paper based on the output signal from the rotation angle detecting device. It deflects the track of drops. The ink droplet control unit is composed of a charging electrode 33, a deflection electrode 34, a gutter 39 and the like.

The charging electrode 33 and the deflection electrode 34 are shown in FIG.
Further, as shown in FIG. 12, the flexible printed wiring board is formed by being formed on the bendable plastic sheets 35 and 36. That is, in each of the sheets 35 and 36 made of non-conductive and flexible polyimide resin, the charging electrode 33 and the deflection electrode 34 made of copper foil are formed side by side in the ink droplet track direction. . Each sheet 35,3
6 is formed to have substantially the same length as the rotary drum 3.

On one plastic sheet 35 adhered to the partition member 30 located on the front side in the rotation direction of the rotary drum 3, as shown in FIG. 10, the deflection electrode 34a is provided.
Is formed over substantially the entire length of the sheet 35, but the charging electrode 33 is divided into a plurality of parts. That is, in this plastic sheet 35, one charging electrode 33 is formed for each lead of each ink ejection hole 6a formed in the rotary drum 3.

On the other hand, as shown in FIG. 12, only the deflection electrode 34b is formed on the other plastic sheet 36 adhered to the partition member 31 located on the rear side in the rotating direction of the rotary drum 3. That is, no charging electrode is formed on the plastic sheet 36. Deflection electrode 3
4b is formed over substantially the entire length of the sheet 36. Then, the charging electrodes 33 and the deflection electrodes 34a, 3
As shown in FIGS. 11 and 13, 4b is formed in the resin layer of each plastic sheet 35, 36.

Each flexible printed wiring board 35, 3
6 is adhered to the insulators 63 and 64 fixed to the antinodes of the partition members 30 and 31. As a result, the wiring boards 35 and 36 are arranged so as to face each other with the slit 32 interposed therebetween, and the charging electrodes 33 formed on the wiring board 35.
Are arranged near the knife edge portion 68, that is, facing the slit 32.

Each charging electrode 33 is separately connected to the power source. Also, each knife edge 68,
69 and the rotary drum 3 are grounded. Therefore, the charging electrode 33 in the ON state generates an electrostatic induction phenomenon with the ink column that is ejected from the rotating drum 3 and is in contact with either one of the knife edges 68 and 69. When the ink column is cut while the electrostatic induction phenomenon occurs, charged ink droplets 47 are formed. Each charging electrode 33 is selectively turned on / off to charge the ink droplet 47 only when necessary.

In addition, the wiring boards 35 and 36 have slits 3
Since they face each other with 2 in between, each deflection electrode 34a,
34b is also arranged facing each other. Then, a voltage having a predetermined value is applied between the deflection electrodes 34a and 34b. Therefore, a Coulomb force is generated between the deflection electrodes 34 a and 34 b, and the ink droplet 4 charged by the charging electrode 33 is discharged.
Deflect the track of 7.

Reference numeral 56 in FIGS. 11 and 13 designates the flexible printed wiring boards 35 and 36 as insulators 6.
It is an adhesive that adheres to 3,64. Further, in the present embodiment, the shapes of the partition members 30 and 31 are set to be relatively simple, but even if the partition members are set to have complicated shapes, the shapes of the partition members 30 and 31 are set to correspond to these shapes. The flexible printed wiring boards 35 and 36 are deformed, so that the flexible printed wiring boards 35 and 36 are favorably fixed to the belly portions of the partition members 30 and 31. Further, each flexible printed wiring board 35, 36 is formed thin. Therefore, the ink droplet 47 passing through the slit 32 is hidden behind the tips of the knife edges 68 and 69 with respect to the rotary drum 3 and does not interfere with the track of the ink droplet 47, and the flexible printed wiring boards 35 and 36 respectively. Pass between

The gutter 39 has a gutter shape. The gutter 39 is fixed to the lower surface of the partition member 31, and receives the received ink droplets from the second window 20c of the support wall 20 or the support wall 21.
It is flowing toward the second window 21c.

In this ink jet head 1,
When not operating, the slit 32 between the partition members 30, 31
To prevent the ink in the housing 2 from drying.
This anti-drying mechanism is rotatably attached to the side surface of the square pipe 19, for example, and covers the arm plate 37 whose tip is located near the gutter 39 and the tip of the arm plate 37, and contacts the gutter 39 to form a slit. It includes a closing member 38 that closes 32, an actuator that moves the arm plate 37 when the inkjet head 1 is activated, and exposes the slit 32. The closing member 38 is made of, for example, a foaming material. Although not shown, for example, a solenoid is used as the actuator. This solenoid is attached to the upper surface of the square pipe 19. Solenoid and arm plate 37
Is attached to the square pipe 19, so that they can be fixed more easily than when attached to a cylindrical pipe. An actuator using a fluid pressure cylinder may be used instead of the solenoid.

Further, reference numeral 40 in FIGS. 8 and 9 denotes a paper feed roller for feeding the recording paper below the ink jet head 1. The paper feed roller 40 is rotated in association with printing by the rotary drum 3, and supplies the recording paper below the rotary drum 3 while sandwiching the recording paper together with the weight roller 41. The recording paper 22 supplied by the paper feed roller 40 and the weight roller 41 moves while sliding on the paper feed table 66. The weight roller 41 is dropped in a U-shaped notch 42a formed in the frame 42 and is restrained in the advancing direction of the recording paper. The sheet feeding roller 40 is shown in FIG.
As shown in, the worm wheel 44 and the worm 45
Stepping motor 4 via a torque transmission means including
Connected to 3. The stepping motor 43 operates in conjunction with the operation of the inkjet head 1.

The ink jet head 1 configured as described above forms ink droplets and operates for printing as follows.

First, the drive motor 13 is activated to prepare for printing. At this time, before the rotation of the rotary drum 3 reaches a predetermined number of rotations, the influence of the rotational force is greater than that of the centrifugal force, and the ink droplet track may be different from that during normal printing. Therefore, until the number of rotations of the rotary drum 3 reaches a predetermined number of rotations, that is, the rotation speed detection unit 93 of the rotation angle detection device.
When the output signal of is in the L state, the ink droplets are controlled by the charging electrode 33 so as to be reliably collided with the gutter 39 by the deflection electrode 34 and collected regardless of the image signal, and rotated by the PLL circuit 99. The rotation speed of the drum 3 is prevented from being locked.

Then, after the rotating drum 3 reaches a predetermined number of rotations, the printing operation is started. At this time, the ink supply port 2
The ink supplied from 8b is supplied to each ink supply hole 8b, 7b.
The ink flows into the rotary drum 3 through a, and is further continuously ejected in a filament form from each ink ejection hole 6a by a centrifugal force generated by the high speed rotation of the rotary drum 3. At this time, the ejected ink is given an initial velocity sufficient to fly, and moves in the rotating direction as if the rotating drum 3 rotates. Then, this ink is used as a pair of partition members 30, 3
At the moment of crossing 1, the ink is cut by each of the knife edges 68 and 69, and the ink of the length corresponding to the time of passing through the slit 32 is ejected as an ink droplet 47 from the slit 32 to the outside of the housing 2.

At this time, the ink droplet 47 is charged by the charging electrode 33 as needed based on the A-phase signal supplied from the rotation angle detecting device. The charging electrode 33 starts ink droplet charging control at a predetermined timing after detecting the zero position of the rotary encoder 17 based on the Z-phase signal supplied from the rotation angle detecting device. Then, after the ink droplets required for recording are charged, the deflection electrodes 34a and 34b are charged.
Since it passes through the gap, it is deflected by the Coulomb force between the deflection electrodes 34a and 34b, passes through the side of the gutter 39, and adheres to the recording paper. The rotary drum 3 is provided with a large number of ink ejection holes 6a, and ink droplets 47 are sequentially formed from the end of the rotary drum 3. Ink drop 47
Is charged by the same charging electrode 33 for each same lead, if necessary, and then track-controlled by the deflection electrodes 34a and 34b. Therefore, the electrode 33 that actually controls the track of the ink droplet 47 moves to the adjacent electrode 33 for each lead as the position where the ink droplet 47 is formed moves. The rotary drum 3 prints one lead for each rotation.

Ink droplets unnecessary for recording are gutter 3
9 is received by the gutter 39 and is transmitted from the second window 20c or 21c through the third flow path 25 or the fifth flow path 27 toward the ink recovery ports 28c, 29b. After that, the ink is collected in each of the ink recovery ports 28c, 2
It is reused after being collected from 9b into the tank.

In a region excluding the moment when the partition members 30 and 31 are passed, that is, in a region after passing through the partition members 30 and 31 and before reaching the partition member again, the ink ejected in a thread form from the rotary drum 3 is The ink collides with the inner peripheral surface of the housing 2 surrounding the rotary drum 3 and collects as unnecessary ink at the bottom of the square pipe 19, and then passes through the second flow passage 24 or the fourth flow passage 26 from the first window 20b or 21b. Drop into the ink recovery port 28c or 29b,
After being collected in a tank (not shown), it is reused.

The above-described embodiment is an example of the preferred embodiment of the present invention, but the present invention is not limited to this, and various modifications can be made without departing from the gist of the present invention. For example, the case where the rotation angle detection device according to the present invention is applied to the inkjet head 1 to control the rotation of the rotary drum 3 has been described, but the present invention is not limited to this, and the rotation angle and the zero point position of the rotating member are detected. Of course, it can be widely applied to the case.

[0066]

As described above, in the rotation angle detecting device according to the first aspect, one of the timing signals is changed so that the changed position corresponds to the zero point of the rotating body. Since the detection circuit for detecting the changed position is provided and the detection timing of the changed position is detected as the zero point position, the rotation angle and the zero point of the rotating body can be detected based on each timing signal. Therefore, the number of constituent members can be reduced, the manufacturing process can be simplified accordingly, and the production cost of the rotation angle detection device can be reduced. Moreover, since the number of constituent members can be reduced, the rotation angle detection device can be downsized.

Further, in the rotation angle detecting device according to the second aspect, a plurality of slits are formed in the rotating body at the same intervals in the circumferential direction, and one of the slits is omitted to pass through the slit. Based on the measurement light, each timing signal is formed so as to increase the signal output value when the measurement light is blocked by the rotating body and decrease the signal output value when the measurement light passes through the slit. Since the zero point detection signal is output when the output signal value increases and reaches the reference value, the zero point of the rotating body can be detected by checking the zero point detection signal.

[Brief description of the drawings]

FIG. 1 is an electric circuit diagram showing an embodiment of a rotation angle detection device according to the present invention.

FIG. 2 is a front view of a rotary encoder of the rotation angle detection device of FIG.

FIG. 3 is a diagram showing a waveform of an output signal of the rotation angle detection device of FIG.

FIG. 4 is a cross-sectional view of an inkjet head in which the rotation angle detection device of FIG. 1 is incorporated.

5 is a vertical cross-sectional view of the inkjet head of FIG.

6 is a perspective view in which a rotary drum of the inkjet head of FIG. 4 is partially cut away.

7 is a vertical sectional view of a rotary drum of the inkjet head of FIG.

8 is a cross-sectional view of the inkjet head taken along the arrow line VIII-VIII in FIG.

9 is a cross-sectional view of the inkjet head taken along the line IX-IX in FIG.

FIG. 10 shows electrodes of the inkjet head of FIG.
It is a front view of the state where the flexible printed wiring board arranged at one side was developed.

11 is a cross-sectional view of the flexible printed wiring board taken along the line XI-XI in FIG.

FIG. 12 shows electrodes of the inkjet head of FIG.
It is a front view of the state where the flexible printed wiring board arranged at the other side was developed.

13 is a cross-sectional view of the flexible printed wiring board taken along the line XIII-XIII in FIG.

14 is a plan view showing a layout of the inkjet head of FIG. 4 and each drive motor.

FIG. 15 is a front view of a conventional rotary encoder.

[Explanation of symbols]

 17 rotary encoder 17a slit 17b zero point position 80 optical detection means 81 detection circuit 83 amplification section 86 A-phase comparator section 87 Z-phase comparator section 90 one-shot multivibrator section 92 integral calculation section 93 rotational speed detection section 95-98 Gate part

Claims (2)

[Claims] 1. A rotation angle detection device for generating a plurality of timing signals for each same rotation angle for one rotation of a rotating body, and detecting the rotation angle of the rotating body based on the timing signals. One of the timing signals is changed so that the changed position corresponds to the zero point of the rotating body, and a detection circuit for detecting the changed position is provided, and the detection timing of the changed position is set as the zero point position. A rotation angle detection device characterized by detecting. 2. A plurality of slits are formed in the rotating body at equal intervals in the circumferential direction, and formation of one of the slits is omitted, and the measurement light is transmitted based on the measurement light passing through the slit. Forming each of the timing signals so as to decrease the signal output value when the measurement light passes through the slit while increasing the signal output value when blocked by a rotating body, the output signal value increases The rotation angle detection device according to claim 1, wherein a zero point detection signal is output when the reference value is reached.