JP3499980B2 - Shuttle unit drive - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shuttle unit drive device having two shuttle units, and in particular,
The present invention relates to a shuttle unit driving device for a printer.

[0002]

2. Description of the Related Art A device equipped with a shuttle unit, for example,
The printer moves the one of the shuttle units, and to keep the stability of the entire apparatus by moving inverting the other of the shuttle units in the opposite direction to the inversion. Hereinafter, the conventional technology of the shuttle device will be described by taking a printer as an example.

FIG. 12 shows a perspective view of a shuttle device in a conventional printer, FIG. 13 shows a plan view thereof, and FIG. 14 shows a drive mechanism of the shuttle device. Further, FIG. 15 shows a print head mounted on the shuttle device, and FIG. 16 shows a print head assembly used for the print head.

First, a predetermined number of 24-pin print head assemblies 11 shown in FIG. 16 are arranged to form a print head 10 shown in FIG. 15 , and the print heads 10 are mounted on a print shuttle 12 to form the print shuttle unit 1. Composed. The print shuttle unit 1 is configured to be movable in the left-right direction in the drawing by penetrating the print shuttle 12 through a stay shaft 31 whose both ends are supported by a frame (not shown).

A roller 13 engaged with the frame is provided at the rear of the print shuttle 12, and the print shuttle 12 is supported by the frame by the stay shaft 31 and the roller 13.

A yoke 14 is provided on the lower surface of the print shuttle 12, and permanent magnets 15 (15a to 15d) are arranged on the lower surface of the yoke 14 as shown in FIG. On the other hand, a coil base 18 is provided on the frame, and electromagnetic coils 16 (16a to 16c) are arranged on the coil base 18 so as to face the permanent magnets 15.

The yoke 14 of the print shuttle 12 is provided with left and right edge marks Lm ₁ and Rm ₁ for outputting edge signals and a timing mark Tm ₁ for outputting position signals as described below. Detection means 17 is provided.

A balance shuttle unit 2 is provided so as to face the print shuttle unit 1 with the paper transporting section interposed therebetween. The balance shuttle unit 2 is configured to be movable in the left-right direction in the drawing by penetrating a stay shuttle 32 having both ends supported by a frame into a balance shuttle 22 having a weight 21 having the same weight as the print shuttle unit 1. .

The balance shuttle unit 2 has substantially the same structure as the print shuttle unit 1 except for the above points, and in FIG. 12 and FIG. The detailed description is omitted here.

As shown in FIGS. 15 and 16, the print head 10 includes twelve print head assemblies 11 each having a 24-pin wire dot, and each print head assembly 11 has 24 dots as shown in FIG. The wires of the pins are diagonally arranged every 12 pins.

In this printer, the print head 10 is reciprocated by the width of the print head assembly 11 and the wire of the print head assembly 11 is driven, so that the ink is fed to the paper conveyed through the paper conveyance path in front of the print head 10. Printing is performed by hitting through the ribbon.

On the other hand, the permanent magnet 15 of the print shuttle unit 1, the electromagnetic coil 16, the permanent magnet 25 of the balance shuttle unit 2 and the electromagnetic coil 26 constitute a linear motor. As shown in FIG. 14, for example, the permanent magnet 15 is Constant speed control magnets 15a and 15d, and inversion drive magnet 15b,
15c, and the electromagnetic coil 16 is also a constant speed control coil 1
6a (L1), 16c (L2), and inversion drive coil 1
6b (L3).

In the above configuration, the print shuttle unit 1
Drives the reversing drive coil 16b, the reversing magnet 1
5b and 15c are moved to the center to perform a reversing operation. When a current is passed through the constant speed control coils 16a and 16c in the forward direction, the coil moves to the right, and when a current is passed in the opposite direction, the coil moves to the left. When the print shuttle unit 1 is driven to the right,
When the balance shuttle unit 2 is driven to the left and the printing shuttle unit 1 is driven to the left, the balance shuttle unit 2 is driven to the right. The balance shuttle unit 2 generates a reaction force to cancel the motive force of the print shuttle unit 1 and prevent the shaking.

FIG. 17 is a functional block diagram for driving the printer device having the above-mentioned structure. The operation of the printer device will be briefly described below with reference to FIG.

The excitation control means 44 inputs a rightward drive signal to the drivers 91a and 91b, the driver 91a moves the print shuttle unit 1 to the right, and the driver 91b moves the balance shuttle unit 2 to the left. .

The direction discriminating means 45 determines whether or not the right edge signal from the edge mark Rm ₁ of the position detecting means 17 is detected, and when the right edge signal is detected, it proceeds to the inversion control of the step.

The pulse period detecting means 41 is a direction determining means.
Position sensor 17a while 45 does not detect the right end detection signal
Period T of timing signal (position signal) from₁Detect
And the cycle T₁Is input to the comparison means 43. Base here
Cycle T set in the quasi-cycle setting unit 42₀And the cycle T₁
Are compared and T₁> T₀When the acceleration signal is
₁<T₀Is output, the deceleration signal is output to the gate means 44.
Force In the gate means 44, the progress indicated by the direction detection means 45 is shown.
The above acceleration and deceleration signals are sent to the left and right excitation signals according to the row direction.
To the driver 91a (91b).

When the direction discriminating means 45 detects the right edge signal in step, the inversion signal is turned on for inversion, the inversion motor unit (magnets 15b, 15c, coil 16b) is driven and inverted, and the right edge signal is again output. When the right edge signal is detected again after determining whether or not it has been output, the inversion drive signal is turned off since the inversion region is exited, and the process proceeds to the leftward movement control .

The driving in the left direction is the same as the driving in the right direction except that the direction is the same, and the description is omitted here. Also, the left inversion operation has the same contents as the right inversion operation in the above step, and therefore will be omitted.

In this way, the control means 40 controls the print shuttle unit 1 from the position signal and the edge signal to perform the constant speed control and the reverse control of the print shuttle unit 1 and the balance shuttle unit 2 to the print shuttle unit. Drive control in the direction opposite to 1 is performed.

[0021]

As described above, the print shuttle unit 1 and the balance shuttle unit 2 are drive-controlled by the control means 40, but the balance shuttle unit 2 does not change the drive signal and the inversion signal for the print shuttle unit 1 as they are. It is controlled by using and does not have its own control mechanism.

However, it is impossible to physically set the printing shuttle unit 1 and the balance shuttle unit 2 to the same physical conditions (weight, friction, resistance due to lead wires, etc.), and due to the difference between them,
Even if they are driven by the same drive signal, a difference in speed may occur during operation.

When a difference in speed begins to occur between the two in this way, the difference gradually increases, and the balance shuttle unit 2 which is not controlled and driven collides with the damper, causing a loss of synchronization. Will not function.

The present invention has been proposed in view of the above-mentioned conventional circumstances, and provides a printer shuttle control system in which position control or speed control is also performed on a balance shuttle unit to prevent out-of-synchronization. It is intended to be provided.

[0025]

The present invention employs the following means in order to achieve the above object. That is, FIG.
As shown in, the position signal Sp ₁ of the print shuttle unit ₁
And the position signal Sp ₂ of the balance shuttle unit 2 are detected by the phase difference detection means 50, and the drive control means 60 performs acceleration / deceleration control for the balance shuttle unit 2 based on the phase difference. .

For example, as shown in FIG. 2, the acceleration / deceleration determination means 6 as the drive control means 60 determines whether or not there is a phase difference between the print shuttle unit 1 and the balance shuttle unit 2.
1 and outputs an acceleration signal or a deceleration signal based on the detection result. As a result, the balance shuttle unit 2 tries to align with the print shuttle unit 1.

By the way, neither the print shuttle unit 1 nor the balance shuttle unit 2 is in position control during reversing. Therefore, not only the phases of the two are the same at the time of reversal entry, but also if the speeds are not the same, the phases of the both are significantly different at the end of the reversal, which may result in uncontrollability.

Therefore, speed control is performed in place of the above-described simple position control. That is, as shown in FIG. 5, the phase difference detecting means 50 detects the magnitude of the phase difference between the shuttles from the position detection signals Sp ₁ and Sp ₂ from the print shuttle unit 1 and the balance shuttle unit 2, and the phase difference is detected. The target speed is set by the speed setting means 64 according to the size. Next, the target speed and the current speed of the balance shuttle unit 2 are compared with each other by a comparison means 66.
Compared as a result, the balance shuttle unit 2
When it is necessary to accelerate, the acceleration signal is output, and when it is necessary to decelerate, the deceleration signal is output. This eliminates an extreme speed difference between the print shuttle unit 1 and the balance shuttle unit 2 at the time of reversal entry, and prevents the phase difference between both units from uncontrollably increasing at the end of reversal.

By the way, the inversion instruction of the balance shuttle unit 2 is given by the edge signal Se _{1 of the} print shuttle unit _1.
Balance shuttle unit 1
The counter 51b (which constitutes the phase difference detecting means 50) for counting the position signal of is reset by its own edge signal Se ₂ . However, the phase of the balance shuttle unit 2 may be significantly delayed for some reason. At this time, the print shuttle unit 1 first outputs the edge signal Se ₁ and inverts it, and also the balance shuttle unit 2 inverts. However, if the phase of the balance shuttle unit 2 is significantly delayed, the balance shuttle unit 2 will This means that the edge signal of the position detecting means 27 cannot be detected.

Counter 51b for counting the position signal Sp ₂
Since being reset by the edge signal Se _2, when the edge signal Se ₂ as described above is not detected will be the counter 51b is not reset, the position control or velocity control becomes impossible.

Therefore, as shown in FIG. 8, the edge mark Lm of the position detecting means 27 of the balance shuttle unit 2 is detected.
₂ , Rm ₂ is printed Position detection means 1 of shuttle unit 1
The edge marks Lm ₁ and Rm _{1 of No.} 7 are arranged at a predetermined distance inside. As a result, even if the balance shuttle unit 2 is delayed within the predetermined distance, the edge signal Se ₂ is detected, and the above inconvenience can be avoided.

In this state, the inversion completion detecting means 71 confirms that the balance shuttle unit 2 has completed the inversion, and the counter 51b for counting the position signal on the balance shuttle side is reset. With respect to the output of the counter 51b, the position of edge marks Lm ₁ and Rm ₁ of the position detecting means 17 of the print shuttle unit ₁ and the edge marks Lm ₂ and Rm ₂ of the position detecting means 27 of the balance shuttle unit 2 are added by the adding means 72. An offset is applied by the number of position signal pulses corresponding to the difference.

[0033]

[Embodiment]

[Embodiment 1] FIG. 2 is a functional block diagram of an embodiment relating to position control of the present invention, and FIG. 3 is a flow chart thereof.

Position detecting means 1 of print shuttle unit 1
Position signal Sp ₁ of the position marks Tm ₁ of 7 is input to the counter 51m constituting the phase difference detecting means 50, the count value M of the counter 51m is input to the phase difference calculation section 52. On the other hand, the position signal Sp ₂ of the position marks Tm ₂ position detection unit 27 of the balance shuttle unit 2 is input to the counter 51b, the count value B of the counter 51b is inputted to the count value M as well as the phase difference computation unit 52 The difference between the count value M and the count value B is obtained here, and the print shuttle unit 1 is driven by the acceleration / deceleration determination means 61 which is the drive control means of the next stage.
It is determined whether the phase of the balance shuttle unit 2 is advanced or delayed with respect to (see step F3 in FIG. 3).
1a → F31b → F32 → F33).

The acceleration / deceleration determination means 61 as the drive control means 60 outputs an acceleration signal to the balance shuttle unit 2 when M> B, that is, when the print shuttle unit 1 is ahead of the balance shuttle unit 2 in phase. , M <B, that is, the balance shuttle unit 2
When the phase is ahead of the print shuttle unit 1,
A deceleration signal for delaying the phase is output to the balance shuttle unit 2. Further, when M = B, neither excitation nor deceleration is performed (Fig. 3,
Step F34). In the above description, if the non-excitation is not performed only when M = B, but the non-excitation is performed within a certain width, the control stability is increased.

On the other hand, the direction determination unit 80 are input edge signal Se ₂ of the position detecting means 27, and instructs be whether the inverted state with respect to the gate means 70. Further, the acceleration signal and the deceleration signal obtained as described above are input to the gate means 70, and are switched to the left and right excitation signals by the gate means 70 according to the direction signal output from the direction determining means 80 as follows. (FIG. 3, step F35).

[0037]

[Table 1]

FIG. 4 is a time chart showing a control example according to the present invention. The figure (a) shows the phase difference between the print shuttle unit 1 and the balance shuttle unit 2, (b) shows the acceleration area, and (c) shows the deceleration area with diagonal lines. That is, when the phase of the balance shuttle unit 2 is delayed with respect to the print shuttle unit 1, the acceleration is performed, and when the phase is advanced, the deceleration is performed. For reference, the edge signal Se ₂ is shown in FIG.

As a result, the print shuttle unit 1 and the balance shuttle unit 2 can be driven synchronously. [Embodiment 2] By the way, the print shuttle unit 1 cuts one of the left and right edge marks Lm ₁ (Rm ₁ ) and starts reversing, and then the same edge mark Lm ₁ (Rm ₁
Position control is not performed on either the print shuttle unit 1 or the balance shuttle unit 2 until the reversal is completed by cutting off m ₁ ). Therefore, if the speeds of the print shuttle unit 1 and the balance shuttle unit 2 at the start of reversal are different by the simple position control as described above, it is considered that the speeds of the two are significantly different at the end of reversal, Even if position control is applied during the next run, control may be lost.

Therefore, as another embodiment, FIGS. 5, 6, and 7 propose to add speed control instead of the above-mentioned simple position control. Also in this embodiment, the position mark Tm ₁ of the position detecting means 17 of the print shuttle unit ₁
Position signal Sp ₁ is input to the counter 51m, and the count value M of the counter 51m is input to the phase difference calculator 52. Further, the position signal Sp ₂ from the position mark Tm ₂ of the position detecting means 27 of the balance shuttle unit 2 is input to the counter 51b, and the count value B of this counter 51b.
Is input to the phase difference calculator 52 as with the count value M.

The phase difference calculator 52 calculates a difference MB between the output of the counter 51m of the print shuttle unit 1 and the output of the counter 51b of the balance shuttle unit 2 and inputs it to the speed determination means 64 (FIG. 6, FIG. 6). F61 → F6
2 → F63). The speed determination means 64 stores the target speed (upper limit value and lower limit value) of a predetermined width according to the magnitude of the phase difference in the ROM 6
5, and sets it in the comparison means 66 (FIG. 6, F6).
4 → F65, FIG. 7, F651).

For example, the difference MB is compared with five reference values R ₁ , R ₂ , 0, -R ₁ , -R _{2 under the} condition of R ₁ > R ₂ .
As a result, when R ₁ ≦ M−B, the upper and lower limit values of the largest speed are set as the target speed in the comparison means 66, and R is set.
_{When 1} > M−B ≧ R _2, it is necessary to set the upper and lower limit values of the next largest speed.

On the other hand, balanced position signal Sp ₂ than shuttle unit 2 is also inputted to the speed detecting means 69, where it is detected the speed of the position signal Sp ₂ periods than the current balance shuttle unit 2 the comparing means It is input to 66 (FIG. 7, F652). The comparing means 66 compares the current speed of the balance shuttle unit 2 with the upper limit value and the lower limit value of the target speed set above (643 in FIG. 7).
a, 643b). The acceleration signal and the deceleration signal output here are as shown in the column of “output of comparison means” in Table 2 (FIG. 7, F).
654a, F654b, F654c).

Further, as shown in the gate output column of Table 2, the acceleration signal and the deceleration signal are directed to the direction via the gate 70 which is controlled according to the direction signal obtained from the direction determination means 80 of the print shuttle unit 1. The corresponding excitation signal is converted and output. The operation of the direction determining means 80 is the same as that described with reference to FIG.

[0045]

[Table 2]

As a result, the balance shuttle unit 2
When the sheet is accelerated or decelerated, the extreme acceleration state and the deceleration state disappear, the speed difference with the print shuttle unit 1 becomes small, and the phenomenon that the speed difference widens at the time of reversing is alleviated.

[Embodiment 3] Also in the above-mentioned configuration, the inversion instruction of the balance shuttle unit 2 is made by using the edge signal Se ₁ from the print shuttle unit 1. However, the difference between the speed of the print shuttle unit 1 and the speed of the balance shuttle unit 2 may be greatly enlarged for some reason.

In this case, when the print shuttle unit 1 starts reversing, the balance shuttle unit 2 starts reversing at the same time, and the balance shuttle unit 2 reverses in a state where the edge mark Lm ₂ (Rm ₂ ) of the position detecting means 27 cannot be detected. May end.

[0049] However, since the counter 51b for counting the position signal Sp ₂ balance shuttle unit 2 is adapted to be reset by receiving the edge signal Se ₂ than self position detection unit 27, in the above state The counter 51b is not reset even after the reversal is completed, and the counter 51b of the print shuttle unit 1 is reset.
A large value B is always output with respect to the count value M of m. This provides a state in which the balance shuttle unit 2 has a phase significantly advanced with respect to the print shuttle unit 1, and the deceleration control is applied to the balance shuttle unit 2 in any of the above two embodiments. As a result, the balance shuttle unit 2 becomes more and more delayed and becomes uncontrollable.

Therefore, in order to eliminate the above-mentioned drawback, FIG.
As schematically shown in FIG. 3, the edge marks Lm ₂ and Rm ₂ of the position detecting means 27 of the balance shuttle unit 2 are provided inside the edge marks Lm ₁ and Rm ₁ of the print shuttle unit ₁ by a predetermined distance. As a result, even if the balance shuttle unit 2 lags behind the print shuttle unit 1 within the predetermined distance, the balance shuttle unit 2
The position detecting means 27 can output the edge signal Se ₂ .

Further, as shown in FIG. 9, an inversion end detecting means 71 is provided on the balance shuttle unit 2 side, and
As shown in (f), when the edge signal Se ₂ at the end of inversion is detected, the counter 51b is reset, and thereafter the count-up is started by the position signal Sp ₂ .

By the way, as shown in FIG. 11, when the counter 51b is reset, the counter 51m has already counted up by the predetermined distance (16 in the example of FIG. 11 (d)). The output from the offset value setting means 73 is added to the output of the counter 51b by the adding means 72 so that the outputs of both counters 51m and 51b are matched as shown in FIGS. 11 (b) and 11 (e). I have to.

The inversion end detecting means 71 is shown in FIG.
As shown in, there by the edge signal Se ₂ than the balance shuttle unit 2 at the inverting and end the reset by the edge signal Se ₁ than print shuttle unit 1 at the start of the reversal in function of outputting a reset signal to the counter 51b For example, either processing by a program or processing by a circuit may be used.

[0054] As shown in FIG. 10, for example, JK and then enter the edge signal Se ₁ than print shuttle unit 1 to the J terminal of the flip-flop 71f, also, the edge signal Se ₂ than the balance shuttle unit 2 to the K terminal Is input, and the output from the Q terminal of the JK flip-flop 71f and the edge signal Se ₂ are ORed.

As a result, the edge signal Se₁By
Then, as shown in FIG. 11, the JK flip-flop 71f
The edge signal output after the Q terminal output of “H” is output
Issue Se ₂Is shown in Fig. 11 → from the AND gate 71b.
Will be output as a reset signal. Well
Edge signal Se₁Is also used as a reset signal
As shown in Fig. 11 →,
Edge signal Se at the start of inversion of the unit 1₁By
The counter 51b is reset and the balance shutoff
Edge signal Se at the end of inversion of the unit 2₂By
Since it is set, the counter 51b is in the "0" state during that time.
Will hold.

However, in the above example, since the output of the counter 51b is "0" until the counter 51m on the side of the print shuttle unit 1 has counted by the predetermined distance (count number 16) from the end of reversal, the counter 51m is Counter 5
When the speed control is performed based on the output of 1b, the balance unit 2 is abnormally accelerated. Therefore, until the counter 51m of the print shuttle unit 1 starts counting until the counter 51b of the balance shuttle unit 2 starts counting, no control is performed or the speed determination is performed before the print shuttle unit 1 starts reversing. It is necessary to hold the speed set in the means 64 until the counter 51b starts counting so that the balance shuttle unit 2 is controlled based on the held speed.

Although the description has been given above only to the case where the print shuttle runs at a constant speed, the print shuttle does not necessarily have to be driven at a constant speed. Also. Although the printer device has been described as an example, the present invention can of course be applied to devices other than the printer device as long as the device uses two shuttles.

[0058]

As described above, according to the present invention, not only the print shuttle unit side but also the balance shuttle unit controls acceleration and deceleration while referring to the position of the print shuttle unit. There is no fear. Further, in the above control, if the speed during acceleration and the speed during deceleration are limited, the speeds of both shuttle units at the time of reversal entry can be made close, and the speed difference (phase difference) at the time of reversal can be increased. Therefore, it is possible to prevent the occurrence of the loss of synchronization.

Further, since the print shuttle unit and the balance shuttle unit are located in mutually symmetrical positions with high accuracy, the print quality is excellent, and this feature is particularly exhibited in the print quality of the vertical ruled lines.

Further, the edge mark of the balance shuttle unit is arranged inside the edge mark of the position detecting means of the print shuttle unit by a predetermined distance. As a result, it is possible to prevent the balance shuttle unit from reversing without generating an edge signal, and it is possible to prevent the appearance of a state in which the phase of the balance shuttle unit is significantly advanced.

[Brief description of drawings]

FIG. 1 is a functional block diagram of the principle of the present invention.

FIG. 2 is a functional block diagram of an embodiment of the present invention.

FIG. 3 is a flow chart of the embodiment shown in FIG.

FIG. 4 is a time chart of the embodiment shown in FIG.

FIG. 5 is a functional block diagram of another embodiment of the present invention.

6 is a flowchart of the embodiment shown in FIG.

FIG. 7 is a flow chart of speed control shown in FIG.

FIG. 8 is a conceptual diagram of still another embodiment of the present invention.

9 is a functional block diagram of the embodiment of FIG.

FIG. 10 is a block diagram showing an example of inversion end detection means.

FIG. 11 is a time chart of the embodiment of FIG.

FIG. 12 is a perspective view of a conventional shuttle device.

FIG. 13 is a plan view of a conventional shuttle device.

FIG. 14 is a drive mechanism of a conventional shuttle device.

FIG. 15 is a perspective view of a conventional print head.

FIG. 16 is a plan view of a conventional printhead assembly.

FIG. 17 is a conventional functional block diagram.

[Explanation of symbols]

1 Printing shuttle unit 2 Balance shuttle unit 10 print head 17, 27 Position detection means 50 Phase difference detection means 60 Drive control means 64 speed setting means 66 Comparison means

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-6-47961 (JP, A) JP-A-1-141754 (JP, A) JP-A-7-1750 (JP, A) Actual Kaihei 4- 94664 (JP, U) (58) Fields surveyed (Int.Cl. ⁷ , DB name) B41J 2/515 B41J 19/18

Claims (3)

(57) [Claims] 1. A balance shuttle unit in which a print shuttle unit having a print head mounted thereon is driven at a constant speed on the basis of a position signal obtained from a position detection means of the print shuttle unit, and reciprocally driven on the basis of an edge signal. In a shuttle unit drive device for performing printing by reciprocally driving the print shuttle unit in a direction opposite to that of the print shuttle unit, a position signal from a position detection means provided in the balance shuttle unit and a position detection means provided in the print shuttle unit are provided. Based on the position signal , the phase difference detection means for detecting the phase difference between the shuttles and the target speed defined according to the magnitude of the phase difference are used to indicate acceleration or deceleration of the balance shuttle unit.
And a drive control means as shown . Wherein said drive control means, and the phase difference detecting means for detecting a phase difference between both the shuttle on the basis of the position signal of the position signal of the print shuttle unit side and the balance shuttle unit side, from the phase difference detecting means and speed setting means for setting a target speed corresponding to the magnitude of the phase difference between the two shuttles obtained, by comparing the rate of actual balance shuttle unit and the target speed, and a comparing means for outputting an acceleration or deceleration signal The shuttle unit drive device according to claim 1, further comprising: 3. A shuttle unit drive device for reciprocally driving a print shuttle unit equipped with a print head and reciprocally driving the balance shuttle unit in a direction opposite to that of the print shuttle unit, wherein the balance shuttle unit is provided. The balance shuttle counts the position signals from the position detecting means.
When the edge mark of the unit is detected, the count value is reset.
The counter for setting and counting the position signals from the position detecting means provided in the print shuttle unit
When the edge mark of the print shuttle unit is detected
And a counter that resets the count value.
The balance shuttle includes: a phase difference detecting means for detecting a phase difference between the shuttles based on a count value of the counter ; and a drive control means for controlling the balance shuttle unit based on an output of the phase difference detecting means. The edge mark of the unit is arranged at a predetermined distance inside the edge mark of the printing shuttle unit , and a value corresponding to the predetermined distance with respect to the output of the counter for counting the position signal from the position detecting means provided in the balance shuttle unit. Shuttle unit drive device characterized by offsetting only.