JPS599624A - Picture recording device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image recording apparatus, and more particularly to an image recording apparatus that digitally records images, such as a laser beam printer or a digital copier.

With the advancement and spread of digital information processing technology, digital image recording devices that process images using digital signals and obtain hard copies from those signals, such as laser beam printers (hereinafter referred to as LBPs) and digital copiers, have attracted particular attention in recent years. ing.

As an example of such an image recording apparatus, FIG. 1 shows the structure of an optical system for performing image scanning in an LBP. In FIG. 1, there is a method in which a laser beam emitted from a laser emitting unit 1 is deflected by a rotating polygon mirror (hereinafter referred to as ``H j'7'') that rotates at high speed, and a document 4 is scanned through a lens 3. Illustrated. Such an optical system is characterized in that it is capable of faster processing than other scanning methods.

In the laser optical scanning system as described above, a drive motor such as a scanner motor, which rotates the polygon 2 at high speed, is the only movable unit and one of the most important components. Therefore, especially in LBPs whose mission is high-speed processing, the drive motor is required to meet various strict conditions such as short start-up time, low power consumption, and long bearing life. For example, if you want to perform higher-speed processing, it is natural that the scanner motor as a drive motor will be required to rotate at a higher speed. The stand-up time until it reaches the operating area becomes proportionally longer, resulting in a longer waiting time until recording can be performed, which reduces the value of the product.

Conventionally, attempts have been made to solve this problem by increasing the power applied to the scanner motor, but with this method, for example, if you are trying to reduce the startup time by half, depending on the rotation speed of the operating area, , approximately twice to four times as much power is required, resulting in an increase in power consumption or a rise in temperature inside the device due to heat generated by the motor. In addition, in large LBPs, etc., a method is adopted in which the motor is kept rotating in the operating range even when it is not in use, but in this case, expensive hydrodynamic bearings that require extremely precise machining and assembly are used. This made it difficult to miniaturize the bearing, and it was impossible to avoid generating noise because it was constantly being rotated.

The present invention has been made in view of the above points, and an object of the present invention is to provide an image recording device having a small and inexpensive scanner motor drive device that consumes less power, generates less heat, and has low operating noise. do.

In order to achieve the above object, in the present invention, the drive motor is rotated at a predetermined rotation speed during image recording, and at a lower rotation speed during rest periods other than that, but at a speed that allows a practically acceptable start-up time. A configuration was adopted in which the machine was rotated.

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings. However, in the following drawings, the same or corresponding parts are denoted by the same reference numerals, and the explanation thereof will be omitted.

FIG. 2 shows a cross-sectional view of the structure of a scanner motor for driving polygons such as LBP. The structure of the motor itself includes a Hall element 10 facing the rotor magnet 8.
is provided, and a stator 9 is further disposed around the rotor magnet 8, constituting a so-called DC Hall motor.

A polygon 2, a high-precision bearing 7.11, and a rotor magnet 8 are fixed to the rotating shaft 12 of the motor, and a preload is applied to the bearing 11 by a spring 13 to maintain rotational accuracy. Furthermore, in order to control rotational unevenness, a tacho generator is provided, which is composed of a pattern printed on the outer periphery of a balance ring 15 fixed to the rotating shaft 12, and a reflective sensor 14 that reads the pattern. The rotation speed of the motor is controlled according to the signal.

However, in the present invention, the scanner motor is not limited to the C Hall motor as described above, but may also be an AC hysteresis motor or a DC brush motor.

Next, FIG. 3 shows a first embodiment of the above-mentioned scanner motor driving device. In Figure 3, scanner motor 2
The output of one tacho generator 22 is input to a comparator 24, and oscillators 23 and 31 for generating two reference frequencies are connected to this comparator 24. The output of the comparator 24 is connected to a drive circuit 25, and a terminal 29 of the drive circuit 25 receives power for driving the scanner motor 21, and a terminal 30 receives a drive command from the CPU of the recording apparatus main body. It is configured like this.

The comparator 24 is configured to compare the output frequency of the tacho generator 22 and the phase of the reference frequency output from the oscillator 23.31, and the drive circuit 25 drives the scanner motor according to the comparison output of the comparator 24. Scanner motor 21 by controlling current of 21
The configuration is such that the rotation speed of the engine is controlled. In addition, the oscillator 23
．． Reference numeral 31 is a device that gives the oscillator 23 a predetermined number of revolutions necessary for image recording, and a number of revolutions (31) when the oscillator 31 is idling when no recording is being performed.
For example, the frequency is set to give 112) at the time of recording, and the comparator 24 switches between these two output frequencies according to the rotation speed control signal synchronized with the drive command input from the terminal 32. do. However, the above-mentioned idling speed may be appropriately set by a person skilled in the art in consideration of bearing durability, power consumption, startup time, etc.

In the above configuration, the oscillator 31 is enabled by the CPU of the main body during the pause period when image recording is not performed, and the oscillator 31 is activated according to the comparison output of the comparator 24.
The drive circuit 25 drives the scanner motor 21 so that the reference frequency of 1 and the output frequency of the tacho generator 22 match.
By controlling the applied current to the scanner motor 2
1 is maintained in an idling state at a rotation speed of about 1/2 of the predetermined rotation speed during image recording. Furthermore, when a drive command is input through the terminal 30, the oscillator 23 is enabled at the same time, and a similar operation increases the rotational speed of the scanner motor 21 to the rotational speed necessary for image recording.

With the configuration shown below, the scanner motor 21 is rotated at a rotation speed of O.
There is no need to start the engine from a stopped state, and if the idling speed is set to about 1/2, the start-up time can be reduced to approximately 1/2 of that required for starting from a stopped state, and power consumption is reduced to 20%. ~30% reduction in operating noise, 15-25% less than when rotating in the constant operating range.
% reduction.

In the above configuration, two oscillators are provided to provide two frequencies, but this may be reduced to one, and a frequency divider or the like may be used to obtain the above frequencies. Further, the rotation speed control signal inputted to the comparator 24 from the terminal 32 can be based on the end of the recording operation of the main body of the image recording apparatus or the end of a standby signal such as an auto shut-off signal.

Next, FIG. 4 shows a second embodiment. The second embodiment described below is a simplified version of the first embodiment.

In general, the rotational speed of a DC motor is uniquely determined by the applied current, so in the second embodiment, the idling rotational speed is determined by the scanner motor 21, the drive circuit 25, the switching circuit 27, and the motor control circuit 28, and the drive command. is input through the terminal 30, the required current for idling is transferred to the scanner motor 21.
The configuration is such that only the number of revolutions required for image recording is provided by the oscillator 23 and the comparator 24, as in the first embodiment (FIG. 3). Here, the rotational speed control command is returned to the switching circuit 27 via the terminal 32, so that two rotational speeds are controlled.

With the following second configuration, the same effects as in the first embodiment can be obtained.

Furthermore, a configuration such as a modification of the second embodiment as shown in FIG. 5 as a third embodiment is also conceivable. In FIG. 5, a timer circuit 37 is connected to the switching circuit 27 of the embodiment shown in FIG. 4, and the scanner motor 21 is driven intermittently in accordance with the output of the timer circuit 37 during idling. This is because the rotational speed during idling does not need to be maintained very accurately, and during idling, the scanner motor 21 alternately repeats two states, a driving state and an inertial rotation state, due to this configuration. During this intermittent drive, the drive time is set so that the rotation speed during idling does not fall below the minimum rotation speed that allows a problem-free startup time even during inert rotation, and the rotation speed required for image recording is set. The power consumption can be further reduced when the motor control circuit 28 is used in an apparatus with large rotational inertia, such as when the polygon 2 to be driven by the scanner motor is large, with the applied power that can be obtained.

Above, three embodiments have been shown using a DC Hall motor, but the above configuration can of course also be applied to an AC motor, and the embodiment shown in FIG. If this is applied to an AC motor 21 having the following configuration, the configuration will be as shown in FIG. In FIG. 6, a known inverter circuit 33 for driving an AC motor is used in place of the drive circuit 25, and this inverter circuit 33 also has an oscillator 34 for providing a reference frequency for determining the rotation speed. .35 is connected.

In this configuration, for example, the rotation speed may be determined by the oscillator 34 during image recording and by the oscillator 35 during idling.

Furthermore, if an AC motor is used in the embodiment shown in FIG. 5, the configuration will be as shown in FIG. 7.

In this configuration, during image recording, the oscillator 34 generates a predetermined number of revolutions necessary for image recording, and during idling, the oscillator 34 generates a frequency corresponding to the same number of revolutions as for image recording, according to the set time of the timer circuit 37, as shown in FIG. The scanner motor 21 may be driven intermittently as in the embodiment.

As is clear from the above explanation, according to the present invention, a predetermined rotation speed is achieved when recording one image, and a lower but practically acceptable rotation speed can be achieved during other periods of rest. Since the drive motor is rotated by the drive motor, the simple and inexpensive structure consumes less power, generates less heat, and makes it possible to provide a small and inexpensive image recording device with low operating noise. can.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram illustrating a document scanning method in a conventional image recording device, FIG. 2 is a sectional view of a DC Hall motor as an example of a scanner motor used in the image recording device of the present invention, and FIGS. FIG. 7 is a block diagram showing the configuration of the scanner motor drive control circuit of the image recording apparatus of the present invention. 2... Polygon 21... Scanner motor 22... Tacho generator 23.31.34.35... Oscillator 24... Comparator 25... Drive circuit 27...
・Switching circuit 28...Motor control circuit 37...Timer circuit Fig. 1 Fig. 2 1 (14, 15)

Claims (2)

[Claims] (1) In an image recording device having a scanner motor drive device for driving a rotating polygon mirror that rotates at a predetermined number of rotations and deflects a laser beam, the motor is rotated at the predetermined number of rotations during image recording, and the image is recorded. An image recording apparatus characterized in that the image recording apparatus rotates at a rotation speed range that is lower than the predetermined rotation speed at least on average over time during rest. (2) The image recording apparatus according to claim 1, wherein the scanner motor is driven intermittently so that the number of revolutions of the scanner motor does not fall below a certain number of revolutions when image recording is stopped.