JP2666405B2 - Paper detection device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet detecting device that detects a sheet mounted on a printer, a typewriter, or the like using a light reflection type sensor.

[Prior Art] Conventionally, as shown in FIG. 7, a carriage that moves in the left-right direction along a platen 53 is provided in this type of paper detection apparatus.
A light reflection type sensor 51 including a light emitting element and a light receiving element is mounted in the vicinity of the print head 54 on the 55, and sequentially detects the amount of reflected light as the print head 54 moves to detect the presence or absence or position of the paper 59. was there. At this time, the light reflection type sensor 51
The platen 53 is located opposite to
Has a black surface in order to reduce the amount of reflected light when there is no paper 59. That is, a rubber platen using black rubber as a material, an aluminum plate subjected to black coating or black surface treatment, or the like is used.

In such a configuration, the white paper 59 is placed on the platen 53.
When the paper 55 is fed, the carriage 55 on which the light reflection type sensor 51 is mounted moves, and when the light reflection type sensor 51 reaches a position facing the white paper 59, much more than when there is no paper 59. In order to input the reflected light, the presence of the paper 59 can be detected.

[Problem to be Solved by the Invention] However, in the paper detection device configured as described above, in order to detect the white paper 59 using reflected light, the surface facing the light reflection type sensor 51 is black. Therefore, although the surface of the platen 53 is usually black, it is not possible to accurately detect the presence or position of a black sheet or a sheet of dark color.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a paper detecting device capable of detecting not only white paper but also various types of paper.

Means for Solving the Problems In order to achieve this object, the present invention provides a platen on which printing paper is mounted, and is disposed on or near the platen in parallel with the platen, and has a high light reflectance. A reflector in which a portion and a lower portion are alternately repeated; a carriage on which a print head or a reading head is mounted and moves along the platen and the reflector; and a position on the carriage facing the reflector. It outputs a predetermined amount of light and receives the reflected light to detect the amount of reflected light. When the carriage is moved to a state where the paper is not mounted, a high level with a large amount of light and a low level with a small amount of light are output. A light reflection sensor for inputting reflected light in an alternating state in which a level is alternately repeated, and the carriage is moved, and the light reflection sensor inputs reflected light in a state other than the alternating state. Then, there is provided a control means for determining that there is a sheet.

[Operation] According to the present invention having the above-described configuration, the carriage is moved along the platen and the reflection plate, and the light reflection type sensor inputs reflected light other than the alternating state, which is inputted when the printing paper is not mounted. Then, the control means determines that there is a sheet.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view of a main part of a printer provided with a sheet detecting device according to the present embodiment. In the printer, a platen 3 is rotatably supported by a frame (not shown). A carriage 5 supported by two carriage rails 6 and 7 is provided in front of the platen 3 so as to be movable along the platen 3. The carriage 5 is moved left and right via a drive belt 8 by driving a carriage drive motor (not shown). An ink jet print head 4 is mounted on the carriage 5, and
Two light-reflection sensors 1 _L and 1 _R are placed with the print head 4 interposed therebetween. A reflection plate 2 is supported by the frame below the platen 3 at a position facing the sensors 1 _L and 1 _R. As shown in FIG. 5 (a), which is a partially enlarged view of the reflector 2, the reflector 2 has a bright portion 2a having a high light reflectance and a dark portion 2b having a low light reflectance on the surface of an aluminum plate. It is formed repeatedly in the shape of a strip having a width. In order to form such a reflection plate 2, a band-shaped mark having the same width on the surface of the aluminum plate having a high light reflectance by silk printing or the like, that is, a dark portion 2b is coated with a black paint having a very low light reflectance. Just print it.

FIG. 2 is a block diagram showing the configuration of the printer.
The control means 10 for controlling the printer includes a well-known CPU (central processing unit) 11, a ROM (read only memory) 12 for storing a program for controlling the printer, and a RAM for rewritably storing various data. (random access memory) 13, a sensor control circuit 19 for controlling the input interface 15 and sensor 1 _L, 1 _R to input data from the host computer 14 is provided. And CPU11
Are a platen drive circuit 16 for driving the platen 3 via a platen drive motor (not shown), a head drive circuit 17 for driving the print head 4, and a carriage drive circuit 18 for driving the carriage 5 via the carriage drive motor. And is configured to control them.

FIG. 3 is an electrical configuration diagram of the sensors 1 _R and 1 _L and the sensor control circuit 19. Since the two sensors 1 _R and 1 _L have the same configuration, only the sensor 1 _L will be described here. The sensor 1 _L includes a light emitting element LED _L that outputs a constant amount of light to the reflector 2 between the power supply V and the ground, and a resistor R between the power supply V and the ground.
A light receiving element PT _L are provided connected via a _1L to enter the reflected light from the reflecting plate 2. The light receiving element PT
_L is constituted by a phototransistor, and the amount of current that conducts is determined in proportion to the amount of input reflected light. Then, from the connection point A _L between the light receiving element PT _L and the resistor R _1L, the voltage signal formed as a high voltage is often reflected light in proportion to the amount of the reflected light input is output to the sensor control circuit 19.

The sensor control circuit 19, and the terminal A _L of the sensor 1 _L, power source V
And a threshold voltage V _TH set by resistors R _2L and R _3L between the ground and the ground, and an amplifier AMP _L that outputs a high-level signal when the voltage from the sensor 1 _L is higher than V _TH is provided. .
A one-shot multivibrator in which the output from the amplifier AMP _L is input as a trigger via a knot circuit, and the trigger inverts the signal output from the output terminal OUT _L after a certain time determined by the capacitor C _TL and the resistor R _TL. MB _L is provided. Similarly, the sensor 1 _R, is connected to an amplifier AMP _R and multivibrator MB _R, between each multivibrator MB _L, MB _R, is selected operate one of the NOT circuit and the sensor 1 _L, 1 _R Terminal is provided. And each terminal CAR, OUT _R and OUT _L
Connected to CPU11.

FIG. 4 is a flowchart showing the operation of the present printer configured as described above. When a print command is input, the present flow is entered.

First, in step S1 (hereinafter referred to as S1), the carriage 5 is moved to the left end of the movement range, that is, a position where the paper 9 cannot exist. Next, at S2, together with the carriage 5 starts moving at a constant speed to the right is a printing direction, at S3, CPU 11 signal is outputted from the terminal CAR sensor 1 _R is activated. Then, sensor 1 _R
A constant amount of light is output from the light emitting element LED _R to the reflection plate 2.

At S4, the light receiving element PT _R, and low light of the low level light reflected from a large light amount high level of the reflected light and the dark 2b from the bright portion 2a on the reflecting plate 2 is alternate state repeating alternately Reflected light is input. Sensor 1 _R
Outputs to the sensor control circuit 19 an alternating signal in which a high level and a low level are repeated as shown in FIG. This signal is converted into a pulse signal whose waveform is shaped by the amplifier AMP _R having the threshold voltage V _TH and the multivibrator MB.
Input to _R as a trigger. Multivibrator MB
_R responds to the trigger of this rise by setting the capacitor C _TR
And it will function to invert the elapsed after the output signal of a constant time defined by the resistors R _TR, since here are entering the alternating signal is the output signal continues to reset the sequential multivibrator MB _R is inverted Never. Thus, while continuing to enter a fixed level signal CPU11 from the terminal OUT _R is determined that there is no paper.

Next, at S5, whether the light receiving element PT _R inputs a reflected light of a predetermined state is determined. If the reflected light in the alternating state continues to be input, S5 is determined to be NO, and the process proceeds to S6. S6
Then, it is determined whether or not the carriage 5 has reached the right end of the movement range. If NO, the process returns to S5. If YES is determined in S6, it is determined that the sheet 9 is not mounted on the platen 3, and this flow ends.

If the decision of step S5 is YES, i.e. as shown in FIG. 6 (a), when the sheet 9 is set on the platen 3 covers a part of the reflector 2, the light receiving element PT _R, sensor 1 _{When R} moves to a position facing the paper 9, reflected light having a constant level of light quantity corresponding to the reflectance of the paper 9 is input. Then
Sensor 1 _R is a relatively if high signal shown in Figure No. 6 (b) the reflectance of light of the sheet 9 such as white, if the sheet 9 is relatively low reflectance of light such as black is The signal shown in FIG. 6C is output to the sensor control circuit 19. When the input to multivibrator MB _R is changed to a constant level of the signal from the alternating signal, after the elapse of a predetermined time from the trigger of the last entered rise, signal output to the terminal OUT _R et CPU11 is inverted Is done. Then, the CPU11 by inversion of the signal at S8, determining the position facing the sensor 1 _R in this case the left end of the non-translucent paper 9. In S9, a left margin as a printing start position is set based on the left end position, and printing is started from the left margin in S10. In S11, the light receiving element PT _R is determined whether again enter the reflected light of the alternating condition, this step is repeated until it is determined that YES. If YES is determined in S11, the process proceeds to S12 and the above-described S8
Similarly, the right end of the sheet 9 is detected. Thereafter, a right margin which is a printing end position is set based on the right end position, and printing is ended at the right margin position in S14.
Then, in S15, it is determined whether or not the currently printed line is the last line. If the determination is NO, the process returns to S1, and if the determination is YES, the flow ends.

In the above flow, the detection operation of the left end and the right end of the paper 9 at the time of the printing operation has been described. However, in this printer, the detection operation of the paper 9 is also performed at the initial setting such as when the power is turned on. , S2, S3, S4, S5, S6,
Steps S7, S8, S11 and S12 are executed.

The printer can also detect the leading and trailing edges of the paper 9. That is, when the paper 9 is fed, the carriage 5 is moved to the vicinity of the center of the platen 2, and the carriage 1 is moved so that the sensor 1 _R or 1 _L crosses the light area 2 a and the dark area 2 b on the reflection plate 2 by several pieces. Move back and forth. In this state, when the sheet 9 is sent between the sensors 1 _R and 1 _L and the reflecting plate 2 in accordance with the signal of the sheet feeding operation, the reflected light in the alternating state is changed to the reflected light in the constant level state. By detecting this, the leading end of the paper 9 can be detected. Also, the rear end can be detected by the same operation.

As described above, the printer according to the present embodiment can detect not only white paper but also any color paper. Also,
In this printer, since the left end and the right end of the paper 9 are detected every time printing is performed on each line, blank printing is not performed on the platen 3. This is particularly effective for an ink jet printer in which ink adheres to the platen 3 due to blank printing and changes the surface of the platen 3.

[Modifications] The present invention is not limited to the embodiment described in detail above, and various changes can be made without departing from the spirit of the invention.

For example, the printer according to the present embodiment is configured to detect non-transparent paper, but may be configured to detect translucent paper such as OHP paper. In this case, the sensor control circuit 19, an amplifier AMP _R with threshold voltage V _TH, in addition to the AMP _L, a pair of amplifiers having a threshold voltage V _TH, the multivibrator MB in their amplifiers
Connect a pair of multivibrators with the same configuration as _R and MB _L ,
The output terminals are connected to the CPU 11.

Then, the OHP paper is mounted on the platen 3, and the fourth
The flow shown in the figure is executed. Then, in S5, the light receiving element PT _R of the sensor 1 _R, and the reflected light of the high level from slightly low light 2 of a high level reflected from the bright portion 2a on the reflecting plate 2 through the OHP sheet, Reflected light in a second alternate state in which second low-level reflected light, which is slightly larger than the low-level light reflected from the OHP sheet in front of the dark portion 2b, is alternately input. That sensor 1 _R by the input of the reflected light, outputs a second alternating signal that repeats FIG. 6 (d) to indicate such a second high level and the second low-level to the sensor control circuit 19. The second high level is the threshold voltage
The second low level is higher than V _{TH and} lower than the threshold voltage V _TL , and the sensor control circuit 19 outputs to the CPU 11 the inverted signal related to the threshold V _TH and the constant level signal related to the threshold V _TL . Thereby, the CPU 11 detects the left end of the translucent paper. In S12, the right end of the translucent sheet is similarly detected.

Further, in this embodiment, the printing direction is only the right direction, but may be both directions. In this case, using the sensor 1 _R at the right printing, the use of sensors 1 _L when the left print, can be detected sheet edge before printing, is very suitable.

In the present embodiment, printing is performed on the paper 9 by the print head 4, but a reading head may be mounted on the carriage 5 to read characters and the like on the paper 9.

Further, in the present embodiment, the reflection plate 2 is used as a separate body from the platen 3, but a bright portion and a dark portion are formed by using a plate-like platen made of a metal such as aluminum and utilizing a part of the platen. Can also obtain a similar good effect. In this case, as a specific means for forming the bright and dark portions, the sensors 1 _R , 1
_A bright portion and a dark portion to be formed are printed on the position facing _L by using a plating-resistant resist ink by a silk screen printing method or the like. After that, the surface of the aluminum platen is oxidized to black, and after the treatment, if the previous resist ink is removed with a solvent, the untreated portion remains with metallic luster and regular light and dark portions are formed. .

In this embodiment, the light part 2a and the dark part 2b are regularly set to have the same width, but rather, the light part width (X) and the dark part width (Y) are set so that X <Y <3X to 5Y. but the light-receiving element PT _R, PR
The change in the output level of _L can be increased. Also, the bright portion and the dark portion of the shape is not limited to the strip in parallel vertically, the sensor 1 _R, 1 _L is sufficient if a change in a certain width or more output level is detected as it moves over the reflecting surface It is.
Therefore, a mark may be formed on the surface of the reflecting plate 2 with a paint as a means for forming a bright portion and a dark portion. Similar effects can be achieved. As a processing method in this case, the irregular reflection portion may be formed by chemical etching, but by regularly depressing a part of the metal by pressing with a mold having a shape of a light portion and a dark portion to be formed. The same effect can be realized.

Further, in the present embodiment, the reflection plate 2 is formed by forming a bright portion and a dark portion on an aluminum plate. However, a slit plate having a high reflectance of light having band-shaped holes formed at regular intervals, and a slit plate having the same. It may be constituted by a rubber sponge provided behind the plate and having a low light reflectance.

[Effects of the Invention] As is apparent from the above description, according to the present invention, the carriage is moved along the platen and the reflection plate, and the light reflection type sensor is input in a state where the printing paper is not mounted. If the reflected light other than the alternating state is input, the control unit determines that there is a sheet, so that not only a white sheet but also various types of sheets can be detected.

[Brief description of the drawings]

FIG. 1 is a perspective view of a main part of a printer provided with a paper detection device embodying the present invention, FIG. 2 is a block diagram showing the configuration of the printer, and FIG. FIG. 4 is a flowchart showing the operation of the printer, FIG. 5 and FIG. 6 are diagrams for explaining the operation of the printer, and FIG. FIG. 2 is a perspective view of a printer including a sheet detection device. In the figure, 1 _R and 1 _L are sensors, 2 is a reflector, 2 a is a bright portion, 2 b is a dark portion, 3 is a platen, 4 is a print head, 5 is a carriage,
9 is a sheet, and 10 is a control circuit.

Continuation of the front page (56) References JP-A-56-99689 (JP, A) JP-A-53-31406 (JP, A) JP-A-156047 (JP, U)

Claims (5)

(57) [Claims] 1. A platen on which a print sheet is mounted, a reflector disposed on or near the platen in parallel with the platen, wherein a portion having a high light reflectance and a portion having a low light reflectance are alternately repeated, and a print head. Alternatively, a carriage on which a reading head is mounted and which moves along the platen and the reflecting plate, and which is disposed at a position on the carriage facing the reflecting plate, outputs a predetermined amount of light and reflects the reflected light. When the carriage is moved to a state where the paper is not loaded, the reflected light in an alternate state in which a high level with a large amount of light and a low level with a small amount of light are alternately repeated is input. A light reflection sensor for inputting, and control means for determining that there is a sheet when the light reflection sensor inputs reflected light other than the alternating state by moving the carriage. Paper detection apparatus according to claim and. 2. The control means moves a carriage,
The paper according to claim 1, wherein the light reflection type sensor determines that a non-light-transmitting paper is present when the reflected light in a constant state in which a constant level of light quantity is input. Detection device. 3. The control means moves a carriage,
2. The method according to claim 1, wherein a position of the light-reflective sensor facing the light-reflective sensor when the input of the light-reflective sensor is switched between the alternate state and the constant state is determined as a sheet edge of the non-translucent sheet. 3. The sheet detecting device according to claim 2, wherein: 4. The control means moves a carriage,
The light reflection type sensor may be configured to output one of the high level and a second high level having a smaller amount of light than the high level, and one of the low level and a second low level having a larger amount of light than the low level. The second is alternately repeated
2. The sheet detecting apparatus according to claim 1, wherein when a reflected light in an alternate state is input, it is determined that there is a sheet of translucent sheet. 5. The control means moves a carriage,
The opposing position of the light-reflective sensor when the input of the light-reflective sensor switches between the alternate state and the second alternate state is determined to be the paper end of the translucent paper. The sheet detecting device according to claim 4.