Printing Device that Controls Discharge Roller Based on Thickness of Recording Medium

Abstract

A printing device includes a printing unit, a discharge roller, and a roller controller. The printing unit performs printing on a recording medium at a printing position. The discharge roller is configured to rotatably contact the recording medium on which the printing unit has performed printing, thereby discharging the recording medium. The roller controller controls the discharge roller to rotate such that the discharge roller discharges a recording medium having thickness greater than or equal to a predetermined threshold value at a first speed and that the discharge roller discharges a recording medium having thickness less than the predetermined threshold value at a second speed higher than the first speed.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

Illustrative aspects in accordance with the invention will be described in detail with reference to the following figures wherein:

FIG. 1 is a perspective view of a printing device according to an embodiment of the invention;

FIG. 2 is a schematic side view showing an internal configuration of the printing device;

FIG. 3 is a block diagram showing an electric configuration of the printing device;

FIG. 4 is a flow chart showing a printing process according to the embodiment;

FIG. 5 is an explanatory diagram showing a testing method for measuring paper discharge positions;

FIG. 6A is a table showing averages and standard deviations which were calculated in a first test;

FIG. 6B is a graph in which a thin line connects each point of calculated standard deviations and a thick curve is a polynomial approximation showing relationship between discharge speeds and the standard deviations, where the standard deviations are shown in a vertical axis and the discharge speeds are shown in a horizontal axis;

FIG. 6C is a graph in which a thin line connects each point of calculated averages and a thick curve is a polynomial approximation showing relationship between discharge speeds and the averages, where the averages are shown in a vertical axis and the discharge speeds are shown in a horizontal axis;

FIG. 7A is a table showing averages and standard deviations which were calculated in a second test;

FIG. 7B is a graph in which a thin line connects each point of calculated standard deviations and a thick curve is a polynomial approximation showing relationship between discharge speeds and the standard deviations, where the standard deviations are shown in a vertical axis and the discharge speeds are shown in a horizontal axis;

FIG. 7C is a graph in which a thin line connects each point of calculated averages and a thick curve is a polynomial approximation showing relationship between discharge speeds and the averages, where the averages are shown in a vertical axis and the discharge speeds are shown in a horizontal axis; and

FIG. 8 is an explanatory diagram showing a paper discharge mechanism according to a comparative example.

Claims

1. A printing device comprising: a printing unit that performs printing on a recording medium at a printing position;a discharge roller that is configured to rotatably contact the recording medium on which the printing unit has performed printing, thereby discharging the recording medium; anda roller controller that controls the discharge roller to rotate such that the discharge roller discharges a recording medium having thickness greater than or equal to a predetermined threshold value at a first speed and that the discharge roller discharges a recording medium having thickness less than the predetermined threshold value at a second speed higher than the first speed.

2. The printing device according to claim 1, further comprising: a feeding cassette that is configured to accommodate at least one sheet of the recording medium;a feeding roller that feeds the recording medium from the feeding cassette;a conveying roller that is configured to contact the recording medium fed by the feeding roller and to rotate in a conveying direction for conveying the recording medium to the printing position; anda motor that rotates the discharge roller and the conveying roller in synchronicity with each other, such that the conveying roller rotates in the conveying direction when the discharge roller rotates in a direction for discharging the recording medium,wherein the roller controller controls the motor to rotate the conveying roller and the feeding roller such that the conveying roller rotates in a direction opposite the conveying direction while the feeding roller rotates in a direction for feeding the recording medium.

3. The printing device according to claim 2, wherein the motor is configured to rotate all of the discharge roller, the conveying roller, and the feeding roller.

4. The printing device according to claim 1, wherein the roller controller controls the discharge roller to rotate such that the discharge roller conveys the recording medium up to a predetermined position at a third speed higher than the second speed and that, from the predetermined position, the discharge roller discharges the recording medium at either the first speed or the second speed depending on the thickness of the recording medium.

5. The printing device according to claim 4, further comprising: a thickness determining section that determines whether the thickness of the recording medium is greater than or equal to the predetermined threshold value; anda size comparing section that compares a size of the recording medium with a reference size that is either one of an A4 size and a letter size,wherein the roller controller controls the discharge roller to rotate such that the discharge roller conveys the recording medium up to the predetermined position at the third speed and that, from the predetermined position, the discharge roller discharges the recording medium at a discharge speed higher than or equal to 12 inches per second and lower than or equal to 14 inches per second, when the thickness determining section that determines that the thickness of the recording medium is less than the predetermined threshold value and the size comparing section determines that the size of the recording medium is the reference size.

6. The printing device according to claim 5, wherein the roller controller controls the discharge roller to rotate such that the discharge roller conveys the recording medium up to the predetermined position at the third speed and that, from the predetermined position, the discharge roller discharges the recording medium at a discharge speed higher than or equal to 4 inches per second and lower than or equal to 6 inches per second, when the thickness determining section that determines that the thickness of the recording medium is greater than or equal to the predetermined threshold value or when the size comparing section determines that the size of the recording medium is smaller than the reference size.

7. The printing device according to claim 4, wherein the predetermined position is a position at which a trailing edge of the recording medium is 15 millimeters upstream from the discharge roller in a direction in which the recording medium is discharged.