JPH0322752A - Image forming device - Google Patents

Abstract

PURPOSE:To obtain compatibility by switching whether an input image signal is processed by an image processing means or printed as it is according to whether or not there is a timing control signal from an external device. CONSTITUTION:The external device 10 outputs an image signal 1 generated by an image signal generator 11 and an image clock signal 2 generated by an image clock generator 12 from a driver 13. The image signal 1 which is inputted to a printer 20 is inputted to a terminal port and processed by the image processor 23 when an image signal switching device 22 detects the image clock signal 2. Further, the image signal switching device 22 is switched to terminal (a) unless the image clock signal 2 is detected and the image signal 1 is outputted immediately to a laser driver 25 through a laser-on generating device 24 and printed. Consequently, the compatibility with an external device which does not output the timing control signal is obtained.

Description

[Detailed description of the invention]

[Industrial Application Field 1] The present invention relates to an image forming apparatus such as a laser beam printer. [Prior Art] Conventionally, laser beam printers scan a rotating drum with a laser beam using a rotating polygon mirror to form a latent image, develop this latent image, and then transfer the image onto paper. It is widely known as a recording device for recording images. Generally, signals exchanged between an external device and a printer are usually in the form of a serial signal and are transferred at a constant clock (period). For this reason, an image clock signal generator for instructing the transfer clock of the image signal is provided on either the external device side or the printer side. FIG. 6 is a block diagram showing an example of a configuration in which an image clock signal generator is provided on the external device side. In the figure, an external device M50 outputs information such as an image signal 7l and a control signal 70 to a printer 60. Further, the printer 60 outputs a horizontal synchronization signal 72 (BD signal). In addition to the laser driver 62, the printer 60 is provided with a main controller 6l that controls the entire printer, and is further provided with an interface circuit (not shown) used for inputting and outputting the above-mentioned signals. In this conventional example, there is no memory for image signals on the printer side, and image signals input from an external device are printed as they are on the printer side. On the other hand, unlike this configuration, a laser beam printer is known that is configured to print after performing predetermined image processing on an image signal input from an external device. This printer has a memory that temporarily stores image signals input from an external device, and by inputting an image clock signal from the external device to the printer, an image signal synchronized with the image clock is written to the memory. It becomes possible to perform image processing. [Problems to be Solved by the Invention] However, in the printer 60 as shown in FIG.
Since it does not receive the image clock signal,
The external device 50 used for this is configured not to output an image clock signal. For this reason, a printer that performs image processing by inputting an image clock signal from an external device has a problem in that it is not compatible with an external device a50 that does not output an image clock signal. The present invention can perform predetermined processing on an image signal based on a timing control signal such as an image clock signal inputted from an external device, and can also be compatible with an external device that does not output a timing control signal. The purpose is to provide an image forming device that can. [Means for Solving the Problems] The present invention provides an image processing means that performs predetermined processing on an image signal input from the external device based on a timing control signal input from the external device, and then sends the image signal to a printing section. and a detection means for detecting the presence or absence of the input of the timing control signal, and when the detection means determines that the timing control @@ sign is input, the above I! When the image signal input from the lIIIt position is sent to the image processing means and the detection means determines that no timing control signal is input,
The apparatus is characterized by comprising a switching means for sending an image signal inputted from the external device to the printing section.

[Effect]

In the present invention, for an external device that outputs a timing control signal, the input image signal is processed by the image processing means based on the timing control signal, and then sent to the printing section for printing. On the other hand, for an external device that does not output a timing control signal, the input image signal is not processed by the image processing means, but is directly sent to the printing section for printing. [Embodiment] FIG. 1 is a block diagram showing a specific configuration of a first embodiment of the present invention. The external device IO has an image signal generator 11, an image clock generator 12, and a driver 13, and has an image signal 1 generated by the image signal generator 11 and an image clock generated by the image clock generator 12. Signal 2 is output from driver 13. On the other hand, the printer 20 includes a receiver 2l, an image signal switching device 1122, an image processing device 1123, a laser-on signal forming device 24, and a laser driver 25. The image clock signal 2 is used to write the image signal 1 into the memory of the image processing device W23 in the printer 20 in synchronization with the image signal 1. When the image signal switching device 22 detects the image clock signal 2, the image signal 1 input to the printer 20 is input to the terminal port, and the image signal 1 is input to the image processing device! It is processed at 123. The image signal 1 then passes through the laser-on signal forming device 24 to the laser driver 2.
Output to 5. Further, when the image signal switching device 22 does not detect the image clock signal 2, it switches to the terminal A and outputs the image signal 1.
is immediately output from the laser-on forming device 24 to the laser driver 25. FIG. 2 is a circuit diagram showing the image clock signal detection means in the image signal switching device 1l22. In this circuit, the counter 30 controls the image clock signal 2.
, and when the set value is reached, the output pulse from the counter 30 is latched by a latch circuit 3l such as a flip-flop, and the switching gate circuit 32
outputs the image signal l to the terminal port. In cases other than the above state, the image signal l is output to terminal i. Further, as shown in FIG. 3, the counter 30 sets the counter value so that the image signal l is switched between after receiving the vertical synchronizing signal and before starting printing. In addition, as shown in Fig. 4, the image signal l is
When a video enable signal 3 is input from the external device 1110 to the printer 20 in order to write data into the memory in the printer 23, it is possible to determine whether to switch the image signal based on the presence or absence of the video enable signal 3. In this case, in the image signal switching device 22, if the video enable signal 3 is not received, the image signal l
is connected to terminal A, and when video enable signal 3 is received, image signal L is connected to terminal port. As the switching means in the image signal switching device 22, as shown in FIG. 5, a configuration in which switching is performed by a switching gate circuit 32 using the video enable signal 3 can be adopted. As described above, by giving multiple meanings to the interface signals between an external device and an image forming device, more sophisticated information can be obtained using a simple circuit. For example, by giving a timing control signal such as the image clock signal shown in the first embodiment a meaning as a switching control signal, image processing may be performed by adding the simple circuit shown in FIG. You can decide whether or not to do so.

【Effect of the invention】

According to the present invention, an input image signal is processed by the image processing means based on the presence or absence of a timing control signal from an external device. I made it possible to switch between printing as is,
For an external device that outputs a timing control signal, the input image signal can be processed by the image processing means based on this timing control signal, and for an external device that does not output a timing control signal, the input image signal can be Compatibility can be achieved by printing the signal as is.

[Brief explanation of drawings]

Figure @i is a block diagram showing the specific configuration of the first embodiment of the present invention. FIG. 2 is a circuit diagram showing the image clock signal detection means in the image signal switching device of the same embodiment. FIG. 3 is a time chart illustrating the operation of the image signal switching device of the same embodiment. FIG. 4 is a block diagram showing the specific structure of the second embodiment of the present invention. FIG. 5 is a circuit diagram showing the image clock signal detection means in the image signal switching device of the same embodiment. Part av! J is a block diagram showing a configuration example of a laser beam printer in which an image clock signal generator is provided on the external device side. 10... External device, l1... Image signal generator, 12... Image clock Generator, 0... Printer, 2... Image signal switching device, 3... Image processing device, 5... Laser driver, 0... Counter, l... Latch circuit, 2... Switching gate circuit.

Claims (2)

[Claims] (1) An image processing means that performs predetermined processing on the image signal input from the external device based on the timing control signal input from the external device, and then sends the image signal to the printing section; input of the timing control signal; a detection means for detecting the presence or absence of a timing control signal; when the detection means determines that a timing control signal is input, the image signal input from the external device is sent to the image processing means, and the detection means determines that a timing control signal is not input; An image forming apparatus comprising: a switching means for sending an image signal inputted from the external device to a printing section when the determination is made. (2) In claim (1), the timing control signal is characterized by comprising at least one of an image clock signal for synchronizing the image signal and an image presence/absence signal indicating the presence or absence of an effective area of the image signal. Image forming device.