JPH0784071B2 - Printer controller - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printer controller for controlling a printer which is connected to an image data generating source and which can change the dot density of an image to be formed.

[Prior Art] A laser beam printer for recording an image by forming a latent image by scanning a laser beam on a rotating drum with a rotating polygon mirror or the like, developing the latent image, and then transferring the latent image on a sheet is well known. It is a thing.

FIG. 14 is a diagram showing an example of the configuration of a conventional laser beam printer, and description will be added below with reference to FIG.

In FIG. 14, 1 is a sheet as a recording medium, 2 is a sheet 1
Is a paper cassette that holds the. Reference numeral 3 separates only the uppermost one of the sheets 1 placed on the sheet cassette 2, and the leading end of the separated sheet is conveyed to the sheet feeding rollers 4, 4'position by a driving means (not shown). The paper feed cam rotates intermittently for each paper feed.

Reference numeral 18 is a reflection type photo sensor. The reflection type photo sensor 18 passes through a hole 19 provided at the bottom of the sheet cassette 2 to feed the sheet 1
Paper out detection is performed by detecting the reflected light of.

When the paper 1 is conveyed to the gap by the paper feed cam 3, the paper feed rollers 4 and 4 ′ rotate while lightly pressing the paper 1 to convey the paper 1. When the sheet 1 is conveyed and the leading edge reaches the position of the registration shutter 5, the sheet 1 is stopped by the registration shutter 5, and the paper feed rollers 4 and 4'slip the sheet 1 while applying a conveyance torque. It occurs and continues to rotate. In this case, by driving the registration solenoid 6 to release the registration shutter 5 upward, the paper 1 is sent to the transport rollers 7, 7 '. The resist shutter 5 is driven at a constant timing with an image formed by the laser beam 20 being focused on the photosensitive drum 11. In addition, 21 is a photo sensor,
It is detected whether or not there is a sheet at the location of the resist shutter 5.

Here, 52 is a rotary polygon mirror, the rotary polygon mirror 52 is driven by a polygon mirror motor 53, the beam 20 from the semiconductor laser 51 is guided onto the photosensitive drum 11 via a reflection mirror 54,
A recorded image is formed on the photosensitive drum 11. Also, beam 20
The beam detector 55 arranged at the scanning start position outputs the BD signal which is the image writing timing in the main scanning direction by detecting the beam 20.

After that, the paper 1 is replaced by the feed rollers 4, 4'and the transport rollers.
Conveyance torque is obtained by 7, 7'and sent to the photosensitive drum 11. The image exposed on the photosensitive drum 11 is transferred onto the sheet 1 by the cooperation of the cleaner 12, the charging device 13, the developing device 14, and the transfer charging device 15. The image-transferred sheet 1 is then fixed by the fixing rollers 8 and 8 ', and the sheet discharge roller
The sheet is discharged onto the stacker 10 by 9, 9 '.

In the figure, A is a guide for regulating the conveyance direction of the sheet 1.

Further, reference numeral 16 denotes a paper feed table, which enables not only paper feed from the paper cassette 2 but also manual paper feed from the paper feed tray 16 one by one. Paper feed stand 16
The paper fed into the space between the upper manual paper feed roller 17 and the manual paper feed roller 17 is lightly pressed by the manual paper feed roller 17, and the leading edge of the paper is the same as the paper feed rollers 4 and 4 '.
It is transported until it reaches the point where it slips. The subsequent transport sequence is exactly the same as that for cassette feeding.

The fixing roller 8 contains a fixing heater 24, and the surface temperature of the fixing roller 8 is controlled to a predetermined temperature based on the temperature detected by the thermistor 23 that makes a slip contact with the roller surface to heat the recorded image on the sheet 1. Establish. A photo sensor 22 detects whether or not paper is present at the positions of the fixing rollers 8 and 8 '.

Such printers are generally not used alone,
It is connected to the controller with an interface cable, receives print commands and image signals from the controller,
The print sequence is performed. The structure of this interface cable and the signals transmitted and received by the interface cable will be briefly described below.

FIG. 15 is a diagram showing an interface signal between a conventional general printer and a controller.

Each of the interface signals will be described below.

PPRDY signal: This signal notifies the controller that the printer is powered on and is ready for operation.

CPRDY signal: This signal informs the printer that the controller power is on.

RDY signal: This signal indicates that the print operation can be started or continued at any time if the print receives a PRNT signal described later from the controller.

For example, when the paper cassette 2 is out of paper and the printer operation cannot be executed, the status is FALSE.

PRNT signal: A signal for the controller to instruct the printer to start the printing operation, or to continue the printing operation when the printer is in the printing operation.

When the printer receives this signal, it starts the printing operation.

VSREQ signal ... Both the RDY signal and the PRNT signal are TRUE and indicate that the printer is ready to receive the VSYNC signal described later.

VSYNC signal: This is a vertical (sub-scanning direction) synchronizing signal for the printed image, which is output by the controller to the printer to synchronize the image on the drum with the paper.

BD signal: A horizontal (main scanning direction) synchronizing signal for a printed image, which is a signal indicating that the laser beam is at the starting point of main scanning.

VDO signal: An image signal to be printed by the controller. The printer outputs TRUE of this signal as black of the output image and FALSE as white.

SC signal: A bidirectional serial 8-bit signal that sends and receives COMMAND, which is a command signal from the controller to the printer, which will be described later, and STATUS, which is a status notification signal, which will be described later, that is sent from the printer to the controller. The SCLK signal, which will be described later, is used as the synchronization signal of the. Since it is a bidirectional signal, the SBSY signal and CBSY signal described later are used for input / output control.

COMMAND is a serial signal consisting of 8 bits. For example, turn off only the fixing heater of the printer,
A so-called sheet feeding command for keeping the energy saving state, a sheet feeding cancellation command for canceling the sheet feeding state and turning on the fixing heater, and a cassette sheet feeding command for feeding the sheet from the sheet cassette, It also includes control commands for the printer such as a manual paper feed command for manually feeding paper.

On the other hand, STATUS is a serial signal consisting of 8 bits. For example, when the printer is in a wait state where the temperature of the fixing device has not reached the printable temperature, when a jam occurs, or when the paper cassette is out of paper. It notifies each state of the printer such as the state.

SCLK signal: Synchronous pulse signal for the printer to fetch COMMAND or the controller to fetch STATUS.

SBSY signal: SC is sent before the printer sends STATUS.
This is a signal for occupying the signal line and the SCLK signal line.

CBSY signal: This signal is used to occupy the SC signal line and SCLK signal line before the controller sends a COMMAND.

GNRST signal: A reset signal for the controller to initialize the printer status.

Next, the mutual operation between the printer unit and the controller unit will be described with reference to the system configuration diagram showing the connection configuration of the printer and the controller.

Now, assume that the power switch of the printer is turned on and the power switch of the controller is turned on. In this case, the printer initializes the internal state of the printer and then sends a PPRDY signal to the controller. Meanwhile, the controller sends the CPRDY signal to the printer after initializing the internal state of the controller. After that, the printer energizes the fixing heater 24 housed inside the fixing rollers 8 and 8 ', and when the surface temperature of the fixing rollers 8 and 8'reaches a temperature at which fixing is possible, sends an RDY signal to the controller. .

After receiving the RDY signal, the controller sends a PRNT signal to the printer as needed for printing. When the printer receives the PRNT signal, it rotates the photosensitive drum 11,
Initialize the potential on the surface of the photosensitive drum uniformly, and at the same time, drive the paper feed cam 3 in the cassette paper feed mode.
The leading edge of the sheet is conveyed to the registration shutter 5 position. In the manual paper feed mode, the paper manually fed from the paper feed tray 16 by the manual paper feed roller 17 is conveyed to the position of the registration shutter 15. When the printer is ready to accept the VDO signal, it sends a VSREQ signal to the controller.

After receiving the VSREQ signal, the controller sends a VSYNC signal to the printer. Upon receiving the VSYNC signal, the printer drives the registration solenoid 6 in synchronization with this signal to release the registration shutter 5. As a result, the sheet is conveyed to the photosensitive drum 11. After issuing the VSYNC signal, the controller uses the BD signal transmitted from the printer as a horizontal synchronization signal, and sequentially transmits the image signal VDO to be recorded to the printer in synchronization with this.

The printer blinks the laser beam according to the VDO signal to form a latent image on the photosensitive drum 11, and the developing device 14
Then, the toner is attached to develop the image, and then the image developed by the transfer charger 15 is transferred onto a sheet, fixed by the fixing rollers 8 and 8 ', and discharged.

Next, when switching the paper feed mode of the printer to the cassette paper feed mode or the manual paper feed mode, the controller sends the 8-bit serial code corresponding to each paper feed mode to the printer via the SC signal line in synchronization with the SCLK pulse signal. Send. When the printer receives the cassette paper feed mode code, the manual paper feed roller 17 is not driven during printing, and the paper feed cam 3 is driven to switch from the cassette to the paper feed mode.

On the other hand, when the printer receives the manual paper feed mode code, the paper feed cam 3 is not driven during printing and the manual paper feed roller 17 is driven to switch to a mode in which manual paper feed is possible.

When the power of the printer is first turned "ON", the printer sets the paper feed mode to the "cassette paper feed mode" as the initial mode.

GNRST is for initializing the printer in response to a command from the controller. When the same signal is received from the controller, the printer resets all jobs on the way and resets to the state immediately after power-on. For example, when a plurality of printers are connected to the controller, this signal is used to bring all the connected printers into the same state.

In the configuration of the conventional example described above, the computer, which is generally a printer and a controller, is mutually connected as shown in FIG.
Interface signals are usually transmitted and received via a connecting cable having a length of 1 m to several m. The number of computers connected to the printer is not limited to one type, and there are many types of computers.

At this time, the dot density to be output is fixed in the conventional printer, and according to the image processing speed of the computer to be connected and the required output dot density, for example, 200 dots per inch with a dot density of 200 dpi.
Dedicated printer, similarly each 240dpi, 300dpi, 400dpi, 480dp
It was necessary to prepare multiple printers with a fixed number of output dots for each output dot density, such as i-only printers, and to select a model that meets the requirements from these.

In addition, other printers are equipped with a dot density switching switch that outputs to the operation panel of the printer, and a service person or user can manually switch the desired output dot density according to the requirements of the connected computer. I was getting.

Not only is the printer type diverse when the output dot density of the printer is fixed, It was impossible for a user who purchased a single model among them to change the print dot density and use it.

On the other hand, in a printer in which the dot density is changed by the switching switch, the dot density to be output is fixed by the switching switch in a bird's-eye manner, and it is not easy to change the dot density. I had to make settings.

Moreover, it was impossible for the computer side to know whether or not the set dot density was proper.

[Problems to be Solved by the Invention] In order to solve the above problems, for example, as in Japanese Patent Application No. 59-221165, a laser scanning speed is changed by a command from a host computer to change the resolution. A laser beam printer capable of performing the above has been proposed.

However, in the above-mentioned conventional laser beam printer, when the resolution is not designated by the computer, the print output is performed at the resolution determined by the printer in advance, so the print output is performed at the resolution different from the resolution desired by the computer. The situation may occur, and printing may be redone.

[Means for Solving Problems] The present invention has been made to solve the above problems, and as one means for solving the problems, for example, the following configuration is provided.

That is, in a printer control device that controls a printer that is connected to an image data generation source and that can change the dot density of an image to be formed, an input unit that inputs a command output from the image data generation source, and the input unit. And a second determining means for determining whether or not the dot density designation command is already input by the input means, and a second determining means for determining whether the dot density designation command is already input by the input means. When it is determined by the determination means that the dot density designation command has already been input, the printer is configured so that the image forming operation is executed at the dot density designated by the dot density designation command determined by the first determination means. And the second determination means determines that the dot density designation command has not been input. If, and having a control means for prohibiting the image formation of all dot density by the printer.

[Operation] In the above configuration, since the printer does not perform the printing process until the output dot density is specified by the image information generation source, the dot density output by the printer and the output dot density desired by the image information generation source side It is possible to eliminate the problem that the printer is executed by the printer with the deviation.

Embodiment An embodiment according to the present invention will be described in detail below with reference to the drawings.

[Structure of Embodiment (FIGS. 1 to 6)] FIG. 1 is a block diagram of a laser beam printer according to an embodiment of the present invention, and the mechanical portion of this embodiment is substantially the same as FIG. Therefore, the same components as those in FIG.

In the figure, 100 is a printer, and 200 is a computer for outputting output information to the printer 100 and controlling the dot density to be output by the printer 100, which will be described later.

Further, 56 in the printer 100 is a drum motor for rotating the photosensitive drum 11, 60 is a laser drive circuit which is controlled by the PCPU 66 via the data line 63, and accordingly drives the semiconductor laser 51 via the control line 57, and 61 is A polygon mirror motor control circuit that controls the polygon mirror motor 53 that rotates the rotary polygon mirror 52 through the control line 58, which is controlled by the PCPU 66 via the data line 64, and a drum motor control circuit 62 that controls the drum motor 56. Circuit, and the drum motor control circuit 62 is also connected to the PCPU66 via the data line 65.
Controlled by the drum motor 56 via the control line 59.
Control the rotation of.

Here, the drum motor 56 is also used as a drive source for paper transport via a gear (not shown).

Here, the image signal from the computer 200 is controlled to be directly input to the laser drive circuit 60 via the input / output interface 30 instead of being transmitted to the laser drive circuit 60 from the data line 63 via the PCPU 66. Good.

Further, 66 is a microprocessor (PCPU) that controls the overall control of the printer 100, and PCPU 66 is a ROM memory 66a that stores a control program and a RAM that stores various control data.
It includes a memory 66b and an I / O port (not shown) that controls input / output.

The PCPU 66 controls all drive systems of the printer 200, for example, a drive system for carrying and carrying out recording paper, a system for executing an electrophotographic process, and the like via an I / O port. Here, of these, only the drive system for the recording paper and the connection / control between the sensor and the optical system provided in the drive system are shown, and the others are omitted. However, it goes without saying that the other parts are also controlled by the Kochi method.

On the other hand, the computer 200 that controls the printer 100 includes an input / output interface 32 that performs serial communication and image communication with the printer 100. The computer
67 in 200 is a CPU that executes various information processing.

The printer 100 and the computer 200 mutually input / output interfaces 30, 32, connection cables 38, mutual I / O buses 34, 3
Connected via 6. The input / output signals of the connection cable 38 have the same configuration as that shown in FIG.

Reference numeral 69 is a switching means constituted by a rotary switch or the like, and the PCPU 66 can read the set value of the switching means 69 through the data line 68 when needed.
This switching means is used for switching the dot density to be output in this embodiment, and the output dot density is judged to be 240 dpi, 300 dpi, 480 dpi or the like depending on the setting position of the switching means 69.

Further, 99 is a BD signal processing circuit for converting a photodetection signal from the beam detector 55 into a digital signal and outputting the digital signal.

The details of the polygon mirror motor control circuit are shown in FIG.

In FIG. 2, reference numeral 71 denotes a crystal oscillation circuit, which outputs the 4 MHz clock oscillated by the crystal oscillation circuit 71 to the counter 72. 72 is a counter that counts down the clock from the crystal oscillator circuit 71 to (1/1000). Reference numeral 73 is a preset counter that counts down to "1 / N" according to the data "N" set in the latch circuit 74. The output clock f ₀ from the preset counter 73 becomes the reference signal for the PLL circuit 75. .

That is, there is a relationship of f ₀ = 4 MHz × (1/1000) × (1 / N).

Further, 74 is a latch circuit, and the latch circuit 74 has a PCPU66
Any value ("1" ~
Any value of "256") is set. Latch circuit
8 bit data line rather than 74 is a preset counter
It is output to 73, and the preset counter 73 determines the countdown value (1 / N) according to the set value of the latch circuit 74.

75 is a PLL circuit, and the PLL circuit 75 generates a signal fc obtained from a rotation pulse signal generator 77 that generates one pulse per one rotation of the polygon mirror motor 53 as the polygon mirror motor 53 rotates. The error signal is detected so that it becomes equal to the reference frequency f _0, and the rotation of the polygon mirror motor 53 is controlled via the amplifier 76 based on the error signal. In this case, PLL circuit 75 is PCPU6
In response to the motor ON signal 79 from 6, the rotation is started, and when the number of revolutions of the polygon mirror motor 53 reaches the specified number of revolutions and a constant rotation is made, a ready signal 80 is returned to the PCPU 66.

FIG. 3 shows the relationship between the output dot density, the number of output clocks of the counters 72 and 73, and the number of rotations of the polygon mirror motor 53 in the above configuration.

As shown in FIG. 3, the oscillation frequency of 4 MHz from the oscillation circuit 71 is reacted with the output dot density to divide the frequency, thereby changing the rotation speed of the polygon mirror motor 53 and changing the light beam 20 from the rotary polygon mirror 52. The scanning speed of is changed to obtain an arbitrary output dot density.

The PCPU 66 performs the data latch to the latch circuit 74 which latches the preset value to the preset counter 73 via the data line 78. The PCPU 66 reads the set value set in the switching means 69 through the data line 68 and latches the value corresponding to the set value in the latch circuit 74.

In addition to being controlled by the PCPU 66, it is sent from the computer 200 via the input / output interface 32 and the connection cable 38. In accordance with an output dot density designation command which will be described later, the dot density directly designated by the latch circuit 74, for example, a value of (N = 100) when 240 dpi is designated, can be set in the latch circuit 74.

The oscillating frequency of the crystal oscillator of the oscillating circuit 71 is selected by back-calculating from the rotational speed of the polygon mirror motor 53 to obtain the required output dot density. That is, the least common multiple of each f ₀ value corresponding to the output dot density is selected.

More specifically, when the dot densities shown in FIG. 3 are required, the required number of revolutions of the polygon mirror motor 53 and the output frequency f ₀ of the preset counter are also the values shown in FIG. , The least common multiple of this f ₀ is 13333.333Hz.

In the present embodiment, an integer multiple (300 times) of this least common multiple is set as the oscillation frequency of the oscillation circuit 71, and 4 MHz is selected.

In this way, the scanning speed of the light beam 20 with respect to the surface of the photosensitive drum 11 is according to the specified command from the computer 200
Alternatively, it can be selected according to the set value of the switching means 69.

In the above embodiment, the preset counter 73 is 8
An example using a bit counter has been described.
Needless to say, if the number of bits is increased, such as by using a 16-bit counter, the scanning speed switching step will become even more multi-stepped accordingly, with 8 bits (2 ⁸ = 25
It is possible to change the step (6 ¹⁶ steps), which is sloppy (2 ¹⁶ = 65536 steps).

With this configuration, it is possible to meet all output dot density requirements.

The contents of the designation command sent from the computer 200 may be designation of how many dpi it is, or may be the data itself to be loaded into the preset counter.

Next, details of the drum motor control circuit 62 are shown in FIG.

In FIG. 4, 81 is an oscillation circuit, 82 is a counter, 83 is a preset counter, 84 is a latch circuit, 85 is a PLL circuit, and 86 is an amplifier. The configuration and role of each circuit are the polygon mirror motor shown in FIG. Since it is substantially the same as the control circuit 61, its description is omitted.

Reference numeral 87 is a rotation pulse generator that generates a pulse signal corresponding to the rotation of the drum motor 56. 89 is a drum motor 56
ON signal, and 90 is a ready signal similar to the ready signal 80 in FIG.

Also in the drum motor control circuit 62, the feed speed of the drum motor 56 can be controlled to a predetermined speed in accordance with the output dot density designating command from the computer 200 or by switching the setting value of the means 69.

FIG. 5 is a diagram showing the details of the BD signal processing circuit 99 shown in FIG. 1, and the beam detect signal which is the detection signal detected by the beam detector 55 is waveform-shaped by the waveform shaping circuit 91, It is output as a BD signal and used to synchronize in the main scanning direction. In addition, the BD signal is a BD error detection circuit.
It is also input to 92, and the BD error detection circuit 92 monitors whether or not the BD signal is output at regular timing. If it is not output at the proper timing, PCPU66
BD error signal is output.

Here, when the output dot density changes, the scanning speed of the light beam 20 also changes, and the BD signal output timing also changes. Therefore, the PCPU 66 supplies the BD error detection circuit 92 with data corresponding to the above-mentioned output dot density. The BD error detection circuit 92 receives, for example, the above-mentioned second
Unblanking signal (UNBL) and error detection auxiliary signal (ERDT) as in the preset counter shown in Figs.
Switch the output timing of.

Here, the unblanking signal (UNBL) is a signal for causing the laser 51 to emit light at the timing when the light beam 20 reaches the beam detector 55 in order to reliably obtain the BD signal. The laser 51 is output to force the laser 51 to emit light at the timing of scanning immediately before the part of the tector 55.

The error detection auxiliary signal (ERDT) is a timing signal for determining whether or not the BD signal detection timing falls within a specified timing width range that varies depending on the output dot density.

That is, the unblanking signal (UNBL) is output after a certain period of time (a little shorter than the BD signal generation cycle) from the immediately preceding BD detection signal. Also, error detection auxiliary signal (ERDT)
Is output for ± Δt times with the output cycle of the BD signal expected to arrive next from the BD signal immediately before. This Δt time may be a variable value or a fixed value corresponding to the output dot density.

Unblanking signal (UNBL) for output dot density
And the error detection auxiliary signal (ERDT) output timing
This is shown in Figures (A) to (E).

Here, FIG. 6 (A) shows a dot density of 200 dpi, FIG. 6 (B) shows 240 dpi, FIG. 6 (C) shows 300 dpi, and FIG. 6 (D).
Shows the output timing in the case of 400 dpi and FIG. 6 (E) shows the output timing in the case of 480 dpi.

If the BD signal is detected at the output timing of the error detection auxiliary signal (ERDT), it is determined that the BD signal output cycle is normal, and the BD signal is other than the error detection auxiliary signal (ERDT) output timing. When detected at the time of, or not detected at all, a BD error signal is output to the PCPU 66 as a BD error.

As described above, according to the BD error detection circuit 92, the unblanking signal (UNBL) and the BD are detected according to the dot density to be output.
The signal error detection timing can be selected to an (arbitrary) optimum value by the PCPU 66, and accurate light beam scanning can be performed for any output dot density, and scanning error detection can also be performed. You can

The details of the laser drive circuit 60 are shown in FIG.

In the figure, 94 is a latch circuit, 95a to 95e are NAND gates, and 96a to 9
6e is a driver transistor, and 97a to 97e are resistors having different resistance values.

The laser drive circuit 60 spots or clears the semiconductor laser 51 in response to the image signal sent from the computer 200.

Further, in this embodiment, the data line 63 from the PCPU 66 is
The configuration is such that the drive current value for driving the semiconductor laser 51 can be changed according to the emission light amount designation data (laser emission light amount change command) sent via the. One of the latch circuits 94 is set corresponding to the emitted light amount designation data from 200, and the NAND gate connected to the set output is satisfied, and an output corresponding to the image signal is performed.

And selected driver transistor for driving the laser
96 turns on / off according to the image signal, and supplies the semiconductor laser 51 with a current value corresponding to the resistance value of the resistor 97 connected to the collector side of the transistor 96. The semiconductor laser 51 emits a light amount corresponding to the supply current.

With the above configuration, I / O from the computer 200
When a laser emission light amount change command is received via the bus 34, the output of the latch circuit 94 corresponding to the corresponding transistor 96 is set, and the semiconductor laser 51 emits light with a specified light amount. In this way, since the computer 200 can change the laser light amount arbitrarily, for example, in the graphic print output mode, the laser light emission amount is weakened, and the print output by a thin dot is generated. It is possible to increase the amount of light and select the print output by using thick dots.

[Operation of the Embodiment] Next, the operation control of the present embodiment having the above configuration will be described below with reference to the flowcharts shown in FIGS.

[First Operation (FIGS. 8 and 9)] The basic control means of this embodiment will be described below with reference to the flow charts of FIGS. 8 and 9.

When the power of the laser beam sprinter of this embodiment is turned on, first, step S10 is executed to initialize the contents of the RAM 66b and the initialization processing such as rotating the rotary polygon mirror 52. Subsequently, in step S20, a command communication control routine described later that executes communication processing of printer control command with the computer 200 and the like is executed, and when a command is received, decoding and reply processing of the received command,
Or, execute the processing corresponding to the received command,
The main routine of step S40 is executed. In the main routine, each control of a known printer is executed.

The details of the command communication control routine shown in step S20 are shown in FIG.

First, in step S21, it is checked whether or not a printer control command from the computer 200 has been sent. If it is not received, the process returns without doing anything, and if it is received, step S22
Check whether or not the output dot density notification request command has been received. If the output dot density notification request command is received, the process proceeds to step S23, the computer 200 is informed of the output dot density currently set in the print 100, the process for the received command is terminated, and the process returns. In addition,
The set output dot density is held in RAM 66b.

On the other hand, if the output dot density notification request command is not received at step S22, the process proceeds to step S24 to check whether or not the output dot density setting command for newly setting (resetting) the output dot density is received. Here, if the output dot density setting command is received, the process proceeds to step S25, and the PCPU 66 first causes the latch circuit 74 of the polygon mirror motor control circuit 61 to correspond to the specified output dot density included in the received setting command. In step S26, the value corresponding to the output dot density that is also specified in the latch circuit 84 of the drum motor control circuit 62 is set in step S26, and in step S27, the output dot density is also output to the BD error detection circuit 92. Set the corresponding value. Thereby, the rotary polygon mirror 52,
The photosensitive drum 11 and the BD signal processing circuit 99 will perform operations matching the designated output dot densities respectively, and terminate the processing and return.

If the printer control command received from the computer 200 in step S24 is not the output dot density setting command, the process proceeds to step S28 to check whether or not the laser emission light amount change command is received. Here, in the case of receiving the laser emission light amount change command, in step S29, the output corresponding to the emission light amount is set to the latch circuit 94 of the laser drive circuit 60. As a result, the semiconductor laser 51 subsequently emits a light amount corresponding to the output of the selected latch circuit 94 in synchronization with the image signal.

If the laser emission light amount change command is not received in step S28, the process proceeds to step S30, the process corresponding to the received command is executed, and after the execution of the process is completed, the process returns.

[Second Operation (FIG. 10)] Next, another operation control of the above-described configuration of the present invention will be described with reference to the flow chart of FIG.

The same step numbers are attached to the same controls as in FIG. Therefore, the description of these steps is the same and will not be repeated.

After executing the command communication control routine of step S20, it is checked in step S35 whether the output dot density setting command has already been received from the computer 200 and the output dot density has been set according to the instruction from the computer 200.
If not received, the process returns to the command communication control routine of step S20 to receive the output dot density setting command. If the output dot density setting command has already been received, the process proceeds to the main routine S40 of step S40.

By controlling as described above, the printer 100 does not execute print processing or the like until the output dot density is specified by the computer 200. For this reason the printer
If printing is executed while the dot density output by 100 and the output dot density desired by the computer are deviated, the trouble can be eliminated.

[Third Operation (FIG. 11)] Next, still another operation control of the above-described configuration of the present invention will be described with reference to the flow chart of FIG.

The same steps as those in FIG. 10 are designated by the same step numbers. Therefore, the description of these steps is the same and will not be repeated.

Here, after receiving the output dot density designation command of step S35, in step S36 the PCPC 66 sends the motor-on signal 79 to the polygon mirror motor control circuit to rotate the rotary polygon mirror 52.
A rotary polygon mirror drive permission flag for outputting to the PLL circuit 75 of 61 is set. As a result, the motor-on signal 29 is output, the polygon mirror motor 53 is rotated, and the rotary polygon mirror 52 is rotated.

In this operation, in the initialization processing in step S10, control for outputting the polygon mirror motor ON signal 79 for driving the rotary polygon mirror 52 is not performed.

In this way, the rotary polygon mirror 52 is not always rotated from the time the power of the printer 100 is turned on to the time the power is turned off, but is controlled not to start rotation until the output dot density is set, thereby controlling the rotation of the motor. At that time, when changing from a certain predetermined number of revolutions to another predetermined number of revolutions, especially when the difference in the number of revolutions is large, depending on the control circuit system of the motor,
There is a possibility that the motor may run away and rotate at twice the number of rotations, for example, but according to the present embodiment, such inconvenience can be eliminated.

[Fourth Operation (FIG. 12)] Next, another operation control of the above-described configuration of the present invention will be described with reference to the flowchart of FIG.

The same step numbers are attached to the same controls as in FIG. Therefore, the description of these steps is the same and will not be repeated.

Here, following the initialization processing routine of step S10,
In step S15, the output dot density of the printer 100 is set to a specific dot density (for example, 200 dpi which is the lowest dot level that can be specified in this embodiment), and after this setting is completed, the process proceeds to step S20 and the subsequent steps. This setting process is performed by the same process as steps S25 to S29 shown in FIG.

By controlling in this way, the printer 100 is automatically set to a specific output dot density immediately after being turned on, and operates at this specific dot density until a new output dot density designation command is sent from the computer 200. . When a new output dot density is designated by the computer 200, the output dot density is changed according to the designation.

Therefore, in a system that does not need to change the output dot density so much and often prints with a specific output dot, it is necessary to specify the output dot density one by one by automatically setting this output dot density. Disappear.

[Fifth Operation (FIG. 13)] Next, another operation control of the above-described configuration of the present invention will be described with reference to the flowchart of FIG.

The same step numbers are attached to the same controls as in FIG. Therefore, the description of these steps is the same and will not be repeated.

Here, following the initialization routine of step S10, the output dot density set in the switching means 69 is read in step S11, and the latch circuits 74, 84 and BD error detection are performed according to the set output dot density read in step S12. The value corresponding to circuit 92 is set. This processing is described in the 9th above.
The same process as steps S25 to S27 shown in the figure is performed. Then, the process proceeds to the command communication control routine of step S20.

By controlling in this way, the default value of the output dot density when the printer 100 is powered on is changed by the switching means 69.
Can be used as the set value of the output dot density, and any output dot density can be selected. Only when the output dot density is specified by the computer 200, the specified dot density can be set.

Therefore, it is possible to prevent the unnecessary transmission of the command for specifying the output dot density from the computer 200.

Further, the above description has been made only for the example of scanning the laser beam on the photosensitive drum 11 by the rotary polygon mirror 52 only in the horizontal direction, but the present invention is not limited to this, and the photosensitive portion is not a drum shape but a planar shape. In such a case, the galvanometer may be configured to perform polarization scanning in the vertical direction, and the current supplied to the galvanometer may be controlled by control corresponding to the same scanning speed setting control as described above according to the output dot density.

Further, the scanning of the laser light is not limited to these methods. For example, when the scanning control of the laser light is performed by the hologram scanner, the rotation of the hologram disk is controlled by the same control as described above to correspond to the output dot density. Control.

Obviously, these control methods are included in the present invention.

As described above, according to this embodiment, the dot density to be output can be easily changed.

Further, it is possible to provide an easy-to-use laser beam printer in which this dot density can be arbitrarily selected by a computer or the like connected to the printer.

As described above, according to the present invention, since the printer does not perform the printing process until the output dot density is specified by the image information source, the dot density output by the printer and the image information source It is possible to eliminate the problem that printing is performed by the printer while the output dot density desired on the side deviates.

[Brief description of drawings]

FIG. 1 is a block configuration diagram of an embodiment according to the present invention, FIG. 2 is a detailed configuration diagram of a polygon mirror motor control circuit of this embodiment, and FIG. 3 is a pre-view of the polygon mirror motor control circuit shown in FIG. FIG. 4 is a diagram showing the relationship between the set value to the set counter and the number of revolutions of the polygon mirror motor and the output dot density. FIG. 4 is a detailed configuration diagram of the drum motor control circuit of this embodiment. 6 is a detailed block diagram of the signal processing circuit, FIGS. 6 (A) to 6 (E) are operation timing charts of the BD signal processing circuit shown in FIG. 5, and FIG. 7 is a detailed configuration diagram of the laser drive circuit of this embodiment. 8 to 13 are operation flowcharts of the respective embodiments according to the present invention, FIG. 14 is a mechanism diagram of a conventional laser beam printer, and FIG. 15 is an interface signal between a general laser beam printer and a controller. Figures and 16 show the general printer and compilation. It is a figure which shows the connection state with a user. In the figure, 1 ... Paper, 2 ... Paper feed cassette, 3 ... Paper feed cam, 4 ... Paper feed roller, 5 ... Registration shutter, 6 ...
... Registry solenoid, 7 ... Conveying roller, 8 ... Fixing roller, 9 ... Paper discharging roller, 11 ... Photosensitive drum, 30,32
...... Interface, 51 ・ ・ ・ Semiconductor laser, 52 …… Rotating polygon mirror, 53 …… Polygon mirror motor, 55 …… Beam detector, 56 …… Drum motor, 60 …… Semiconductor laser drive circuit, 61 …… Multiface Mirror motor control circuit, 62 ... Drum motor control circuit, 69 ... Switching means, 71, 81 ... Oscillation circuit, 7
2,82 …… Counter, 73,83 …… Preset counter, 74,
84,94 …… Latch circuit, 75,85 …… PLL circuit, 92 …… BD error detection circuit, 95a to 95e …… NAND gate, 96a to 95e ……
Driver transistor, 99 ... BD signal processing circuit.

Claims (1)

[Claims] 1. A printer control device for controlling a printer which is connected to an image data generation source and is capable of changing a dot density of an image to be formed, and input means for inputting a command output from the image data generation source, First determining means for determining whether the command input by the input means is a dot density designating command, and second determining means for determining whether the command input by the input means has already been input, When it is judged by the second judging means that the dot density specifying command has already been inputted, the image forming operation is executed at the dot density specified by the dot density specifying command judged by the first judging means. The dot density designation command has not been input by the second discriminating means while controlling the printer. When it is determined that the printer control device prohibits image formation of all dot densities by the printer, the printer control device.