JP2001071581A - Printing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printing apparatus with a paper-detecting device of an equal constitution to a printing apparatus having a head gap-adjusting device which can automatically detect a proper printing gap when set to a carriage and can obtain printing gap information at all times by moving together with the carriage. SOLUTION: A carriage is provided with a head gap-adjusting device. The head gap-adjusting device comprises a proper gap-detecting device (a detection lever 22, a contact member 23 and a sensor 24) and a gap-changing device. A lower limit position of the contact member 23 is made lower than a leading end of a printing head. The proper gap-adjusting device is suspended to the carriage to be freely movable upward from the lower limit position. A set upward movement position of the contact member is detected, and driving the gap-changing device is stopped based on the signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a paper detecting mechanism of a printing apparatus and an automatic print gap adjusting mechanism using the same mechanism.

[0002]

2. Description of the Related Art The print gap between a print head and a sheet is
Since the set proper value must be maintained, it is necessary to adjust the position of the print head when using paper having different thicknesses. For this reason, various proposals have hitherto been made, but the structure is complicated, and the printing gap cannot be detected during the printing operation.

The automatic paper thickness adjusting mechanism disclosed in Japanese Patent Application Laid-Open No. 3-97579 has a detection lever that comes into contact with the paper surface and a sensor that is turned on / off by turning the detection lever, and is provided on a carriage before printing is started. The detection lever is sufficiently separated from the surface of the sheet by the detection lever driving unit, and after the sheet is inserted, the urging force of the detection lever driving unit is released to bring the detection lever into contact with the surface of the sheet again. Then, when the sensor is activated by gradually raising the platen, it is determined that the gap position is appropriate, and the movement of the platen is stopped. Then
The detection lever in contact with the sheet is pulled up to start printing. For this reason, it is necessary to raise and lower the detection lever each time the paper is inserted and printed, and it takes time to start printing, and the detection lever is raised before printing starts. No print gap information can be obtained. In addition, since the detection lever driving section is provided on the carriage, the carriage is heavy, and there is a problem that the motor for driving the carriage becomes large, the entire apparatus becomes large, and the cost increases accordingly.

A mechanism for detecting the presence or absence of a sheet or a document by using an actuator is not described in Japanese Patent Application Laid-Open No. H10-245137. However, this actuator is characterized in that it has a structure capable of absorbing the error even if there is an error in the mounting height of the substrate to the actuator, and the structure is close to the lever type paper sensor described above. ,further,
It is not a structure that can move left and right with the print head.

Further, when a printing apparatus which receives a print signal starts printing, there is a device which detects the presence or absence of a sheet as a condition. As a detection device for this purpose, there are a non-contact type optical sensor and a lever type. In the case of the photoelectric type, the powder generated when the paper is rubbed may adhere to it, which may hinder the function.The lever type detects the presence of the paper by rotating with a slight force due to the paper being placed. However, the operation tends to be unstable when the paper is thin and light. Further, even if the lever type can detect the front and rear ends of the sheet and the presence or absence of the sheet, a special configuration is required to detect the left and right ends of the sheet.

[0006]

SUMMARY OF THE INVENTION The present invention is directed to a head gap adjusting device which can be attached to a carriage to automatically detect an appropriate print gap, and which can be integrated with the carriage to constantly obtain print gap information. An object of the present invention is to provide a printing apparatus provided with a paper detecting apparatus which is capable of detecting the presence / absence of paper and the front and rear ends of the paper as well as the left and right ends of the paper by moving together with the carriage.

[0007]

A printing apparatus includes a plate having a paper transport surface, a platen arranged facing the paper transport surface, and a carriage reciprocating along the platen. [Head gap adjusting device] The head gap adjusting device has an appropriate gap detecting device and a gap changing device. The appropriate gap detection device is attached to the carriage and includes a contact member. The contact member is attached to the carriage so as to freely move up and down so as to face the sheet transport surface. Then, the lower limit position is set lower than the leading end of the print head, and the upper limit position is free to move upward. The proper gap detecting device is moved from above to below together with the carriage by the gap changing device. When the contact member contacts the sheet by moving downward, and is still moved downward, the contact member that contacts the sheet relatively moves upward, and switches the signal when it reaches the set upper position.

The downward movement of the carriage by the gap changing device means the adjustment of the printing gap. When the contact member reaches the set upper position and switches the signal, the downward movement of the carriage is stopped. Means that the distance between the sheet and the paper surface has reached an appropriate value. The printing device starts printing while maintaining this state. In the proper gap detecting device, the contact member is mounted on the carriage so as to be freely movable up and down so as to face the sheet conveying surface. Therefore, when a force is applied to the contact member, the contact member easily moves upward and detects the proper gap. Even if the carriage is moved right and left in the state of the time, no particular trouble occurs. Therefore, there is no time loss such as starting printing after the contact member is retracted upward. Further, the head gap detecting device using the movement of the contact member can be used as a device for detecting the presence or absence of a sheet or a device for detecting the front, rear, left and right ends of the sheet.

Further, since the contact member constantly presses the paper near the print head even during the movement of the carriage, accurate printing can be performed. One specific example of the appropriate gap detecting device includes a lever provided on the carriage, which can rotate around an axis, a contact member in contact with a lower end thereof, and an on / off sensor provided in an upper end portion. The lever is always
The lower end is biased in a direction to move downward. The contact member may be a ball such as a metal ball, and may be supported by a bottomless truncated cone-shaped receiving portion provided on the carriage. This ball is free to rotate and move upward in the receiving part, and
It has low resistance to paper and is suitable as a contact member. The on / off sensor may be provided at a position where the movement of the lever can be detected, and is not limited to the upper end portion.

[Paper Detecting Device] A print head and a paper detecting device are mounted on a carriage. The sheet detection device includes a contact member. The contact member has the same structure as that in the head gap adjusting device described above, and is freely movable up and down, the lower limit position thereof is below the tip of the print head, and the upper end of the paper transport is freely movable from the lower limit position. It is installed facing the surface. The sheet detecting device detects the sheet by moving the contact member up and down, and switches the signal when the contact member reaches the set upper position. Signal switching depends on the sensor,
As the sensor means, it is composed of a magnetic sensor or a light emitting element and a light receiving element, and when the contact member rises, the lever member swings around a swing axis provided on the carriage,
The end of the lever member approaches the element of the magnetic sensor,
There is a structure in which switching is performed by separating, or by transmitting light between a light emitting element and a light receiving element or by blocking light transmitted between them.

Since the contact device is freely attached to the carriage so that it can move up and down, the carriage can be moved up and down to detect the presence or absence of a sheet.
It is also possible to detect the left and right ends of the sheet by moving in the left and right direction together with the carriage. Further, the front end and the rear end of the sheet can be detected when the sheet enters or leaves. Use this function to compare the actual width and length of the loaded paper with the information about the paper size in the print signal, or to correct the inclination of the paper axis with respect to the transport direction (skew correction).
It can be used for such purposes. Further, it can be moved together with the carriage to detect paper waving and changes in thickness in the width direction (left and right) of the paper. On the other hand, the movement of the contact member together with the carriage also exerts a function of correcting the floating of the sheet by sequentially pressing the portions close to the printing portion of the sheet with the movement of the print head. In this case, the contact member is light in weight, but has such a weight that the lifting of the paper can be crushed. Thereby, it is possible to perform printing without unevenness.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an outline of a printing apparatus 1, and those which are not particularly necessary for describing the invention of the present application are omitted. The main body frame 2 has left and right side walls 3 and 4 and a horizontal wall 5 therebetween, and a paper transport plate 6 is attached to the horizontal wall 5. Reference numeral 7 denotes a carriage, left and right side walls 3,
It is slidably mounted on a carriage shaft 8 (FIG. 2) which is supported by being supported between the four, and is reciprocally movable left and right by being guided by an upper guide frame 9. The carriage shaft 8 is hollow and has an adjustment shaft 10 inside.
Is penetrating. The adjustment shaft 10 is supported by left and right side walls, and is rotated by an adjustment motor 11 or a manual operation lever 12 (FIG. 3). Since the adjustment shaft 10 is mounted so as to rotate eccentrically, when it rotates, the carriage 7 moves up and down via the carriage shaft 8.

The carriage 7 has a print head 13 mounted thereon and an appropriate gap detecting device 14 mounted thereon.
The carriage 7 is driven by a carriage motor 15 and a timing belt 16 (FIG. 2). In FIG. 2, reference numeral 17 denotes a home position sensor of the carriage 7. Reference numeral 18 denotes a platen (FIG. 1),
Are supported in the left-right direction facing the sheet conveying surface from below the horizontal wall 5. Reference numeral 19 denotes an ink ribbon cartridge which is detachably mounted by being bridged between left and right side walls 3 and 4 in a fixed position circulation type, and which is drawn out.
Are arranged so as to pass between the print head 13 and the paper.

The holes provided in the paper transport plate 6 are for arranging a paper feed roller and for mounting a lever-type paper detection sensor. Reference numeral 21 denotes a control device, which is a normal device having an input / output device, a RAM, a ROM, and a CPU, stores various processing programs in the ROM, and transmits signals and data from various sensors provided in the printing device. Received in the input device, stored in the RAM, and running the program based on the command of the CPU, the CPU judges the signal and calculates the data, outputs an operation command based on the result from the output device, and outputs the various commands in the printing device. Controls the operation of.

The proper gap detecting device 14 includes a detecting lever 22, a contact member 23, and a sensor 24 (FIGS. 4 and 5). In these figures, components that are not particularly necessary for the description of the invention are omitted. Detection lever 22
Is disposed on the left side surface of the carriage 7 and is rotatable in the front-rear direction about a shaft 25. The position of the shaft 25 is below the detection lever 22, and the displacement of the lower end of the detection lever 22 is large at the upper end. The contact member 23 is a steel ball (referred to as a steel ball 23) in this embodiment, has a truncated cone shape provided at the lower end of the carriage 7, and is inserted from above into a funnel-shaped holder 26 (FIG. 4) having no bottom. Supported. That is, the steel ball 23 is supported by facing the sheet transport surface in a state of being suspended from the carriage 7, that is, the steel ball 23 is freely movable in the vertical direction facing the transport surface. When the carriage 7 is moved upward and the steel balls 23 are suspended, the lower surface of the steel balls 23 protrudes downward from the bottom of the holder 26, and the position of the steel balls 23 is lower than the lower end 13 of the print head 13.
a (FIG. 5). In FIG. 4, reference numeral 27 denotes a cover of the appropriate gap detecting device 14.

The lower end of the detection lever 22 is formed in a dish shape, the lower surface of which is in contact with the upper surface of the steel ball 23, and the upper end of the detection lever 22 is a coil having one end attached to the carriage 7. The spring 28 always draws the carriage 7. The sensor 24 is magnetic and is fixed at a position where the upper end of the detection lever 22 of the carriage 7 approaches. Therefore, when the carriage 7 is lifted upward, the steel ball 23 is suspended and moves downward, and the upper end of the detection lever 22 is moved forward by the bias of the coil spring 28, and the signal of the sensor 24 is output. It is on (FIG. 4). When the carriage 7 is gradually lowered from this state, first, the lower surface of the steel ball 23 comes into contact with the sheet P, and when the carriage 7 is still lowered, the steel ball 23 moves upward in the holder 26 and the detection lever 22 Since the lower end is pushed up, the upper end of the detection lever 22 moves rearward against the coil spring 28, separates from the sensor 24, and turns off the signal of the sensor 24.

When one print command transmitted from an accounting machine or the like is completed, the control device 21 of the printing machine drives the adjustment motor 11, rotates the adjustment shaft 10, raises the carriage shaft 8, and moves the carriage 7. The printing is completed in a state where it is moved upward, and a standby state is set. The upper end of the detection lever 22 moves forward, and the signal of the sensor 24 is turned on. The control device 21, which reads this ON signal from the RAM, determines that the printing gap is inappropriate or that the paper P does not exist. When the next print command is issued, the paper P is fed into the largely gapped print gap, and then the adjust motor 11 is driven,
The adjustment shaft 10 is rotated to lower the upper surface of the carriage shaft 8 to move the carriage 7 downward. As the carriage 7 moves downward, the steel balls 23 (contact members 2
3) arrives at the paper P and stops, and the carriage 7
The detection lever 22 is rotated by the steel ball 23 which relatively rises due to the lowering of the sensor, and the upper end moves rearward to turn off the signal of the sensor 24 (FIG. 6).

The control device 21 which has read this off signal
Indicates that the paper P is present at the print location and that the print gap is properly adjusted,
Stop driving. That is, the adjustment shaft 10 and the adjustment motor 11 constitute a gap changing device, and the contact member 23, the detection lever 22, and the sensor 24 constitute an appropriate gap detection device. The gap adjusting device is constituted by the gap changing device, the proper gap detecting device and the control device 21. When the print gap between the print head 13 and the paper P is properly set when the carriage 7 stops, the printing operation is started as it is.

In the printing operation, the steel ball 23 of the appropriate gap detecting device 14 also moves on the paper surface in accordance with the left and right movement of the carriage 7, but there is almost no resistance due to the rolling movement.
Further, even if the steel ball 23 swells or slips off the edge of the sheet, since the upward movement is free, the movement of the carriage 7 is not hindered. Therefore, the transition to the printing operation is quick, and the printing efficiency is improved. Further, with the movement of the carriage 7, the steel balls 2
3 also moves while being in contact with the paper, so that the paper at the print location is pressed, and accurate printing can be performed while correcting the swelling of the paper. Although the steel ball is taken up as the contact member 23, the structure is not limited to the steel ball but may be a slider-like structure that can freely move up and down.

Although the description has been given of the gap adjusting device provided with the contact member 23, this structure can also be used as a paper detecting device. That is, the sensor 24 may be arranged to switch the signal when the detection lever 22 is rotated upward due to the presence of the sheet. According to this configuration,
Since the sheet detecting device moves together with the carriage 7, the left and right ends of the sheet can be easily detected, and can be used for determining the sheet size.

[0021]

According to the first aspect of the present invention, when the control device lowers the carriage, an appropriate print gap is automatically set. After setting the appropriate printing gap, the printing operation can be performed immediately without raising the detection lever and the like, and the efficiency is good. In addition, since the carriage moves while the gap detection device is in contact with the paper, the contact member of the detection device functions as a paper press close to the printing location, and accurate printing can be performed. According to the configuration of the second aspect, no special driving device for moving the detection lever is required, the structure is simple, and the weight of the carriage does not increase much. Therefore, the carriage and the entire apparatus can be made compact.

According to the third and fourth aspects, the presence or absence of a sheet can be detected with a simple structure, and not only the front and rear ends but also the left and right ends of the sheet can be detected. Furthermore, the contact member of the detection device functions as a paper press close to the printing location, and accurate printing can be performed. According to the configuration of the fifth aspect, since the steel ball as the contact member is supported by freely rotating and moving upward, the steel ball has low resistance when moving in contact with the paper and drives the carriage. The burden on the device is small.

[Brief description of the drawings]

FIG. 1 is a perspective view schematically showing a printing apparatus.

FIG. 2 is a perspective view showing a part of a carriage.

FIG. 3 is an exploded perspective view showing a main part of the gap changing device.

FIG. 4 is an exploded perspective view showing an essential part of the appropriate gap detecting device.

FIG. 5 is a side view showing the operation of the appropriate gap detection device (before detection).

FIG. 6 is a side view showing the operation of the appropriate gap detection device (at the time of detection).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Printer 2 Main body frame 3 Left side wall 4 Right side wall 5 Horizontal wall 6 Paper transport plate 7 Carriage 8 Carriage shaft 9 Guide frame 10 Adjust shaft 11 Adjust motor 12 Operation lever 13 Print head 14 Appropriate gap detection device 15 Carriage motor 16 Timing Belt 17 Home position sensor 18 Platen 19 Ink ribbon cartridge 20 Ink ribbon 21 Controller 22 Detection lever 23 Contact member 24 Sensor 25 Axis 26 Holder 27 Cover 28 Coil spring

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Yoshiro Kato 6-11-12 Honcho, Tanashi-shi, Tokyo Inside the Tanashi Works of Citizen Watch Co., Ltd. (72) Katsuhiko Sato 6-1-112, Honcho, Tanashi-shi, Tokyo No. Citizen Watch Co., Ltd. Tanashi Factory F-term (reference) 2C058 AB05 AF31 GB02 GB03 GB12 GB30 GB47 2C064 DD01 DD10 DD12

Claims (5)

[Claims] 1. A head gap adjusting device comprising: a plate having a sheet conveying surface; a platen arranged facing the sheet conveying surface; a carriage mounted with a print head and reciprocating along the platen; and a head gap adjusting device. The apparatus has a proper gap detecting device attached to the carriage and a gap changing device for changing the distance between the platen and the carriage, and the proper gap detecting device has a contact member provided on the carriage so as to face the sheet conveying surface. The lower limit position of the contact member is lower than the tip of the print head, and the contact member can be freely moved upward from the lower limit position. The upper movement position set by the contact member is detected and the gap is changed based on the signal. A printing device characterized in that the driving of the device is stopped. 2. The proper gap detecting device comprises a detecting lever provided on a carriage, which can rotate around an axis, a contact member in contact with a lower end thereof, and an on / off sensor,
2. The printing apparatus according to claim 1, wherein the lower end of the detection lever is constantly biased in a downward moving direction, and the signal of the on / off sensor is switched at an upper moving position set by the contact member. 3. A plate having a paper transport surface, a platen arranged facing the paper transport surface, and a carriage reciprocating along the platen, the carriage having a print head and a contact member. The contact member is vertically attached to the carriage so as to be opposed to the paper transport surface, and the lower limit position thereof is below the tip of the print head, and the contact member is freely movable upward from the lower limit position. The printing apparatus is characterized in that the sheet detection device detects the presence or absence of a sheet by detecting a set upward movement position of the contact member. 4. The printing apparatus according to claim 3, wherein an end portion of the sheet is detected by detecting a set upward movement position of the contact member. 5. The device according to claim 1, wherein the contact member is a ball, and the contact member is rotatably and upwardly supported by a bottomless truncated cone-shaped receiving portion provided on the carriage.
The printing device according to any one of claims 1 to 4.